GB1170605A - Rotary Pumps and Motors - Google Patents

Abstract

1,170,605. Rotary pumps and motors. DOWTY HYDRAULIC UNITS Ltd. Feb.16, 1967 [Feb.17, 1966], No.6994/66. Heading F1F. A rotary pump or motor unit comprising two or more pumps or motors affording two or more separate flows, comprises a first rotor having a shaft mounted for rotation in bearings in the casing and at least one further rotor which is centrally apertured and supported upon a land formed on said shaft, the or all the further rotors being indirectly supported by the bearings of the first rotor with a small clearance between the land and the aperture and small clearance between the rotor side faces of the or each further rotor and the adjacent side faces of the casing to permit a limited amount of tilt of the or each further rotor with respect to the shaft. Described as a twin gear pump, a pair of intermeshing gears 13, 14 formed with integral shafts are bearingly supported in liners in D- shaped bearing bushes 23, 24 and liners mounted in bores in a casing port 32. Reduced diameter extensions 33, 34 of the shafts are formed with respective lands 37, 38 midway of their lengths which co-operate with constant diameter bores 39, 40 in a pair of further intermeshing gears 15, 16 locked upon the respective extensions by keys and slots. The gears 15, 16 are of the same external diameter as the gears 13, 14 but less in width and each pair of gears is associated with its own inlet and outlet. The D-shaped bushes 23, 24 are pressure loaded in conventional manner by dividing a space behind the bushes into two zones 49, 50 separated by sealing rings and subjected respectively to inlet and delivery pressure. Each pair of gears is associated with a pressure relief valve, a ball valve 53 is shown for the gears 15, 16. The D-shaped bushes may be replaced by a single integral bush and the separate inlets to the two pumps may be connected to the same source of supply. Instead of providing the lands on the shaft extensions, the bores in the gears 15, 16 may be provided with splines over the middle third of their lengths. The gear pumps may be replaced by rotary sliding vane pumps or one pump may be a gear pump and the other a rotary sliding vane pump.