Im working on a Volvo a35e dump truck, the serial number is VCEOA35EC00010230 When i went out to it there was 1 hydraulic line pouring oil out and 3 others dripping constantly, so I replaced all 4 of them and put 18 gallons of hydraulic oil back into the machine. Then I replaced the air dryer because it was leaking air out of the blow off valve constantly. The problem I’m having and the real reason I went out to it, was it cranks and runs. But it Won’t release the park brakes and the warning light come’s on for the brake pressure when i mash the pedal. I put a mechanic gauge on the hydraulic accumulators that’s inside the bed’s frame rails and I’m getting 400 psi while it’s running,and it sounds like the hydraulic are growing on the back of the cab Does anybody know the correct psi the accumulator should have. I’m guessing one of the hydraulic pump went bad, Thank you for all and any help
See attached. Let's first separate air brakes from hydraulic brakes. Here's literature to focus on air side.
Here's the hydraulic side.
More than likely the reason your park brake is stuck on is the solenoid MA5501/MA5502 is no longer working, getting a relatively common fault on these trucks now as they are getting older. normal electrical solenoid, stick a screw driver next to it and see if she energises when operated.
Thank yall for all the info. I got stuck working on other stuff, but I’ll be back on it probably Tuesday. I’ll let y’all know how it goes Thanks