and contraction application_number US 72857510 A description referring to fig1 a regulator valve 10 includes a valve body 12 a cylindrical chamber 14 formed in the body and ports 16 17 18 spaced mutually along the wall of the body and opening into the chamber a valve spool 20 located in the chamber 14 is formed with axially spaced control lands 22 24 which open and close the ports and hydraulic connections among the ports as the spool moves along the axis 26 of the chamber at least one port is an inlet port through which supply flow enters chamber 14 at least one other port is an outlet port 18 through which flow is exhausted to lower the pressure in chamber 14 at least one other port is a control port 17 through which pressure at a regulated magnitude exits the valve through chamber 14 depending at least in part on the degree to which the inlet and outlet ports are fully or partially opened by a control land 22 24 a compression spring 28 located in chamber 14 applies a spring force to the spool 20 at land 24 where the spring contacts the spool the force produced by spring 28 continually urges the spool axially toward a piezoelectric variable force actuator 30 located at the opposite axial end of the chamber 14 from the location of the spring.