GB1179762A - Improvements in or relating to Gear Pumps an Motors - Google Patents

Abstract

1,179,762. Rotary positive-displacement pumps and motors. NARADI, NARODNI PODNIK. Feb.1 1967 [Feb.8, 1966], No.4895/67. Heading F1F. A rotary positive-displacement hydraulic pump, or motor, of the externally-meshing gear-type has shafts 7, 7' for gear-wheels 10, 10' lodged in bearing bushes that are axially and radially pressure-loaded to minimize leakage of working fluid e.g.. oil, between the high-pressure low-pressure sides, each bush including two separate segments 8, 9, or 8', 9', with gaps 25, 27, 25a, 27a, or 25', 27', 25'a, 27'a, therebetween. Pistons 23, 23a, or 23', 23'a in the segments 8, 8' are pressed against a housing 1, so that these segments are urged towards the shafts, while the segments 9, 9' are pressed against the ends of the gear-wheels by the pressure of the working fluid on the high-pressure side communicated to recesses 16, 16' through ducts 17, 17' from which said pressure is also transmitted to the pistons by way of passages 15c, 15c' and ducts 20, 20'. The segments 8, 8' are thinned at their centres whereby (as a consequence of these segments being urged towards the shafts) the gear-wheels are pressed against the housing in regions on the high-pressure side between grooves 13, 13'. Pistons 15, 15' in the segments 9, 9' are subject to pressure through the passages 15c, 15c' so that these segments are biased towards the aforementioned regions. The grooves 13, 13' facilitate escape of leakage fluid from the gaps aforesaid gaps 26, 26', and grooves 24, 24' in the segments 9, 9', which grooves are traps for fluid leaking from the high-pressure side. The leakage fluid in the various gaps beforementioned lubricates the shafts. Recesses 9a, 9a' and 18, 18' minimize cavitation in the gear-tooth spaces and compression of fluid between the intermeshing gear-teeth, respectively.