GB1177922A - Gear Pumps and Motors - Google Patents

Abstract

1,177,922. Rotary positive-displacement pumps and motors. DOWTY HYDRAULIC UNITS Ltd. May 9, 1967 [Feb.17, 1966], No.6993/66. Heading F1F. In a rotary positive-displacement hydraulic pump, or motor, of the externally-meshing gear-type, pressure-loaded bearing-bushes 20-- 23 for shafts 16--19 carrying a pair of gears 14, 15 are lubricated by small quantities of working fluid at low-pressure entering a groove 48 in each bush through a radial slot 46, or 47, in the face of the bush adjacent the respective gear and an annular groove 38, 39, 40 or 41 in the corresponding shaft, the slot aforesaid being located adjacent a low-pressure port for said fluid. The working fluid enters each of the slots 46, 47 whenever one of the gear-tooth spaces is in register therewith. To ensure proper lubrication, a groove 50 in each bush is connected to the associated groove 48 by a further groove 53 and to another groove 55 by a chamber 36, 37, 42 or 43 and a channel 54, the groove 55 being situated such that suction is effected therein by the gear-teeth on each gear that are disengaging the gear-tooth spaces on the other gear. Pressureloading is effected by chambers 34, 35 connected to the high-pressure side of the gears and sealed by rings 30, 31 located eccentrically by projections 28, 29 to distribute axial thrust in accordance with the hydraulic gradient across the gears. The bushes 20, 22 and 21, 23 may be rendered integral with each other; and each of the grooves 53 may be replaced by at least one helical groove. There may be more than two gears.