# US 5,341,893 A · Four wheel drive working vehicle having transmission clutches separately operable for driving right and left rear wheels

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,341,893 A
- Document ID: US5341893A
- Status: Granted
- Kind: A
- Application number: 07/893,659
- Filed: 1992-06-05
- Granted: 1994-08-30
- Earliest claimed: 1991-12-13
- Assignees: Kubota Corporation
- Inventors: Tetsu Fukui; Yoshimi Oota; Shigekazu Hasegawa
- Web page: https://patentgrep.com/patent/US5341893A

## CPC

- F16H 48/30: using externally-actuatable means
- B60K 17/348: having differential means for driving one set of wheels, e.g. the front, at one speed and the other set, e.g. the rear, at a different speed (B60K17/346 takes precedence)
- B60K 17/3505: {with self-actuated means, e.g. by difference of speed}
- B60K 23/0808: {for varying torque distribution between driven axles, e.g. by transfer clutch}
- B60W 2540/18: Steering angle
- F16D 25/0638: with more than two discs, e.g. multiple lamellae
- F16D 25/10: Clutch systems with a plurality of fluid-actuated clutches (arrangements or mounting of clutches in vehicles B60K17/00)
- F16H 48/22: using friction clutches or brakes
- F16H 48/32: using fluid pressure actuators
- F16H 2048/205: {using the steering as a control parameter}
- F16H 2200/2071: using three freewheel mechanism
- Y10T 74/19005: Nonplanetary gearing differential type [e.g., gearless differentials]
- 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
- F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A four wheel drive working vehicle having transmission clutches separately operable for driving right and left rear wheels. Power for driving right and left front wheels is transmitted thereto from a change speed device through a front differential, while power for driving the rear wheels is transmitted thereto from the change speed device through the transmission clutches, respectively. When the front wheels are steered from a straight running position beyond a predetermined angle in order to turn the vehicle, the transmission clutch corresponding to the rear wheel lying on the inside of the turn is disengaged while the transmission clutch corresponding to the outside rear wheel remains engaged. Consequently, the rear wheel lying on the inside of the turn and describing the smallest turning radius is placed in free rotation state. The working vehicle can change running directions and make small, sharp turns smoothly without a rear differential.

## Claims

### Claim 1

A four wheel drive working vehicle comprising:
an engine;
front wheels and rear wheels;
front wheel steering means for steering said front wheels;
a front differential connected to said front wheels;
change speed means for changing speed of power received from said engine, and transmitting the power to said front differential and to said rear wheels;
a first clutch for controlling power transmission from said change speed means to a righthand one of said rear wheels;
a second clutch for controlling power transmission from said change speed means to a lefthand one of said rear wheels; and
clutch control means for controlling said first and second clutches, said clutch control means being interlocked to said front wheel steering means to disengage one of said first and second clutches corresponding to one of said rear wheels lying on the inside of a turn when said front wheels are steered in excess of a first predetermined angle, wherein said rear wheel lying on the inside of the turn is placed in a nondriven, free rotation state by the disengagement of said corresponding clutch, wherein said change speed means includes a front wheel speed changer for selectively producing a first mode to drive said front wheels and said rear wheels at substantially the same speed, and a second mode to drive said front wheels faster than said rear wheels, and front wheel speed control means for switching said front wheel speed changer from said first mode to said second mode when said front wheels are steered in excess of a second predetermined angle.

### Claim 2 (depends on 1)

A four wheel drive working vehicle as claimed in claim 1, wherein said first predetermined angle is 10 to 20 degrees, and said second predetermined angle is about 40 degrees.

### Claim 3 (depends on 1)

A four wheel drive working vehicle as claimed in claim 1, wherein said front wheel speed changer is operable in said second mode to drive said front wheels approximately twice as fast as said rear wheels.

### Claim 4 (depends on 1)

A four wheel drive working vehicle as claimed in claim 1, wherein said first predetermined angle is less than said second predetermined angle.

### Claim 5

A four wheel drive working vehicle comprising:
an engine;
front wheels and rear wheels;
front wheel steering means for steering said front wheels;
a front differential connected to said front wheels;
change speed means for changing speed of power received from said engine, and transmitting the power to said front differential and to said rear wheels;
a first clutch for controlling power transmission from said change speed means to a righthand one of said rear wheels;
a second clutch for controlling power transmission from said change speed means to a lefthand one of said rear wheels; and
clutch control means for controlling said first and second clutches, said clutch control means being interlocked to said front wheel steering means to disengage one of said first and second clutches corresponding to one of said rear wheels lying on the inside of a turn when said front wheels are steered in excess of a first predetermined angle of about 10 to 20 degrees thereby placing said rear wheel lying on the inside of said turn in a nondriven, free rotation state;
wherein said change speed means includes a front wheel speed changer for selectively producing a first mode to drive said front wheels and said rear wheels at substantially the same speed, and a second mode to drive said front wheels approximately twice as fast as said rear wheels, and front wheel speed control means for switching said front wheel speed changer from said first mode to said second mode when said front wheels are steered in excess of a second predetermined angle of approximately 40 degrees.