air actuated hydraulic jack help

[mattman]

so I have a 20 ton, air actuated hydraulic jack. it requires 90 psi to raise the 20ton. so i am wondering, if i hook a regulator up to the air inlet and gradually increase the air pressure (5psi at a time). will that gradually increase the hydraulic force? or just pump the jack slower? we need to do a bending test and control the force accurately. i am not sure how the jacks work, so i dont know if we are just going to apply 20 ton right off the bat, just slowly, or if the lower air pressures will actually be proportional to 20ton at 90psi. any idea?

[team08]

The only thing that the air does is replace the hand pump action. It is just "ratcheting" the same way that you would work the hand pump. It does not exert full pressure until it is under load, but it would be very difficult to measure/repeat accurate pressure calculations.