Austin Western motor grader steering problem

[cgarai]

H
I just picked up an AW Super 300 grader. Serial number 366 16470. I have a couple of issues I'm trying to sort out:

1. The steering is very stiff and "jerky". By jerky I mean the steering wheel feels jerky when trying to turn hard. This does not translate to the front wheels. The system on this machine is fully hydraulic. There is a ram at the front axle and a small cylindrical steering valve at the end of the steering wheel shaft. How do I trouble shoot this system?


2. The circle lock on this machine doesn't stay down, so under load at the blade toe the lock pops up and then allows the circle to rotate. A previous owner cobbled a rope and pulley so that the lock can be puled up, but there clearly needs to be something that holds it in place. The manual I have looks like it is a pedal actuated hydraulic mechanism, but on my machine there is no pedal and the mechanism looks like there might be a solenoid. I have yet to pull it apart.

Thanks!
Chris

 

[ROUSTABOUT]

I've worked on and used some graders. Aggravating when the blade don't hold and the steering don't work. Does it have a gerotor valve on the hydraulic steering or a regular steering box with a directional switch like a ram assist steering? Do you know whether or not piston seals are leaking in steering cylinder? Usually on a gerotor steering if you take it apart, there are Teflon rings with a rubber O ring under them. Usually the O ring is in crumbs and let's it leak between circuits. Causes a little bit of a problem when that happens. I have gotten by with replacing O rings and Teflon rings are always good, unless someone else had it apart and messed one up. I have never bought a manufacturer kit. Always one cobbled together from a hydraulic shop. Very similar to swivel joints on log loaders and track hoes, excavators, etc ... If it doesn't have a gerotor valve, well, I guess you can take all this information and add $ 1.69 with it and get a coffee at McDonald's.

 

[cgarai]

I believe it must have a gerotor because the only connection to the front end is hydraulic. When the power is off I can turn the steering wheel and the front wheels slowly move. The feeling is bumpy or jerky which I'm guessing is the pulses of the gerotor? When the engine is running it feels the same, but it provides some assistance.

How hard is it to disassemble the steering valve? It looks complicated inside from the youtube videos I've watched.

I looked at the circle lock and there is a solenoid (currently disconnected) that pops it up, but I don't see how when it's relaxed and the lock is in place how it could keep the lock from squeezing up under assymetrical pressure on the blade. The teeth on the lock look tapered. I can't decide if they are worn or were designed that way.

Thanks,
Chris

 

[cgarai]

I bench tested the circle latch solenoid and it seemed strong, but it doesn't open the latch. I should have jiggled the circle control and it would have popped up. The problem is that the teeth on the latch are tapered and with load, grease and vibration they pop up out of the circle teeth. There doesn't appear to be a mechanism that was intended to hold the latch in place. Perhaps the teeth are worn and that's why they are tapered? Should I grind the taper out?