Fizzy,
Don't forget that the pressure the pump actually needs to produce is proportional to the area of the ram. A 1/8" diameter ram has a cross sectional area of only 0.0123 sq. inches so to produce 100psi the pressure on the ram only has to be 1.23psi so the pressure trying to lift the cylinder off the port face is very low. Think that's right anyway!
Most good lubricators will easily produce several hundred psi. The biggest problem is getting the ram to be a good enough fit in the cylinder bore. I like the Jim Ewins type where the ram goes through two O rings which seal perfectly.
The LBSC oscillating type usually have a packed gland on the cylinder to seal the ram.
Whilst the ram may seem to seal perfectly when the oil is cold, as soon as it gets hot they may leak like a sieve!
John
Edited By John Baguley on 21/07/2015 18:26:30
Edited By John Baguley on 21/07/2015 18:27:57