Patent GB-1053434-A (GB)
IPC: F16H61/46
Abstract: 1,053,434. Hydraulic transmission of power; swash-plate mechanisms; hydrostatic brakes. INTERNATIONAL HARVESTER CO. July 4, 1963, No. 30436/64. Divided out of 1,053,433. Headings F2C, F2D, F2E and F2K. [Also in Division F1] A hydromechanical variable-ratio transmission comprising a pump and a motor has a power take-off fed through a valve by the pump. As shown, a hydromechanical transmission for vehicles comprises an input shaft 23 fast with a housing 27 in which reciprocate the pistons 32, Fig. 2 (not shown) of an adjustable capacity swashplate pump, surrounding a driven shaft 41, 41<SP>1</SP> secured to a slotted valve plate 39 rotating therewith and transmitting liquid from the pump to a fixed housing 119 containing the pistons 103 of an adjustable capacity swash-plate motor. The swash-plate 47 of the pump pivots at 48, Fig. 2 (not shown), on the driven shaft 41<SP>1</SP> with which it rotates, and is slidably engaged by bearing slippers 32<SP>1</SP> on the ends of the pistons 32 rotating with the input shaft 23. The angle of the pump swashplate 47 is controlled, to vary the capacity of the pump, by supplying liquid under pressure through a follow-up servo valve 61 to oppositelydisposed cylinders 54, 55 rotating with the driven shaft 41<SP>1</SP> and containing pistons 57 themselves engaging the swash-plate through bearing slippers. Change of pump swash-plate angle is initiated by manual or by hydraulic &c. power actuation of a link 81, e.g. from the position shown to a postion 81<SP>1</SP>. The servo valve 61 is thereby operated to energize the cylinders 54, 55, and the swash-plate 47 tilts, carrying along a ring 89 rotating with but sliding in the housing 27. The ring 89 in turn slides a non- rotary ring 85 which reacts back upon the follow-up valve 61 so as to shut-off the supply of liquid to the cylinders 54, 55 when the selected swashplate angle has been reached. Similarly, the angle of the motor swashplate 113, Fig. 2a (not shown), which pivots at 117 on the driven shaft 41, is controlled by manual or by hydraulic &c. power movement of a link 161 actuating a follow-up servo valve 119, through which liquid under pressure is supplied to cylinders 122, 123 in a housing rotating with the driven shaft 41 and containing pistons carrying bearing slippers slidably engaging the swash-plate. The motor swash-plate 113 pivots and thus slides a non-rotating ring 136 axially to react back upon the follow-up valve 119. The two control links 81, 161 enable the capacities of the transmission to be so adjusted that the ratio between the input and output shafts is varied continuously from neutral to direct drive, or gives greater or lesser speeds in the same or reverse directions, or alternatively the output shaft can be braked or locked. Liquid under pressure for the swash-plate tilting motors 54, 55; 122, 123 is derived from the main fluid paths 166, 167 which are in the form of arcuate slots through the valve plate 39 connecting the pistons 32, 103 of the transmission pump and motor. The valve plate 39, rotating with the output shaft, is formed with passages and facial grooves feeding passages in 'mounting blocks 62, 101. The passages, Fig. 6 (not shown), include one-way valves 176, 178, 183, 185 so arranged that, irrespective of the direction of rotation of the input shaft and the housing 27, a main pipe 180 is always connected to the high pressure fluid path. Main pressure 180 is fed through pipes 100 to the follow-up servo valves 61, 119, and is also fed through a pipe 181 and a control valve 182<SP>1</SP> to a power take-off in the form of hydraulically-powered auxiliaries 182, whence it is returned at low pressure through a pipe 187<SP>1</SP>, 187 to the low pressure fluid path 166 or 167 connecting the pump and motor. An hydraulically-controlled by-pass valve 196 connects the high and low pressure pipes 180, 187 and can be so actuated as to effect braking of the driven shaft 41 when the transmission pump is adjusted to zero capacity. A make-up pump 190 driven from the input shaft 23 feeds from a sump 189 to the low pressure pipe 187.