Good day all Looking for a little help with my machine. very week blade and swing operation, swing motor and pilot system gear pump are new. I can hear the fluid bypassing over the pilot system relief valve at idle. Took it apart and it looks like one o-ring is gone. In the attached photo there is a small metal ring where I think an o-ring should be. Just looking for someone who is a little more familiar with valve construction to second my opinion. Open to other thoughts as well, thanks in advance Grant
Good day Can you see the maker & model of the main control valve that could help to provide information, normally a servo system relief valve is active while the motor is running. Kind regards Uffex
thanks for the reply The valve itself has 21013-30761 which is a Kayaba part number (obsolete) and then 180 027 304 below. I will see if i can identify the main control valve
Upon closer inspection of the circuit, the swing motor and blade (both very, very slow) receive power from a gear pump mounted on the back of the double piston pump, not the little pilot pump as I had thought. Makes more sense, there is no way that little pump would have the output needed to for blade and swing. The port I took a pressure reading from was the output of this section of pump, not the pilot pump (which in turn is mounted to the back of the gear pump..). I'm not certain there is any adjustment for the gear pump output but starting to think it may be the problem. I can sure hear something bypassing and the hydraulic fluid heats up hot within about 20 min of operation. Have not ruled out a valve body issue on the blade or swing either though as something is heating up the fluid quickly.
Good day The combination of the circuits from a common pump can most proably be either a pump section failing or a leaking relief valve. If you can post a few photo's of the pumps & Main valve I will try to help some more. Kind regards Uffex
thank you - I am away for a few days but will post up some more photos when I'm back.
Been away for a while but back at it now but more trouble.... suddenly lost all bucket functions - boom, arm and bucket curl. Dead. The articulating boom (foot pedal) works fine as do the travel motors in low and high speed. Each travel motor is powered by a separate half of the 2 section axial piston pump as is the articulating boom so I don't think* the pump let loose. These functions are all pilot hydraulic operated so I did suspect the pilot pump may have died although it only has a few hrs on it... strangely the 2 speed travel (which gets is signal from pilot hyd pump) works fine. Puzzling... Uffex - Ill have some photos for you shortly once I pull the covers
Good day Do you have a hydraulic schematic for the machine you can post ? Kind regards Uffex
I have some 'flow diagrams'.. it would be stretch to call them schematics. I'll work on separating them out and posting. Update on my pilot hydraulics, I think it is the safety solenoid (dead) as I tested for pressure to the control body and it is good. Makes sense as all pilot functions are dead but the 2 speed travel is fine. The 2 speed is a manual valve fed by pilot pump, stick functions are on the other 'side' of that solenoid. It has power, but think its broken internally and remaining closed.
The valve seat face is wrecked on that valve. The little metal is part of the valve seat that has broken off, imo
Thank you very much - I'll pull another to compare. Very much appreciate your thoughts!
I agree. The metal ring (blue arrow) came from the seat face (red arrow) that is alongside it. Look at the wear & damage on the chamfered face of the valve body (2nd red arrow). IMO it is scrap. The groove where the metal ring is located is the wrong profile to take an O-Ring IMO.
yes that makes total sense to me. thank you very much - I will start the parts search
It might also pay you to look closely at whatever body, etc, that valve screws into. With the amount of damage that is visible on your photo there might well be some corresponding damage on the mating face in the valve body, fording you to replace both pieces.