MadModder

The Craftmans Shop => New from Old => Topic started by: awemawson on June 10, 2015, 06:47:34 AM

Title: JCB 803 Saga
Post by: awemawson on June 10, 2015, 06:47:34 AM
About five weeks ago I bought a 17 year old JCB 803 3 ton mini-digger which has given me a bit of grief  :bugeye:

Having had a brand new engine fitted 200 hours before I got it, at least that area was sound, but the day after I got it, it developed a massive oil leak dripping from the area of one of the track motors. A bit of investigation showed that in fact the oil was leaking from the 'Orbiter', and running down into the lower chassis and exiting by the track motor. The Orbiter is a rotary hydraulic coupling that takes ten hydraulic lines from the cab and super-structure that rotates 360 degrees, down to the track chassis to feed the tracks and dozer blade.

I decided I was too long in the tooth to be crawling about in and under, so packed it off to a local (ish) commercial garage to fit a new set of seals in the orbiter. Seals duly arrived from JCB - chap fitted them and the blasted thing leaked worse than ever  :bang: I reluctantly authorised buying a brand new one. New one needs a conversion kit say JCB as there's been a design change - all in not much change out of £1000  :(

I went to see progress on Monday to find JCB not only were not able to supply the conversion kit, they had no drawings of what it consisted  :bang: While I was on site they rang up to say that at last they'd found a drawing and it would be a further 3 weeks for them to make it  :scratch:

Time for a bit of research  :coffee: I tracked down a breaker hundreds of miles away who had an 803 only 70 different in serial numbers, and yes it still had the orbiter and it was mine delivered overnight for £230 - a result. I took it to the garage yesterday and await results  :scratch: The £1K one has gone back  :ddb:
Title: Re: JCB 803 Saga
Post by: awemawson on June 10, 2015, 06:57:00 AM
Now while this machine has been away I've been trying to source it's right hand servo control lever - just a two part plastic moulding as a hand grip - it contains also one button for the horn. Previous owner had broken / lost / been vandalised and had fixed a length of plastic pipe on instead.

JCB were happy to provide me with a handle for £180  :bugeye: :bugeye: :bugeye: and that didn't include the micro-switch for the horn, or the special rubber grommet that you press as a button to operate it - yes button thing available for £34 plus VAT !!!

Now initially my new friend the machine breaker was reluctant to part a handle from it's servo control, but a bit of sweet talking liberated what looked to be a bit of a grotty version, taped together with Elastoplast and missing switch and button for £20 - but beggars can't be choosers - no one else had one to break! Surely I can fix it. It even came with it's rubber gaiter (that was slowly falling apart) thrown in.
Title: Re: JCB 803 Saga
Post by: awemawson on June 10, 2015, 07:05:25 AM
When it arrived, in fact it was far better than it had looked. The micro-switch and cable form were in place, just the button missing  :ddb:

A quick bit of cleaning up and the handle is perfectly serviceable - even the gaiter was glueable using some magic stuff intended for fixing tears in welly boots. So what about that special grommet / button jobby?

The original was a domed 9 mm blanking grommet that had an extra rubber protrusion downwards from the centre of the dome to operate the micro-switch. I had some domed 9 mm grommets in stock - and tried gluing rubber cord to the under dome, but they were not flexible enough.

Then I thought, all it really needs is a piece of (say) 8 mm rubber cord retained in the handle hole - so a sort of dumb bell or diablo shape whose inner part is 8 mm and outer is 9 mm

Time to make a mould and get out the hot melt glue gun :ddb:
Title: Re: JCB 803 Saga
Post by: awemawson on June 10, 2015, 07:06:51 AM
Now that button wasn't very well moulded - it sort of stuck a bit and was indistinct BUT IT WORKED  :ddb: :ddb:
Title: Re: JCB 803 Saga
Post by: awemawson on June 10, 2015, 07:09:52 AM
A bit of experimentation showed that with a light squirt of WD40 on the mould it produced far better results  :thumbup:

So flushed with success I ordered some hot melt glue sticks in JCB Yellow just to be a bit of a poser
Title: Re: JCB 803 Saga
Post by: awemawson on June 10, 2015, 07:16:33 AM
Now the left hand servo control has two similar switches, and although the original buttons are 'sort of' still there, they are badly worn away - simple matter to make two more buttons awaiting the return of the machine.

Incidentally here also is a picture of the welly glue - it is remarkably good stuff - I was sceptical at first but a short tear in my working wellies has stood the test of the last year
Title: Re: JCB 803 Saga
Post by: John Rudd on June 10, 2015, 07:50:31 AM
And they say necessity is the mother of invention..... :dremel:

Nice job Andrew... :thumbup:
Title: Re: JCB 803 Saga
Post by: vtsteam on June 10, 2015, 08:17:31 AM
Andrew you've invented the manual 3D printer!  :smart:
Title: Re: JCB 803 Saga
Post by: edward on June 10, 2015, 09:06:08 AM
OT:

I use Stormsure and its brother, Aquasure, to repair my dry suit for diving. if you get the surface prep right and give it a good wipe with Cotol 240 before you apply it, it is near impossible to remove. mixed with fine sand it makes a good non-slip surface.

For quick waterproof fabric repairs, there is a flexible tape product called Tear-aid which is amazing stuff.

Andrew, your repair and problem solving skills are facinating to watch, thanks for documenting them.
Title: Re: JCB 803 Saga
Post by: awemawson on June 10, 2015, 06:12:27 PM
OT:


Andrew, your repair and problem solving skills are facinating to watch, thanks for documenting them.

Well thank you Edward. I come from an era when things were fixable, not throw away, and I've spent a professional career fixing complex systems for others, often against the odds and in quite critical situations. Failure to fix was never an option, and if you start from the premise that it's fixable you get in a mind set that helps hugely !!!
Title: Re: JCB 803 Saga
Post by: edward on June 11, 2015, 03:29:32 AM
Despite being only 42 (!) I have inherited the same mindset from my (now sadly deceased) grandfather. I also inherited my little old Drummond lathe, manual shaper and drill and lots of tools from him.

It really upsets me to see what gets chucked away. Currently repairing an electric toy quadbike for my son that was chucked away by a neighbour. It needed a quids worth of nylon gears and a dab of araldite. Cost over £100 from the toyshop! Not quite the same as your JCB though!
Title: Re: JCB 803 Saga
Post by: awemawson on June 11, 2015, 08:48:50 AM
Well I'm pleased to report that the second hand Orbiter rotary coupling is now fitted and (so far !) not leaking  :ddb:

Chap is now able to concentrate on finding one more hydraulic oil leak that may or may not be coming from a spool block in a very inaccessible position, under the floor but also under the seat assembly. If he can't find it I may have to pop over with my 'camera on a wire' - it's a 10mm diameter usb camera on a long cable intended for sewer inspections - all of about £10 on ebay !

... something like this (not exactly mine) :

http://www.ebay.co.uk/itm/5-M-10-M-USB-Endoscope-Borescope-car-Inspection-Wire-Snake-Scope-Drain-Camera-/121401829087?pt=LH_DefaultDomain_3&var=&hash=item1c441ce6df
Title: Re: JCB 803 Saga
Post by: vtsteam on June 11, 2015, 08:58:45 AM
I've got one of those, and have used it to check inside the PM pipe boiler I built. Quite handy.
Title: Re: JCB 803 Saga
Post by: awemawson on June 12, 2015, 09:46:46 AM
Well I reckon we've found the hydraulic oil leak. It seems to be coming from between 'slices' of the valve block - hard to be absolutely certain as access is so difficult, but that's what looks to be happening. They clamp together with rods though the stack, with common oil feed and return down the centre, with 'o ring' seals between the slices. It is leaking even when no spool is operated so on the 'neutral' circuit.

Plan is to remove the block and try and prove the fault on the bench, then replace the O rings and try and 'unprove' it  :lol:

The machine that I sourced the Orbiter from has already had this spool block removed  :bang:  traced another one but it's been toasted in a fire, then finally found one in Southern Ireland for £700 plus VAT (£3000 new) so really want to avoid having to buy that one if possible  :bugeye:
Title: Re: JCB 803 Saga
Post by: mattinker on June 12, 2015, 10:18:13 AM
Andrew, if it's between the "slices" and in the neutral position what else could it be but "O" rings? shouldn't need anew one unless there other surprises!

Regards, Matthew.
Title: Re: JCB 803 Saga
Post by: awemawson on June 12, 2015, 11:48:53 AM
Yes that's my thought as well. Trouble is Matthew it is bolted to a solid chassis that is hidden under another plate as it's not possible to see the oil emerging, only the trickle when it has emerged  :(

In the pictures below it doesn't look too bad, but actually getting spanners on it is pretty awful. The rear connections can only be acessed by removing the engine sump protector and coming in from the rear.
Title: Re: JCB 803 Saga
Post by: mattinker on June 12, 2015, 12:34:22 PM
Hmm, a nightmare!

All the best! Matthew
Title: Re: JCB 803 Saga
Post by: Pete. on June 12, 2015, 01:26:08 PM
Man I had one of those type of leaks on an old Brokk at work. I had the spool valve block apart twice before I found it was a crack in a small bore steel link pipe at the bottom of the stack.

It's always the hard to get at bits that give trouble.
Title: Re: JCB 803 Saga
Post by: awemawson on June 22, 2015, 01:34:05 PM
Well the diagnosis was wrong  :bang:

In fact (having had the block out and re- O ringed between slices) the leak is actually from the sliding spool itself - ie it's worn or the bore is worn  or more likely both :(

Wasted a week with a red-herring where a breaker claimed to have a spare full block of all the spools (but he didn't - it was a different one!) so have ordered a spare spool "slice" from JCB (please pass the hat round) - should arrive tomorrow  :med:
Title: Re: JCB 803 Saga
Post by: vtsteam on June 22, 2015, 06:53:49 PM
This is kinda sounding like my Ford tractor after I first bought it Andrew, -- lots of unfortunate discoveries!

Nevertheless, I'm now glad I have it.  :dremel:
Title: Re: JCB 803 Saga
Post by: mattinker on June 22, 2015, 06:58:55 PM
Well the diagnosis was wrong  :bang:

In fact (having had the block out and re- O ringed between slices) the leak is actually from the sliding spool itself - ie it's worn or the bore is worn  or more likely both :(

Wasted a week with a red-herring where a breaker claimed to have a spare full block of all the spools (but he didn't - it was a different one!) so have ordered a spare spool "slice" from JCB (please pass the hat round) - should arrive tomorrow  :med:
It had to be the only other place possible! Well, it's hopefully the answer!

All the best, Matthew.
Title: Re: JCB 803 Saga
Post by: awemawson on June 28, 2015, 04:37:49 PM
Well at last the JCB 803 is back home, and certainly from a first inspection 'seems' not to be leaking it's hydraulic life blood  :thumbup:

It turned up this evening on a flat bed behind a friends huge John Deere tractor, that has tyres taller than me (and cost £8K a set). Not done much testing as it's nightfall, but one interesting fact is that the dozer blade, that was a bit under powered and lazy previously, now is energetic and easily capable of lifting the machine. It's the valve spool for the dozer that was leaking, so I expect that it was not only leaking to the outside world, but also internally across the spool flow and return.

Lots more to attend to - need to put the floor back, rebuild the end of the dipper with new bushes and pins, then replace a few grease nipples and give it a good service, but that won't happen tomorrow, as I have 100 kg of dis-assembled piglets to turn into bacon and ham after I collect them from my commercial butcher, who cuts the carcasses to my specification. In this case it was three 5 month old Saddleback boars weighing in at 55, 54, and 49 kGs live weight that as I say should produce 100 kg of meat.
Title: Re: JCB 803 Saga
Post by: mattinker on June 28, 2015, 05:07:10 PM
Good news about the JCB, these things are sent to try us!

Regards, Matthew.
Title: Re: JCB 803 Saga
Post by: Will_D on June 28, 2015, 05:24:01 PM
In this case it was three 5 month old Saddleback boars weighing in at 55, 54, and 49 kGs live weight that as I say should produce 100 kg of meat.
Great news about the JCB It will be great to see her restored and not leaking :beer:

Now about the 100's of kg of meat (note howe I slipped in the 's  :thumbup: )

It is customery on this site to offer something in exchange for something else  :D

So hows about 5 kgs of steel offcuts for a bit of pork   :nrocks:

Only joking Great news all along

Will
Title: Re: JCB 803 Saga
Post by: Pete. on June 28, 2015, 05:47:05 PM
Wehey - all round Andrew's for bacon sarnies and black pudding :D
Title: Re: JCB 803 Saga
Post by: vtsteam on June 28, 2015, 11:33:20 PM
Good to hear,Andrew!  :beer:
Title: Re: JCB 803 Saga
Post by: awemawson on June 29, 2015, 02:54:20 AM
Thanks chaps, and yes you're all welcome to come round for a B&Q  :beer:
Title: Re: JCB 803 Saga
Post by: dsquire on June 29, 2015, 03:15:32 AM
Thanks chaps, and yes you're all welcome to come round for a B&Q  :beer:

Thanks for the invitation Andrew. Looks like another sucess and I enjoyed watching.  :D

Cheers  :beer:

Don
Title: Re: JCB 803 Saga
Post by: awemawson on June 29, 2015, 12:58:08 PM
Thanks Don, and it's on going !!!

So those piglets produced 108 kg of. meat including 33 kgs of sausages and burgers - spent the morning collecting it, and curing the joints I'm hamming and baconing. Belly pork, tenderloins and a couple of legs are being kept back for roasting.

I actually managed to get a bit of play time, putting back the digger floor pan, and going over every grease point making sure that the grease is getting through. Replaced five missing grease nipples, changed some hard of access ones for 45 degree offset ones, but the hardest was on the boom lift cylinder lower eye. The shroud has been clobbered at some times preventing a grease gun fitting. It took a bit of nifty work with an angle grinder and cold chisel to remove enough of the bent shroud to get the old nipple out and replace it
Title: Re: JCB 803 Saga
Post by: awemawson on June 29, 2015, 01:07:41 PM
Amazingly I've got through two full cartridges of grease - the main ring bearing that the entire digger revolves on took 20 pumps of the gun at the four quadrant points (ie 80 pumps) and still there was no tell tale grease emerging ! Service is supposed to be four pumps at each quadrant.

I left the dipper end as I have a rebuild kit to fit tomorrow with all new bushes and pins so it seemed a little pointless to grease the old stuff !
Title: Re: JCB 803 Saga
Post by: Pete. on June 29, 2015, 01:12:44 PM
Yeah there's nothing more fun than changing freshly-greased pins and bushes :D
Title: Re: JCB 803 Saga
Post by: awemawson on June 30, 2015, 02:58:08 PM
So today's job was to remove the old bushes from the dipper, along with the 'banana links' and the 'bucket 'H' frame'

This is the general arrangement:

Title: Re: JCB 803 Saga
Post by: awemawson on June 30, 2015, 02:59:14 PM
First job, drop the bucket - then strip everything off
Title: Re: JCB 803 Saga
Post by: awemawson on June 30, 2015, 03:09:24 PM
So not too bad really just rather mucky. Now that lot were off I could inspect the various bits that wear. The bush location in the end of the dipper arm was worst being somewhat ovaled, as was the rod eye on the bucket ram to a lesser extent.

Long term both these will have to come off and (somehow  :bugeye: ) got onto the Bridgeport table and bored oversize for bushes to be loctited in, but to keep the job going forwards, for the time being I turned up a bush for the rod eye that largely lost the wear, and used magic on the dipper end  :ddb:

Magic in this case being Devcon Titanium loaded epoxy putty. The wear bush is a nylon sleeve, the original having completely vanished !. New one was a reasonable fit except for the outer inch or so where it bellmouthed. I pressed the bush in and packed the Devcon around and into the wear cavity, making sure that the grease passage was still free. I very much doubt it'll last long, but the stuff is rated at 105 Mpa compressive force and specified for building up bearing housings so we'll see  :scratch:
Title: Re: JCB 803 Saga
Post by: awemawson on June 30, 2015, 03:22:01 PM
The Devcon has already set rock hard on my 'control sample' that I left on the bench, but I'll still leave it a full 24 hours before I re-swing the bucket.

Pressing the second nylon wear bush into the end of the bucket H frame compressed it enough that it would't pass a 35 mm bucket pin  :bang: Fortunately I have a 35 mm reamer, albeit on a 4 MT, so I passed that through the bush with a spanner on the tang - it's still very tight but no doubt a bit of use will sort that out  :clap:

Then after I'd cleaned up a bit and fed the pigs, fitted that replacement right hand handle complete with it's custom moulded button, and also put the jazzy button tops on the left hand handle
Title: Re: JCB 803 Saga
Post by: mattinker on June 30, 2015, 03:24:37 PM
Andrew,

I always like seeing your post, since I visited you they are all the more vivid, I can put a face to the words and a picture to add to the photos! I don't know when I'll be getting over to the UK again, but I'll try and get to see you again and maybe taste some barbecued pork!

All the best, Matthew
Title: Re: JCB 803 Saga
Post by: awemawson on June 30, 2015, 03:27:36 PM
Matthew it would be very nice to see you  :thumbup:
Title: Re: JCB 803 Saga
Post by: dsquire on June 30, 2015, 03:29:13 PM
Hi Andrew

Looks like you have this puppy all figured out. I'll keep watching.  :D

Cheers

Don

P. barbequed pork. mmmm
Title: Re: JCB 803 Saga
Post by: vtsteam on June 30, 2015, 07:56:11 PM
Andrew I made a similar backing for a new bush that I bonded into a hole worn oval at the front axle pivot on My John Deere Model M tractor 14 years ago, using JB Weld.

That tractor built my house, hauled logs for the sawmill and heat, plowed snow into 6' high banks, cut brush, carried gravel and sand all over the property, dug a pond, hauled bridge timbers, and buit a 600 foot long driveway..And it's hardly ever spent any time on level ground doing all that.

The repair is still completely intact and indistinguishable from the cast iron casting the pivot pin bushing is bonded to.
Title: Re: JCB 803 Saga
Post by: awemawson on July 01, 2015, 04:06:07 AM
Steve, that's very encouraging. My concern is how far I managed to force the putty down the side of the bush - its quite stiff and there undoubtedly will be voids. It's a nylon so wont be able the bridge cavities !

Put the wide ditching bucket back this morning before  breakfast, and it's all remarkably tight with virtually no wobble. A bit unsettling as I've only used diggers with wobbly buckets before where positioning was a bit hit and miss.  bit of use and the play will come back I'm sure.

Anyway I now can at last shift the pile of pig poo that been getting out of hand.

Next major job to do on this machine is replace the tracks and idler sprockets. One side is ok (ish) but the other is rather scrunchy with it's chain and sprocket well worn out. Bits are on order and should arrive later in the week
Title: Re: JCB 803 Saga
Post by: awemawson on July 01, 2015, 11:15:58 AM
Well the Devcon has at least lasted for one day's light digging  :thumbup:

Pig poop all tidied up, transported to the wife's vegetable patch compost heap, and the (rather large) entire heap turned over in a 'sides to middle' fashion.

The bad news it it's developed another oil leak  :bugeye: - I noticed oil dripping onto the left hand track. After a lot of fumbling about and wrapping dry towel around fittings one by one I've located it on the Main Relief valve block where the input from one of the pump sections enters. (This machine has three hydraulic pumps all on the same shaft on the engine). It's either the 'O ring' in the face seal on the pipe or the bonded washer seal where the pipe adaptor screws into the valve body.

Fortunately there is a removable section of floor to the left of the drivers seat giving access from above, and it's fairly open below if the cab is slewed to 45 degrees so that it's between the tracks. However try as I might I cannot get the fitting unscrewed  :bang: It needs special pipe fitting spanners.

Special man with special spanners coming tomorrow (same chap who did the hose on that Hedge Flail last year.)
Title: Re: JCB 803 Saga
Post by: mattinker on July 01, 2015, 11:21:01 AM
Your getting to know this digger too well too soon!

Regards, Matthew
Title: Re: JCB 803 Saga
Post by: awemawson on July 01, 2015, 01:05:11 PM
Your getting to know this digger too well too soon!

Regards, Matthew

Ain't it always the way  :lol:

No doubt a few more gremlins will come out of the woodwork pipework before it settles down  :bugeye:
Title: Re: JCB 803 Saga
Post by: Pete. on July 01, 2015, 04:18:32 PM
I have a handful of old britool/king dick ring spanners heated and bent and with the ring cut for doing this work on our Brokk machines. I DID have an old bronze one with very heavy walls around the ring which worked for one particular purpose where previous steel spanners had spread but one of the guys at work used it and left it in the rubble :(
Title: Re: JCB 803 Saga
Post by: awemawson on July 03, 2015, 11:40:19 AM
Well this is going from bad to worse  :bugeye:

Mr Spanner had van problems (Ford ECU packed up) so only got here today at lunchtime - got the fitting out only to find that the actual leak is the main aluminium housing having a crack adjacent to the fitting  :bang: :bang: :bang:

Needless to say they are like hens teeth, and every machine being broken currently seems to have been robbed already. JCB want about a grand for just the block without any of the gubbins.

Theoretically it should be possible to reverse engineer the existing block and make a copy, but in practise there are so many interconnecting threaded bores, most with a seat cut at the inner end for a relief valve or pressure setting valve that the chances of success are slim. It runs at 3000 psi so needs to be sound.

Talking to specialist breakers this seems to be a known problem, especially in hot weather. When did it happen - hottest July day on record  :(

At the moment my hope is with a breaker in Wales who thinks he may have one of unknown goodness, but still £250  :bang:

It's tempting to strip it down and attempt a repair using one of the low temperature aluminium solders - probably mill a channel with a ball ended cutter and fill the trench. (I think TIG welding is likely to distort things too much).

If the breaker turns up trumps, I'll fit his, and if it works use it, and if not attempt a repair on one of them.

In all not a good day  - the replacement tracks, idler sprockets and drive sprockets arrived yesterday so I'm in too deep to stop now - it's a bit like the addicted gambler who has to double his stake every time he looses to keep up with his stake :scratch:
Title: Re: JCB 803 Saga
Post by: vtsteam on July 03, 2015, 11:59:18 AM
Andrew, you can make one, I'll wager -- despite the number of interconnected channels. Hell, you've brought 70's CNC machines to life!! It's a block with holes in it. You can do it!
Title: Re: JCB 803 Saga
Post by: awemawson on July 03, 2015, 12:40:39 PM
Steve, thanks for your confidence but it would be a last resort, as it would be quite a long term project, and meanwhile the digger sits unmovable, and I need to use it !

The day isn't getting any better - the chap in Wales has just rung back to say he has not got one  :(

There is a slim hope that a fellow in Southern Ireland may, but he's the chap who let me down before over the control valve
Title: Re: JCB 803 Saga
Post by: mattinker on July 03, 2015, 12:45:44 PM
Andrew,

Very bad news! Were is it broken? Is there no way you could stitch it like metal stitching in cast iron? A slot at right angles to the split, a tongue of Al with stainless screws coming in from the side to lock it in place, may be a bit of a mad idea, possibly in conjunction with low temp solder.

Can't you pre heat the whole block and TIG it?

All the best, Matthew
Title: Re: JCB 803 Saga
Post by: awemawson on July 03, 2015, 06:06:52 PM
Matthew I'd be very wary of tigging or any other high temperature method unless I had a second block to fall back on. There are (seemingly) reamed bores in there for the various valves to seal onto that can easily be distorted, and I suspect seats for valves at the base of some bores.

Until the whole caboot  is stripped I cannot be sure exactly how things connect up in side. There is a 'main pressure release valve', a (logically) T shaped one way valve pair, and a bit I don't fully understand that changes the pressure setting dependant on how much oil is demanded from each of the three pump sections - I have the hydraulic diagram but translating it into physical reality isn't simple.

I want to try and set up my Gopro camera pointing at  it to see exactly where the oil emerges as once it starts everything gets covered and the forensic trail gets blurred  :bang:

It's been suggested that I could replicate it using standard hydraulic components 'off the shelf' but I have a feeling it's made as it is as it's operation is more subtle that that approach can achieve.
Title: Re: JCB 803 Saga
Post by: mattinker on July 03, 2015, 06:23:32 PM
Andrew,
I thought you'd got further into stripping than you have, so you don't actually know where it's leaking? OK, you don't need any more suggestions for the moment!

Good luck with pinpointing the leak, regards, Matthew
Title: Re: JCB 803 Saga
Post by: awemawson on July 04, 2015, 02:05:06 AM
Matthew, as far as I can tell the crack has propagated from the root of the female thread that that fitting I highlighted with a red arrow on a photo up thread.

My current hair brained thought is that IF the crack is within the length of the male threaded fitting I can just assemble it with loctite thread seal.

Currently the hydraulic seal is an o ring in a recess under the hex of the fitting, so the 3000 psi pressure is acting between the male and female threads, if that space is full of thread seal I might affect a cure.

Second hair brained thought if that fails is to make up a clamp that bridges the crack, and bed it down with that magic Titanium Putty I used building up the dipper bush
Title: Re: JCB 803 Saga
Post by: mattinker on July 04, 2015, 02:25:58 AM
Andrew, another thought, if it's the female that has split, bore oversize re-tap and loctite in a stainless ( or even mild steel) sleeve, threaded inside and out. The "O" ring would then be between the sleeve and the coupling and the pressure taken by the sleeve. A lot would depend on how much space there is around the coupling!

All the best! Matthew
Title: Re: JCB 803 Saga
Post by: awemawson on July 04, 2015, 03:24:01 AM
Yes Matthew all those thoughts have been going through my head over night  :bang:

There's actually not much space - the female thread is very close to the top of the block.

However, this morning I have managed to get a picture definitely locating the crack - I started the engine and very gently lifted the boom slightly until oil seeped rather than torrented out, and took this picture.

When the rain stops I'll crawl back under, pull out the fitting and measure how deeply it penetrates. I imagine that the female is somewhat deeper than the male on the fitting, so I can possibly make a longer adapter if the threads don't reach in deeper than the crack.
Title: Re: JCB 803 Saga
Post by: mattinker on July 04, 2015, 09:32:18 AM
Andrew, pin pointed!
I'm on tenter hooks! Hows it going?

All the best, Matthew
Title: Re: JCB 803 Saga
Post by: awemawson on July 04, 2015, 09:57:26 AM
Well I unscrewed the original fitting, and by measurement there seems to be only 2 threads 'beyond' the crack. So I came up with a cunning plan. Indeed the female looks to be threaded deeper in than the crack, so by making an adapter with a longer male part, just maybe I can seal it all up with Loctite  Hydraulic Thread Seal.

The hole in the block is threaded 7/8 UNF - 14 tpi and it is made from 28 mm hex bar. I decided to make a male / female adapter rather than try and copy the part that the hose goes on.

So first job - find some 28 mm hex - well I ended up making some from 32 mm stainless bar
Title: Re: JCB 803 Saga
Post by: awemawson on July 04, 2015, 09:59:57 AM
Then cut the male and female ends to form the adapter.

I decided to use those 'bonded washers' to avoid threading too close to the shoulder
Title: Re: JCB 803 Saga
Post by: awemawson on July 04, 2015, 10:01:53 AM
Then with loads of Loctite Hydraulic seal it all went back together.

I'll leave it overnight to set fully as I reckon it's only a 25% chance it'll work anyway and no point in putting 3000 psi on it unless the gunge is fully cured
Title: Re: JCB 803 Saga
Post by: mattinker on July 04, 2015, 10:08:48 AM
With baited breath!
Title: Re: JCB 803 Saga
Post by: awemawson on July 04, 2015, 12:14:18 PM
Yes - me too Matthew :med: it needs 18-28 hours for full strength (Loctite 542)

Mean while I've bee trying get to grips with exactly what is inside this ridiculously expensive block of aluminium. In the attached picture the area marked '1' inside a dotted line represents the block:

1F are dual non-return valves

1B is the Digging and Tracking Main Relief Valve

1D is the Pressure Reducing Valve


So presumably high pressure oil from Pump 3 and Pump 2 pass straight though the block onward to various spool valves, but they both can vent back to the tank via the '1F' non return valves, and the '1B' Digging and Tracking Main Relief Valve, onward through the oil cooler '24' and  the Return Filer 17 (which has a bypass).

Now to the bit I don't understand: there is a dotted line implying a control dependency, between 1B and 1D, and the input to 1D comes from Pump 1 via '23A' which is a 'Pressure Maintenance Valve' and this is associated with a 'Solenoid Lock Valve 21' that I know is operated by a micro-switch in the left hand hand rest preventing the servo circuits working unless the arm is folded down.

So everything in the block '1' could be replicated with off the shelf bits if I understood the linkage between 1B and 1D. Unscrewing the 1B Digging and Tracking Main Relief Valve there is visible a peg protruding from the device on the other side of the block that I suspect bears on the plunger of 1B opening it up. So I think that that is the physical linkage - there is a bit of verbage in the manual thus:

"The main relief valve for P1 is located on the inlet side of the four section control valve block and is set to open at 172 bar (2500 psi). The main relief valve for P2 and P3 is located in the Main Relief Valve Block (my problem child!) and has dual setting of 207 bar (3000 psi) and 175 bar (2550 psi) depending on the hydraulic load on the engine. The valves are designed to protect the pumps against over pressurisation when a selected service is stalled or the ram reaches the end of it's travel"

Title: Re: JCB 803 Saga
Post by: mattinker on July 04, 2015, 01:34:40 PM
I agree, in the "verbage" I  read that  these are mechanical interlocks to prevent loss of pressure or damage through back pressure when two valves dump at the same time. The three circuits are running at different pressures but they dump through a common filter circuit. I imagine that there is some other security device so that if one is dumping another can dump elsewhere. How many of these circuits can function at the same time? What about dumping through separate circuits or adding non return valves to avoid the need for an interlock?

Thoughts! Regards, Matthew
Title: Re: JCB 803 Saga
Post by: awemawson on July 05, 2015, 03:11:36 AM
So what was the result?

Well, rather like the Parson's Egg - good in parts. The leak is very much reduced, the photo below was taken with the main boom ram fully extended so the the pressure was maximum and the relief valve was working. So the theory worked but the practise didn't  :bang:

Frankly if it was like this you'd not notice the leak, but that crack is quite long and can only propagate further and the leak will undoubtedly go torrential just at a critical moment. So I think I'm going to have to stump up for a new block  :bugeye:

I've not yet checked the JCB actually have one in stock, just got a price. Maybe if they are out of stock I'll give it another go but I don't want an impending disaster looming!
Title: Re: JCB 803 Saga
Post by: lordedmond on July 05, 2015, 03:33:24 AM
Andrew

Now this may be a dumb idea but could you not clamp a patch/ plate on the outside with some suitable gunk on it at the least it would stem the flow in case of a failure

With your cnc machines you may be able to cut a o ring grove into the plate for added seal

Just thinking out loud

Stuart
Title: Re: JCB 803 Saga
Post by: David Jupp on July 05, 2015, 03:39:49 AM
Since crack is only a couple of threads down and female thread deeper than male - is there scope to counterbore beyond the crack?  Move the whole fitting inboard a small distance?

Trouble with Aluminium is that there is no 'knee' in the fatigue curve - on cyclic duty it will fail eventually, no matter how low the stresses.  If re-making the whole block, consider steel. 

If you have an industrial hydraulics design company nearby, they probably make custom manifold block routinely - could be another option if you have to replace.
Title: Re: JCB 803 Saga
Post by: awemawson on July 05, 2015, 03:45:17 AM
Stuart,

I had considered (see post #50 above) making a clamp plate that straddled the block with bolts down the side of the block into an under plate, and cutting a slight rebate where the leak is. Then bedding it all down using the magic Devcon Titanium Putty that I used to set the main dipper bush, which is pretty amazing stuff.

All these things are bodges though and I'm not too keen on bodges.

BTW it almost looks as though the block is made of layers bonded together, but I can't imagine it really it  :scratch:
Title: Re: JCB 803 Saga
Post by: awemawson on July 05, 2015, 03:55:19 AM
David,

The extended adapter I made goes in as far as is possible without fouling a counter bore coming in from the side, so it's not really feasible to sink in further.

I suppose it's a design error, as this appears not to be an uncommon failure mode - the block should have had more meat in it above this particular threaded hole.

I suspect that a custom manifold would be a close match in price to the proper one by the time they'd done the design and machining. But thanks for the suggestion.
Title: Re: JCB 803 Saga
Post by: mexican jon on July 05, 2015, 03:59:41 AM
All these things are bodges though and I'm not too keen on bodges.

I don't see them as bodges  :scratch: A bodge is something that you do with no intention of putting it right when time or parts allow  :scratch: What you you would be doing is a temporary repair  :thumbup:

That's the way I was taught during my early years of keeping machinery running  :loco:
Title: Re: JCB 803 Saga
Post by: David Jupp on July 05, 2015, 04:13:38 AM
Pity about the side bore! - maybe a groove and cross drill in an extended fitting?

Manifold block - though not cheap, getting a block made (in steel?) by somebody that routinely makes manifolds might not be too horrendous.  Where possible they will adapt standard general purpose (off the shelf) manifold blocks to keep the cost down, you might be lucky with any critical dimensions of the block....

I'm sure you will find a way.



Title: Re: JCB 803 Saga
Post by: awemawson on July 05, 2015, 04:30:36 AM
If I manage to escape from family commitments I'm going to make that straddling 'bandage' today. Top piece is a simple plate with holes for the bolts. Lower one needs rebates to accommodate the three sticking out blanking plugs, the four tapped holes for the mounting bolts.
Title: Re: JCB 803 Saga
Post by: mattinker on July 05, 2015, 08:48:12 AM
I hope I'm wrong, but I can't see your straddling block working. Although you've stemmed the flow, the leak will eventually get up to working pressure. If your strap is very strong and you machine a groove as Stuart suggests in both the strap and the block, you might get sealing from the outward pressure pushing the "o" ring into the joint.

Now that you've shown exactly where the leak is, you've got below it with the extended fitting, how about sleeving as well? I doubt that you have room to put an "O" ring at the bottom of the hole were it would do most good!

More photos of the block once it's out please!

Frustrated for you, regards Matthew

Title: Re: JCB 803 Saga
Post by: awemawson on July 05, 2015, 11:43:38 AM
Matthew,

I've decided to bite the bullet and buy a new block, as I agree the fault can only get worse. However, I've made up the straddling clamp as a temporary measure, bedded it with Devcon Titanium Putty, and lightly tightened the screws. When it's hard in the morning I will tighten them down properly.

Have some pictures - you'll notice I had to move one of the clamping bolts as it fouled a fitting. The recesses are to clear various plugs in the base of the block
Title: Re: JCB 803 Saga
Post by: mattinker on July 05, 2015, 02:14:44 PM
So the worst has come to the worst! having made the decision to buy a new one, why not pull it pre-heat the block and TIG it? Tig the split and weld a reinforcing plate over the top, you might just resolve the design fault!

As things are, you at least have time to find another one!

Regards, Matthew..
Title: Re: JCB 803 Saga
Post by: awemawson on July 05, 2015, 02:18:29 PM
It's likely to take a while for the new block to arrive - I'll order it Monday first thing - (well second thing actually as I need to order some Electronic sheep tags!)

I've patched it as I have a pile of road planings that I need to shift asap.
Title: Re: JCB 803 Saga
Post by: Pete. on July 05, 2015, 03:09:00 PM
Buying a new block is a good way of ensuring the temporary repair out-lives the owner :)
Title: Re: JCB 803 Saga
Post by: mattinker on July 05, 2015, 04:06:10 PM
It's easy to make suggestions, it's another to deal with the problem and the associated imponderables like moving pig poop^or whatever!

all the best, Matthew.
Title: Re: JCB 803 Saga
Post by: awemawson on July 06, 2015, 09:31:12 AM
Well the temporary repair has at least allowed me to shift 5 ton of road planings and squash them down. It did leak a bit but nothing like it had been, and it didn't gush anything like the bucket hose I caught in the tree  :bang: Easy hose change and I might even have the bits to crimp one.

I ordered the replacement block which should be here next week - only £1126.27 with the various seals and carriage and VAT  :bugeye:
Title: Re: JCB 803 Saga
Post by: mattinker on July 06, 2015, 09:38:14 AM
Ouch!
Title: Re: JCB 803 Saga
Post by: lordedmond on July 06, 2015, 10:32:58 AM
Andrew

Now you have a conundrum do you carry on useing the one you have on the machine and keep the gold plated one as a spare , but you may not need it  :D


Stuart
Title: Re: JCB 803 Saga
Post by: Pete W. on July 07, 2015, 04:27:33 AM
Hi there, Andrew,

I've been following your battle with the JCB.  All I can say is 'Hang in there!'.

 :offtopic: but how many days hence is your daughter's wedding?  Shall you post a photo or two? 
Title: Re: JCB 803 Saga
Post by: awemawson on July 07, 2015, 06:11:48 AM
Hi Pete thanks for the interest.

Yes wedding approaching like an out of control juggernaut - it's on Saturday 25th :bugeye: :bugeye: She (and I as father of the bride), will be delivered to Battle Abbey in an old Series 1 Land Rover (her choice  :scratch: ) so no doubt my new clothes will be crumpled and oily, as will her dress  :med:

Then back to the farm for the reception - all the local hotels are now fully booked and also there's a fair few hardy souls bringing tents and caravans.

As I type this we have light drizzle, which with 260 guests in a field will be horrendous - there will be marquees, but it's supposed to be al fresco with hay bales for out door seating areas and child play areas, and a hog (several actually) roast.

I've been encouraging the happy couple to elope to Gretna Green but with no success so far  :clap:
Title: Re: JCB 803 Saga
Post by: awemawson on July 07, 2015, 06:29:16 AM
Andrew

Now you have a conundrum do you carry on useing the one you have on the machine and keep the gold plated one as a spare , but you may not need it  :D


Stuart

I'll put the new one on Stuart. The bodge is still dripping oil onto the left hand track, albeit at a greatly reduced rate, but it gave me confidence that it wouldn't develop into a major issue leaving the machine unmovable in a difficult place when I shifted those road planings. It's now back on the workshop forecourt on solid concrete where repairs are so much easier  :thumbup:

I've a new pair of tracks, idler sprockets and drive sprockets to fit, but I don't want oil on them un-necessarily hence definitely fitting the new block.
Title: Re: JCB 803 Saga
Post by: awemawson on July 10, 2015, 07:16:45 AM
 :clap: :clap: Well look what Father Christmas brought  :clap: :clap:
Title: Re: JCB 803 Saga
Post by: awemawson on July 10, 2015, 07:36:43 AM
Now contrary to the enquiry I made when I ordered this, it DOES come complete with the two relief valves, and the blanking plugs. This is a GOOD THING but gives me a slight quandary. I would image that, as they are adjustable, they will be set as part of a machines commissioning, and I have no means of measuring that sort of pressure, so do I just put in the old valves?  :scratch:

On balance I think not - I'll see how it works first rather than disturb them.   :med:

Itching to fit it, but too much else happening - I may get a chance tomorrow.

Of course the bad news is it came with an invoice  :bugeye:
Title: Re: JCB 803 Saga
Post by: appletree on July 10, 2015, 09:49:56 AM
It says customer not present, is that a reference to a state of mind? Big money in some ways but if it makes life easier and the machine is now reliable allís good, will the overall price for the machine have been good value when itís done?   
Title: Re: JCB 803 Saga
Post by: awemawson on July 10, 2015, 10:56:38 AM
Definitely a state of mind  :clap:

If I add up what it's cost to fix and add that to the cost of purchase I could have bought a more modern machine - whether it would have been any better is debatable.

It's looking like Monday to fit it - got a pile of bacon to turn into rashers tomorrow, and Sunday is taken up by getting the sheep in, ear tagging them, and packing 38 off to pastures new, and pulling out three cull ewes ready for the abattoir on Tuesday morning.
Title: Re: JCB 803 Saga
Post by: mattinker on July 10, 2015, 11:22:00 AM
Andrew,

I'd go with the new valves, they should be pre set!

Looking forward to it working properly!

Regards, Matthew.
Title: Re: JCB 803 Saga
Post by: Pete. on July 10, 2015, 12:52:35 PM
I too would go with the new valves unless the literature says otherwise. It's supplied ready to fit so one would presume that it's ready to work.
Title: Re: JCB 803 Saga
Post by: lordedmond on July 10, 2015, 02:03:27 PM
I go with fit it also.

That is a field replacement part , fit it and get the machine working again , don't earn much when they are not working.

Also there are no test rigs in the field

Just my 2 cents


Stuart
Title: Re: JCB 803 Saga
Post by: Will_D on July 10, 2015, 06:06:35 PM
Having just spent that amount of wonga with Mr. Bamford's successors I would HOPE that the customer service line would give some FREE advice re. pressure settings and factory default settings.
Title: Re: JCB 803 Saga
Post by: awemawson on July 11, 2015, 02:55:01 PM
Well the bacon got sliced and vacuum packed - all 18 kGs, and the hams sorted and stacked ready for freezing, which left me a little  bit of play time  :thumbup: Not enough to fit that valve block but something to help along the way.

The left hand control pod is supposed to hinge up out of the way so making getting into the cab easier. Under it is a microswitch that inhibits all the servo controls when in the up state. There is supposed to be a gas strut that toggles it between the up and down states, that fixes between two welded on 8 mm pegs, one on the pod frame and one on the seat frame. The strut and the peg on the pod were missing, as was the arm that prevents you climbing in unless the pod is up.

I'd managed to source the arm, complete with it's red handle from a breaker, but the gas strut had to be bought new at a ridiculous price.

So this afternoon I fitted them. This is officially 'A GOOD THING', as to access the relief valve block through the floor I've been jamming a bit of timber in to keep the pod 'up', so this will help when it comes to changing the block.

All fairly straight forward except that access to the 6mm bolts holding the blown plastic moulding on the pod arm was a right pain  :bugeye: The peg on the pod frame had broken off, and without total dismantling welding wasn't an option, so it got replaced by an 8 mm HT hex bolt

Now at least it makes it much safer leaving the cab if the engine is running, as before it was quie easy to bump the paddle control and swing the cab as you were climbing out onto the tracks  :bugeye:
Title: Re: JCB 803 Saga
Post by: awemawson on July 12, 2015, 07:36:37 AM
Well the chap buying my sheep turned up HOURS earlier than had been arranged, so it was all done and dusted by 09:30. Excellent as it meant I could crack on (pun intended) changing that split block.

First job, identify the six pipes with coloured Ty-Wraps so that I stand a chance of getting them back in the right place  :scratch:

Normally I'd put Ty-Wraps of the same colour on the pipe, and the fitting it goes on, but in this case the fittings were being removed, so that would be pointless. Instead I took lots of photos
Title: Re: JCB 803 Saga
Post by: awemawson on July 12, 2015, 07:43:15 AM
Next, scrupulous clean up around the ports, undo a few fittings, try and dodge the oil, how hard can it be  :scratch: I didn't entirely avoid the oil  :bang: At least it's clean hydraulic oil  :thumbup:

Well you may remember before I found the crack, I was unable to undo the first pipe joint so I wasn't looking forward to this part. They were put in mighty tight - several needed my biggest rubber 'dead blow' hammer on the end of a spanner, but eventually they yielded, all apart from one :bang:

This one decided to start unscrewing the fitting from the block and twisting the pipe - manipulating two spanners under there and applying significant force wasn't a walk in the park, but eventually with a bit of judicious violence I got there, and out came the faulty block
Title: Re: JCB 803 Saga
Post by: awemawson on July 12, 2015, 07:48:44 AM
So now to transfer all the fittings to the relevant port in the block. I bought the correct 'O' rings from JCB when I got the block because some are far from standard sizes. The fittings are the 'face seal' style, which I'm always slightly concerned with, as the ring sits in a groove and is highly likely to fall out as the block goes back in.

Fittings transferred and nicely tightened down in the vice - so much easier - so much more room  :thumbup:
Title: Re: JCB 803 Saga
Post by: awemawson on July 12, 2015, 07:58:37 AM
So no more procrastination, shove it back  :ddb:

Went in fairly easily, only issue was my 24 mm pipe ring spanner - the slotted variety you can put over a pipe - decided to open up and slip onto the points of the hex and get thoroughly jammed. It's a decent quality spanner but I suppose the spreading forces are quite large. Took a bit of cogitation to find a way to lever it off, as it's all a bit tight round there.

So how did it go - well as the oil was cold I started the engine and left it on fast idle while I cleared up the not insignificant pile of tools. Then took her round the yard for a trundle and exercised the dozer and boom a bit lifting the machine to ensure the relief valve was being used.

 :thumbup: :thumbup: :thumbup: Not a drip, not a spot - phew  :thumbup: :thumbup: :thumbup:

So that gave me enough confidence in it to put the floor panel back, and crawl into the shower to get rid of that oil  :palm:

So just both tracks, track drive sprockets, and track idler sprockets to fit, then sort out the fuel gauge and make the right hand control pod a little more secure - it's wobbling all over the place at the moment
Title: Re: JCB 803 Saga
Post by: mattinker on July 12, 2015, 08:05:26 AM
The joys of hydraulics, it may be clean hydraulic, but it seems to get every where. I hate the stuff!

Regards, Matthew
Title: Re: JCB 803 Saga
Post by: awemawson on July 13, 2015, 08:36:50 AM
So flushed with success with the relief valve it's time to sort the tracks out - never mind the fact it's drizzling  :bugeye:

Firstly need to raise the digger one side at a time to free the relevant  track from the ground. Conventional way is to use the digger boom and dipper to tilt the machine, but doing it this way means that the boom and bucket are beside the track that you are working on. As I was going to be doing this single handed and the tracks are extremely heavy I wanted to be able to get my fork lift in from that side to manoeuvre the tracks so a few days ago I made some substantial stands from bits cut off a hedge flail.

Tilting in the normal way, I then could prop the machine up safely and slew the boom out of the way of the forklift.
Title: Re: JCB 803 Saga
Post by: awemawson on July 13, 2015, 08:44:02 AM
Almost all tracked vehicles use the same method of track tensioning. The idler sprocket slides in a track way, and is forced outwards by a grease filled cylinder the other end of which rests against a massive spring seated firmly against the chassis. The tension is applied by pumping grease into the cylinder.

So to remove the track you undo the grease fitting and let the piston in the cylinder move back releasing tension (and masses of grease!) With the tension released I had a devil of a job getting the first track off, levering, prying, cussing a bit. Eventually I decided to remove the bolts from the drive sprocket as I was changing it anyway, thus allowing the track to slide sideways. Eventually it came off  :bang:
Title: Re: JCB 803 Saga
Post by: awemawson on July 13, 2015, 08:47:02 AM
With that off, I had to unbolt the grease cylinder from the old idler sprocket, bolt it on to the new idler, and fit the new drive gear on the track motor.
Title: Re: JCB 803 Saga
Post by: awemawson on July 13, 2015, 08:52:57 AM
So now to put the new track on.

At this stage I was delighted that my friend Steve turned up wanting me to mend his clay-pigeon thrower, and being a nice chap gave a hand and made a difficult job far easier  :ddb:

Then it was a case of 'rinse and repeat' and we did the other side resulting in new tracks and sprockets all round  :thumbup:
Title: Re: JCB 803 Saga
Post by: awemawson on July 13, 2015, 08:59:30 AM
So was it all really necessary  :scratch:

Oh yes, what a difference. The machine now tracks smoothly without the clunking it made before, and just look at the hooking on these teeth.

Anyway there was a nail in the old tracks - they'd never hold air  :lol:


Sadly Steve's clay launcher was beyond fixing - imagine a 'hamster wheel' of 6 mm plate sides and 6 mm rods for the bars, all bent significantly squiffy by being dropped on on edge while attached to a heavy machine which fell on top  :bugeye: The end plates were bent all over the place and every bar was bent like an off set bend.
Title: Re: JCB 803 Saga
Post by: mattinker on July 13, 2015, 02:55:13 PM
I'm glad you found the puncture, but I was a bit disappointed about the clay pigeon thrower!

Cheers, Matthew.
Title: Re: JCB 803 Saga
Post by: awemawson on July 13, 2015, 03:35:12 PM
I'm glad you found the puncture, but I was a bit disappointed about the clay pigeon thrower!

Cheers, Matthew.

Update on that Matthew - we gave it much violence later on, knocking it very roughly back into shape. Then welded back the bits that broke off in the process. It has bars that channel the clays into the firing line and I don't know how critical their alignment is.

Whether it will actually work is debatable
Title: Re: JCB 803 Saga
Post by: mattinker on July 13, 2015, 03:40:20 PM
So there is a glimmer of hope!
Title: Re: JCB 803 Saga
Post by: awemawson on July 14, 2015, 11:10:51 AM
 :doh: :doh:Yesterday was the day of the TWIT, with me in the starring role  :doh: :doh:

All done and dusted, clean up, put the tools away, wipe down the controls with a clean rag, give the hydraulic tank a final top up (all rams need to be in the fully closed position for the level gauge to read correctly), then move the boom and dipper and bucket back to a more convenient position for parking up. Half way through I lost all controls, no movements at all. Hang on, what's that volcanic eruption just to the rear of my seat?

I'd forgotten to screw the hydraulic filler cap back on. This is actually the top of the filter unit and return oil enters just below the filler under slight pressure. I'd dumped about 35 litres of brand new hydraulic oil EVERYWHERE  :bang:

35 litres of oil makes a BIG MESS  :( Now fortunately the inner farm yard is deep road planings, which love a bit of oil to make them bind better together. Well they got a bit more than a bit !

I swept what I could off the concrete, and onto the planings, and the plan was that when I got back from the abattoir this morning, I'd dig out my steam cleaner, fire it up and steam clean the oil off the concrete. It's always been a bit temperamental firing up when it's been idle for a while, but try as I might I could NOT get the burner to fire. Ended up just pressure washing it off which worked remarkably well.

But I can see that I need to find a few days to 'breathe' on the pressure washer. It has a flame failure device that uses a CdS cell to look at the flame and decide whether to pump the oil or fire the ignition and I think I need to re-build it. I'd fit a commercial flame flailure unit from a domestic boiler, but this runs off 12V DC as the machine is completely self contained and doesn't use mains.
Title: Re: JCB 803 Saga
Post by: lordedmond on July 14, 2015, 12:02:15 PM
Andrew

Are you sure you bought a JCB and not the Tory Canyon


If the size of the oil slick is a thing to go by


Good work on fixing it up but it seem that it has to have the lat word/spill

Stuart
Title: Re: JCB 803 Saga
Post by: Will_D on July 15, 2015, 04:29:21 AM
 Before doing anything radical to the FFD just check to see that the glass window/cell is clean as a build up of soot cuts down the light entering the photo cells!
Title: Re: JCB 803 Saga
Post by: awemawson on July 15, 2015, 06:46:55 AM
Will, that was one of the checks I did. Had the CdS cell out and cleaned it, also the (very) thin glass window, which at some time I must replace as it's in two pieces! I suspect in fact thinking about it, either diesel isn't being sprayed in, or the ignition system isn't firing.

When the time comes I'll start a thread just on this subject rather than divert this one.

Meanwhile I put all the removed tracks, sprockets, idlers, and dipper parts on eBay this morning starting at 99p - hopefully they'll help someone stuck for funds sort out an otherwise marooned digger.
Title: Re: JCB 803 Saga
Post by: vtsteam on July 15, 2015, 11:49:53 AM
Good to catch up here and see you're through the problems,  Andrew!

I remember the cap coming off my bar oil chamber on a Stihl chainsaw, without me noticing right away. I'd just filled up and was carrying it into the woods when I realized my whole right side from belt to shoes was covered in bar oil. It was a long squishy walk back. That was about a 1 pint spill. I can imagine the moment you noticed the overflow on the excavator return!
Title: Re: JCB 803 Saga
Post by: awemawson on July 27, 2015, 11:17:53 AM
Thanks Steve - good to see you back.

Tidying up after daughters wedding today. Had to remove dry hay bales from the marquee before they dropped it (time / date unknown) and also move a pile of huge slices of oak tree that had been used as cake stand and various decorations. Just as well I got on with it, as just as I finished they came to collect the marquee and it started raining!

Having to hang about waiting for the various subcontractors (generator, chairs ,dance floor, bar etc) to collect their stuff I was looking for a little job that I could get on with but easily put aside, so decided to try and sort the wiper motor out.

It's a dual speed one with parking, and I'd already removed it to investigate and found the motor stuck solid, so time to dismantle and look further.

To remove the motor you have to remove the worm wheel. To remove the worm wheel you have to remove the mounting bracket.

Lots of pictures as I used them as an aide memoir for re-assembly.
Title: Re: JCB 803 Saga
Post by: awemawson on July 27, 2015, 11:28:28 AM
So at last being able to remove the motor it was obvious that it had filed up with water and rusted nicely over the last 18 years or so  :bang:

The whole thing is assembled by sliding the components into a deep pressing that is the outer casing that has permanent magnets bonded inside. So disassembly had to be from one end. The brush holders are a pair of nylon mouldings held into the case by swaged lugs which proved quite hard to release. One of the brush springs was a total write off as it had rusted through.
Title: Re: JCB 803 Saga
Post by: awemawson on July 27, 2015, 11:35:29 AM
At this stage I thought that it was a write off, but decided to press on anyway and see what could be done. Actually the armature cleaned up quite reasonably, as did the magnet holding case. I even managed to rescue the sintered bronze bush on the inner end of the armature and clean it up and soak it in oil.

Then I had to find a suitable spring from my spring hoard. I had quite a job getting one brush to slide nicely. It derives it's two speed function by having brushes set at differing angular locations.
Title: Re: JCB 803 Saga
Post by: awemawson on July 27, 2015, 11:42:10 AM
So now it's a case of putting it all back together and seeing what happens!

I did check leakage from the windings to the spindle. Initially it was reading 5K ohms - not too concerning for a 12 volt motor, but obviously better if the leakage wasn't there at all. I gently warmed it using the workshop hot air hand drier, and the leaking slowly came down, eventually getting to about 120k ohm.

So back together:
Title: Re: JCB 803 Saga
Post by: awemawson on July 27, 2015, 11:52:33 AM
so a quick bench test - just the motor as the parking wiring / contacts is rather complicated and needs the two pole three position switch that's in the machine.

Well slightly to my surprise it works ! Both speeds work and the crank goes back and forth giving the correct motion.

Popped it back in the machine, and yes the parking function works  :ddb:

So now that I'm on a roll I re-fit the wiper blade and adjust it, BUT the motor hasn't the torque to reliably move the blade, even wetting the screen  :bang:

Either the brushes need to 'bed in', or there is a short on the armature windings, or the magnets have demagnetised. I left it running for a while to 'bed in' but things didn't improve much. I may at some time take the armature out again and do a 'growl test' on it, but meanwhie I'll keep an eye open for one on ebay at less than the staggering £180 that a new one costs  :bugeye:
Title: Re: JCB 803 Saga
Post by: tom osselton on July 27, 2015, 12:39:22 PM
I'm suprised the armature cleaned up so well.
Title: Re: JCB 803 Saga
Post by: John Rudd on July 27, 2015, 01:26:43 PM
I reckon its all that grease you packed into it that's causing your problem...... :lol: :lol:
Title: Re: JCB 803 Saga
Post by: awemawson on July 27, 2015, 02:25:32 PM
I'm suprised the armature cleaned up so well.

So was I  :lol:
Title: Re: JCB 803 Saga
Post by: awemawson on July 27, 2015, 02:30:51 PM
Small update:

I'd forgotten that to remove the spherical sintered bronze bush from the inner end of the spindle, I'd had to shorten it by a few tens of thou. When I put it back together I'd not tweaked the end float adjustment to compensate - this is just a grub screw and lock nut externally mounted. I've just removed it from the machine, tweaked the end float until it felt right, and re-fitted it. I reckon the armature was moving outwards a  bit and fouling on something. It's by no means as powerful as I'd like, but it wipes a wet window now  :clap:
Title: Re: JCB 803 Saga
Post by: vtsteam on July 27, 2015, 08:15:26 PM
Satisfying to get something so seemingly gone, back working again!  :beer:
Title: Re: JCB 803 Saga
Post by: awemawson on July 28, 2015, 01:00:03 PM
There's been a spate of small digger thefts in Southern England in the last few weeks - with one or two people actually advertising rewards for recovery on eBay. Considering the silly amount of dosh I've sunk into this machine I decided to fit a 'Track Lock'.

It comprises a heavy slotted plate that you weld to the undercarriage, and a sort of 'hasp and staple' arrangement slots through it, the pins of which pass through the steel 'chain' of the tracks. Stops the digger being driven onto a trailer - it doesn't stop it being lifted by a Hiab though.

Title: Re: JCB 803 Saga
Post by: AdeV on July 28, 2015, 01:04:56 PM
Surely you only need to put a copy of this thread on the driver's seat - any potential thieves would take one look & run a mile....  :lol:
Title: Re: JCB 803 Saga
Post by: awemawson on August 02, 2015, 07:09:31 AM
Still doing a bit of tidying up on this machine. I was determined to get the horn working. The wiring was a mystery  :scratch: None of the illustrations either in the workshop manual or the parts books seemed to match up. Both showed the horn as located in the right hand drivers 'pod' - not only was it a daft place to put it, it wasn't there and nor was the wiring  :bang: A bit of searching and eventually I found it where it should logically be placed, under the cab frame at the front. I pulled it off, tested it, cleaned it up and replaced it. A pair of wires were close but unconnected - on they went as their colours matched the diagram and sure enough I can now scare the sheep out of the way  :ddb:

Originally there would have been a pair of working lights on the boom, and another pair on the top front of the cab. Vestigial bits of wire to the cab but all lost off the boom. A bit of searching around and I eventually found a pair of correct coloured wires emerging from the loom under the floor terminated in an AMP 'Econoseal' female connector with one pole horribly charred.

I managed to source some Econoseal connector pairs on ebay which are rated at 10 amps per way. Not sure what wattage the original boom lights were but I reckon someone had put too large a bulb in. I sourced a pair of Chinese LED lights rated at 27 watts each so far lower than the originals would have been.

The wires for the boom lights have to follow the same route as the hydraulic pipes as of course as things articulate they get bent - I think I've left enoughy slack  :scratch:

Don't you love Chinese products. The lights had nicely made stainless steel mountings and nuts and bolts. 13 mm a/f nuts with 14 mm a/f bolts  :bang:

Rather than put another pair of work lights on the cab I've got a 'light bar' as it fits neatly over the windscreen and will mount on a length of 'Unistrut' - it's 120 watts so should shine into dim corners rather nicely  :lol:

(Waiting on a couple of Unistrut spring loaded nuts so not yet mounted)
Title: Re: JCB 803 Saga
Post by: awemawson on August 02, 2015, 07:18:56 AM
Another job that's been outstanding for a while is to make up some replacement covers. One of the track adjuster covers was present - the other was missing. As was the cover that keeps prying fingers out of the hydraulic oil filler and filter housing.

Both were originally 3 mm mild steel and I had a sheet of 3 mm Zintec delivered weeks ago but not got around to making them. Bright and early this morning I got on with it, cut the profiles, drilled the holes, gave them a coat of zinc rich primer and a spray of JCB yellow. I'll leave them a day or two to harden. While it was off I cleaned up the existing track adjuster cover and sprayed it as well.
Title: Re: JCB 803 Saga
Post by: RussellT on August 02, 2015, 11:30:37 AM
Well done with this machine Andrew.  Persistence pays off again.

I've always rather approved of nuts and bolts having different sized hexagons - that way you only need to own one set of spanners - but I suspect I wouldl spend ages looking for a 14mm spanner while I could find half a dozen 13mm ones.

Russell
Title: Re: JCB 803 Saga
Post by: edward on August 03, 2015, 04:35:12 AM
I did a bit of clearing up the other week and found that between the car, garage and my 4 year old sons toolbox, we have 8 13mm combination spanners and a couple of offset rings and ratchets. God knows where they have come from! Only got 2 or 3 14mm though:)
Title: Re: JCB 803 Saga
Post by: awemawson on August 03, 2015, 05:55:49 AM
Before I fit the cab roof 'light bar' I wanted to replace the window seal, that will be trapped under it's mountings. Amusingly it is the exact same stuff used on the Traub CNC lathe  :clap:

Taking the old stuff off revealed that water had been trapped behind it where the wiper arm comes to rest to the extent that there were holes in the window frame  :bugeye:

My first intention had been to wire brush off the rust, and make a 'bondo' repair using perforated zinc sheet to both re-inforce it and give a degree of anodic protection, but my conscience got the better of me and I decided to cut out the rust and weld a proper patch in. My first reluctance was based on the fact that access to the back is neigh on impossible, but then I realised that it is 3 mm thick and that by bevelling the patch and frame I could get perfectly adequate penetration from one side.
Title: Re: JCB 803 Saga
Post by: awemawson on August 03, 2015, 05:59:53 AM
So, mark out what needs chopping out, make a pattern, and cut a patch - how hard can it be ?

In fact it all went very well, except that first time I cut the 'wrong half' of my pattern and wondered why the patch didn't fit.  :bang: Never mind, only a matter of minutes to make another  :lol:
Title: Re: JCB 803 Saga
Post by: awemawson on August 03, 2015, 06:02:48 AM
So having done a trial fit holding it in with magnets, I went at it with the mig aiming for full penetration without melting the lot. In fact it was slightly too shallow, but perfectly adequate as there is no strain on this bit other than holding the window trim.
Title: Re: JCB 803 Saga
Post by: awemawson on August 03, 2015, 06:05:35 AM
A little bit of fettling with a coarse sanding disk on the angle grinder, a dust off with zinc rich primers and altogether I'm quite pleased with it. Not exactly car bodywork standard, but hey - it's a digger  :ddb:

Just waiting for a tin of the right grey paint to arrive and the job'll be finished.
Title: Re: JCB 803 Saga
Post by: John Rudd on August 03, 2015, 07:49:00 AM
Nice job..... :clap:

Are you going to re-upholster the seat? :dremel:
Could do with a new cover.... :coffee:
Title: Re: JCB 803 Saga
Post by: awemawson on August 03, 2015, 07:59:42 AM
Nice job..... :clap:

Are you going to re-upholster the seat? :dremel:
Could do with a new cover.... :coffee:

Thanks John.

Funny that you should mention the seat - I've been keeping my eye open on ebay for a suitable replacement, none have turned up, and I was idly day dreaming just now of trying a bit of d-i-y upholstery if I could find suitable material.

Yet to find how it comes off, but I'm sure that it must somehow :scratch:
Title: Re: JCB 803 Saga
Post by: John Rudd on August 03, 2015, 08:03:10 AM


Funny that you should mention the seat -
Yet to find how it comes off, but I'm sure that it must somehow :scratch:

Hammer/Angle grinder/Gas axe come to mind.......... :lol:

For material,how about your local friendly upholsterer ? Got one nearby? Local market stalls?
Title: Re: JCB 803 Saga
Post by: appletree on August 03, 2015, 08:45:45 AM
Iím far better at welding when the work is horizontal, especially with stick, all the old sayings fit at times, did the pigeon get away, weld inclusion in the slag etc, actually iím not too bad.
I have a 160 amp inverter stick welder, so hand and light weight and easy to use, perhaps not quite as forgiving as the big oil cooled ones we had at work, but they were 3 phase probably 500amp or more .
Title: Re: JCB 803 Saga
Post by: awemawson on August 03, 2015, 10:47:12 AM
I used my big 3 phase Butters AMT3205 Mig with 1 mm wire and pure argon. Why? as it's the easiest of my machines to wheel outside. Why pure argon? As years ago I bought a cylinder to bubble argon through molten aluminium to remove the dissolved hydrogen, and it now get shared by my Tig and this mig welder.

It's a fearsome beast quite capable of punching holes in 8 mm plate if you turn it up full whack  :lol: However it can also be turned down and tamed  :ddb:
Title: Re: JCB 803 Saga
Post by: wgw on August 03, 2015, 11:23:46 AM
Mr. Mawson- seat cover- fertilizer bag. Mine has air-con as well. As well as no windows.
Title: Re: JCB 803 Saga
Post by: awemawson on August 03, 2015, 11:35:35 AM
 :lol: :lol: :lol: :lol: :lol:
Title: Re: JCB 803 Saga
Post by: awemawson on August 04, 2015, 10:47:55 AM
Well today I was determined to get the seat out to examine it and see what refurbishment possibilities there were.

The upper seat frame is on a slider that wouldn't slide, (I later discovered that the handle that releases it was missing) Held down by four 8 mm cap screws - the heads are in the channel, the bolt pokes upwards through the seat frame with nuts above. The front pair were easy - nice and accessible - the the rear pair obviously had been put in with the slider backwards, and it wouldn't slide  :bang: Nuts were loose enough to turn but of course the cap screw turned as well with no way of holding it.

No room for an angle grinder. After much head scratching, I reckoned the only way was to use a nut splitter and fracture the nuts in-situ. I had to thin down my smallest splitter for it to fit against the frame, and then with quite a bit of acrobatics the nuts were vanquished and the seat was OUT  :ddb:
Title: Re: JCB 803 Saga
Post by: awemawson on August 04, 2015, 10:54:34 AM
This revealed two VERY USEFUL bits of information.

Firstly - the missing lever was a fairly simple bent bit of 10 mm heavy wall tube that spring locates onto four odd shaped pegs (It's similar to but slightly narrower than the yellow one for the lower slider in the picture) I reckoned I could make one of those  :ddb:

Secondly - there was a label on the previously invisible side of the seat frame revealing the it is a KAB T1 seat  - KAB seats are still around so I put some feelers out
Title: Re: JCB 803 Saga
Post by: awemawson on August 04, 2015, 10:58:27 AM
Looking at what materials I had to hand I found some 9.5 mm heavy walled steel tube - close enough I reckoned - so I rolled out the oxy-acetylene cylinders, drew some chalk lines on the welding bench and bent up an operating lever.

It got zinc primer and satin black paint as the JCB Yellow pot was sealed and it wasn't worth mucking up the spray gun (it doesn't brush very well)
Title: Re: JCB 803 Saga
Post by: awemawson on August 04, 2015, 11:03:59 AM
So now that the seat slides back and forth, getting it in and out is a (relative) doddle.

Then the phone rang . . . YES seat squab and back covers, complete with foam inserts and fixing clips should be delivered later this week, and cost less than half what I'd been quoted for re-upholstering them  : :clap:

Only bit I need to sort out now is the raising and lowering mechanism. It's currently stuck solid, but when I dismantle the seat to fit the new upholstery and thus have a bare frame, I'm sure that can be sorted out.


(google is suggesting that this seat was fitted as the drivers seat in some FX4 London Taxi's)
Title: Re: JCB 803 Saga
Post by: awemawson on August 06, 2015, 08:42:51 AM
I spent today wrestling with the new upholstery covers for the seat. (They arrived yesterday but we had house guests so had to wait)

So I pulled the seat out (easy now  :clap:) and started removing the raising and lowering mechanism. Although not visibly rusty it was stuck absolutely solid. It has a pair of pantograph arms that allow either the back, front, or both to rise up if you take your weight off the seat. They can then be locked in your chosen position.

(I've taken lots of pictures to help me get it back together !)
Title: Re: JCB 803 Saga
Post by: awemawson on August 06, 2015, 08:55:23 AM
The pivots are all riveted joints, so not practical to dismantle. I must have spent a good hour thumping it, heating it, spraying it with Plus Gas. Eventually I got it to move but very stiffly. It's not a major issue as I didn't use it previously, but it would be nice to get it working properly.

Then to stripping off the old upholstery. The back and squab had ties running through slots in the foam to stop them 'bagging out'. The back is basically a cloth tube with a pair of steel rods in the hems that pull tightly around the foam and are secured with 'hog rings' The sqab it pulled around the foam then clipped to the frame.
Title: Re: JCB 803 Saga
Post by: awemawson on August 06, 2015, 09:00:02 AM
Now to start rebuilding it  :bugeye:

The new kit seemed to be correct, and the 'hog rings' are actually identical to the ones I've used for fencing, so my Hog Ring Pliers actually fitted  :thumbup:

I started with the squab - if I were doing it again I'd start with the back, as the squab foam make fitting those hog rings rather difficult.
Title: Re: JCB 803 Saga
Post by: awemawson on August 06, 2015, 09:02:09 AM
Well it looks dramatically better than it did  :clap:

That raising / tilting mechanism it too stiff to use but it matters not a lot
Title: Re: JCB 803 Saga
Post by: lordedmond on August 06, 2015, 09:49:12 AM
So Andrew

Are you going to mill out a RR badge for it now sure looks comfy well done you are a inspiration to us all start a job and finish it


Stuart
Title: Re: JCB 803 Saga
Post by: DMIOM on August 06, 2015, 09:54:14 AM
similar thoughts to Stuart - except my question was whether the next item would be a walnut veneer dash?

Dave
Title: Re: JCB 803 Saga
Post by: John Rudd on August 06, 2015, 10:05:18 AM
It needs some bling :lol:


I feel a new thread coming on.......'Pimp my JCB 803'

Could be made into a tv series you know..... :coffee:

Nice jcb job on the seat Andrew..... :thumbup:
Title: Re: JCB 803 Saga
Post by: awemawson on August 06, 2015, 10:35:55 AM
Thanks chaps for the comments.

...bling ... Now I did consider cutting out a stencil on the laser cutter to paint stencil the JCB logo back on to the seat, as this one doesn't have it  :ddb:


Mind you, paint and me don't seem to get on too well recently. I got some grey to touch in that bit of the window frame I welded up. It was far too dark. Never mind I thought - it's Xylene thinned, and I have some white paint that thins with xylene, I'll put a few drop of that in and we'll be good to go. Sadly not, mixed apparently ok in a jam jar. When I did a test spray I couldn't get the spray settings right, it was going in fits and starts. Turns out that the two paints are reacting with each other and making flocculations that were blocking the nozzle. :bang:
Title: Re: JCB 803 Saga
Post by: DMIOM on August 06, 2015, 11:00:06 AM
.... Now I did consider cutting out a stencil on the laser cutter to paint stencil the JCB logo back on to the seat, as this one doesn't have it .....

Obviously paint is the wrong thing for the seat - if your machine collection doesn't yet have one, you clearly need one of those CNC embroidering sewing machines, so you can embroider the logo !   

Dave
Title: Re: JCB 803 Saga
Post by: trapper on August 06, 2015, 11:25:45 AM
Almost all tracked vehicles use the same method of track tensioning. The idler sprocket slides in a track way, and is forced outwards by a grease filled cylinder the other end of which rests against a massive spring seated firmly against the chassis. The tension is applied by pumping grease into the cylinder.

So to remove the track you undo the grease fitting and let the piston in the cylinder move back releasing tension (and masses of grease!) With the tension released I had a devil of a job getting the first track off, levering, prying, cussing a bit. Eventually I decided to remove the bolts from the drive sprocket as I was changing it anyway, thus allowing the track to slide sideways. Eventually it came off  :bang:
Title: Re: JCB 803 Saga
Post by: vtsteam on August 07, 2015, 10:29:19 PM
Nice job on that seat, Andrew!  :bow: :bow: :beer:
Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 06:36:13 AM
Thanks Steve, more down to the materials than my skills I fear.

One of the minor irritations with this machine which is now becoming more major, is the non working fuel gauge. When I got it, I knew it wasn't working as there was no needle on the gauge  :scratch:

I had rather hoped that it was 'just missing' and at some time I could get around to making one. Well as is life, there proved to be a little more to it than that  :bang: I made a tiny little needle, got it fixed, but still no joy - no movement, zilch.
Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 06:51:08 AM
So time for a little more investigation. The wiring diagram shows the gauge is in series with the transducer and the pair are across the 12v supply from the ignition switch - so no surprises there. Pulling it out of the dash and testing it on the bench across the connections purporting to be the only ones going to the indicator it measured 150 ohms - so reasonable. Applying 12v from a current limited power supply moved the needle to full scale - whoohay  :ddb: But absolutely nothing short of poking the needle with a finger would move it back to zero from when the 12v supply would move it back  :scratch: :scratch:

Doing a bit of  :coffee:  :coffee: and  :scratch: :scratch: Google gave me interesting facts about fuel gauges - seems that there are several variants - I'd presumed that they were basically a crude ammeter - but this style has a 'low' coil, and a 'full' coil as well as a third the purpose of which is a bit confusing  :bang:

About this time I thought it best to measure the tank transducer - or 'sender' as they seem to be called - basically a variable resistor operated by a float. In this case there is a vertical rod fitted from the base of the tank, surrounded by a float that I assume to be magnetic, that rises and falls with fuel level. All very well, but surely it shouldn't be INFINITE ohms  :bang: :bang: Yes the transducer is open circuit. I strongly suspect that the indicator has failed putting too much current through the 'sender'

So a parts hunt ensued. The 'sender' is available so I ordered one, but the gauge is made from unobtainium, I traced there to be ONE spare in the world, and the dealer somewhere in the US wanted $7K so obviously wants to keep it for ever !

The actual gauge module unplugs as per these pictures
Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 07:04:03 AM
Try as I might I could not track down any vehicle gauge or even normal ammeter, small enough to fit in the available space - so what to do  :scratch:

Well it's not rocket science - we need a bit of electronics that basically shows a reading varying with the variable resistance of the sender - in this case I measured 9 ohms with the tank dry, and 180 ohms with the float all the way up.

After a few false starts playing with miniature digital volt meters I thought it best to design something myself using the LM3914 Bargraph Driver. This chip accepts a DC voltage, and drives it's ten LED driver outputs in an increasing bargraph representing the voltage coming in. It also has provision for scaling, zero offset, and brightness, all in a single 18 pin chip for about a pound sterling !

So I set off pulling out bits of Veroboard to wire up my simple circuit and then thought - I bet someones done this before - go west young man and GOOGLE  :ddb:

Sure enough, a nice man in Canada had used the self same chip, in his case to make a VU audio meter, and was selling the very nicely made PCBs on a well know auction site for absolute peanuts including postage, so I placed an order
Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 07:29:08 AM
So by leaving out his op amp pre-amplifier, and putting links where he had capacitors for AC coupling I ended up with precisely the circuit that I had intended to glue together on strip board but in a much neater format  :ddb:

Firstly I built it to run directly off the 12v vehicle voltage, but testing showed that as battery voltage varied from 11.5 to 14.5 there was an unacceptable variation in indication. As the PCB allows for insertion of a regulator I tried regulating down to 8 volts and running off that. Excellent results that are stable over the range of voltage that I'd expect in the machine.

Only down side of this is that the regulator dissipates a watt or two and runs hot, and will need a heat sink when mounted. I tried to reduce the dissipation by putting the LM3914 chip into 'single bar mode' so that a single bar 'walks' the indication, but there is an oddity with this integrated circuit that when in this mode, the tenth bar never illuminates  :bang:

At the moment I've set it up so that only 24 mA passes through the 'sender' - a nice low level but it might prove noise sensitive. Easy to alter as it means changing a single resistor and re-tweaking the twiddle pots on the PCB.

Here is my prototype running on the bench and using my wire strippers as a heat sink  :lol:

(The LEDs are green asnd although bright enough in real life don't show up very well in the pictures)
Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 07:35:23 AM
I have some red bargraph LEDs and might try those.

All that remains is to physically mount it in the instrument cluster - there is enough room but will need a bit of cogitation to work out a best way - then make a mask to put in front to conceal all but the LEDs.

Then of course I need to drain the diesel tank and install the new transducer, but it's wetter than a wet thing with wet bits on it outside so that might have to wait until the Ark is built and all the pairs of animals are safely aboard  :ddb:
Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 12:32:08 PM
So how to mount it? I decided to copy the way that the hours meter is mounted, using 'posts' of thick wire soldered to the board, with tubular spacers separating the two pcb's.

Drilling holes matching those already in the display pcb placed 3 conveniently within the ground plane on the main pcb, but the fourth emerged right between a 12v trace and ground, so some careful soldering required so as not to short the supply out  :bugeye:
Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 12:35:43 PM
I decided to mount the voltage regulator on flying leads off the board, and bolt it to the largish 0v copper plane on the main pcb as a heat sink - time only will tell if it is enough.

Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 12:41:30 PM
I think I will just snip off the thick mounting wires and bend them over as retaining tabs rather than solder them, so that I can easily disassemble it in the future should the need arise.

I should perhaps point out that this is a different display board from the prototype one in my earlier posts that used ic sockets - I decided to solder in the display and ic as it's likely to get a bit of vibration, and anyway the lower profile was an advantage.

So a quick test to see it works - phew it does - then a tweak with the pots to calibrate 'empty' and 'full', and all that remains is to cut a bezel to surround the LEDs and hide the electronics
Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 01:47:54 PM
So I cut a bezel - oh I like my Laser Engraver  :lol:

Popped it in the hole, secured by a drop of super-glue and put it all together for a soak test to see how hot it gets.
Title: Re: JCB 803 Saga
Post by: awemawson on August 26, 2015, 01:52:55 PM
That's actually the second bezel I cut.

Both were cut from some smoked brown perspex that I have squirrelled away that were water screens on my wire EDM machine that I replaced with clear polycarbonate. The perspex was a bit scruffy, so when it had been cut I cleaned it with IPA (Industrial Pure Alcohol - not the beer  :drool:) and it instantly started forming stress cracks.

Now I've heard of this before but never seen it. The second bezel was cut from the same sheet, in fact with in a few mm of the first one, but this time I cleaned it with soap and water.

Have a picture of the cracks:
Title: Re: JCB 803 Saga
Post by: Bluechip on August 26, 2015, 02:40:50 PM
Oh yeah, done it myself  :doh:

One day at work on a IBM 1403 line printer, the print cartridge oiler reservoir was a Perspex block arrangement and it had some crap in it, so Dick-Ed here squirted it with AF spray ....  :bang:

Just like dropping an ice cube into water ..  :lol:

Didn't quite fall apart so I wrapped tape around it and ordered a new one.  :scratch:

Dave

Title: Re: JCB 803 Saga
Post by: AdeV on August 26, 2015, 06:44:19 PM
IPA (not the beer) is Iso-Propyl Alcohol. Never heard it called Industrial Pure before - did you get the Chinese stuff?  :lol:

If you get bored of the linear bar graph, Sparkfun do some rather cool radial ones: https://www.sparkfun.com/products/11492

I bought a stack of LED products a while back, pretty sure I got some of the radial ones, you're welcome to one if you like.
Title: Re: JCB 803 Saga
Post by: awemawson on August 27, 2015, 06:51:04 AM
... heat ... heat ... heat  :bang:

This module only consumes 2.2 watts at the worst case of 15v battery voltage (on charge) and all bars illuminated. Yet on my soak test the regulator was getting unacceptably hot (48 degrees C after a couple of hours)

The dissipation is split about 50 / 50 between the regulator ( 15v -> 8v @ 150 mA = 1.05 Watts) and the LEDS & drive chip. I'm not too concerned about these as the dissipation is over a couple of square inches of board, but the regulator needs sorting.

I'd tried using a largish area of the 0v copper pcb, and when that was insufficient bent up a small sheet copper fin that the bolt fixing the regulator retained. This improved things, but all the heat to the heat sink had to pass through the 3 mm bolt so not ideal.

Not much point doing anything inside the case as the heat has to be got away. I hit on the idea of drilling a 10 mm hole in the pcb for the end of a cylindrical external copper heatsink to protrude into the case with the regulator directly bolted to it.

I turned a 1" bar as per the picture below, tapped it's internal end M3, painted it matt black and super glued it to the rear of the main pcb.

So at least now the regulator heat is exported fairly efficiently, and it's back on soak test to see the results

You'd not think that a couple of watts would be so much trouble  :bang:
Title: Re: JCB 803 Saga
Post by: DMIOM on August 27, 2015, 10:27:28 AM
Andrew,

If you want a cab heater, then ignore this .....

Otherwise, hot electronics => increased failure rates.  It sounds like you're using a linear regulator, which is just chucking the power out as heat. I only uses linears on very small projects now; there are pin-compatible switching equivalents for most of the 78xx/79xx series regulators, and they can approach 90+% efficiency.

If your board is now permanently populated with a linear regulator, I'd finding out what its minimum input voltage is and then running an upstream switching reg so that the linear reg does the least amount of work necessary.

Dave
Title: Re: JCB 803 Saga
Post by: John Rudd on August 27, 2015, 10:31:14 AM
Minimum delta-v for the 78 xxxx series is 2.0 volts.....
There are drop in switchers on a pcb with a TO220 pin out....but expensive ( Ebay - typically £4 ish for a 7805 replacement) oops DMIOM already said....

Can't you reduce the led current a bit?
Title: Re: JCB 803 Saga
Post by: Pete W. on August 27, 2015, 10:55:59 AM
SNIP

Can't you reduce the led current a bit?

It's surprising how dim an LED can be out of doors when the sun is shining!

Well, to be pedantic: the LED is just as bright but the high ambient sunlight causes the eyes to accommodate, so it LOOKS dimmer!!!!
Title: Re: JCB 803 Saga
Post by: awemawson on August 27, 2015, 12:20:36 PM
Thanks chaps, but I'll stick with the linear regulator, as the new heat sink is doing it's job  :thumbup:

The rain actually stopped after lunch, no longer giving me an excuse not to drain the fuel tank and fit the new sender. Draining the tank was easier than I'd expected as I managed to disconnect the feed to the main filter and extend it into a 25 litre drum. When I got up close and personal with the sender, it turns out that the original has a whacking great 2" AF nut, and although I have spanners that size there's no way I could get past the gubbins such a slew rams and pipes, so the tank had to come out.

Actually not too bad a job. flow and return pipes of course, and four bolts and out she came. Fortunately the thread on the new sender is also 2" bsp, but the sealing methods were not the same. Original tightened up on a flange with a sealing washer, replacement was intended to seat onto a female taper.

No way I'm cutting a 2" taper on the tank boss, so I've put my trust in Loctite 577 pipe seal, which is pretty fantastic stuff for threads over 3/4" bsp. If there's a puddle of diesel under the machine tomorrow morning I'll eat my words  :ddb:

So putting it all back together, I firstly checked that the gauge showed empty, then I slowly syphoned the diesel back into the tank while carefully watching for drips. None so far, and we have 'three bars' on the new fuel gauge.

A quick trundle down to my 'red diesel' bowser, fill her up sir ? - yes please, and lo and behold we have all 'ten bars'.

So at long last we have a working fuel gauge - what a palaver  :bugeye:

Only one more issue to sort now on this digger. One track can track at slow and fast rate, whereas the other will only do slow rate, which unless you know, leads to some interesting driving. There is a spool valve bolted on each motor that controls oil flow (either fast low flow, or slow high volume) and I'm pretty sure that one is stuck - it's another crawl about on the ground job I keep putting off  :lol:

Title: Re: JCB 803 Saga
Post by: AdeV on August 27, 2015, 01:35:16 PM
After all that work, don't tell me you're not going to de-rust & repaint it? Or will you leave it with that "rat look"?
Title: Re: JCB 803 Saga
Post by: appletree on August 27, 2015, 02:03:53 PM
After all that work, don't tell me you're not going to de-rust & repaint it? Or will you leave it with that "rat look"?
Yea I was just about to say the same LOL
Title: Re: JCB 803 Saga
Post by: awemawson on August 27, 2015, 02:33:23 PM
Well it's a working tool. It needs to function and be reliable  but doesn't need bling  :ddb:

If for instance I removed the dipper arm to weld up the worn bushes and re-machine them, I'd probably sand blast it and respray, but I've no intention of doing a cosmetic makeover - can't have the local travelling fraternity thinking it's worth nicking  :lol:
Title: Re: JCB 803 Saga
Post by: John Rudd on August 27, 2015, 02:40:06 PM
Well it's a working tool. It needs to function and be reliable  but doesn't need bling  :ddb:


Says he just adding an led fuel gauge..,, :)

Pimp my JCB.....lol....
Title: Re: JCB 803 Saga
Post by: PeterE on August 27, 2015, 03:53:46 PM
Ah, so paintwise you are going down the "too much used camouflage" look then ... 
Title: Re: JCB 803 Saga
Post by: awemawson on August 27, 2015, 03:58:56 PM
To be honest, unless you totally dismantle a machine like this for re-painting, the 'repaint' looks a mess. Just a 'quick blow over with a spray gun' may make it 'ten yards pretty' but the charm is lost when you get close  :lol:
Title: Re: JCB 803 Saga
Post by: PeterE on August 27, 2015, 04:43:03 PM
Of course, I agree. Like most  farm and industrial machinery it will get that "used" look and there is no way of keeping a polished one without a recurring stripdown - and that does not improve the machine performance so it is just as good to skip that.

But keeping a tin or so of the main colour for patching is useful, as it will make it more agreable to have a machine that looks maintained.

I am impressed by your skills, fearlessness and ingenuity to take on that wide variety of projects  :clap:  I always learn a thing or two for each thread I read.

Title: Re: JCB 803 Saga
Post by: awemawson on August 27, 2015, 05:24:24 PM
Thank you for your kind words Peter. It's reassuring to hear that someone is reading my drivel  :lol:
Title: Re: JCB 803 Saga
Post by: Stilldrillin on August 27, 2015, 05:29:47 PM
I've been here, from the start.   :wave:


I am impressed by your skills, fearlessness and ingenuity to take on that wide variety of projects  :clap:  I always learn a thing or two for each thread I read.

My thoughts, too.......  :thumbup:

David D
Title: Re: JCB 803 Saga
Post by: tom osselton on August 28, 2015, 12:38:47 AM
I'm following along too. .... Thinking CANDY APPLE  RED!
Title: Re: JCB 803 Saga
Post by: DMIOM on August 28, 2015, 02:32:40 AM
.....
I am impressed by your skills, fearlessness and ingenuity to take on that wide variety of projects  :clap:  I always learn a thing or two for each thread I read.

+1     :beer:

Dave
Title: Re: JCB 803 Saga
Post by: awemawson on August 28, 2015, 02:42:42 AM
IPA (not the beer) is Iso-Propyl Alcohol. Never heard it called Industrial Pure before - did you get the Chinese stuff?  :lol:

If you get bored of the linear bar graph, Sparkfun do some rather cool radial ones: https://www.sparkfun.com/products/11492

I bought a stack of LED products a while back, pretty sure I got some of the radial ones, you're welcome to one if you like.

Hi Ade,

Now if I'd known they existed I might well have used them if they fitted into the space, but it's not worth revisiting this as life is too short and the present set up is working.

They look fun to use though  :thumbup:
Title: Re: JCB 803 Saga
Post by: awemawson on August 29, 2015, 08:26:54 AM
As for once this morning it wasn't raining I decided to try and tackle the issue I have with the left hand track motor only going at low speed and not high speed.

Each track motor (left and right) has a  two spool block attached, one spool of which is a balancing spool and I don't think that it's involved in speed changing, and the other spool controls track motor speed. The left and right hand versions of these spools are driven by a common oil line (ie they both work in parallel) and the spool is pressed into the low speed position by a spring, and into the high speed position by the oil (sourced by a solenoid valve controlled by a manual switch).

Now as the right hand motor speed changes the solenoid valve must be supplying oil pressure (  :scratch: )

This is the general arrangement, circuit diagram and description from the book of words:
Title: Re: JCB 803 Saga
Post by: awemawson on August 29, 2015, 08:36:28 AM
Now I was working on the assumption that as obviously the right hand spool is changing speed, oil pressure is being supplied to the left hand spool and maybe it is stuck. So time to dismantle it.

By slewing the cab at 90 degrees the access is quite good, the spool block being behind a cover plate on the inner face of the under carriage. Taking off the plate, I gave things as good a clean as was possible in situ, identified the hoses with tywraps and started dismantling.

It was at this point I discovered that one of the four M8 caphead bolts retaining the spool valve onto the track motor was sheared off  :bugeye:

I decided to centre the sheared stub of bolt by running an 8 mm drill down the hole before removing the spool block, so that it acted as a guide. That way I could more easily drill it out
Title: Re: JCB 803 Saga
Post by: awemawson on August 29, 2015, 09:07:05 AM
Now the manual stresses the need to tighten those cap screws evenly, presumably as any distortion would jam the spool and possibly cause the symptoms that I'm getting, so just maybe that sheared bolt was the issue.

So  I removed the spool block, cleaned it up a bit more on the bench, and pulled the spool out. All seemed free moving and clean with no grit. I also checked the other spool while it was on the bench.

A bit of careful drilling removed the broken end of the cap screw, but I wasn't happy with the remaining female thread - running a tap down it, it was rather a loose fit, so I decided to 'helicoil' it - fortunately M8 is a size I carry.
Title: Re: JCB 803 Saga
Post by: awemawson on August 29, 2015, 09:14:59 AM
Putting it all back together was just a simple reverse of the dismantling.

Well the good news is that sealing face with all those 'O rings' didn't spew oil everywhere as I feared that it might. However the bad news is that the symptoms remain unchanged - left hand track motor happily runs in slow mode but not in high  :bang:

Difficult to know how to further the diagnosis. I would like to positively prove that there is hydraulic pressure to the spool, and the only way I can think of doing that, is to intercept it's feed hose with a made up 'Tee' arrangement with a pressure meter on it - rather a bind but possible.

Unless you have any other suggestions .........   :scratch: :scratch: :scratch:
Title: Re: JCB 803 Saga
Post by: vtsteam on August 29, 2015, 09:17:42 AM
The great thing about watching your projects Andrew is that you generally repair sad cases into better than new. So sorry to say, this, I love seeing you have problems   :) :) :) :) :) :beer:
Title: Re: JCB 803 Saga
Post by: TD4 on August 29, 2015, 09:40:42 AM
Good day. I have never owned or needed JCB 3 ton. mini digger, but having followed this saga from its purchase, I now feel I want buy one!! ( not working). So at my age I would have a challenge every day for the rest of my life. your skill and ingenuity amaze me. Malcolm. 
Title: Re: JCB 803 Saga
Post by: modeldozer on August 29, 2015, 11:17:17 AM
Hi Andrew,

Can not make out from the exploded picture but if possible the ideal testing poins are the passages marked in red,  in high speed mode there should not be any pressure in them.

Abraham
Title: Re: JCB 803 Saga
Post by: awemawson on August 29, 2015, 11:27:59 AM
Abraham thanks for that. Sadly those red bits are passages within the casting

I have a possible postulated theory :ddb:

IF the chap who replaced the Orbitor for me inadvertantly swapped the pressure and the drain hoses under the floor all would be explained. They are identical. Absolute pain now to get at the Orbitor end but no reason I cannot swap them at the spool block end. I just need to assure myself that if my theory is wrong I won't damage something.
Title: Re: JCB 803 Saga
Post by: JD on August 29, 2015, 03:45:56 PM
Andrew, if all else fails could you swap the spool valves side for side to see if you get the same problem. I have been following this thread with great interest.
You don't half pick em  :nrocks:
John
Title: Re: JCB 803 Saga
Post by: awemawson on August 29, 2015, 04:12:32 PM
I could John but it would be a 'right pain'

The more I think about it I reckon that the fitter who replaced the Orbiter has cocked up a pair of hoses on the left hand side. Until I REALLY studied the plumbing I had assumed that the pilot servo feed that feeds both left and right dual speed spool valves were paralleled by a Tee fitting in the under carriage. In fact the Orbiter  has an output on left and right hand sides for both the pilot feed and the 'drain return' which logically do the Tee function without a Tee !

Can't really blame the chap as it's an absolute pig to get at (which is why I didn't do it myself), and he had it in and out several times as originally it came out to have seals replaced, then they found that the seals were wrong, then they found the right seals still leaked, then I found then a second hand one that worked !

I'm going to try swapping the pipe at the spool valve tomorrow unless it's pouring down

The hoses in question are marked '2' in the following pictures, there are a pair for each side, and as you can see at the orbiter where they start with a 90 degree fitting it would be dead easy to mix them up. In the diagram '1' is the rotary orbiter and '3' the flow and return to the track motors.
Title: Re: JCB 803 Saga
Post by: awemawson on August 30, 2015, 03:35:50 AM
Up with the lark, mucked out the pigs, and it still wasn't raining (quite a change from recently) so with no delay I got 'out and under'

Whipped the cover plate off, undid all four pipes (as the servo ones are to the rear of the main drive one), swapped over the servo pipes, replaced the main drive ones all with a minimal oil loss, as this time I knew that a Sharpie pen with a rubber glove over it neatly plugged the pipes  :ddb:

Cleared the deck of tools and drip trays, up into the cab, lifted her up onto the dozer blade and dipper arm so that the track were off the ground, and gave it a try ....

IT WORKS

WE HAVE TWO SPEED TRACKING

 :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb: :ddb:


Rather a relief actually, as if it hadn't been that the chap had inadvertantly reversed the hoses at the Orbiter, then I really would have been stumped for the next move
Title: Re: JCB 803 Saga
Post by: DMIOM on August 30, 2015, 03:42:41 AM
Logic triumphs    :clap:  :clap:  :clap:  :clap:  :clap:  :clap:
Title: Re: JCB 803 Saga
Post by: Will_D on August 30, 2015, 06:45:09 AM
Delighted that it was a simple fix (for once)

Its threads like this that keep me going!

 :proj:
Title: Re: JCB 803 Saga
Post by: vtsteam on August 30, 2015, 08:19:10 AM
Great feeling!  :thumbup: :clap: :beer:
Title: Re: JCB 803 Saga
Post by: awemawson on August 30, 2015, 08:38:16 AM
Thanks for the kind words chaps  :thumbup:

Yes as you say Steve, a great feeling. I celebrated by taking the wife and dogs for a walk round Bewl Water (local large reservoir) followed by a pub lunch

Now I'm told that I have to pick runner beans !

I've a couple of hoses to replace, but they are only on the breaker attachment points to the quick release fittings (I don't have a breaker) and I've already crimped up the hoses, it's just a matter of getting round to it.
Title: Re: JCB 803 Saga
Post by: John Stevenson on August 30, 2015, 10:12:29 AM

I've a couple of hoses to replace, but they are only on the breaker attachment points to the quick release fittings (I don't have a breaker) and I've already crimped up the hoses, it's just a matter of getting round to it.

You don't have a breaker ???????????

You just cannot admit this on a public forum and keep face.

What happens if you decided you have to rip up 2 square acres of concrete ?

The channel tunnel might need blocking up to stop the immigrants ?

You might have a severe case of hemeroids, no make that a very severe case.
Title: Re: JCB 803 Saga
Post by: awemawson on August 30, 2015, 11:05:57 AM
OK John let's qualify that:

I have a Kango electric breaker that shakes the bejesus out of you  :bugeye:

I have a JCB Beaver stand alone hydraulic breaker that will shake the bejesus out of lots of people holding hands  :bugeye: :bugeye:

I have a pneumatic breaker 'road drill' that runs off my '3 gun' 160 cfm 'road compressor' that would shake out any bejesus that may be left from the other breakers  :bugeye: :bugeye: :bugeye:

But no I confess, I don't have a breaker to hang on the dipper of the JCB 803, but if necessary it will run the Beaver breaker acting as it's power pack  :lol:

Does that in any way restore my street cred  :scratch:
Title: Re: JCB 803 Saga
Post by: John Stevenson on August 30, 2015, 11:13:50 AM
Grudgingly, somewhat.   :borg:
Title: Re: JCB 803 Saga
Post by: vtsteam on August 30, 2015, 11:44:38 AM
You have to pick runner beans?????

scarlet?
Title: Re: JCB 803 Saga
Post by: awemawson on August 30, 2015, 12:26:22 PM
Only the ones SWMBO cannot reach  :lol:
Title: Re: JCB 803 Saga
Post by: tom osselton on August 30, 2015, 05:13:28 PM
Its cheap too!

http://www.aliexpress.com/item/Free-Shipping-NEW-60cm-Long-Arm-Reaching-Pick-Up-Claw-Gripper-Grabber-Helping-Hand-Kitchen-Tool/32393776322.html?currencyType=CAD&src=google&albch=shopping&acnt=494-037-6276&isdl=y&aff_short_key=UneMJZVf&albcp=230049721&albag=13539119881&slnk=&trgt=63000991512&plac=&crea=en32393776322&netw=&device=t&mtctp=&gclid=CN38lrHc0ccCFQuQaQodVl4B9A
Title: Re: JCB 803 Saga
Post by: lordedmond on August 31, 2015, 02:50:10 AM
Grow the beans in a heap as they should grow not up sticks the the management will be able to reach them all

Ps
They will be much less woody as the heap keeps the humidity up so they do not dry out

Great repair as is your normal resurrection of the junk/ quality equipment you buy  :lol:


Stuart
Title: Re: JCB 803 Saga
Post by: PekkaNF on August 31, 2015, 05:15:26 AM
That bolt....on the picture before reminds one thing long ago. O-rings on Cetop-valves needs to be quite right and servo valves needs to be mounted pretty much right torque or the spool does not move reliably. On one setup we had problem of oil seeping on valve stack. Checked it once and doublecheeked shema and measurement....should be fine, but it's not fine. Then I checked and measured the bolts...fine, but ends had a slightly crushed thread.....what rhymes with a clacking bell? The threaded holes/threads were just too short (shorter than spesified) and some innovative cad user had reenginered the valve block thread upon on catalog bolt/stack height. Crapity crap! No thin rider/dummy block to mach next longer bolts, needed to get innovative with the bolts and order a new valve block, can't just leave someone else to find what's wrong with it.

For an electrical engineer hydraulics is weird sometimes, because if you can't trust the schema and you can't trace the pipes/hoses you are left armed only with your vivid imagination.

Pekka
Title: Re: JCB 803 Saga
Post by: awemawson on August 31, 2015, 04:20:52 PM
Before I chucked it out I investigated the faulty diesel tanks 'Sender' .

The original was a capacitive one - an aluminium outer tube / housing with an inner tube made from plastic water pipe with a central stainless steel rod. Encapsulated in the large 2" hex nut (which was plastic) was an electronic module which presumably sensed the varying capacitance and emulated a varying resistor. Obviously the electronics had failed. Not much to see by the time I'd squashed it in the vice to crack the potting, but the date 1997 was on the pcb which is right for original equipment, and there were discrete transistors.

No idea how the replacement works - it measures 'genuine ohms' on a meter as the plastic doughnut moves up and down the stainless rod - I assume that the doughnut is magnetic, but what the variable resistive element is, is a mystery to me :scratch:
Title: Re: JCB 803 Saga
Post by: DMIOM on September 01, 2015, 01:54:46 AM
......No idea how the replacement works - it measures 'genuine ohms' on a meter as the plastic doughnut moves up and down the stainless rod - I assume that the doughnut is magnetic, but what the variable resistive element is, is a mystery to me :scratch:

Andrew,

I wonder if its similar to the magnetically-coupled corrosive liquid pumps - a magnet in the float and another magnet on a slider in the core running a wiper up & down a length of constantan or similar - actually I think it might need several magnets (min 3) to prevent too much drag on one side of the core.  Any patent nos. on it?

Dave
Title: Re: JCB 803 Saga
Post by: awemawson on September 01, 2015, 02:31:49 AM
It's in the tank now Dave and I didn't take a look beforehand, so sorry I don't know, but I don't think that there were.