Hi All, I have CAT M315 with bit of a steering problem. After replacing seals in steering piston (by customer/third party), excavator started pulling to the right and steering wheel had to be constantly turned to the left to keep it straight on the road. I had a look today thinking there might be air trapped in there somehow, but it is a fairly somple system, and air should bleed itself out. Can anyone confirm this for me, or is there a bleeding procedure after cylinder was open? Another thing that intrests me the most, that I don't know , do these cylinders overflow when they come to a hard stop (when fully extended / retracted)? To check if the cylinder is passing, I loosened opposite return hose on it, RHS hose and turn the teering completely to the right, after it hits hard stop, I still get oil flowing from the loose hose. Looking at the diagran, there should be nothing coming from the steering wheel valve. So this leads me to believe that cylinder is passing, unless they are built to overflow back to the tank when at the end of a stroke, this is something that I don't know, and if someone can please clarify. Given that nothing else was touched, i'm tipping on damaged seals during installation, or air in the sysem (doubtfull tough). To make matters worse (or better), after me mucking around with it, letting oil out ext. Steering actually improved, but not yet what it was. It started wotking both ways, but with about two turns of steering wheel before wheels start moving. now, I don't know if seals start working better as the tempaeature rises, or did I actually bleed some air from the system. Thanks all!!!
Nope, back to same as before, just had a call from the customer, constantly to the right.
This is a wheeled excavator, correct? I've only worked on 1 of them. A rare bird in these parts. I seem to recall they use a Spicer axle similar to a telehandler. In that case, I'd say you shouldn't have oil passing through it. Makes sense, if oil can bypass the seals or cylinder (both sides of the steering rod are equal diameters), then the steering cylinder will essentially float and naturally drift to whichever side that pulls it. Post your S/N, maybe someone with SIS can confirm the steering cylinders aren't supposed to bypass.
You are right, wheeled excavator with spicer kind of an axle. Serial is 7ML01682. One of my favourite machines. Worked hard and no periodical maintenance what so ever. Keeps me in business with these emergency repairs, especially if somebody else screws it up before I come to have a look at it.
They're not built like that and shouldn't pass oil when the cylinder is at full stroke either one way or the other. See parts diagram below. I think you have a leaker.....
Nige you are the man!!!! I'll do another test where I'll remove one hose completely, just to make sure I'm not getting oil from the valve, and if it's coming from the cylinder, out with the piston for new seals.
Due to improper installation, internal piston seals were damaged. Seals replaced, all good!!!