I have a 953C that blew a hyd. hose (crossover hose for the travel pumps). The operator got the loader to a safe place to make repairs. However, in doing so most of the hyd. oil was drained from the tank. The blown line was replaced, tank refilled. The loader operated correctly the rest of the day. However, the next day the boom would NOT lift or lower after after 5 or 6 lifts. We shut the loader off, relieved the tank pressure, same thing 5 or 6 lifts it would lift and lower extremely slow. Checked the charge pressure it is 390 @ idle 412 @ high. Attached gauge to pump pressure tap, gauge would start at 0. First lift it would go to 1,200-1,500 psi and remain when lowered. Second lift pressure would increase to 2,000psi, third lift 2,300psi, after more lifts pressure reached 3,300psi and remained never going to relief.
Then, we could stall the lift circuit 4 to 5 times the pressure would drop back to 0. And, the boom would lift as expected with pressure going from 0-1,300 psi while lifting then back to 0. The same symptoms would not occur unless i relieved the tank pressure. Does anyone have any suggestion s on what could be causing this?
I have been searching through SIS and have not found whether or not the pump pressure tap should or should not have pressure when the pilot valve is released. My initial thought was that the pilot valve was sticking in one direction but, i have not found one to be sticking. Any information is appreciated.
Then, we could stall the lift circuit 4 to 5 times the pressure would drop back to 0. And, the boom would lift as expected with pressure going from 0-1,300 psi while lifting then back to 0. The same symptoms would not occur unless i relieved the tank pressure. Does anyone have any suggestion s on what could be causing this?
I have been searching through SIS and have not found whether or not the pump pressure tap should or should not have pressure when the pilot valve is released. My initial thought was that the pilot valve was sticking in one direction but, i have not found one to be sticking. Any information is appreciated.
