Hi guys:
I have an application where I need a foot-operated, reciprocating hydraulic pump for a lift cylinder. The load is light (few hundred pounds), but I need to move enough fluid to advance the cylinder as much as possible with each stomp. So I'm looking at low-pressure/high-displacement for each stroke. I've looked at all the ready-made pumps available and they tend to be high-pressure/low-displacement types.
I'm kicking around the idea of using a hydraulic (or perhaps oil-compatible air) cylinder as a pump. I foresee a check valve on the exit line to the lift cylinder and another check valve, in the opposite direction, to an oil reservoir. The pedal mechanism connected to the pump rod would provide a spring-return. A relief valve from the cylinder to the reservoir would lower the load.
Do any of you have experience with doing this, or something similar? What are the caveats? Thanks for all replies.