Good day everyone, need some advice on this problem i'm having. No Swing, everything else works fine. What i've already checked: Swing Brake Release Pressure = 600 PSI Swing Brake Solenoid test - > Ok. Pilot Signal to swing (full stroke) = 500 PSI Swing Stall Pressure = 2000 PSI at start of swing lever operation, then drops to 0 PSI when the swing lever reaches full stroke. We've swapped the two swing motors with two others from a working machine and same results. Case Drain Test (removed line from top swivel joint, capped off the end on the swivel and placed hose from top swing motor into container) low rpm full swing stroke to the right. ---> 4 seconds fulls 6 Gallon Container From this we see that all the oil flow from pump gets dumped back into the case drain line, normally we think it's the motor at fault, but motor showed no sign of being worn out or damaged, but we still changed them both with two others and still same results, We've also capped off the swing supply line to the swing motor (line between swing motor and main control valve) and stalled pressure were 5000 psi (main relief valve set pressure) so we know every thing should be fine in the swing circuit only until it enters the swing motors. Seems like the oil just flows in and out the motors without doing any work. I'm really just curious as to what can cause the motors to dump all the oil back into case drain. Even if i hold the swing lever to that point i can read 2000 psi on the gauge, there's still no swing movement or any attempt to swing. Thank you all for your time, looking forward to any replies. best regards.
How did it appear the first time, suddenly or progressivly getting weaker? I assume you turned the machine by hand to verify the gearboxes are ok?
The problem just occurred instantly without any warning or indication. I was thinking that since the swing brake solenoid was disconnected, i even had the swing brake line disconnected from the swing motors, therefore the swing motors should "lock" and i'll obtain a stall pressure, which should be around 4500 psi; according to the gauge the pressure only read around 2000 psi at the idle pump test port and 0 psi on top of the swing motor (plug removed to install tap and gauge), i believe this shows the pressure drops within the motors as I've confirmed with the case drain test. Swing motors were replaced and still same results.
Today we found out the swing motors were at fault, the valve plates weren't seating off properly onto the piston blocks, ordered new valve plates and the swash plate as well to make sure there's enough height for the block to seal against the valve port. The other two motors that came off another 345 were faulty as well... apparently water got in and the valve plates were corroded, that equipment was down awhile pending on engine repairs, mechs took apart the hose around it and was left exposed. When new parts arrive and motors assemble i'll report again.