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JD radial piston pump in open center sytem?

wrwtexan

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I am building up a new service truck and mounting a full hydraulic Liftmoore 6K crane on it. The truck is an '06 International 4300 with Allison auto and a Muncie PTO which had been used for propane delivery. My research is showing it to be a 7-900 RPM output which without a speed increaser, won't direct drive a gear pump fast enough. I had been looking at building a gas powered hydraulic sled unit but it will take up a lot of room in my bed. I do have a John Deere 23cm 9 GPM radial piston pump from a cotton stripper salvage job and am wondering if it could be used in and open center system for the crane and outriggers. I would mount the pump under the bed and run a jack shaft to it with an overhead reservoir as it had on the stripper. It would never be able to go to standby but they can handle constant operation. Ford used piston pumps on their smaller farm tractors in open flow. Volume would be reduced as it wouldn't be turning at normal engine speed but it would probably be fairly close to my 6 GPM need. My I&T manual for the tractors that run this pump showed a flowmeter rating of 5.5 GPM at 1000 RPM. Anyone ever tried this or seen it done? Any input is greatly appreciated before I jump off into and unknown build!
 

Delmer

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If you already have the pump and no use for it, I don't see why not. It will go into standby if your relief is set higher than standby and you deadhead or stall the hydraulics, otherwise it should work fine.

Is the objection the cost of a salvaged pump? I'd rather have a relatively simple but well built piston pump rather than a cheaper built even simpler pump.
 

John C.

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The Deere radial piston pumps I'm familiar with use high pressure to hold the pistons off the cam ring that drives them. In an open center system you would never go into standby. Do you have any idea of what the operating pressure might be for your crane?
 

wrwtexan

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Thanks for replies. I have the piston pump sitting on a shelf gathering dust at no further expenditure. All I will need to procure is a jack shaft as I have several salvage reservoirs to choose from on various junked farm machines. These pumps are usually set around 22-2400 PSI to destroke and then a lesser pressure keeps pistons off cam roller until standby pressure drops and pistons fall back and resume pumping. In an open center application, other than reaching standby pressure in a stall, it will always be in operation. One other aspect that is drawing me to this build is a piston pump in theory doesn't drop pressure as RPM's decrease as a gear pump does due to leakby, so a low speed PTO drive wouldn't be a problem other than flow volume. My crane specifies 2750 PSI and 6 GPM (for optimum performance) and these pumps can be turned up in pressure to some degree, enough to meet my need. The big question was mainly will this pump function properly without the deadheading of a closed system.
 

John C.

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I'm thinking it should work even though it never reaches standby. Really when you think about it, the Deere pump is basically a fixed displacement just like a gear or vane pump. It just has the additional provision of being able to go into standby when at high pressure. They used to use horsepower summation in excavators back in the big gear pump days. Mounting and plumbing might be the biggest hassle in the installation.
 

wrwtexan

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Much obliged for idea confirmation! Doing a direct under bed mount and drive and plumbing will be much easier than the gas powered skid I had originally planned to build. Its amazing how quickly I was going to fill up a 4.5' by 15' bed with an air compressor, 6K crane, welder, and then a hydraulic power unit!
I'll have to get the air shift and idle up controls for the truck which shouldn't be too hard to come by. I'll call Vander Haag's where I got the bed and see what they might have salvaged.
 

56wrench

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I personally do not particularly like the jd radial pumps-there are too many potential problems especially older designs such as broken springs in the inlet and outlet valves, valves coming loose in the housing, etc. especially if they are used at maximum flow for any length of time. the early ones were not designed for continuous flow but low flow and high-pressure standby with only occasional max flow. they are not a pretty sight when they grenade and expensive to replace. I prefer axial piston pumps ie.-fixed displacement, variable displacement, or bent-axis. they are also expensive. gear type is cheapest and simplest for this application. if the oil gets too hot you would also need a cooler. just my 2 cents
 

John C.

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I don't know where you had your problems but they were used in Haulpak trucks for the steering a brake system and in over 5,000 hours of operation that I saw, they never gave us a problem. Maybe the application makes a difference?
 

56wrench

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ag tractors( 20,30,40, and 50 series) and 410 backhoes( approx. 5000hrs and above). the ag tractors mostly gave problems when there was a need for continuous max flow like running air seeder fans. the bigger displacement pumps weren't as bad because they weren't running at full stroke unless they were running 2 fans at once. they could also blow the valve plug threads out of the housing if the stroke control valve wasn't set right or stuck(if I remember correctly). the early ones were only set to 2250psi because at that time that was all that was needed. nowadays we need at least 2500 or more in a similar application. if an engine was hard starting ( cranking hard), because of the hyd pump load, an electric destroke kit could be added to the stroke control valve.
 

John C.

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I see your concern. At least wrwtexan will know what to look for should he have a problem.
 

56wrench

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oh ya, the radial pumps usually need a charge pump to supply oil to the inlet. I don't remember how much pressure but I can look in one of my manuals if you need to know- probably about 30 psi
 

repowerguy

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I remember Condor man lifts using Deere radial pumps in open center hydraulic systems, I don’t remember them having a charge pump though.
oh ya, the radial pumps usually need a charge pump to supply oil to the inlet. I don't remember how much pressure but I can look in one of my manuals if you need to know- probably about 30 psi
 

repowerguy

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Yeah no problem 56, it’s been 8 years since I’ve seen, let alone worked on a Condor. I just don’t remember if they had a charge pump, may have had one, memory is foggy anymore .
 

crane operator

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Have you actually engaged the current PTO and tried to check RPM's on it?

And I'll just throw these two other ideas out-

1. I would think a used pto and mated pump would be super easy to source from vander haag's. All those bucket trucks are allisons. And I usually don't give much for used Pto's with pumps.

2. I think what some of these guys are doing with a electric hydraulic pump like a tommy lift or a rollback bed have, would be really slick to use the truck inside a building. Also not have to have the truck running all the time in the field. Put a dedicated deep cycle battery on it and a charger to use plugged in in the shop. Run the truck a little when the deep cycle gets weak out in the field. Have a battery disconnect so you don't drain the truck batteries with the crane battery.

I would think a electric over hydraulic would last quite a while in the mechanic crane use. It's not like you're running it all day long up and down and in and out. Most of the time when we use our 4k, its for less than a minute, then sits still for 5 or 10 and bump up and down placing something. Rarely does it run a lot for a extended period of time. I don't have that on ours, but I've seen pictures of other's, and really could see how that would be nicer than having the truck sit and run all the time.
 

56wrench

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just for curiosity sake I checked my old 772BH manual and min charge pressure oil warm was 3psi at idle so maybe a gravity feed system would work if the oil is not too thick(emphasis on maybe). the jd spec is for Hy-Gard fluid or universal tractor-hydraulic fluid
 

wrwtexan

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As far as charge pressure, on the tractors, they were pressure supplied as the trans is several feet behind and a few inches below the pump. On the cotton stripper, it was pulling straight out of the reservoir filled with red ATF. I have seen and very recently the repaired the damage of a grenaded pump, wow what a mess. That tractor still doesn't have a working rear lift from the shrapnel through the system but that'll have to wait for his time crunch and finances to ease...

Crane op; I will call Vander Haag's and see what they could do for me on a used complete unit. One question though is how common are units which will generate the 2750 PSI the crane calls for? The few I've dealt with are high volume low pressure units on scrap tippers. One other function I plan to use the hydraulic system for is to have a set of remote couplers to run hay balers, plow lifts, and a tractor wrecker trailer, so I think the electric route won't meet my need. With my line of generally farm repair work, I rarely see an enclosed building to work in, much less one tall enough to raise this monster in or tight enough for exhaust to be a problem.

Hatch; If it has cruise, I haven't driven it enough to find out. User manual is gone and I'm not sure what which buttons on the steering wheel do yet.:rolleyes:

Great responses and thanks!
 
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