Low rise lift hydraulic ideas

I don't think you could easily convert it to straight pneumatic. I hope you are not confusing air/ hydraulic pump. Rams are pretty simple. You take the diameter of the piston, figure the square inches, and using the line pressure, you can figure the "push" the ram delivers. You would have to duplicate that with a pneumatic ram, and it would have to be MUCH larger, because you are operating with about a 10:1 pressure drop from hydraulic to air