# US 9,435,417 B1 · Automatic torque compensating drive system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,435,417 B1 - Document ID: US9435417B1 - Status: Granted - Kind: B1 - Application number: 14/456,544 - Filed: 2014-08-11 - Granted: 2016-09-06 - Earliest claimed: 2011-11-01 - Assignees: Hydro-Gear Limited Partnership - Applicants: Hydro-Gear Limited Partnership - Inventors: Nathan W. Bonny; K. Mike McCoy - Web page: https://patentgrep.com/patent/US9435417B1 ## CPC - F16H 39/00: Rotary fluid gearing using pumps and motors of the volumetric type, i.e. passing a predetermined volume of fluid per revolution (control of exclusively fluid gearing F16H61/38) - B60K 17/105: {Units comprising at least a part of the gearing and a torque-transmitting axle, e.g. transaxles (B60K17/14 takes precedence)} - B60K 23/00: Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for - B60W 10/04: including control of propulsion units - B60W 10/10: including control of change-speed gearings - B62D 11/001: {control systems (B62D11/183 takes precedence)} - B62D 11/02: by differentially driving ground-engaging elements on opposite vehicle sides - B62D 11/18: the additional power supply being supplied hydraulically - B62D 11/183: {Control systems therefor} - F16H 61/427: Motor capacity control by mechanical control means, e.g. by levers or pedals - F16H 61/456: Control of the balance of torque or speed between pumps or motors - B60K 7/0015: {the motor being hydraulic} - B60K 2007/0038: {the motor moving together with the wheel axle} - B60K 2007/0092: {the motor axle being coaxial to the wheel axle} - B60Y 2200/223: Ridable lawn mowers - F16H: GEARING - B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES - B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) - B60Y: INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY ## Abstract An automatic torque compensating drive system for a hydrostatic transmission, having a torque compensating control mechanism adjusting the swash plate of the hydraulic motor, the swash plate being spring biased to a low-torque, high-speed position and rotatable through a range of positions to a high-torque, low-speed position in response to increasing hydraulic system pressure. When used with a pair of transmissions, a linkage may join the control mechanisms of each transmission to synchronize their torque adjustments. ## Claims ### Claim 1 A torque control mechanism for adjusting a torque level of an output of a transmission from a low-torque value to a high-torque value, wherein the transmission includes a hydraulic motor having an adjustable swash plate, said torque control mechanism comprising: a camshaft; a cam member slidingly engaged to the camshaft and configured to operatively engage the swash plate; and a biasing member operatively engaged to the cam member to bias the swash plate to a biased position. ### Claim 2 (depends on 1) The torque control mechanism of claim 1, wherein the biasing member comprises a spring. ### Claim 3 (depends on 1) The torque control mechanism of claim 1, wherein the biasing member is disposed inside a housing in which the hydraulic motor is located. ### Claim 4 (depends on 1) The torque control mechanism of claim 1, wherein the cam member is slip fit onto the camshaft. ### Claim 5 (depends on 1) The torque control mechanism of claim 1, wherein the output of the transmission is adjusted toward the high-torque value as the load experienced by the transmission increases. ### Claim 6 (depends on 5) The torque control mechanism of claim 5, wherein the output of the transmission is adjusted toward the low-torque value as the load experienced by the transmission decreases. ### Claim 7 (depends on 1) The torque control mechanism of claim 1, wherein the biased position corresponds to the low-torque value of the output of the transmission. ### Claim 8 A drive system comprising: a transmission disposed in a housing and producing an output; and a torque control mechanism engaged to the transmission and configured to adjust a torque level of the output between a low-torque value and a high-torque value, the torque control mechanism including means for biasing the torque level of the output to the low-torque value, and the torque control mechanism automatically adjusts the output of the transmission in response to load. ### Claim 9 (depends on 8) The drive system of claim 8, wherein the means for biasing comprises a spring. ### Claim 10 (depends on 9) The drive system of claim 9, wherein the spring is disposed in a receiving pocket of the housing. ### Claim 11 (depends on 8) The drive system of claim 8, wherein the transmission comprises an axial piston hydraulic motor having a swash plate pivotable between a first position corresponding to the low-torque value and a second position corresponding to the high-torque value. ### Claim 12 (depends on 11) The drive system of claim 11, wherein the swash plate comprises an integrally formed pivot surface that rides in a corresponding channel formed in the housing. ### Claim 13 (depends on 11) The drive system of claim 11, wherein the means for biasing comprises a spring, and the drive system further comprises a cam member operatively engaged to the swash plate and the spring, wherein the cam member acts upon the swash plate under motive force from the spring to drive the swash plate to the first position, and wherein the cam member is forced into a receiving pocket in the housing by the swash plate as the swash plate moves to the second position. ### Claim 14 (depends on 13) The drive system of claim 13, wherein the cam member is fixed to a shaft extending outside of the housing to engage the spring via a control arm. ### Claim 15 (depends on 8) The drive system of claim 8, wherein the output of the transmission drives at least one output axle. ### Claim 16 (depends on 15) The drive system of claim 15, wherein the torque control mechanism is disposed entirely internal to the housing. ### Claim 17 A drive system comprising: a hydraulic motor disposed in a housing and comprising a cylinder block having a plurality of pistons disposed therein, and an adjustable swash plate engaged to the plurality of pistons; and a torque control mechanism engaged to the swash plate and configured to move the swash plate between a first position that corresponds to a low-torque value of the output of the hydraulic motor and a second position that corresponds to a high-torque value of the output of the hydraulic motor. ### Claim 18 (depends on 17) The drive system of claim 17, further comprising means for biasing the swash plate to a biased position. ### Claim 19 (depends on 18) The drive system of claim 18, wherein the means for biasing the swash plate comprises a spring, and the biased position corresponds to the first position. ### Claim 20 (depends on 19) The drive system of claim 19, wherein the spring is disposed inside the housing. ### Claim 21 (depends on 17) The drive system of claim 17, further comprising at least one output axle disposed in the housing and driven by an output of the hydraulic motor. ### Claim 22 (depends on 21) The drive system of claim 21, wherein the torque control mechanism is disposed entirely internal to the housing. ### Claim 23 A drive system comprising: a first transmission disposed in a first housing and producing a first output; a first torque control mechanism engaged to the first transmission and configured to adjust a torque level of the first output between a low-torque value to a high-torque value, the first torque control mechanism including a first biasing member configured to bias the torque level of the first output to the low-torque value; a second transmission disposed in a second housing and producing a second output; a second torque control mechanism engaged to the second transmission and configured to adjust a torque level of the second output between the low-torque value to the high-torque value, the second torque control mechanism including a second biasing member configured to bias the torque level of the second output to the low-torque value; and an operative linkage between the first torque control mechanism and the second torque control mechanism configured to cause the torque level of the first output and the torque level of the second output to be substantially similar.