Cat 955K hydraulics.

Oil level should be maintained in the sight glass.
What viscosity oil are you using? Should be SAE 10W.
Original pump spec is 50.4 gpm, 1,000psi @ 1830 rpm with engine at 2000 rpm.
1/2 speed rating (915 rpm) is 24.3 gpm @ 1,000 psi.
Cat runs closed system to utilize air cushion to limit hydraulic shock.
At 540 rpm I'd say your running the pump too slow.

Hi old magnet cheers for the info. Yes I understand pump might be going to slow, I’ve got some photocopies of hydraulic system specs out of the manual.

What I don’t understand though is that surely when the pump is running, regardless of speed there would still be a marginal amount of oil flow, given there is no load? Or is there a sort of check valve that will only open and allow pump flow at a certain pressure?

Yes I noticed the sight glass, which is abouve the baffle. Would it need to be fill up to there to allow any operation?

I guess I’m just wondering if I can get by with only adding more oil, or only increasing pump speed.

I do eventually intend to gear up the pump to get better cycle speed, just hooked it up as so to check everything works.

I would suspect the pump outlet is deadheaded or pump cartridge is shot as in no vanes left if its not moving any oil.

It is certainly an open center pump and should pump oil anytime the shaft is turning. When you pull a spool, the low pressure circulation is blocked and diverted to one side of the piston, making the cylinder move.

I wonder if you might have the cylinder(s) hooked up to oppose each other or the hoses hooked to ports of two different spools. I have seen the same situation by cross connecting hoses from farm implements.

Also possible that you have a linkage problem and a spool is not in neutral.

Vane type pumps are not a positive displacement pump, they depend on a certain amount of centrifugal force and pressure to load the vanes as Josh stated above. They have a very steep rpm to displacement curve and drop off rapidly below certain rpm. They are also sensitive to oil temperature and viscosity. They do not pump at all with high viscosity oil and cold temperatures.

Thanks all for the help.

Okay, so upon checking the oil is “Castrol hyspin aws 46” I’m pretty sure that means it’s 46 weight oil. So that’s probably a large part of my issue. I bought the oil on discount several months back, figured an old machine wouldn’t be too fussy!

I guess that’s the reason why the pump is apparently producing no flow.

But now just wondering whether it does need to be up to sight glass in order to function.

Second queustion, what is the system pressure for this machine? I always assumed it was 3,000 psi but after some research I’m a bit doubtful.

ISO 46 is equivalent to SAE 20 wt engine oil.
I've used that in some vane pump applications and got nothing until the oil warmed up.
Recommended SAE 10 wt is equivalent to ISO 22/32. ISO 32 is about as high a viscosity as you want to go (for tired pumps).
As I stated in the 955K pump specs, system pressure is 1,000 psi.
The tilt cylinders are 5" diameter, a good size for splitter application but need 2,500 to 3,000 psi source to make the tonnage for splitting big stuff. I doubt the cylinders are rated for that pressure.
I run 5" cylinder on my splitter at 2,500 psi at about 2,500 rpm with two stage gear pump (3,000 psi & 3,600 rpm capability). Haven't seen the log yet that would stop it.

Ah sorry I see now where you said 1000 psi. The cat guy said it was 3k and a few others I spoke to. This is a “high production” splitter, will split 8-9 peices per stroke. The two cylinders are in parrallel with each other, pushing a sled contained by two parallel columns, which in turn pushes the round into the knives.

If it doesn’t have enough power I can just trade the cylinders I’ve got for bigger ones or add a third.

was just made aware our 2010 jd has 1000 pto speed, I’ll hook it up to that and see if anything functions. If not I guess I’ll be sourcing some different oil.

Would like to see some pictures of that set up!
What type wood are you splitting, Gum??