770 hydraulic issues

Ron force

Member
I have a 1968 oliver 770 with dual hydraulic capabilities. question is what could be wrong with the hydraulics, oil level is good but have no pressure. There is a electric cord attached to the control housing that has a 6 ft lead on it with a 4 pin connector that is not connected to anything and i have no idea where it should be connected or how it effects the hydraulics. Any ideas or explanations would be greatly appreciated.
 
Did you do a pressure check with a gauge? I'm not familiar with a 770 but have a 1550. It could be the pump, relief valve, or control valve. Or something else. Mine was pushing 500 psi when I got it. Thought it was the pump. Pump was OK but the seals were shot. New seal kit fixed it up. Now it runs 200 psi with no hydraulic load. The lead is for the hydralecric connection to a remote cylinder, does not affect hydraulic pressure. Post more of what you have tried.
 
Further to what Mike said, the wires are for the Hydra-lectric system- it was a system whereby you could pre-set the depth of your implement by setting a depth stop on the cylinder by just pushing a button. Required a special Oliver hydraulic cylinder. Most have long since been abandoned, and I'm surprised the wire is still there on yours. It has nothing to do with the hydraulic system itself. I'd start by testing the pressure of the pump.
 
(quoted from post at 06:40:23 07/27/17) I have a 1968 oliver 770 with dual hydraulic capabilities. question is what could be wrong with the hydraulics, oil level is good but have no pressure. There is a electric cord attached to the control housing that has a 6 ft lead on it with a 4 pin connector that is not connected to anything and i have no idea where it should be connected or how it effects the hydraulics. Any ideas or explanations would be greatly appreciated.

Could you check the pressure? Plug a 2000 psi gauge in the remote and try it. A good pump will make 800 to 110 psi. A pump that is worn will likely have the end plates in the pump chewed up. You will need a rebuild. Bad bearings can also allow the gears to contact the center plate allowing oil to slip by.
oliverhydraulicpump.com
 
yes the pto works, so are you telling me the pto needs to be engaged to make the hydraulic pump run. or does the pto
engage after the point where the pump is driven on the shaft!
 
the pto engages after the pump, the long shaft drives the pump all the time and the pto is engaged by a clutch pack in the back. Chuck
 
that what I was thinking on the pto, so far we checked the hydraulic lines for pressure by holding the lines when the
lever was moved. So now we can hook up a pressure gauge and see what is there, my understanding is 800 to 1000 psi
which I have a gauge for.Thanks all for the information, will check it out and get back to all
 
If someone else had it and redone the pump, could installing the large gear shaft backwards not engage the splines ?
 

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