GB1216483A - An hydraulic motor or an hydraulic device capable of operation as a pump or a motor - Google Patents

Abstract

1,216,483. Hydraulic reciprocating pumps and motors. PRATT PRECISION HYDRAULICS Ltd. March 6, 1968 [April 7, 1967], No. 15983/67. Heading F1A. [Also in Division B3] A hydraulic machine operable as a reciprocating pump or motor comprises spherical pistons 10, preferably of steel, co-operating with a stationary camplate 12 having a surface 11 which is either concave or, as shown, convex in the section in Fig. 2, but which is linear in the direction normal to the plane of Fig. 2. The surface 11 may be provided with a grooved track for the pistons, the track being formed by copy grinding or by rolling by steel balls and thereafter hardened and surface finished by vapour blasting. The valving arrangement comprises a valve plate 7 with four equallyspaced arcuate channels therein, one diametricallyopposite pair delivering fluid into the cylinders 9 and the other diametrically-opposite pair receiving fluid from the cylinders. When the machine is a motor, the direction of rotation can be reversed by reversing the fluid-flow through the channel pairs. When the machine is a pump the pistons 10 can be biased against the camplate by helical compression springs arranged within the cylinders. Leakage is drained through a port 20. In a modification, the cylinder block may be the stator and the camplate may be the rotor, providing the valving arrangement is suitably modified. The hydraulic motor may be incorporated in an electrohydraulic pulse motor having a valving arrangement in which the four arcuate channels may be subdivided into independently served apertures.