Hydraulics & pneumatics
Hydraulics: pressure creates force, flow sets speed
One cylinder example connects the circuit to first-principles mechanics.
For an ideal cylinder, force is pressure difference times effective area: F = ΔpA. Piston speed is flow divided by effective area: v = Q/A. These come from pressure as force per area and conservation of volume.
Worked example
An 80 mm bore has area π(0.08)²/4 = 0.005027 m². At 5 MPa differential pressure, ideal extension force is 25.13 kN. At 20 L/min into the cap end, ideal extension speed is 0.0663 m/s.
What changes in practice?
Rod-side backpressure, friction, leakage and load direction change the force balance. Retraction uses the annulus area. Compressibility affects transients. Use the hydraulic calculators to compare the two areas.
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