Auxilliary hydraulic pump for FEL- what size pump?

[Pete O]

I have an old Ford 4100 that I spent considerable time and money rebuilding a few years ago, including a new hydraulic pump. Last year I overhauled the FEL, including adding a 3rd function, and this year I built a grapple which has been an absolute boon. When I bought the tractor, it came with a PTO-driven auxilliary power pack that had been used to power the FEL. It is essentially a big steel tank that mounts on the 3pl and has a geared pump inside it driven off the PTO. When I was overhauling the loader, I pulled the pump out and cleaned out the old milky oil and gunk, stripped down the pump and cleaned it out but it is, not surprisingly, quite worn. I decided to reassemble the unit with fresh oil and see how functional it would be.
I now find that, unsurprisingly, the worn-out pump lacks power. The tractor's own hydraulic pump lacks the flow to move the FEL and grapple at a good rate (I have remotes on the tractor so I can power the FEL when using the 3pl / PTO for other implements).
I plan to replace the pump in the auxilliary hydraulic power pack. I am seeking advice on what size pump would provide a suitable flow rate to give good functionality to the FEL and grapple. The old worn-out pump in the aux unit is, according to my measurements and an online calculator, approx 19cc per rev. I don't know what this equates to in GPH / LPM etc.

 

[oldnslo]

To figure flow in LPM multiply displacement in cc/rev by operating RPM then divide by 1000

I suspect there was some increase between the PTO and pump on that power pack so you have determine what that ratio is to know the pump RPM.

 

[Pete O]

Thanks, it does have a step-up gearbox but I did not record the gear ratio when I had it apart. I'll pull the pump out of the tank in the next couple of days and figure out what the gearbox ratio is.

 

[Zebrafive]

My JD 2030 has 1.38 cubic inch pump which equals 23 CM3 so approximately 1.2 times larger than 19 CM3 pump.
It produces 9.5 GPM at 2100 rpm.
There is an optional pump, 2.40 cubic inch, 50 CM3, that produces 18.5 GPM at 2100 rpm
Once you determine your pumps rpm, you can compare to these numbers
I think you will want 10 GPM or more
The 2030 has a 60 PTO HP engine. You need to take inconsideration your HP too.

 

[oldnslo]

Pete
Another option is figure flow rate required based on desired lift time. You can then use this information to size your pump.

you also need to consider flow rating of your loader valve so that you don’t try to run 100 LPM through a 50 LPM valve

Formula is:
flow = cylinder velocity times cylinder area

big thing to remember is there are two lift cylinders so figure flow for one and double that number.

 

[Pete O]

I figured out the required flow rate in order to roll the bucket through it's full rotation (about 220 degrees) in 8 seconds would be about 29 litres (7.6 gal) per minute (this would also close the grapple in about 2 seconds which might even be a shade too quick). I need to find out the gear ratio and a suitable speed so I can figure out what size pump will do this.
Info about what size pumps are on other similar setups that work well, is very handy to know in order to confirm I am in the ballpark.
The flow rating of the valve is a good point- would it be marked on the valve? I bought a new valve for the loader rebuild and to add a third function but it sat on my shelf for a few years and the sale info is long gone.

 

[Dave M7040]

Don't forget the power requirements for the pump you select. Often during these projects the owner focuses on quick loader action and selects a pump which is too big for the tractor pto/engine to power.

The loader valve flow capabilities are part of the valve specifications which are on web sites and pieces of paper. The valve flow capabilities at 3,000 psi will be a lot higher than if the valve is operating at 2,200 psi. Better to have a valve slightly smaller than the max flow as this provides precise motion control. Further, rare to be using the loader with the tractor engine at max rpm's

Dave M7040

 

[Pete O]

Thanks for the replies. I've figured out a few things so far; the loader spool valve that I have is rated to a 45l/min nominal flow; the pump is geared up at just over 3 to 1, i.e. the pump spins approx 3.1 turns for every turn of the PTO shaft. It is a DIN mount which means that a replacement pump with this mount style is readily available in various displacement sizes.
The tractor is rated at 45 hp at the PTO.
I measured the rams, the curl rams are 2.5" bore x 24" stroke and the grapple rams 2.5" x 6". This makes the volume to extend the curl rams 118 cubic inches, 1.93litres. 2 rams, 3.86 litres. I think a reasonable time to roll the bucket over (it rolls through about 220 degrees) is about 8 seconds, or 0.133 minutes, 3.86 /.133 makes it 29 l/min. That would close the grapple in 2 seconds.
A 25cc pump geared at 3.1:1 at 540RPM would flow approximately 42 LPM; given that, as stated above by Dave M7040, I don't generally run the thing at full noise, I'm thinking this would provide a good working rate at reasonable working revs.
If the 60hp JD2030 can power an optional pump with a 70LPM flow, I'm thinking my 45hp should be able to run 42LPM easily enough.
Am I missing anything? Does this all sound reasonable?

 

[Zebrafive]

That's why I listed my 2030 PTO HP. To let you know what size pump was used for that HP. The 45PTO HP JD 1530 also uses a 23 CM3 pump, but no optional larger pump was offered.
I usually run 1500 rpm for loader use, so I am at about 75% of rated flow, so at PTO speed of 540rpm, about the same as me running 1674rpm.
I have not timed my grapple closing time, but would estimate it takes longer than 2 seconds. I don't think you need a 2 second closing time, that seems very fast.
What is your engine speed for 540rpm, at the PTO? For my 2030 it's 2100rpm

 

[Pete O]

Yes I think 2 seconds is probably too quick but that would be at the full 540 RPM at the PTO; I have not measured engine RPM vs PTO RPM, one of the things on my list to check out; I have an analogue RPM gauge and have been wanting to check engine RPM against the tacho since refurbishing the instrument cluster. The only time I ever seem to think of doing it is when I'm inside at the computer.
I generally run the tractor pretty slowly when using the loader and the grapple otherwise it is very hard on the clutch. Would be nice to get a decent speed in the hydraulics without having to rev the guts out of the thing.
I have ordered a 25cc pump off a UK seller, even with shipping it is way cheaper than I could get one locally and shipping from the UK to Australia usually beats the time I can get one from my nearest major city.