Patent GB-527359-A (GB)
Title: Improvements in or relating to multi-piston hydraulic pumps and motors
IPC: F04B49/10
Filed: 1939-03-31
Abstract: 527,359. Hydraulic pumps and motors : bearings. ARMSTRONG, J. J. V. (Vickers, Inc.). March 31, 1939, No. 10043. [Class 102 (i)] [Also in Groups XXIX and XXXIV] A multi-piston hydraulic pump or motor of the kind described in Specification 380,578 in which when the device acts as a pump a driving- shaft 18 actuates a rotating barrel 44 by means of a rod 64 and ball-and-socket joints 66, and also causes the reciprocation of a number of pistons 48 in cylinders 46 in the barrel is constructed with two sets of thrust bearings for the shaft 18, one set 22 being normally held in fixed position axially by a cap 24, and the other set being a slipper thrust set 70, 72 of the Kingsbury type of which the slippers 74 are normally held out of action by springs 80 and are brought into action at the required pressure by means of plungers 78 supplied with fluid through passages 82, 86, 100, when a valve 90 opens due to rise of pressure in the pressure pipe 164. A valve 88 supplies the pressure when the pipe 162 is the pressure pipe. The shaft 18 is also mounted in anti-friction bearings 20 in the main frame 10, and a flange on shaft 18 is connected to the pistons by means of rods 30 and ball-and-socket joints. The barrel 44 is carried by a swinging yoke 34 adjustable about hollow trunnions 32, 33, and the piston stroke varies with the inclination of the yoke to the axis of the shaft 18. The pistons cause the liquid (oil) to be delivered through ports 52 into the valve ports 142, 146 through passage 150 and trunnion 32 to the main line conduit 162. Fluid is drawn into the cylinders through the valve ports 144, 148, from the conduit 164 and passage 152. A wear-resisting plate 138 is arranged between the valve plate and the rotating barrel 44 which is of cast metal. The plates 138 have arcuate valve ports 142, 144, which are formed on each side with annular bearing surfaces 154, 156 (Figs. 8 and 9, not shown) to bear on the valve 38 and the barrel 44. Drain passages lead from the space enclosed by the annular bearing surfaces 154, 156 to prevent removal of the valve plate 138 out of position by hydraulic pressure. The yoke 34 is mounted in such a manner that the bearing loads at the trunnions are hydraulically balanced, and to ensure that no loads are transmitted to the yoke arms in a direction axially of the trunnions 32, 33. Each trunnion has a pair of radially opening ports 110, 112 extending through an arc of somewhat less than 180 degrees falling to the right in Fig. 2. The arms 36 have bearing portions 114 embodying the trunnions formed with ports 116, 118 registering with the ports 110, 112, and formed with flexible packing members 120. Fig. 3, of rectangular section. Drilled passages 122 connect the rear faces of the packing with the ports 116, 118 and through a groove 124 oil is distributed through the entire back face of packing 120. The area of the packing 120 is so chosen that the radial force due to fluid pressure tending to move the arm 36 to the right balances the load on the trunnions imposed by the thrust of the pistons 48. The bearing member 114 is provided with pressure relieving grooves 126 opposite to the ports 110, 112. The ports 116, 118 are also connected by balancing grooves 130 surrounded by packing, and conduits 134 connect the grooves 130 with the conduit 104 at trunnion 32 when this trunnion is under pressure and the valve 88 is open and valve 90 shut. The piston load is thus balanced when either conduit 162, 164 is under pressure. In a modification (a) the springs 80 may be dispensed with, and (b) the slippers 72 may be mounted in fixed position and the ports 70 of the Kingsbury bearings may be movable axially under spring pressure with the bearings 22, which are relieved of thrust when the members 70, 72 engage. In a further modification, Fig: 11, the Kingsbury bearings are brought into action by a governor 194 at the required speed of rotation of the pump or motor which in this case is formed with a yoke or casing and pump cylinders set at a fixed angle. The governor operates a valve 198 controlling the supply of pressure fluid to pistons which bring the slippers 72 into action. A number (four) of auxiliary pumps 178, Fig. 1, may be used in conjunction with the main pump or motor. The driving shafts 176 of these pumps may be plugged in to the shafts 168 of helical gears 170 driven by a helical pinion 172 keyed to the main shaft 18.