Hello, I'm new to hydraulics so please excuse my ignorance, I've recently purchased a old PelJob Eb22, mostly fine (by my expectations) but it does have a number of issues I'm working on resolving but can't find any help The Servos for the Arm only work if Aux (hammer) foot pedal is down and the hammer hookup pipe is looped back on itself, ie Feed into Return? I believe its a TRIPLE P1AAN 8+8+4 pump on it, and on selecting the Aux circuit the engine is put under load. I'm willing to replace the pump but I'm confused over why the select the Aux pedal should make the arm work. Additional info: It tracks straight, seems to be more jerky with Aux selected for Arm It can drive and slew at the same time. I do apologise if this is an idiot question, but I'm well out of my depth Thank you
..I've a theory as to the answer and would welcome comment The pump is a triple gear pump, with the Aux (Hammer) circuit joining the two double pumps 8+8 for the aux circuit I'm guessing that on engaging the aux, I'm effectively joining the output of the two double pumps for all functions within the control block, and the looping pipe is to relieve the pressure on the aux circuit which otherwise would hit the end-cap plugs? If this is so, I'm looking at a reduced output on the pumps (through wear?) ie, I'd need to renew the pump for full function. (luckily I can still get one, but it's expensive) Any ideas how I could check this, or am I still way off the mark. Also, to fix I wouldn't need to change anything other than the pump? (ie no pipe reconfiguration) I can't get any workshop manual or schematics from Volvo as it's too old, so no way for me to check the pipe routing.
Answering myself, but may help others I was way off the mark... the hydraulic servo controlled circuits failed to work unless previously a none servo control was operated, (the hammer circuit was performing this function) The fault was the Pressure Accumulator diapgram had leaked, leaving the servo controls without any reserve pressure until none servo circuits is operated. Easy fix to replace the accumulator, but another £300 quid from Volvo (who had the part in stock!)