GB645420A - Improvements in and relating to hydraulic power transmission systems - Google Patents

Abstract

645,420. Swashplate pumps. VICKERS, Inc., and SHIELDS, R. Nov. 25, 1946. No. 34119/47. Divided out of 34830/46. [Class 102(i)] [Also in Group XXIX] The casing 14, 16 of a hydraulic power transmission, (see also Group XXIX), is divided by a plate valve 18, Fig. 1, into two compartments, the former housing a reversible, variable-displacement swashplate pump. The pump shaft 20, which is journalled in the casing part 16 and the plate valve 18, has a partly-spherical splined portion 52 in loose engagement with a rotatable cylinder barrel 34. The latter incorporates a number of axial cylinders 36 that. contain pistons 38, the outer ends of which abut a swashplate 44. The swashplate is carried in two trunnions one of them being fixed to the swashplate and arranged to be manually adjustable. Outwardly of the splined portion 52 the shaft 20 is flanged at 56 to support the cylinder barrel 34 and so enable its own centre of rotation to be found on the valve plate and to permit it to follow any slight lateral movement of the shaft due to loading or misalignment and so prevent leakage between these parts. Springs 64 located in chambers. formed in the cylinder barrel axially urge the latter into Firm, contact with the valve plate. The valve plate embodies two arcuate ports which cooperate with ports 72- in each cylinder 36 and communicate. with vertical passages 74, Fig, 7, in the plate valve. The passages 74 are controlled by a ball valve 76 located in stepped bores 78 which communicate through cross-bores 80 in the plate valve with the passages 74 and blind-bores 84 in the casing part 16. The cross-bores 80 are diagonally arranged and place the spring chambers into communication with the two casing compartments. Relief valves 82 ' are positioned at the inner end of the blind-bores 84, the outer ends of which lead through cross-connections 86 to the opposite vertical passage 74. A plunger pump 88, Fig. 1, which is provided for replenishing purposes, comprises a bore 90 that has a ball discharge valve 96 located at the bottom, whilst above this valve is a spring-loaded piston 97, operated by an eccentric 102 on the pump shaft 20. An inlet port 104 opens into the bore 90, whilst liquid passing the valve 96 enters an accumulator. In a modification, Fig. 8, the cylinder barrel 134 in the pump housing 116 is directly supported at its outer extremity by the splined portion 150. The position of the latter is such that the tipping couples acting on the cylinder barrel 134, due to side thrust transmitted to the upper pistons by the swashplate, are counterbalanced by the side thrust on the lower pistons, so that any misalignment of the shaft does not break the intimate contact of the cylinder barrel and valve plate and give rise to leakage.