Champion 710a steering issue

[jpstucky]

Hello All,

Our city has a 710a Champion grader 1991. Recently, the steering has begun to act up. When the grader starts up cold, the steering cylinders react to the steering wheel with only a little lag in reaction. As the system warms up, the reaction gets less and less until there the steering wheel can be turned continuously in either direction with little to no response at all. At the advise of a local tech, the steering valve was replaced. This did not resolve the issue. I'm curious if any of you would have a recommendation on the next best place to start? In my opinion, these are some possible culprits.

1.Hydraulic pump. (However, the brakes and clutch seem to work fine--am I correct in seeing from the schematic that the pump supplies flow to steering, clutch and brakes).

2. Seals in the steering cylinders. I feel like this is another area that as the oil warms up would get worse. However, the cylinders also appear to be hooked in Master/slave set up. I think it would have to be both cylinder seals bad for it to react that way?

3. I'm curious about the cushion valve near the cylinders. If I understand it correctly, if the cartridge in this is bad it could allow oil to completely bypass the steering cylinders. Perhaps simply pulling the cartridge out would give us a clue.

I'd appreciate any ideas for testing/troubleshooting you could give.

Thanks!

John S.

 

[Welder Dave]

I'm not sure the cushion valve is for the steering but maybe. You might have an issue with the orbitrol/steering valve the steering wheel attaches to. May need new seals or rebuilding. How does it steer when you pick the front wheels up? Might be good to do some pressure checks.

 

[jpstucky]

Thanks Dave. The orbital valve was actually replaced but did not resolve the issue. Lifting the front up is a good idea. Also, the schematic in the service training manual states the the cushioning valve will allow the steering hoses to interconnect if the pressure on either side is greater than 1200 psi. I'm suspicious that if something is wrong in that valve the oil could completely bypass the steering cylinders.

 

[Welder Dave]

I'm not sure how cushion valves work but maybe if something is stuck they redirect the oil. Maybe you could bypass the cushion valve just to try the steering without it. I've got a lock/cushion valve on a ripper. When I went out to clear my driveway the ripper was down. Odd because it always stayed up and when I went back out a few weeks later it was still up. I wondered if maybe I lowered it just slightly so it wasn't tight against the ripper frame? Thinking maybe it depends on the last way the valve was activated. If I lifted the ripper then it doesn't creep. If I last lowered it slightly it creeps.

 

[Cliffy]

Continuous spinning of the orbitrol when hot sounds like steering cylinders to me. Easy way to check steering cylinder is hold it on the lock (if you can) and feel if the cylinders get hot. Or crack the opposite hyd line.

 

[jpstucky]

Thanks Guys--gonna try a couple of those things this weekend and will report back.