# US 2014/0196961 A1 · Crawler work vehicle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0196961 A1 - Document ID: US20140196961A1 - Status: Published application - Kind: A1 - Application number: 13/995,545 - Filed: 2012-10-01 - Published: 2014-07-17 - Earliest claimed: 2012-05-01 - Assignees: Komatsu Ltd. - Inventors: Takeshi Yoshikawa; Taneaki Fujino - Web page: https://patentgrep.com/patent/US20140196961A1 ## CPC - B62D 11/08: using brakes or clutches as main steering-effecting means - B62D 11/001: {control systems (B62D11/183 takes precedence)} - B62D 11/005: {Hydraulic control systems} - E02F 9/2025: {Particular purposes of control systems not otherwise provided for (E02F3/16, E02F3/26, sub-groups of E02F3/43, E02F3/651, sub-groups of E02F3/84, E02F3/907, E02F5/145 take precedence)} - E02F 9/225: {Control of steering, e.g. for hydraulic motors driving the vehicle tracks (steering in general B62D)} - F02D 29/04: peculiar to engines driving pumps - F02D 31/001: {Electric control of rotation speed} - F02D 41/021: {Introducing corrections for particular conditions exterior to the engine (conjoint control of vehicle sub-units for propelling the vehicle B60W30/18)} - 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) - E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00) - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) ## Abstract An occurrence of steering clutch slippage is reliably determined in order to protect the steering clutch. A crawler work vehicle includes left and right steering clutches, left and right steering brakes, a rotation speed detecting difference device, a clutch hydraulic pressure obtaining device, and a clutch protecting device. The rotation speed difference detecting device detects a rotation speed difference between the input and output of each of the steering clutches. The clutch hydraulic pressure obtaining device obtains a clutch hydraulic pressure supplied to each steering clutch. The clutch protecting device refers to the rotation speed difference and the clutch hydraulic pressure, computes a steering clutch heat rate, and compares the computed heat rate with a preset first threshold to execute a steering clutch protection process. ## Claims ### Claim 1 A crawler work vehicle comprising: an engine; left and right travel devices that respectively have a crawler and a drive wheel for driving the crawler; a power transmission device that transmits power of the engine to the drive wheels of the left and right travel devices; left and right steering clutches that are disposed between the power transmission device and the left and right drive wheels,. and that transmit or block power; left and right steering brakes that are respectively disposed between the left and right steering clutches and the left and right drive wheels, and that brake rotation of the left and right drive wheels; a rotation speed difference detecting device that detects a rotation speed difference between an input and an output of each of the steering clutches; a clutch hydraulic pressure obtaining device that obtains a clutch hydraulic pressure supplied to the steering clutches; and a clutch protecting device that refers to the rotation speed difference and the clutch hydraulic pressure, that computes a steering clutch heat rate, and that compares the steering clutch heat rate that was computed with a preset first threshold to execute a steering clutch protection process. ### Claim 2 (depends on 1) The crawler work vehicle according to claim 1, wherein: the clutch protecting steering clutch reduces the engine output upon determining the steering clutch heat rate is equal to or greater than the first threshold. ### Claim 3 (depends on 2) The crawler work vehicle according to claim 2, further comprising: an engine rotation speed determining device that determines whether the engine rotation speed is a preset accepted minimum engine rotation speed; the clutch protecting device executing a warning process without reducing the engine output while the engine rotation speed is lower than the minimum rotation speed upon determining the steering clutch heat rate is equal to or greater than the first threshold. ### Claim 4 (depends on 2) The crawler work vehicle according to claim 2, wherein the clutch protecting device increases the engine output by a certain amount upon determining the steering clutch heat rate is equal to or less than a second threshold that is smaller than the first threshold. ### Claim 5 (depends on 1) The crawler work vehicle according to claim 1, wherein the clutch protecting device disengages the steering clutch while the steering clutch heat rate equal to or greater than the first threshold upon determining the steering clutch heat rate is equal to or greater than the first threshold. ### Claim 6 (depends on 5) The crawler work vehicle according to claim 5, wherein the clutch protecting device executes a warning process after disengaging the steering clutch upon determining the steering clutch rate value is equal to or greater than the first threshold. ### Claim 7 (depends on 1) The crawler work vehicle according to claim 1, wherein the power transmission device includes a torque converter that transmits power through operating fluid. ### Claim 8 (depends on 3) The crawler work vehicle according to claim 3, wherein the clutch protecting device increases the engine output by a certain amount upon determining the steering clutch heat rate is equal to or less than a second threshold that is smaller than the first threshold. ### Claim 9 (depends on 2) The crawler work vehicle according to claim 2, wherein the power transmission device includes a torque converter that transmits power through operating fluid. ### Claim 10 (depends on 3) The crawler work vehicle according to claim 3, wherein the power transmission device includes a torque converter that transmits power through operating fluid. ### Claim 11 (depends on 4) The crawler work vehicle according to claim 4, wherein the power transmission device includes a torque converter that transmits power through operating fluid. ### Claim 12 (depends on 5) The crawler work vehicle according to claim 5, wherein the power transmission device includes a torque converter that transmits power through operating fluid. ### Claim 13 (depends on 6) The crawler work vehicle according to claim 6, wherein the power transmission device includes a torque converter that transmits power through operating fluid.