Abstract: A solenoid operated hydraulic control valve system including a solenoid operated valve having a specially ported spool valve to statically balance spool forces in the opened and closed positions.

Abstract: A solenoid operated hydraulic control valve which has a specially ported spool valve to statically balance spool force in the opened and closed positions, and a specially designed solenoid operator which includes very small ratios of gaps to cross-sectional areas for the working and non-working gaps between the armature and stator.

Abstract: A precise pressure regulator includes a housing defining a bore having pressure and relief zones, a pressure port communicating with the pressure zone, a relief port communicating with the relief zone, and a control port. A follower is slidable and a spool is rotatable in the bore. The spool defines a first passage for communicating the pressure zone with the control port and a second passage for communicating the control port with the relief zone. A spring biases the follower in one direction tending to block the first passage. Pressure in the pressure zone biases the follower in the opposite direction tending to block the second passage. A step motor rotates the spool in discrete steps to precisely control its position, which position determines the level at which pressure is regulated.