Author Topic: JCB 803 Saga  (Read 72740 times)

Offline tom osselton

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Re: JCB 803 Saga
« Reply #175 on: August 28, 2015, 12:38:47 AM »
I'm following along too. .... Thinking CANDY APPLE  RED!

Offline DMIOM

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Re: JCB 803 Saga
« Reply #176 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

Offline awemawson

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Re: JCB 803 Saga
« Reply #177 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:
Andrew Mawson
East Sussex

Offline awemawson

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Re: JCB 803 Saga
« Reply #178 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:
Andrew Mawson
East Sussex

Offline awemawson

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Re: JCB 803 Saga
« Reply #179 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
Andrew Mawson
East Sussex

Offline awemawson

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Re: JCB 803 Saga
« Reply #180 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.
Andrew Mawson
East Sussex

Offline awemawson

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Re: JCB 803 Saga
« Reply #181 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:
Andrew Mawson
East Sussex

Offline vtsteam

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Re: JCB 803 Saga
« Reply #182 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:
I love it when a Plan B comes together!
Steve
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Offline TD4

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Re: JCB 803 Saga
« Reply #183 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. 

Offline modeldozer

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Re: JCB 803 Saga
« Reply #184 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

Offline awemawson

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Re: JCB 803 Saga
« Reply #185 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.
Andrew Mawson
East Sussex

Offline JD

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Re: JCB 803 Saga
« Reply #186 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
If you cant fix it hit it with a bigger hammer

Offline awemawson

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Re: JCB 803 Saga
« Reply #187 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.
Andrew Mawson
East Sussex

Offline awemawson

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Re: JCB 803 Saga
« Reply #188 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
Andrew Mawson
East Sussex

Offline DMIOM

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Re: JCB 803 Saga
« Reply #189 on: August 30, 2015, 03:42:41 AM »
Logic triumphs    :clap:  :clap:  :clap:  :clap:  :clap:  :clap:

Offline Will_D

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Re: JCB 803 Saga
« Reply #190 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:
Engineer and Chemist to the NHC.ie
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Offline vtsteam

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Re: JCB 803 Saga
« Reply #191 on: August 30, 2015, 08:19:10 AM »
Great feeling!  :thumbup: :clap: :beer:
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline awemawson

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Re: JCB 803 Saga
« Reply #192 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.
Andrew Mawson
East Sussex

Offline John Stevenson

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Re: JCB 803 Saga
« Reply #193 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.
John Stevenson

Offline awemawson

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Re: JCB 803 Saga
« Reply #194 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:
Andrew Mawson
East Sussex

Offline John Stevenson

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Re: JCB 803 Saga
« Reply #195 on: August 30, 2015, 11:13:50 AM »
Grudgingly, somewhat.   :borg:
John Stevenson

Offline vtsteam

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Re: JCB 803 Saga
« Reply #196 on: August 30, 2015, 11:44:38 AM »
You have to pick runner beans?????

scarlet?
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline awemawson

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Re: JCB 803 Saga
« Reply #197 on: August 30, 2015, 12:26:22 PM »
Only the ones SWMBO cannot reach  :lol:
Andrew Mawson
East Sussex


lordedmond

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Re: JCB 803 Saga
« Reply #199 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