I have a choice of two hydraulic power units with specs as follows:

A. 2.2kW motor, 8lpm flow rate, 120 Bar pressure rating

B. 1.1kW motor, 2lpm flow rate, 200 Bar pressure rating

Using F=PA I assume pump B is capable of producing more force in the same system (albeit a lot slower!)

However, hearing the phrase "resistance to flow produces the pressure not the pump" many times gives me a nagging feeling.

Am I correct or is there something I'm missing?



1 Answer 1


For a given cylinder, B has higher pressure and will produce a larger force.

You could select a larger diameter cylinder for A such that it would produce the same or larger force.

If a cylinder is moving with zero resistance, the pressure in the cylinder will be very low (just enough to overcome its own friction).

You are likely looking for maximum force (pump max pressure x cylinder head area) which occurs when the cylinder blocked or fully extended (zero flow).

At flowrates and pressures in between full flow zero pressure and full pressure zero flow will require a pump curve, plumbing information, and more involved calculations.


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