Hydraulic positive displacement rotary machines

Claim 1

A HYDRAULIC POSITIVE DISPLACEMENT ROTARY MACHINE COMPRISING A CAM MEMBER, A PORT MEMBER HAVING A MAIN INLET PORT AND A MAIN OUTLET PORT, A CYLINDER BLOCK WHICH IS ROTATABLE RELATIVE TO THE CAM MEMBER AND PORT MEMBER, A PLURALITY OF CYLINDER IN THE CYLINDER BLOCK HAVING PORTS EACH ARRANGED TO REGISTER IN THE COURSE OF SAID RELATIVE ROTATION ALTERNATELY WITH THE MAIN INLET AND OUTLET PORTS IN THE PORT MEMBER, PISTONS IN THE CYLINDERS RECIPROCABLE UNDER THE CONTROL OF THE CAM MEMBER, AT LEAST ONE AUXILIARY PORT IN THE PORT MEMBER DISPOSED BETWEEN SAID MAIN INLET AND OUTLET PORTS, WHICH AUXILIARY PORT HAS A PRESSURE-FLUID CONNECTION TO ONE OF THE MAIN PORTS AND IS REGISTRABLE WITH THE CYLINDER PORTS AS THEY MOVE TOWARDS REGISTRATION WITH THE MAIN PORT TO WHICH THE AUXILIARY PORT IS CONNECTED TO PERMIT FLUID FLOW DUE TO DIFFERENTIAL PRESSURE BETWEEN THE MAIN PORT AND A CYLINDER CONNECTED THROUGH THE AUXILIARY PORT TO THE MAIN PORT, AN ADJUSTABLE OBTURATOR IN THE CONNECTION BETWEEN THE AUXILIARY PORT AND MAIN PORT, AND CONTROL MEANS CONNECTED TO SAID OBTURATOR TO REGULATE THE RATE OF FLUID FLOW BETWEEN THE MAIN PORT AND SAID CYLINDER.