Patent GB-1232657-A (GB)
IPC: F16H47/04
Filed: 1968-05-24
Abstract: 1,232,657. Hydrostatic transmissions; clutch combinations. H. L. TRAUTMANN. 24 May, 1968, No. 24872/68. Headings F2C and F2D. A transmission comprises a first disc 40, Fig. 1, rotatably mounted on a spool and having at least one bore mounting a piston, the inner bore end communicating with first and second spool passage 72, 74 as the disc is rotated, means for varying the piston stroke caused by rotation of the disc; a second disc 64 rotatably mounted on the spool having at least one bore mounting a piston therein which bore also communicates with the passages 72, 74, a ring gear 62 rotated by the second disc and engaged by a planetary gear which meshes with a sun gear 52, fluid filling the passages and bores so that a variable fluid flow is produced between the first and second discs through the passages to drive the ring gear and provide an output speed from rotation of the planetary gear about the axis of the sun gear according to the combination of speeds and directions of the ring and sun gears. Function summary.-The transmission comprises a pump unit producing a flow variable in volume and direction which is supplied to a fixed volume motor driving a ring gear, sun and planetary gears with the sun gear driven by the pump unit so that an output speed is obtained from the rotation of the planetary gears about the axis of the sun gear according to the combined speeds and directions of the sun gear and ring gear. The input shaft 28 drives a pump disc 40 which is mounted on a fixed concentric spool 42 having longitudinal passageways 72, 74 interconnecting end slots 78 . . . 81 which register with the disc 40 and the motor disc 64. The input shaft 28 also drives the sun gear 52 via shaft 38 and the planetary cage 59 drives the output shaft 32. Radially arranged pump pistons (70), Fig. 3 (not shown), engage a ring bearing 84 mounted in an adjustment plate 88 which can be moved radially of the input shaft axis by rotation of a hand wheel 92. The disc 40 has a gear 126, Fig. 4, which drives a priming pump 134, 136 via a gear 128 to supply fluid from the housing 20 via holes 140, 142 and passage 144 to a ring groove (146), Fig. 5 (not shown), in the spool 42. The fluid from groove (146) is supplied to passages 72 or 74 via a one-way valve (166), Fig. 6 (not shown), when the priming pump pressure exceeds the pressure in either passage, the priming pump pressure being otherwise relieved through valve 151. Operation.-Disc 40 and sun gear 52 are driven in the same direction by input shaft 28 and if bearing 84 is positioned eccentrically as in Fig. 1 the inward movement of pistons (70) as the disc 40 rotates causes increased pressure in passage 72 which is directed to pistons 114. Outward movement of the latter causes rotation of the ring gear 62 in the same direction as the input shaft 28. The continued rotation of ring gear 62 causes inward movement of pistons 114 so that the fluid displaced thereby is returned via passage 74 and slot 72 to cause outward movement of pistons 70. The planetary gears are rotated about sun gear 52 to rotate output shaft at a speed which is an additive combination of the speeds of ring gear 62 and sun gear 62. By reducing the eccentricity of bearing 84 the speed of output shaft is gradually reduced until the ring gear 62 becomes stationary when the speed of shaft 32 is only rotated at the speed of sun gear 52. Further adjustment of the eccentricity (i.e. in the opposite direction from Fig. 1) causes the ring gear 62 to rotate in the opposite direction to shaft 28 so that the speed of shaft 32 is gradually reduced to zero and with further movement bearing 84 commences to move in the opposite direction. In modifications the ring bearing 84 may be positioned in discrete steps e.g. by a lever arm having a number of detent positions or by a mechanism providing coarse and fine adjustments or by an automatic mechanism responsive to speed.