ok so this is a bit different, I'm sure. I bought this excavator cheap because the guy before thought he would save some money by cutting corners. The bucket hydraulic cylinder was leaking bad so he took the cap off and wrapped string around the shaft at the output end to try to help seal the leak. Needless to say, the string came loose and is now lost in the hydraulic system somewhere. None of the other hydraulics are affected but there is no movement at all on the bucket control now. Without stripping this machine to the frame and starting over, does anyone have any idea where I should look to find this blockage?
It would seem that if he wrapped only under the rod cap to stop or reduce the leak, then the pressures would push the string OUT of the cylinder, not in. If, on the other hand, he wrapped the rod piston inside the cylinder the string would end up in the system and eventually in the hydraulic filter or screen. This would impact all functions. No movement at all on this one cylinder indicates instead that the cylinder piston seal is missing, or there is no pressure/flow going to the cylinder ...check upstream. I would expect that a local hydraulic shop service guy could find and resolve the problem much faster than you or I could.
yes, the string would have been pushed out of the cylinder. It does seem like the engine is running a bit rough as though the string has made it to the pump but, nothing else is affected. It may be inside the valve body spool valves, but I am just guessing at this point
I would think even if the piston seal inside the bucket cylinder is non existent you would still hear the pump stroke somewhat or make some kind of noise like it's trying to do something. Is that the case? If a cylinder is bypassing there's a good chance you'll feel it by placing a hand on the cylinder roughly where the piston should be. You could also crack a line if you know how to release system pressure first. How accessible is that main control valve?
I feel nothing. I think I have tracked the problem to the valve body. It appears to be a cable activated spool valve that I need to pull to look for blockage. I have not dealt with these before and would appreciate someone with know how to instruct on the removal of this spool
Eliminate the cylinder first.
Good luck with that. You mentioned you think you've tracked the problem to the man control valve, how? If you're sure maybe post some pictures of the control valve. I'm imagining a cable connected on one end of the spool and a cap on the other end that can be removed where the spool/springs can slide out. How accessible this is I have no idea.
I followed the lines through the body back to the main control valve box. First pic shows outside of spool valve (held in place by allen screws) second shows cap on inside end.
To check the spool it looks like that cap will have to come off. That will most probably be spring loaded with shims in there also. Again I can't tell how accessible it is but it doesn't look fun. If this is cable operated where are the cables? Are you sure it's not pilot operated? As Vetech alluded to I'd put inspecting this spool further down in the list of things to eliminate. If it's cable operated, make sure the cable is moving the spool. If it's pilot operated make sure you have pilot pressure at the spool first, etc.
On second looks the cables appear on the bottom left of the second pic just out of focus, if I see correctly. I'm also taking your word for it that the cap is the bit you circled. At first glance it looks like a line relief. Hard to tell in those pics.
I am back on this project again. The spool valve is hydraulic operated. I need to pull it out. Can someone assist me with the procedure? Is there only a spring under the cap? Is there anything of concern taking the pilot line off? All tips and help muchly appreciated.
it is the spool valve. It is stuck in the open position. With lines off it shoots fluid in the air. It must come out.
You should be able to pull the spool out of the valve by removing the pilot line on the side of the valve body with the larger cap. The return spring is on one end of the spool and that’s why one cap is larger. The string has probably lodged itself in the spool lands and won’t let the spool move so it may be difficult to get the spool out.