Patent GB-1052354-A (GB)
IPC: F16H39/16
Abstract: 1,052,354. Hydrostatic transmissions. FORD MOTOR CO. Ltd. May 26, 1965, No. 22300/65. Headings F2C and F2D. A hydrostatic transmission comprises two units 18, 20 connected through a two-part valve 172, 174 having a flexible seal 190, 192 permitting a small degree of universal movement between the parts, each part having a face 178, 202 in sealing engagement with elements 62, 38 of the transmission. The units 18, 20 have seven and eight balls 44, 70, respectively, held in cylinders 42, 68 in bodies 38, 66 by cam rings 46, 160. The cylinders 42 have axial ports 214 communicating via ports 206, 198 or 216, 200 in valve 172, 174 with passages 170, 168, respectively, which connect with cylinders 68 through radial ports 166. The passages 170, 168 are in a member 62 which is splined at 76 to shaft 78 driven from input shaft 10 and is connected by bolts 60 to the body 38 of unit 18 and by bolts 162 to the cam ring 160 of unit 20, the body 66 of unit 20 being splined at 118 to a sleeve 112 of output shaft 30 whilst the cam ring 46 is pivoted to housing 16 at 50 and is movable by two actuators, Fig. 2 (not shown), under the control of an automatic control valve to change the eccentricity of ring 46 relative to the axis of body 38. Body 38 is rotatable on a fixed member 34, 36. A supercharge vane type pump 152, 154 is driven from the input shaft via member 62, ring 160, and member 158 and delivers fluid via passages, not shown, to a port 171 to the left of a piston 132 and then via ball valve 96 to the low pressure side 168 of the system and also via passages etc., 200, 232, 234 in fixed member 34, 36 to the control valve. Pressure from ports 206 in valve 172, 174 passes via ports etc. 236, 238, 240 to act as a control pressure in the control valve; also a valve member 244 in body 38 is moved by centrifugal force against a spring 248 to restrict the connection of a passage 258 to exhaust port 252 causing a pressure build up in passage 258 which acts in the control valve to give an indication of engine speed. In the under-drive range of cam ring 46, i.e. with shaft 10 rotating faster than shaft 30, unit 20 acts as a pump producing a reaction on ring 46 which is added to the input torque to produce an increased effective output torque. When the ring 46 becomes concentric with body 38 there is a hydraulic lock between units 18 and 20 for direct drive. In the over-drive range of ring 46 unit 18 acts as a pump and unit 20 as a motor to drive the output shaft 30 faster than the input shaft. In a neutral position of the ring, the output of unit 20 equals the capacity of unit 18 and the output shaft speed is zero. At positions of ring 46 close to neutral the speed of shaft 30 is low; at low engine speed, pressure from pump 152, 154 is low and constant pressure from a valve in sump 140 acts via passages 136, 134 on piston 126 to move this piston and hence member 86 to the left until projections 90 open ball valves 96, 98 to connect passages 168, 170 to decouple the input and output shafts. When ring 46 is moved to reverse, the flow rates of the two units become equal when the effective speed of unit 20, i.e. the difference in input and output speed, exceeds the speed of unit 18 and this only happens when shaft 30 is reversed.