Speed adjustment control for a fluid motor

Claim 1

A speed adjustment control device for fluid motors, said device comprising: a. a valve body defining laterally spaced inlet and outlet passages adapted to be connected at one end to high pressure inlet and low pressure outlet openings respectively of a fluid pressure operated motor; b. said body defining inlet and outlet ports to the other ends of said inlet and outlet passages respectively, said inlet port being adapted to be connected to a source of fluid under pressure; c. a cylindrical recess in said body intersecting said inlet and outlet passages intermediate the ends of said passages; d. a cylindrical metering valve element rotatively mounted in said recess coaxially therewith and having a transverse opening therethrough movable circumferentially into and out of register with said outlet passage to variably restrict flow of fluid through said outlet passage responsive to rotation of the metering valve element, said metering valve element having an inner end disposed between said inlet and outlet passages; e. means for imparting rotary movement to said metering valve element; f. said body further defining shunt passage means communicating at one end with said inlet passage and at its other end with said outlet passage intermediate said metering valve element and said outlet port, said shunt passage means including a portion of said recess between said inner end of the metering valve element and said inlet passage; g. a shunt valve element disposed in said recess portion of the shunt passage for movements axially of said recess portion between valve closed and various valve open positions in said shunt passage means to control shunt flow of fluid therethrough; h. said metering valve element defining an axial pocket connected to said transverse opening and opening toward said shunt valve element; i. and a compression spring having one end disposed in said pocket and an opposite end engaging said shunt valve element and yieldingly urging said shunt valve element toward said valve closed position thereof.