Patent GB-595762-A (GB)
Title: Hydraulic drive for a motor vehicle
IPC: B60K17/14
Filed: 1945-10-09
Abstract: 595,762. Motor-vehicle transmission. SWAIN, F. E., and DARBY, D. Oct. 9, 1945, No. 15. [Class 79 (ii)] [Also in Groups XXVI and XXIX] A hydraulic drive for a motor-vehicle comprises a hydraulic motor incorporated in the hub assembly of a roadwheel, and means for selectively supplying the hydraulic motor with motive fluid from a number of pumps so that different torques can be applied thereto. The stator end plate 49 of the motor, Figs. 10, 11, is connected to an axle 51 by a king pin 52 and is formed with a stub axle 53 upon which the rotor 21 is journalled through a roller bearing 54. A driving shaft 60 having a splined connection 62 with the rotor transmits the drive to a hub 57 having a flange adapted to receive a bolted-on road wheel and journalled through ball bearings 58 upon a hub 59 fast with the stator end plate 50. The rotor 21 contacts with the stator 20 at a point 24 and comprises arcuate vanes 26 which slide in arctuate slots 27, the circumferential length of which is equal to that of the vanes, and are pressed by torsion springs 29 to make sealing contact between the ends 28 and the stator wall. The springs 29 are connected between brackets 45 fast with the vanes and abutment plugs '46 carried by a detachable end plate 36x. Sealing at each end of the rotor is provided by grooves 37. Leakage fluid is drawn off through a'hollow bolt 48x. The pump unit comprises two coaxial rotors A, B, Figs. 7, 8, of unequal axial length and separated by a wall 73. A rotary valve 70 comprises parts 70A, 70B, coacting with outlet ports 31A, 31B, respectively. Port 70A can be turned through 90 degrees from the open position shown to close the outlet port 31A and to provide a bye-pass between the latter and the inlet port 30A. In an intermediate position the passages 84, 85 are bridged, which is equivalent to free wheeling. The part 70B is in general similar to the part 70A, but its ports 87B are spaced axially and angularly from one another, and its position in relation to the part 70A is such that in one position of the valve 70 both of the pumps A, B are delivering fluid, both bye-pass passages 90A, 90B being closed while in two further positions either A or B only is in operation, thus giving a choice of three speed ratios. When both parts 70A, 70B are closed, the motor circuit is blocked, i.e., the road wheels are fully braked. A reversing valve 71, comprising conduits 88 which provide communication between passages 84 and 68 and 85 and 86 respectively for forward running, has flats 95 each of which communicates with a flat 96 on the opposite side of the valve by means of a spiral groove 98 to provide a reversal of the connections when the valve is turned through 90 degrees from the position shown. The level of fluid in the pump may be maintained from a reservoir 92 which communicates with the inlet ports through non-return valves 93. In an alternative construction, Figs. 3, 5, a sliding valve 75B can be lowered from the open position shown to close the inlet and outlet connections of pump B, at the same time the waisted portion 76 providing a bye-pass between inlet and outlet and the waisted portion 78 providing a connection between a bore 80 and a passage 77 whereby the level of fluid in the pump may be maintained from a reservoir. A similar valve 75A is provided for pump A. The valves may be operated by a single control cam 82.