Author Topic: !2 volt DC hydraulic power pack advice please  (Read 383 times)

Offline appletree

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!2 volt DC hydraulic power pack advice please
« on: April 19, 2019, 07:41:48 AM »
Hi all I have a Maxilift 800kg crane fitted to mu LDV tipper truck. The problem I have is that the 12 volt Hydraulic power pack I drawing in air, in self not a big issue however when the crane is lowered (solenoid drain to tank) oil and air escape from the vent.
The Ideal solution is a new powepack, I have tried 2 ex tipper ones but they pump to many LTRs per minute.
All the units I can find are replacements for tippers and are 2 galls per minute, obviously this is where the market is and my requirement is a bit special..
I have guessed the volume of the ram and timed the travel, it would appear I need in the region of 1.5 to 2 LTRs per min.

So the question is, is it feasible to throttle the flow rate of one of the bigger pumps? Is there an expert in these setups out there that could give me some ideas?

I appreciate Throttleing is not ideal, could damage the relief valve seat, wasteful of energy, etc etc.

thanks in advance Phil   

Offline awemawson

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Re: !2 volt DC hydraulic power pack advice please
« Reply #1 on: April 19, 2019, 09:36:48 AM »
Phil, do you have drawings of the units construction. Presumably a seal has gone somewhere and needs replacing.

There are loads of variations of the way they put these units together - perhaps with a few pictures someone may recognise your unit ?
Andrew Mawson
East Sussex

Offline appletree

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Re: !2 volt DC hydraulic power pack advice please
« Reply #2 on: April 19, 2019, 10:22:31 AM »
Hi Andrew
Thanks for the reply, I really think total replacement is the order of the day, itís 1998 vintage, I have been coaxing it all on for some time, itís well worn, brushes, bushes, etc. Has been sounding rougher and rougher.
Maxilift have been less than helpful, the pump unit itself is made by Efel.


Phil

Offline chipenter

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Jeff

Offline appletree

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Re: !2 volt DC hydraulic power pack advice please
« Reply #4 on: April 19, 2019, 04:17:05 PM »
Hi Jeff thanks for the link, I had seen that unit, just thought it might not be industrial enough. Looking at completed link stings on eBay, there have been some secondhand ex tail lift etc we look like the Would probably do.

Phil


Offline mc

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Re: !2 volt DC hydraulic power pack advice please
« Reply #5 on: April 20, 2019, 04:37:15 PM »
I would think 10MPa (~100bar) would be too low a pressure.

You'd really need to find out the maximum pressure of the existing pump (or at least what the pressure relief valve is set to). Flowfit do some cheap hydraulic power packs, and could probably recommend something, but they'd very likely want to know specs, especially as lifting is involved.

Offline appletree

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Re: !2 volt DC hydraulic power pack advice please
« Reply #6 on: April 21, 2019, 12:01:07 AM »
I would think 10MPa (~100bar) would be too low a pressure.

You'd really need to find out the maximum pressure of the existing pump (or at least what the pressure relief valve is set to). Flowfit do some cheap hydraulic power packs, and could probably recommend something, but they'd very likely want to know specs, especially as lifting is involved.

I think probably in the region of 160 bar, will have to see if I have a gauge, had a look at Flowfit site, prices seem ok.cannot fid any power packs or even pumps small enough in any form.

I still keep coming back to the original question.
Phil

Offline naffsharpe (Nathan)

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Re: !2 volt DC hydraulic power pack advice please
« Reply #7 on: April 21, 2019, 05:23:40 PM »
I would say yes to throttled flow. The Flotech ZZ004234 Double acting, Double solenoid at 5ltrs/min should do. Increase the return pipework size and expect to replace the oil frequently. You could possibly leave all as is and use a 3 port valve upstream of the pump to reduce flow, port 1 being input, port 2 being output and port3 being a return to tank. Just thoughts. Nathan.

Offline appletree

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Re: !2 volt DC hydraulic power pack advice please
« Reply #8 on: April 22, 2019, 04:58:49 AM »
I would say yes to throttled flow. The Flotech ZZ004234 Double acting, Double solenoid at 5ltrs/min should do. Increase the return pipework size and expect to replace the oil frequently. You could possibly leave all as is and use a 3 port valve upstream of the pump to reduce flow, port 1 being input, port 2 being output and port3 being a return to tank. Just thoughts. Nathan.

Thanks, the current system runs the pump when lifting, driving a single acting ram.
I did a bit of work yesterday, in the absence of a pressure gauge I filled a 1 tonne bag until the crane ceased lifting.
I fitted the small pump I have and tried lifting the same load, I only had to remove 2 off 400mm paving slabs then it was ok. The crane lifts 800kg on it shortest boom length. Admittedly I was on the full extent but the test is valid, I think the time taken to lift will end up taking a shade long, I was limited by the tank volume, if I use this pump I wil need to make a bigger tank.

Having said the above I fancy the idea of using one of hand he larger pumps I have.
Is the 3 port valve you mentioned effectively a needle valve and a relief valve? Does it include a bypass for reverse flow?


Phil