[Shop-talk] air over hydraulic bottle jacks

[Karl Vacek]

Zackly how most air-powered pumps work.  Paint, oil, grease, etc. piston 
pumps work that way.  The air and fluid circuits are completely divorced - a 
leak in one will typically leak to the outside, not into the other side of 
the pump.

The pressure is simply developed by the ratio between the air and fluid 
piston sizes, and the pumps are usually rated by their pressure ratio.  For 
example, a 10:1 pump will produce 1,000 PSI fluid pressure with a 100 PSI 
air supply (less losses of course).

Karl



> I don't think it works like that.  I have an air over hydraulic floor 
> jack, and when I was shopping for it, I was thinking the way you are.  But 
> the way it works is that there is a sort of a pump that is run by air, but 
> it pumps hydraulic fluid.