Chelsea C1-P-602 on a Kenworth T800 tractor Trailer box went up no problem last night. Driver got loaded this morning and it took him an hour to manage to get the box to go half way up and get most of the load off. He said when it went up, the hydraulics were smooth, no jerking or inconsistent flow. When I hit the PTO switch in the cab, I cant hear the PTO engaging. I checked the power to the solenoid on the front of the pto and had 14 volts. The solenoid was too hot to grab by hand. I replaced the solenoid, thinking it was shorted. Didn't fix it.
Pull the solenoid off the actuator and ensure you can manually engage and disengage the pto. I'll bet the shift fork apparatus has come apart disallowing the solenoid to do it's job. With the solenoid coil being hot, it is either shorted, or pulling for all it's worth but unable to move anything.
I wasn't able to figure out how to manually engage/disengage it. Everyone else I talked to said its most likely the clutches inside the pto that failed. I put a new pto in and no change. I took off the hydraulic line that goes to what ill call the up/down valve, which comes right from the discharge side of the hydro pump. I hooked up a gauge to the line, tried it and it now puts out 2000 psi. It sounds like its sucking air in the hydraulics. Assuming the hydro pump was air locked previously. Could that up/down valve have failed seals that allow air into the hydraulic system? Ill send a picture of the valve to clear up any confusion.