Hydrostatic transmissions

Claim 1

A hydrostatic transmission assembly comprising a rotary radial piston pump and a rotary radial piston motor, the said pump and motor each including a non-rotating pintle and a rotary cylinder member mounted for rotation on the said pintle and provided with a plurality of radial cylinders each containing an individual radially movable piston, each pintle having fluid supply and return passages extending lengthwise thereof and communicating respectively with supply and return ports in the external surface of the said pintle, to permit the flow of liquid to and from the said cylinders on rotation of the respective cylinder members, said support member being formed with internal fluid supply and return passages communicating respectively with corresponding passages in said two pintles, and in which the said two pintles are separately formed and identical, and the assembly includes a common support member having two faces lying in mutually perpendicular planes, means mounting the said pintles respectively on the said mounting faces with the axes of the pintles perpendicular to one another, a casing for each of said pump and motor units, said casings being respectively secured and sealed to said common support member to surround the respective rotary cylinder members, drive shafts extending through said casings and respectively connecteD through universal couplings to said rotary cylinder members, bearings supporting said drive shafts respectively from said casings, adjusting means within the said casing surrounding said pump for varying the volumetric capacity thereof, and control means extending through an aperture in said casing and operatively connected to said adjusting means.