I have been saying for years that H&P is all about education. If you will refer to our March 2008 issue you will find what I am referring to at http://www.hydraulicspneumatics.com/200/Issue/Article/False/79450/Issue which is the second in a series on hydraulic systems and at
http://www.hydraulicspneumatics.com/200/Issue/Article/False/79456/Issue
which is a thoughtful article on the proper steps in selecting an air cylinder.

Both are very good educational articles that are must reading for designers, maintenance people, and all students of fluid power.

For steady state conditions, bottom line boils down to: is the system pressure/force limited or volume limited?

Pressure and force limited is the VCCM equations and orifices in the valves. The sum of forces on the piston = loads and accelration, basic Summation of F = MA

Flow limited is simple open loop gear pump and cylinder or motor. Big valve, smaller supply. Speed determined by pump and pressure drops are heat but not limiting the final velocity or forces.

Jacks curves show the parabola from Stall force at no speed, to slewing speed at no force. Just depends on if the pump/supply limits the circuit before it gets to pressure limited, or the pressure/valve/cylinder limit the circuit by pressure drops.

Accel and dynamics are Peter's world....