Hydraulic apparatus

Claim 1

A HYDRAULIC MOTOR HAVING THE FOLLOWING FEATURES IN COMBINATION: (A) A ROTATABLE CYLINDER BLOCK INTENDED FOR ROTATION IN EITHER DIRECTION HAVING OR SUPPORTING CYLINDERS PARALLEL OR INCLINED TO THE BLOCK ROTATION AXIS, (B) PISTON IN THE CYLINDERS RECIPROCATED DURING BLOCK ROTATION BY MEANS EXTERNAL TO THE BLOCK, SUCH FOR EXAMPLE, AS A SWASH PLATE, (C) A NON-ROTARY VALVE ON WHICH THE BLOCK IS ARRANGED TO ROTATE, (D) A FLAT VALVE SURFACE OF THE VALVE IN ROTARY CONTACT WITH A FLAT BLOCK SURFACE OF THE BLOCK, (E) A PAIR OF MAIN PORTS IN THE VALVE SURFACE HAVING SUPPLY AND RETURN FUNCTIONS, (F) CYLINDER PORTS IN THE BLOCK SURFACE ARRANGED TO PASS ALTERNATELY OVER THE MAIN PORTS DURING BLOCK ROTATION, (G) THE CYLINDER BLOCK BEING ARRANGED FOR AXIAL AND TILTING MOVEMENT TO ENSURE THAT THE VALVE AND THE BLOCK SURFACES REMAIN IN CLOSE CONTACT, (H) THE HOLDING FORCE EXERTED ON THE BLOCK BY THE PRESSURE IN THE CYLINDERS HOLDING THE BLOCK AGAINST AXIAL OF TILTING MOVEMENT AWAY FROM THE VALVE SURFACE BY A PARTING FORCE GENERATED BY HYDRAULIC PRESSURE AT THE PORTS, (I) THE TWO PAIRS OF ADJACENT ENDS OF THE MAIN PORTS IN THE VALVE SURFACE ARE SPACED APART BY PORTIONS OF THE VALVE SURFACE REFERRED TO AS BRIDGES OF WHICH AT LEAST ONE BRIDGE WHICH IS OF CONSIDERABLE GREATER ANGULAR EXTENT THAN A CYLINDER PORT, (J) AS THE CENTER OF EACH CYLINDER PORT PASSED AT OR NEAR THE CENTER OF THE BRIDGE, THE ASSOCIATED PISTON PASSES A DEAR-CENTER POSITION (K) FROM EACH MAIN PORT A RESTRICTED FLOW PASSAGE OPENS INTO THE VALVE SURFACE IN THE BRIDGE IN THE PATH SWEPT BY THE CYLINDER PORTS, (L) A SMALL AUXILIARY VALVE PORT IS LOCATED NEAR THE BRIDGE BUT SPACED FROM THE PATH SWEPT BY THE CYLINDER PORTS, (M) THE AUXILIARY PORT IS CONNECTED BY CONNECTING MEANS TO THE PRESSURE OF THE MAIN PORT ON TO WHICH EACH CYLINDER WILL PASS FROM THE BRIDGE NEAR THE AUXILIARY PORT IN ACCORDANCE WITH THE DIRECTION OF ROTATION, AND (N) A PLURALITY OF AUXILIARY CYLINDER PORTS EXTEND FROM THE CYLINDER PORTS EACH BEING ARRANGED FOR CONNECTION TO THE AUXILIARY VALVE PORT WHEN THE ASSOCIATED CYLINDER PORT IS PASSING OVER THE BRIDGE.