JD 955 implement pump (gear pump)

[Mechanos]

Cleaned up the gear pump to remount to the tractor tonight on my basket-case project tractor. Is the gear pump suppose to be spin freely? or should have some resistance when turning the input shaft. I can turn it over by hand, but it does require a little effort.

 

[wdchyd]

Cleaned up the gear pump to remount to the tractor tonight on my basket-case project tractor. Is the gear pump suppose to be spin freely? or should have some resistance when turning the input shaft. I can turn it over by hand, but it does require a little effort.

You should feel some resistance when turning....some new pumps can't be turned with your fingers but require help with pliers or such....

 

[Mechanos]

OK... good. I can't turn the bare shaft by hand, but If I put the pump shaft coupler on the shaft, I can get enough of a grip in it that I can turn it over by hand. Base on your info, it sounds like it's good to go.

 

[dfkrug]

I agree, it should be hard to turn by hand. Before you put it back in,
you may want to open it up and look inside. The internal condition
(scored rotors?) will tell you something about the maintenance of the
tractor. The pump could work and yet not be able to put out the
specced flow and pressure (7+GPM and 2500psi as I recall).

 

[J_J]

I had a pump that would pump the GPM's, but only about half pressure. Tore it apart, and it was about half dead. Only put out half of the specified psi.

 

[Mechanos]

Thanks for the advise guys. I really need to get the tractor moving under it's own power for now, so I'm just going to give it a try as is. If it does need repair or replacing, it's super simple to remove since it just mounts on the end of the rockshaft housing with four bolts.

 

[dfkrug]

All my ex-rental tractors were a bit down in implement pump pressure
output. Since none had damaged pumps, I attributed the low pressure
to "tired" RV valve springs. A before-and-after pressure guage test,
with a slight adjutment of the RV and I was back on spec.

 

[Mechanos]

All my ex-rental tractors were a bit down in implement pump pressure
output. Since none had damaged pumps, I attributed the low pressure
to "tired" RV valve springs. A before-and-after pressure guage test,
with a slight adjutment of the RV and I was back on spec.

Can I simply plug a gauge into one of the SCV output quick connects and check the pressure that way (by operating the valve of course)? Or do I need to tee into a line somewhere?

 

[J_J]

Just plug it in the QD's

 

[kennyd]

Can I simply plug a gauge into one of the SCV output quick connects and check the pressure that way (by operating the valve of course)? Or do I need to tee into a line somewhere?

That is the way to do it...you want to "deadhead" the pump (for a few seconds only) to read the PRV setting.

 

[dfkrug]

Can I simply plug a gauge into one of the SCV output quick connects and check the pressure that way (by operating the valve of course)? Or do I need to tee into a line somewhere?

If you do not have a QD fitting, you can also just disconnect a hose from
a FEL cyl and put a guage there. Those fittings are cheaper. You do
need to have the work circuit you use at the end of its cylinder's stroke
(extend or retract) so the RV opens. I also cap the open fitting to avoid
spills. Then start the tractor and operate the FEL valve.

 

[Mechanos]

If you do not have a QD fitting, you can also just disconnect a hose from
a FEL cyl and put a guage there. Those fittings are cheaper. You do
need to have the work circuit you use at the end of its cylinder's stroke
(extend or retract) so the RV opens. I also cap the open fitting to avoid
spills. Then start the tractor and operate the FEL valve.

I dont' have a loader (yet) so I'm just going to plug the gauge into one of the QD's. I have a bag full of the male QD's that I can just screw a gauge directly into.

 

[kennyd]

I dont' have a loader (yet) so I'm just going to plug the gauge into one of the QD's. I have a bag full of the male QD's that I can just screw a gauge directly into.

Here is a picture of my gauge, couldn't post it earlier from work:

 

[Mechanos]

Well, the pump appears to be fine. I got the tractor running tonight and took an open ended hose and attached it one port at a time and flushed out all the SCV lines. Then I plugged my gauge into one of the ports and the gauge peaks a little over 2500 psi before the PRV opens and pressure starts to bleed down. If I continued to hold the valve open, the pressure would bleed down to about 2200 psi.