Hi i have a komatsu pc 50uu-1 i cant get it to swing or the blade to go up or down it was a sudden thing. ive put a new seal kit in the pump and it looks all good. ive put new filters throughout and oil ive pulled the 3 way spool out and disasembled it but im thinking it could be a stuck valve. anyone got any sugestions cheers tony lovegrove
You probably already know that the swing, the blade and the high speed travel are all together on the 3 spool valve. That valve is fed by the third stage of the main pump. Given your symptoms it has to be either the pump or valve. The third stage of your pump is the smallest of the three, and last in line as far as oil pickup. You could have a collapsed pickup line, bypassing in that particular stage of the pump, or a bad relief valve on the 3 spool block. On the pressure output line of the third stage of the pump, there is a 1/8" pipe plug that is easily accessible. Put a 4000 psi gage in that port and operate the swing or blade to see if you're building any pressure. Against the relief you should have about 3200 psi. Does anything happen when you try to swing or try the blade? Any movement at all, or is it just weak? Greg