Abstract: A vane type variable displacement motor comprising a body having an elliptical first bore, end caps with axial bores, an axial drive shaft journaled therethrough and a rotor on the shaft. A plurality of radial vanes are movably mounted upon and around the rotor and are biased toward the first bore and react to pressurized liquid delivered through intake and exhaust passages in the body. Rotative pistons upon the shaft within the end cap bores have a series of radial slots to receive the vanes whereby the pistons are adapted for axial movement relative to the vanes into the first bore for modifying the effective internal volume of the first bore and speed of shaft rotation. Pilot ports in the end caps are connected to a variable pressure source for biasing the pistons variably into the first bore.

Abstract: A power transmission includes a chambered housing having a horizontal axis with a rotatable crankshaft disposed therethrough and outwardly of the housing independently mounted upon a suitable support. A pair of diametrically opposed radial rods on said crankshaft pivotally mount a pair of pistons which on rotation of the crankshaft are yieldably biased outwardly. Cam rollers on said pistons bear against cam bore within said housing. Said bore includes a circular portion of maximum radius throughout 180.degree. approximately, merging into a cam surface gradually reduced to minimum dimension which merges into a circular pivotally adjustable segment portion of minimum radius throughout less than 90.degree.. The irregular cam bore provides for one piston traversing the maximum radius of said cam bore an increased leverage with respect to the other piston simultaneously traversing the cam portions and reduced radius portions of said bore.