Pulsating hydraulic control

Claim 1

A HYDRAULIC SYSTEM COMPRISING A FIXED VOLUME PUMP; A FLUID CIRCUIT ENERGIZABLE BY SAID PUMP AND IMPOSING A VARIABLE LOAD THEREON; A PULSING VALVE FOR CONTROLLING FLOW FROM THE PUMP TO SAID CIRCUIT, SAID VALVE HAVING A CASING DEFINING A VALVE CHAMBER, AN INLET PORT AND AN OUTLET PORT EACH OPENING INTO SAID CHAMBER, A CIRCUIT PORT OPENING FROM THE CHAMBER TO SAID FLUID CIRCUIT, A VALVE SPOOL RECIPROCABLE IN SAID CHAMBER BETWEEN A NEUTRAL POSITION PLACING THE INLET AND OUTLET PORTS IN COMMUNICATION WITH EACH OTHER AND A SHIFTED POSITION PLACING THE CIRCUIT PORT IN COMMUNICATION WITH THE INLET PORT WHILE SHUTTING OFF THE OUTLET PORT FROM THE INLET AND CIRCUIT PORTS; MEANS BIASING THE SPOOL TO SAID NEUTRAL POSITION; AND MEANS FOR EFFECTING RECIPROCATION OF THE VALVE SPOOL COMPRISING A VALVE FOR THROTTLING FLOW OUT OF THE OUTLET PORT, AND A CONDUIT CONNECTING ONE END OF THE VALVE CHAMBER TO A POINT BETWEEN SAID THROTTLING VALVE AND THE OUTLET PORT, WHEREBY SELECTED RESTRICTION OF FLOW FROM THE OUTLET PORT BY SAID THROTTLING VALVE DEVELOPS PRESSURE ACTING THROUGH SAID CONDUIT ON THE VALVE SPOOL IN OPPOSITION TO SAID BIASING MEANS.