The VCCM equation is handy for computing the maximum steady state speed of a hydraulic servo system. In reality the value calculated for the maximum steady state velocity must be reduced some what because the supply pressure usually drops during motion.

Where:

v_{ ss } is the maximum steady state velocity

K_{ vpl } is the valve flow constant of the powered land or edge computed from the valve specifications.

P_{ s } is the supply pressure

A_{ pe } is the area of the powered or pushing side of the piston.

F_{ l } is the load force. Subtract if opposing motion, add if aiding motion.

{ \rho }_{ v } is the ratio of the flow constant of the power land to the exhausting land. Normally valves are symmetrical so { \rho }_{ v }=1

{ \rho }_{ c } is the ratio of the piston’s pushing area to the side that is exhausting.

Since the maximum steady state speed is reached when the control signal is at 100% the VCCM equation is necessary to calculate the open loop gain of the system which will have units of velocity per % control output. Notice that v_{ ss } is normally be different when extending and retracting so a model and controller should account for different open loop gains for motion in direction