Attention: TDR Forum Junkies 
I have a hydrostat powewed manlift. It has hydraulic 9 piston pumps that work off of belt driven pulleys driven by a 30 horse Wisconsin motor. The problem I am having is these motors are positive displacement and one of them depends on a unloader valve to pop off and return oil to the low pressure lines and back to the tank. I believe that this valve failed and the resulting overpressure took out a piston . The rebuild kit costs one grand and the pump failed again at five hours of use. OUCH!
What I want to modify is the high pressure line that feeds the valve group that this unloader valve is located in . There is an outlet port in a high pressure oil filter can that could be used to tee into the pressure line . I feel that if I could install a pressure gauge and adjustable pop off valve of about 1500 PSI, then I could return any fluid that exceeds safe pressure back to the hydraulic fluid tank. I would also put all low pressure lines in a manifold and filter the oil before returning it to the tank.
IF anyone has any ideas or sources for parts , please post. Thanks!
What I want to modify is the high pressure line that feeds the valve group that this unloader valve is located in . There is an outlet port in a high pressure oil filter can that could be used to tee into the pressure line . I feel that if I could install a pressure gauge and adjustable pop off valve of about 1500 PSI, then I could return any fluid that exceeds safe pressure back to the hydraulic fluid tank. I would also put all low pressure lines in a manifold and filter the oil before returning it to the tank.
IF anyone has any ideas or sources for parts , please post. Thanks!
