Abstract: A drive assembly for a four wheel drive vehicle, which drive assembly, during forward driving, automatically assumes a freewheeling position if the speed of the dependent wheel axle is higher than that of the permanently driven axle, with the four wheel drive function otherwise being maintained with a reduced driving torque, even during reversing, the drive assembly providing the freewheeling unit with a second viscous coupling which is connected in parallel and whose torque transmitting capacity is smaller than, or equal to, that of the first viscous coupling.

Abstract: In a vehicle having first and second wheels (e.g., front and rear wheels) to be driven with a speed difference, the wheels are driven by a toroidal type continuously variable transmission having a single input shaft and which is effective to accommodate the speed difference between the first and second wheels without a separate differential for such purpose.

Abstract: A four-wheel drive torque transfer mechanism splits torque from the transmission gearing section of a vehicle into a front-wheel torque and a rear-wheel torque, transmitting the front-wheel torque to the front-wheel drive shafts and the rear-wheel torque to the rear-wheel drive shafts. A central differential connected to the transmission gearing section distributes the torque from the transmission gearing section. A central differential limiting mechanism, provided between the input and output sides of the central differential, limits the rotary differential operation of the differential arrangement responsive to a control torque signal. Control gain values representing optimized turning characteristics are calculated for each of the turning conditions of the vehicle and stored in a memory. A controller for controlling the differential limiting mechanism reads the control gain values from the memory and calculates the products of detected turning conditions and the control gain values corresponding thereto.

Abstract: A vehicle power distribution and control system controls and distributes the power supplied to the wheels of a motor vehicle with at least two driven axles. One of the axles includes an axle differential gear. The control system includes a steering angle sensor, rotational speed sensors to monitor the rotational speeds of the wheels of at least one axle, and an electronic control unit. A differential lock for the axle differential gear is controlled by the control unit to equalize sliding effects that can occur between the wheels of one axle. The control unit calculates a theoretical rotational speed difference ratio from the value of the sensed steering angle for conditions of rolling without any slip and an actual rotational speed difference ratio from the sensed rotational speed values.

Abstract: A control system for a four-wheel drive vehicle includes a center differential provided between a front shaft and a rear shaft. The control system also includes a device for restricting a differential between the front shaft and the rear shaft by operating the center differential to be in a locking condition and a controller for controlling the differential restricting device so that a differential restricting force is increased based on an increase in an engine output. The differential restricting force is decreased based on an increase in a vehicle body speed.

Abstract: An engine and a first final drive are disposed proximate a first set of road wheels, while the transmission and a second final drive are disposed proximate the second set of road wheels. A torque tube which operatively interconnects the engine containing section with the section in which the transmission is disposed, houses a first propeller shaft which transmits engine torque to the transmission, and a hollow second propeller shaft which is disposed coaxially about the first one, and which transmits torque back from the transmission to the engine containing section for application to the first set of road wheels.

Abstract: A control system for a four-wheel drive vehicle includes a first differential provided between a front shaft and a rear shaft and a second differential provided between a right wheel and a left wheel. The control system comprises a first device provided in the first differential for restricting a differential between the front shaft and the rear shaft, a second device provided in the second differential for restricting a differential between the right wheel and the left wheel, and a device for controlling the restricting operations carried out by the first device and the second device. The controlling device includes a device for controlling operational timings in the first device and the second device so that the timing when the first device maintains the first differential in locking condition is different from the timing when the second device maintains the second differential in locking condition.

Abstract: A transfer apparatus for a vehicle has an input shaft which is connected to pinion shafts so as to rotate together with the pinion shafts in a transfer casing. Pinion gears, provided on the pinion shafts, mesh with first and second differential side gears provided around the input shaft. A first output shaft is formed as a unitary body with the first differential side gear. Since a clutch mechanism is disposed on one side of and beside the first output shaft, the entire transfer apparatus structure is compact in both axial and radial directions of the input shaft. The second differential side gear is connected to a sprocket, which connected to a second output shaft. In order to transfer rotation of either the input shaft or the second differential side gear to the clutch mechanism, either a differential casing or a portion extending from the sprocket is provided so as to connect with the clutch mechanism.

Abstract: A differential gear lock controller, in which it is judged that a speed sensor has failed if the throttle opening or the number of revolutions of an engine is greater than or equal to a predetermined value and if the state in which the vehicle speed is zero elapses a predetermined time or more, or if the deceleration of the vehicle speed is greater than or equal to a predetermined value. In such a case, the operation of controlling a driver for driving a mechanism for locking a rear differential gear is stopped.

Abstract: A drive system for a tractor which is operable in either a two wheel or a four wheel mode of operation. The drive system includes a control apparatus which automatically establishes a drive connection between a power source on the tractor and a front pair of tractor wheels through regulated operation of a normally engaged clutch assembly in response to application of service brakes on the tractor. Thus, the decreasing inertia of the power source, inherent with deceleration due to braking, is utilized to substantially equalize wheel slippage between front and rear pairs of wheels thereby advantageously improving braking performance especially as the tractor operates at relatively high speeds.

Abstract: A microcomputer-based electronic control system for a full time four wheel drive torque transfer case monitors the relative slip between the front and rear output shafts of the transfer case, and generates a signal to engage an electromagnetic clutch for a predetermined time period in the event a first predetermined slip threshold is exceeded. In the event the driver has actuated the vehicle service brakes, the electromagnetic clutch is only engaged if the relative slip is less than a second predetermined slip threshold greater than the first predetermined slip threshold.

Abstract: The invention relates to a drive assembly for a four wheel drive vehicle with the distributor assembly for distributing driving torque arranged between the front wheels and the rear wheels of a driving axle. A distributor differential (13) and axle differential (15) distribute the driving torque. Both the distributor differential (13) and the axle differential (15) may be at least partially locked via viscous couplings (39, 40) in order to cancel the differential function. I order to achieve the shortest possible design, the two viscous couplings (39, 40) are arranged coaxially one inside the other.

Abstract: An arrangement for the operating of clutches of an all-wheel transmission line has two hydraulically operated clutches inserted in the transmission line of a motor vehicle. The first clutch is used as the separating clutch to a first vehicle axle; the second clutch is used as a locking clutch for the blocking of a lock system by which the second vehicle axle can be connected as a function of the rotational speed. The separating clutch can be closed against the force of a diaphragm spring by a first hydraulic piston with a second hydraulic piston, which is concentric with respect to the first hydraulic piston, the locking clutch can be opened against the force of a diaphragm spring.

Abstract: A four-wheel drive vehicle has a center differential which transmits the output torque of a power plant to both front and rear wheels in such a manner as to permit the front and rear wheels to rotate at different speeds. A differential control system has a differential rotation limit member which acts on the center differential to limit differential rotation of the front and rear wheels to a degree which is increased as the difference in rotational speed between the front and rear wheels increases. The degree of limitation on the differential rotation of the front and rear wheels is changed according to a predetermined characteristics which nullifies the degree of limitation in a range where the difference in rotational speed is relatively small and provides a gain in a range where the difference in rotational speed is relatively large. The gain is changed according to a factor which governs the running condition of the vehicle.

Abstract: Apparatus and method for increasing the ability of a cotton module mover to reach remote locations in soil conditions which typically hinder travel; to load and unload modules on soft, uneven, and wet ground; and, to equalize the horizontal movement of the ground engaging portions of the tires, the track units, and to drive the live floor of the mover's bed at the same horizontal rate as the mover's actual movement with respect to the ground. The invention includes self-adjusting supports which distribute a portion of the weight of the mover equally to each of the track units and allows each track unit to independently extend to various positions below the mover. The equalization of the horizontal movement of the tires, the track units, and the live floor includes mechanically interconnecting the tires and track units and controlling the live floor with a system which detects the mover's actual movement relative to the ground and then drives the live floor at that speed.

Abstract: A drive assembly for a four wheel drive vehicle, which drive assembly, during forward driving, automatically assumes a freewheeling position if the speed of the dependent wheel axle is higher than that of the permanently driven axle, with the four wheel drive function otherwise being maintained with a reduced driving torque, even during reversing, the drive assembly providing the freewheeling unit with a second viscous coupling which is connected in parallel and whose torque transmitting capacity is smaller than, or equal to, that of the first viscous coupling.

Abstract: A system for controlling torque distributed to front wheels and rear wheels of a motor vehicle comprises a planetary gear device including a first sun gear connected to an output shaft of a transmission, a carrier, first and second planetary pinions coupled with each other and rotatably supported on the carrier, and a second sun gear disposed between a front torque transmitting member and a rear torque transmitting member. The first planetary pinion is engaged with the first sun gear, and the second planetary pinion is engaged with the second sun gear. A fluid operated multiple-disk clutch is disposed between the carrier and the rear torque transmitting member so as to restrict the differential operation of the planetary gear device.

Abstract: A traction control system is provided which is applicable to a four-wheel drive vehicle in which a torque split system is incorporated. The torque split system is operable to distribute engine torque to front and rear wheels by an engine torque distribution ratio of front to rear wheels variable based on a difference in rotational speeds between the front and rear wheels. The traction control system is responsive to a slippage ratio of the rotational speeds of the wheels to a vehicle speed greater than a preselected threshold to reduce engine torque to control the traction of the wheels. Therefore, the traction control is effectively carried out while ensuring yaw control of a vehicle body by means of the torque split control.

Abstract: A full time four wheel drive system has a housing in the vicinity of an engine and a transmission, a central differential gear assembly and a viscous coupling assembly containing a front differential gear assembly. The central differential gear, front wheel differential gear, and viscous coupling assemblies are disposed in parallel relationship within the housing for uniformly distributing the load of axle and drive shafts according to the road conditions. The system has a simple structure and economically uses the space in the engine compartment.

Abstract: In an all-wheel driven field tractor whose front-axle differential (6) and rear-axle differential (15) are permanently driven in arable land by output shafts (2 and 3) of a gear change (1) so that a rigid connection exists between front and rear axles, the higher speeds of the front axle (7) appearing when cornering must be compensated. Besides, a mechanism for compensating the axle speeds must be adapted to be integrated in the field tractor without substantial constructural changes. For this purposse there is situated between the crown gear (12) and the differential cage (14) of the rear-axle differential (15) a clutch (16) designed as a control slip clutch having its slip status regulated according to the parameters of the track radius to be executed and/or the traction needed.

Abstract: A transfer shift apparatus for shifting a vehicle between two wheel drive and four wheel drive includes a shift mechanism including a reversible motor which is continuously driven to rotate in one direction of rotation according to a shift signal so as to shift the vehicle into a desired drive condition. A motor drive controller controls the motor to stop its rotation when detecting a predetermined load on the motor and not to rotate in another direction for a predetermined time period from a time the shift signal disappears.

Abstract: The distribution of drive power produced by a drive power source is controlled in a four-wheel-drive motor vehicle having main drive wheels and auxiliary drive wheels. Drive powers produced by the drive power source are independently regulated and transmitted to the left and right auxiliary drive wheels. While the drive power distribution ratio between the main and auxiliary drive wheels is maintained at a suitable value, the drive powers are variable distributed between the left and right auxiliary drive wheels by a drive power distribution control system. The drive power distribution control system determines the drive power distribution ratio between the left and right auxiliary drive wheels depending on a detected lateral acceleration exerted to the motor vehicle, and transmits the drive powers to the left and right auxiliary drive wheels according to the determined drive power distribution ratio.

Abstract: A power transmitting apparatus on a four-wheel-drive motor vehicle can distribute and transmit drive power from a power unit to front and rear drive road wheels such that the rotational speeds of the front and rear drive road wheels can differ from each other.

Abstract: In a four wheel drive vehicle having an anti-lock brake system in combination with a front differential gear, a rear differential gear and a center differential gear, a center differential lock mechanism between the front differential gear and the center differential gear is automatically disengaged when a throttle opening sensor detects a low degree of throttle opening independently of the vehicle speed. The device for automatically disengaging the center differential lock mechanism is operated under the control of an operating unit receiving input signals from a center differential gear operating switch, a vehicle speed sensor, a rear wheel speed sensor, a brake lamp sensor and a throttle opening sensor.

Abstract: A four wheel drive system for a vehicle includes comprising a power plant for producing a driving force, a front wheel driving mechanism for transmitting the driving force to drive right and left front wheels, a rear wheel driving mechanism for transmitting the driving force to drive right and left rear wheels, and right and left wheel clutches provided in one of the driving mechanisms for controlling the amount of the driving force transmitted to the wheels. A cut-off clutch is provided for controlling the driving force transmitted to the wheels of the one of the driving mechanisms, and a control device causes the cut-off clutch to engage before the wheel clutch is engaged. The driving force is transmitted sequentially rather than instantly from the cut-off clutch, the wheel clutches and to the wheels so as to suppress the torque shock creative in connection with a change in the drive condition.

Abstract: The present invention provides a motor vehicle cold shift assist system for selectively actuating an axle connecting mechanism to automatically connect the non-driven wheels to its associated axle drive mechanism immediately following synchronization for counteracting the inertial loading acting on the transfer case synchronizer clutch mechanism. The axle connecting mechanism is actuated prior to the transfer case being locked in the four-wheel drive mode. As such, the present invention substantially reduces the shift resistance and gear clash encountered upon the vehicle operator shifting into the four-wheel drive mode during cold weather conditions.

Abstract: A brake system with electronic anti-lock control for all-wheel driven automotive vehicles possesses two control channels, to which diagonally each one front wheel (VR or VL) and one rear wheel (HL or HR) are connected. Rotational speed sensors (24, 25) are provided at the front wheels only. During anti-lock or slip control, front wheels and rear wheels are coupled such that a brake torque is transmittable at least from the rear wheels to the front wheels. Preferably, brake torques are transmitted also from the front axle to the rear axle. For coupling, a differential lock (6) is arranged in the distribution differential (3) which lock is controllable by a signal of the anti-lock control system.

Abstract: The present invention provides a motor vehicle cold shift assist system for selectively and automatically connecting the non-driven wheels to its associated axle drive mechanism under certain operational and temperature conditions for counteracting the inertial loading acting on the transfer case synchronizer clutch mechanism. The present invention substantially reduces the shift resistance encountered upon the vehicle operator subsequently shifting into the four-wheel drive mode during cold weather conditions.

Abstract: A four wheel drive system of a vehicle including a power plant for producing driving force, has a front wheel driving mechanism for transmitting the driving force to drive a right and left front wheels and rear wheel driving mechanism for transmitting the driving force to drive right and left rear wheels. Right and left wheel clutches provided in one of the driving mechanisms for control the amount of the driving force transmitted to the wheels, and steering angle detecting device detects a steering angle of a steering wheel. A control device increases torque distribution for the rear wheel driving mechanism in a cornering condition of the vehicle as a steering angle change rate is increased. The system provides the vehicle with a desirable torque distribution during a cornering operation so that improved cornering property is obtained.

Abstract: A device for electrohydraulic actuation of a clutch of a differential transmission (31) situated between an automatic transmission (3) and the drive wheels of the vehicle comprises an actuating piston (23) actuated by pressurized fluid supplied via a main contorl line (4) through a safety valve (6) and a clutch valve (13), a pressure reducing valve (5) is provided for supplying a reduced constant pressure fluid to a pilot control line (7) which is connected to both the safety valve (6) and the clutch valve (13), and a pressure control valve (11) is provided in the pilot contorl line (7) and, when the pressure control valve (11) is closed, the clutch and safety valves (6, 13) are both closed by the reduced pressure fluid thereby preventing the flow of pressurized fluid to the actuation piston, and when pressure control valve (11) is open, the flow of pressurized fluid to the actuation piston (23) is allowed by the safety and clutch valves (6, 13) thereby allowing engagement of the clutch and the locking of the

Abstract: A planetary gear device as a central differential distributes an output torque of a transmission to the front wheels and the rear wheels of a four-wheel drive motor vehicle. A fluid operated clutch is provided between a sun gear and a ring gear of the planetary gear device. A desired speed ratio between front-wheel speed and rear-wheel speed at cornering is calculated based on vehicle speed and steering angle of the vehicle. A torque distribution ratio is determined in accordance with a difference between the desired speed ratio and an actual speed ratio between the front-wheel speed and the rear-wheel speed. The clutch pressure is controlled in response to the torque distribution ratio for engaging the clutch so that the average speed ratio coverages to the desired speed ratio.

Abstract: A central differential distributes an output torque of a transmission to front wheels and rear wheels of a vehicle. A fluid-operated restricting device is provided for restricting the differential operation of the central differential. The central differential is arranged to distribute a larger torque to the rear wheels than the front wheels. A slip ratio of the rear wheels is calculated based on rear-wheel speed and vehicle speed. The fluid-operated restricting device is operated in accordance with the slip ratio, in such a manner that the restricting magnitude increases with an increase of the slip ratio.

Abstract: A central differential comprising a planetary gear device is parallel to front axles of a motor vehicle, and coaxially to a transfer shaft of a transfer device. The planetary gear device comprises a first sun gear connected to an output shaft of a transmission, a carrier, first and second planetary pinions integral with each other and rotatably supported on the carrier, and a second sun gear. The first planetary pinion is engaged with the first sun gear, and the second planetary pinion is engaged with the second sun gear. A fluid operated multiple-disk clutch is disposed coaxial to the central differential so as to restrict the differential operation of the planetary gear device.

Abstract: A control apparatus for a power train shifting mechanism is designed so as to deenergize a motor when a load larger than a given value is applied to the motor as a driving source in shifting a power train in accordance with a stroke displacement. When the shift position is shifted from a stroke end position to an intermediate position other then the stroke end position, a load value for deenergizing the motor is set to a larger value than that of shifting the shift position in other ways.

Abstract: A drive control system of a four-wheel drive vehicle has a differential device interposed between front and rear wheels and a differential restricting device mounted to the differential device. The differential restricting device is subjected to feedback control so as for the wheels to reach a target slip ratio. In this control, a control target value is given by way of slip ratios of the wheels and the target slip ratios are then converted into a wheel speed difference between the front and rear wheels. The feedback control of the differential restricting device is performed by comparing the target wheel speed difference with an actual wheel speed difference between the front and rear wheels.

Abstract: A central differential is composed of a planetary gear device. The planetary gear device comprises a first sun gear connected to an output shaft of a transmission, a carrier, a pinion set comprising first and second planetary pinions integral with each other and rotatably supported on the carrier, and a second sun gear. The first planetary pinion is engaged with the first sun gear, and the second planetary pinion is engaged with the second sun gear. The first and second planetary pinions are in the same phase, and a plurality of the pinion sets are equiangularly disposed around the first and second sun gears.

Abstract: A central differential for splitting output torque of a transmission is formed by a complex planetary device. The planetary device comprises an input sun gear operatively connected with an output shaft of the transmission, a plurality of output sun gears, a carrier, and a pinion member comprising a plurality of planetary pinions integral with each other and rotatably supported on the carrier. Fluid operated friction clutches are provided for selectively connecting one of the output sun gears to an output member of the central differential.

Abstract: A central differential distributes output torque of a transmission to front wheels and rear wheels of a vehicle. A fluid-operated restricting device is provided for restricting the differential operation of the central differential. The central differential is arranged to distribute a larger torque to the rear wheels than that to the front wheels. A slip ratio of the rear wheels is calculated, and a desired slip ratio is set based on driving conditions of the vehicle. A slip ratio deviation of the rear-wheel slip ratio from the desired slip ratio is obtained. The fluid-operated restricting device is operated in accordance with the slip ratio deviation, in such a manner that the restricting magnitude increases with an increase of the slip ratio deviation.

Abstract: A central differential comprising a planetary gear device is coaxially mounted on one of the axles of a motor vehicle. The planetary gear device comprises a first sun gear connected to an output shaft of a transmission, a carrier, first and second planetary pinions integral with each other and rotatably supported on the carrier, and a second sun gear. The first planetary pinion is engaged with the first sun gear, and the second planetary pinion is engaged with the second sun gear. A fluid-operated multiple-disk clutch is disposed so as to restrict the differential operation of the planetary gear device.

Abstract: A fluid-operated transfer clutch provided adjacent a rear differential so as to transmit output torque of a transmission to a front differential. A fluid-operated restricting clutch is provided adjacent the rear differential and disposed between a differential case and a corresponding axle so as to restrict differential operation of the rear differential. Clutch pressure of each clutch is controlled in accordance with driving conditions of the vehicle.

Abstract: An interaxle differential includes a central drive member that continuously connects an input shaft with a first output shaft, a clutch disk normally connecting the central drive member with a second output shaft, a rotational velocity responsive device operable from a deactivated position to an activated position for disengaging the clutch disk when the second output shaft overruns the first output shaft by a given value, a fail safe device for biasing the velocity responsive device toward its deactivated position, a first device for displacing the velocity responsive device toward the activated position, and an override device for selectively disengaging the clutch disk. In a second embodiment, the rear clutch disk is operable by the operator to disconnect the interaxle differential from the first output shaft, thereby to avoid the trapping of torque within the interaxle differential when the vehicle is maneuvered downhill in a turn.

Abstract: A system for controlling torque distributed to front wheels and rear wheels of a motor vehicle. A planetary gear device including a first sun gear connected to an output shaft of a manual transmission, first and second planet pinions integral with each other, a carrier provided to rotatably support the pinions and operatively connected to the front wheels, and a second sun gear operatively connected to the rear wheels is disposed to distribute the torque to front wheels and rear wheels. The first planetary pinion is engaged with the first sun gear, and the second planetary pinion is engaged with the second sun gear. A fluid operated multiple-disk clutch selectively connects two of the first sun gear, the carrier and the second sun gear so as to restrict the differential operation of the planetary gear device.

Abstract: A motor vehicle with four driving wheels and driven differential gearing for the drive, where (in the case of rotational-speed differences occurring between the wheels) a control device intervenes to distribute the drive power of an engine to the permanently driven wheels and/or the other driven wheels. This intervention occurs for a particular holding time which is progressively extended if a new intervention by the control becomes necessary after a test disconnection of the respective intervention. In addition, or alternatively, the control device can respond more sensitively and thus more quickly to rotational-speed differences of the wheels which may later occur during, or after, a test disconnection.

Abstract: A pressure generation and responsive mechanism is provided wherein several blade members bodily movable with a first member is received within a space formed in a second member. The second member provides a first flat end surface in friction engagement with the blade members, and an actuation piston, by itself or in cooperation with the second member, provides a second flat end surface in friction engagement with the other ends of the blade members. Silicon oil is filled within several space sections defined by the first and second flat end surfaces and the blade members. When the first member is moved relative to the second member, the blade members compulsorily displaces the silicon oil within the several space sections against friction resistance with the first and second flat end surfaces. Thus, a pressure is generated within each of the several space sections to actuate the actuation piston.

Abstract: A driving force distribution control system for a 4WD vehicle includes a torque distributing clutch for varying a driving force transmitted to secondary drive wheels such as front wheels in response to a control signal, one or more sensors for determining a vehicle speed, and a measured wheel speed difference between a sensed speed of primary drive wheels such as rear wheels and a sensed speed of the secondary drive wheels, and a controller for producing the control signal. The controller determines a correction quantity which increases as the vehicle speed increases, further determines a corrected wheel speed difference by subtracting the correction quantity from the measured wheel speed difference in order to eliminate an undesired influence of a tire diameter difference between the front and rear wheels, and produces the control signal in accordance with the corrected wheel speed difference.

Abstract: A drive force distribution control system for a motor vehicle controls a drive force distribution ratio between drive road wheels based on a steering torque and a lateral acceleration.

Abstract: A transfer case operation mode shifting apparatus used on a vehicle equipped with part-time four-wheel drive which having a center-differential shiftable between a differential-locked and differental-free drive mode of operation and between a two-wheel and a four-wheel drive mode of operation and a transfer shiftable between a high-speed range and a low-speed range drive mode of operation. The transfer case is shifted in its drive mode of operation by an operation mode selecting member for selecting a desired drive mode of operation. A power drive operation mode shifting device is provided in cooperation with the drive mode selecting member and a controller to actually shift the transfer case from one drive mode of operation to another. The controller is adapted to detect that the center-differential gear assembly of the transfer case is in a differential-locked four-wheel drive mode of operation so as to inhibit a transition of the center-differential to a two-wheel drive mode of operation.

Abstract: A vehicle such as a tractor having front and rear drive axles with crown wheel and pinions (10 and 11) driven from a prime mover (E) via an inter-axle differential (12). The rear drive axle has left and right hand brakes (40) and the inter-axle differential has a lock (22, 23, 24) for locking-up the differential. The lock is biased to an engaged condition by a spring (25) and an hydraulic actuator (27). A control system (CS) is provided which is arranged to engage the lock (22, 23, 24) when both rear axle brakes (40) are applied.

Abstract: A four-wheel drive vehicle including an engine of which output shaft extends transversely, a transmission connected with one side of the engine transversely through a clutch or a torque converter, an inter-axle differential machanism constituted by a planetary gear machanism, a first inter-wheel differential mechanism of a bevel gear type for transmitting a driving force to first wheels which are located closer to the engine than second wheels longitudinally, second inter-wheel differential mechanism for transmitting the driving force the second wheels through transfer gear mechanism, propeller shaft mechanism, and inter-axle differential restricting mechanism for restricting a differential operation. The inter-axle differential mechanism, input gear means of the transfer gear mechanism and the first inter-wheel differential mechanism are coaxially disposed on an axle of the first wheels.

Abstract: A transfer differential gear lock controller in accordance with the present invention interlocks a switching operation of a transmission device between a low speed range and to a high speed range with a differential gear lock operation, controls a center differential gear lock mechanism to a lock state by detecting the operation state of the transmission device in the low speed range and makes it possible for a driver to complete his operation with only one shift operation to the low speed range. The controller makes it also possible to select between the lock state and free state for the center differential gear lock mechanism in response to the detection of the operation state of the transmission device in the high speed range through the driver's operation.