973 track loader no reverse on right side

[pasinead1991]

Hi everyone I have a 973 track loader that will not reverse on the right track motor a check by pressures I'm getting no pressure on the Rivese side I pulled out the axel and I can see the shaft turning when in forward and jotting when in reverse. The motors have been changed and transmission was removed to repair tranny mounts I opened the top cover replaced all lines and hoses in side the tranny and resealed the servo cylinders while the trans was out. Any help would be great. I also replaced the seals on the replenishing valve.

 

[sealark37]

Have you checked the foot pedal and mount for full range travel? The bearings in the pedal mount can lock up tight with a little corrosion. Regards, Clark

 

[pasinead1991]

Yes pedals and linkages are good. good pressure when forward is selected up to 5200 psi on both sides when I do the stall test but only 1500 in reverse on left side and 0 psi on right side. No case pressure in motors when performing tests. Any help would be great thanks.

 

[pasinead1991]

Is there pressure valves that would only effect reverse for each side

 

[Cmark]

If you resealed the servo cylinders you would have had to remove the pump head. Did you get the servo cylinder anchor pin back in correctly?

There are two main relief valves, one left and one right. The same valve relieves both fwd and rev on one side so no, your relief valve shouldn't be the problem.

 

[pasinead1991]

Serial # 32z00495. The pressure should be the same in forward and reverse on same side is this correct.

 

[pasinead1991]

If the motors are good no internal leakage where else could I loose the oil supply from pumps to track motors. Thank you for your help.

 

[Cmark]

Serial # 32z00495. The pressure should be the same in forward and reverse on same side is this correct.

If you're building enough pressure to hit the relief valve, yes.

 

[Cmark]

If the motors are good no internal leakage where else could I loose the oil supply from pumps to track motors. Thank you for your help.

"IF" the motors are good then you could be losing flow at the pump port plates, but seeing how you are getting good pressure in FWD that scenario seems unlikely. It sounds more like the pumps aren't stroking.

Did you remove the pump head?

 

[pasinead1991]

Thank you for your response I will double check tomorrow I removed the plates on the right side of the trany so I could see the servo cylinder and it moves the same distance when I put it in reverse as in forward.

 

[pasinead1991]

Ok I stewed in the sink valve on the left side of the trany to separate the loops and checked pressure left side pressure is 5200 psi forward and reverse and right side is 5200 forward and 0 psi in reverse and I have 0 psi case pressure on track motors. Any ideas. Thank you.

 

[Cmark]

Use the LH steer linkage to neutralise the LH pump and put the RH pump in reverse.
Is the underspeed valve raising? Does the RH pump sound like it's doing anything.
Disconnect the RH drive hoses and install blanking plates to dead-head the pump. Any difference?
Did you dismantle the RH replenishing valve?
Again, did you remove the pump head?

 

[pasinead1991]

I'm making plates now to do just that. No I didn't remove the head and yes I resealed the replenishing valves both sides. The right side pump sounds like it's under load in forward but notting in reverse. If it was the pump or port plate I would have 0 psi forward or reverse is this correct. What's in the pump head that could cause this. Thanks for your quick response.

 

[pasinead1991]

The under speed valve is raising also

 

[Cmark]

The right side pump sounds like it's under load in forward but notting in reverse. If it was the pump or port plate I would have 0 psi forward or reverse is this correct.

Not necessarily so but very likely, yes.

The reason I ask about the head is that it's possible that the servo cylinder wasn't reattached when the head was installed.

If you blank off the drive lines and still get zero pressure in rev, and it doesn't sound like the pump is doing anything then I would say either it's not stroking or there is a problem in the replenishing valve. Can you look down at the servo cylinder and swash plate to see it they're moving?

Did this problem occur since you installed the tranny or was it there before? I'm also thinking maybe the piston has come adrift inside the servo cylinder.

 

[pasinead1991]

The servo cylinders are definitely anchored correctly I checked that and yes I can see the awash plates moving back and forth when I select forward or reverse. Won't get to block off hoses today. I removed the servo cylinders without removing the pump head got them out easy enough from the top had to remove servo valve assemblies. The original problem was the brake unit came apart in the final drive on right side and wiped out the splines on the track motor shaft. Rebuilt motor brake unite and replaced bearings on final drive. Installed every thing and this is where we are. No reverse on right side

 

[pasinead1991]

All other pressures seem to be within specs

 

[pasinead1991]

I will double check the replenishing valve again and let u know.

 

[pasinead1991]

Hi sorry I did not get back to you guys sooner but I checked the replenishing valves they look good I blocked off the hose ifor the reverse on the right side track I still got no pressure but when I screwed in the sink screw on the left side of the transmission I got pressure I put sink screw back and got no pressure any ideas. I got up to 5000 PSI with sink screw screwed in and hose blocked off when hose is not blocked off and sink screw in normal position no pressure