Hydraulic pump or motor

Claim 1

IN A MULTI-CYLINDER, RECIPROCATING PISTON TYPE FLUID PRESSURE ENERGY TRANSLATING DEVICE IN WHICH THERE IS RELATIVE MOVEMENT BETWEEN A CYLINDER BLOCK AND A FLUID HANDLING SECTION WHICH DEFINES INTERNAL, SPACED, LOW AND HIGH PRESSURE DUCTS, AND IN WHICH SUCH RELATIVE MOVEMENT SUCCESSIVELY BRINGS OPEN ENDS OF THE PISTON CHAMBERS IN THE CYLINDER BLOCK INTO ALTERNATE OPEN COMMUNICATION WITH THE LOW AND THE HIGH PRESSURE DUCTS IN THE FLUID HANDLING SECTION, AND IN WHICH PISTON RECIPREOCATION AND THE RELATIVE MOVEMENT BETWEEN THE CYLINDER BLOCK AND SAID FLUID HANDLING SECTION IS TIMED SO THAT EACH PISTON TRAVELS ON AT LEAST A PORTION OF ITS COMPRESSION STROKE BETWEEN THE TIME ITS CHAMBER BREAKS COMMUNICATION WITH SAID LOW PRESSURE DUCT AND THE TIME ITS CHAMBER BEGINS DIRECT COMMUNICATION WITH SAID HIGH PRESSURE DUCT, STRUCTURE FOR ADJUSTING THE PRESSURE IN EACH SUCCESSIVE PISTON CHAMBER TO SUBSTANTIALLY EQUAL THE PRESSURE IN SAID HIGH PRESSURE DUCT BETWEEN THE TIME EACH PISTON CHAMBER BREAKS COMMUNICATION WITH LOW PRESSURE DUCT AND THE TIME IT STARTS COMMUNICATION WITH SAID HIGH PRESSURE DUCT, COMPRISING: A LIQUID FILLED PRESSURE CONTROL CHAMBER LOCATED BETWEEN SAID LOW AND HIGH PRESSURE DUCTS DEFINED BY THE SAID FLUID HANDLING SECTION; A DIFFERENTIAL PRESSURE MOVABLE BARRIER TRAVERSING SAID CONTROL CHAMBER AND CONTINUOUSLY DIVIDING IT INTO (A) A VARIABLE VOLUME, PISTON CHAMBER PRESSURE REGULATING COMPARTMENT, AND (B) A SEPARATE VARIABLE VOLUME, PRESSURE REGULATION ASSISTING COMPARTMENT, SAID PRESSURE REGULATING COMPARTMENT HAVING AN OPEN PORT LOCATED TO OPENLY COMMUNICATE WITH THE OPEN END OF EACH SUCCESSIVE PISTON CHAMBER BETWEEN THE TIME THE PISTON CHAMBER BREAKS COMMUNICATION WITH SAID LOW PRESSURE DUCT AND THE TIME THE PISTON CHAMBER BEING DIRECT COMMUNICATION WITH SAID HIGH PRESSURE DUCT; AND DUCT MEANS AFFORDING OPEN COMMUNICATION BETWEEN SAID HIGH PRESSURE DUCT AND SAID PRESSURE REGULATION ASSISTING COMPARTMENT, WHEREBY, DURING THE TIME EACH PISTON CHAMBER IS IN COMMUNICATION WITH SAID PRESSURE REGULATING COMPARTMENT, THE LIQUID IN BOTH IS SUBJECTED, THROUGH THE MOVABLE BARRIER, TO THE PRESSURE EXISTING IN SAID HIGH PRESSURE DUCT, AND VICE VERSA, AND THE PRESSURE ON THE LIQUID IN EACH SUCCESSIVE PISTON CHAMBER IS THUS ADJUSTED, PRIOR TO THE START OF ITS COMMUNICATION WITH SAID HIGH PRESSURE DUCT, TO SUBSTANTIALLY EQUAL THE PRESSURE THEN EXISTING IN THAT DUCT.