Patent GB-892714-A (GB)
Title: Universal joints
IPC: F16D3/205
Filed: 1958-04-11
Abstract: 892,714. Universal joints. WAHLMARK, G. A. April 11, 1958 [April 25, 1957], No. 11561/58. Class 80 (2). [Also in Groups XXVIII and XXIX] A universal joint comprises driving and driven members, one of which carries an odd number of drive elements with substantially no tangential play and in close-fitting tangential engagement with drive surfaces on the other member, radial clearance being provided in order to permit wearing of the axis of one of the members during operation. As shown in Figs. 1 and 3 a driving-shaft 14 has three trunnions 15 carrying balls 16 rotatable about their respective trunnions and slidable axially along them. The balls engage in bores having cylindrical surfaces 27 formed in a driven member 12 and are held outwardly by centrifugal force against the cylindrical surfaces so that they are always equidistant from the axis 19 of the driven member regardless of the angle between the axes of the driving shaft and driven member. This arrangement means that the end 22 of the shaft 14 shifts its position 180 degrees with respect to the axis 19 for every 60 degrees rotation of the shaft 14. This shifting is slight and is accommodated by flexing of the shaft 14 or by slight angular play in a joint connecting shaft 14 to its driving member. In a simplified construction for lowspeed applications, balls 16 may be fixed to the trunnions or the trunnions may be dispensed with and the balls be fixed to the shaft and to each other. Fig. 4 shows two universal joints in a fixed displacement swash-plate pump or motor having a rotary cylinder block 39 and a swash-plate 35. The cylinder block and swash-plate are drivingly interconnected by means of a shaft 49 having three radial trunnions 50 at each end. A drive roller 51, having part-spherical surfaces 52, 57, is mounted on each trunnion, and the sets of rollers engage recesses in the cylinder block and the swash-plate respectively. The trunnions at one end of the shaft are offset 60 degrees relative to those at the other end so that shifting of the ends of the shaft is 180 degrees out-of-phase to reduce vibration. The swash-plate is supported in a stationary housing 32 by roller bearings 36, 37, and a ball thrust bearing 38. The cylinder block is urged against a stationary valve plate 41 by means of a spring 61 which is disposed in a bore in the shaft 49 and urges a stud 62 against a seat element 66 bearing on the cylinder block. The other end of shaft 49 bears against a seat element 69 fixed to the swash-plate, the swash-plate having internal splines 47 for the reception of an input or output shaft. In this device the universal joint does not carry full torque between the cylinder block and swashplate, but is provided in order to properly " time " their rotation. In the embodiment of Fig. 6 a swash-plate pump or motor having a rotatable cylinder block 86 and a variable inclination swash-plate 85 is shown. A hollow drive-shaft 107 has external splines 119 engaging internal splines formed within the cylinder block, and has internal splines 108 engaging external splines 109 formed on a shaft 98 which has internal splines 99 for receiving splines on a connecting shaft. Splines 108, 109 are formed so that there is no rotational play but slight angular play is permitted to accommodate shifting of the driveshaft during rotation. Three radial trunnions 110 are provided at one end of the drive-shaft, and a roller 111 is rotatably mounted on each trunnion by means of a ball-bearing 112, so that the roller cannot move axially of its trunnion. Rollers 111 have part-spherical surfaces 114 engaging drive surfaces formed in a socket ring 94 of the swash-plate. In this embodiment the joint carries full torque. The drive-shaft 107 is located axially, and the cylinder block biased against a valve plate, by means of a spring 120 located in a bore in the shaft 98 and bearing against a seat member 122 secured in the shaft 107. A flanged end 117 of the shaft 107 bears against the outer race of a ball-bearing 89 which in turn bears against the cylinder block 86. The cylinder block is thus urged against a wear-plate 104 which is secured to the valve plate. The far end of shaft 98 abuts a bearing 126 secured within a stationary housing 82. Specifications 835,936 and 861,876 are referred to,