Fluid displacement device usable as a hydraulic motor or pump

Claim 1

A FLUID DISPLACEMENT DEVICE USABLE AS A HYDRAULIC MOTOR OR PUMP AND COMPRISING: A FIXED OUTSIDE GEAR HAVING AN ANNULAR SERIES OF INTERNAL GEAR TEETH; MEANS COACTING WITH THE OUTSIDE GEAR TO PROVIDE TWO FLUID POCKETS CIRCUMFERENTIALLY SEPARATED WITHIN THE OUTSIDE GEAR, SAID MEANS INCLUDING AN INSIDE GEAR ECCENTRICALLY MOUNTED WITHIN THE OUTSIDE GEAR AND HAVING A SMALLER NUMBER OF EXTERNAL GEAR TEETH FOR MESHING ENGAGEMENT WITH THE INTERNAL GEAR TEETH ON THE OUTSIDE GEAR AND PROVIDING THEREWITH THE INNER AND OUTSIDES OF SAID POCKETS, SAID INSIDE GEAR BEING ROTATABLE ON ITS OWN AXIS AND BEING REVOLVABLE ORBITALLY ABOUT THE AXIS OF THE OUTSIDE GEAR TO MOVE SAID POCKETS CIRCUMFERENTIALLY AROUND THE INSIDE OF SAID OUTSIDE GEAR; MEANS FOR PASSING HYDRAULIC LIQUID TO AND FROM SAID POCKETS BETWEEN THE GEARS; A ROTARY SHAFT; AND OLDHAM COUPLING MEANS ACTING BETWEEN THE INSIDE GEAR AND THE SHAFT FOR IMPARTING ROTATION BETWEEN THEM.