GB917442A - Improvements in swash-plate pumps - Google Patents

Abstract

917,442. Swash-plate pumps. PITT, A., and BUDZICH, T. March 14, 1961 [March 21, 1960], No. 9383/61. Class 102(1). A swash-plate pump having a ring shaped cylinder block 25, has an annular gallery 26 extending from a peripheral surface of the block 25 thereinto and intersecting each cylinder bore 27 into two axially spaced portions 27a, 27b. A hollow piston 28 extends between each pair of bore portions 27a, 27b and a sleeve 40 defines with the cylinder block 25 a closed annular space whereby leakage of fluid past the pistons from the working cylinder 27b fills the space with pressurised fluid tc reduce further leakage and lubricate the pistons in the bores.27a. Fluid leaking from the latter bore is scavenged through an outlet 2C in the pump body 10. The cylinder block is mounted over a drive shaft 15 with sufficient clearance to allow limited transverse movement or it may be skewed slightly to the shaft axis. The sleeve 40 extending across the gallery 26 provides a drive between the shaft 15 and the cylinder block 25, the sleeve 40 being connected thereto by shear pins 41. The portion 42 of the sleeve 40 is splined to the shaft 15, the splines permitting a limited eccentricity of the shaft and sleeve. The axial forces in the shoes 32 are balanced by supplying pressurised fluid into recesses 32a through apertures 45 in the pistons 28. A relief valve 46 prevents excessive build up of pressure in the gallery 26 and the pins 41 are designed to shear at a torque corresponding to the maximum permissible pressure in the outlet passage 37.