Abstract: A differential action control device of a vehicle includes an inter-axle differential disposed between axles for making a differential action between the axles, an inter-wheel differential disposed between wheels for making a differential action between the wheels, and a parameter setting device for detecting a vehicle running condition and setting a predetermined parameter based on the vehicle running condition detected. The device further includes target yaw rate setting device for setting a target yaw rate of the vehicle based on the parameter, a yaw rate detecting device for detecting an actual yaw rate of the vehicle while running, and a differential control device for controlling a differential action of the inter-axle and inter-wheel differentials based on a deviation between the actual and target yaw rate of the vehicle. The steering characteristic of the vehicle can be changed to get a desirable characteristic by making the differential action control.

Abstract: A torque split control apparatus for use with an automotive vehicle including an engine for producing a drive. The automotive vehicle is supported on a pair of primary drive wheels and a pair of secondary drive wheels. The drive is transmitted from the engine to the primary drive wheels and to the secondary drive wheels through a torque distributing clutch capable of varying a torque transmitted to the secondary drive wheels. A control torque is calculated based upon a difference between the primary and secondary drive wheel rotational speeds. The control torque is transmitted through the torque distributing clutch to provide a desired turning characteristic to the vehicle. At least one vehicle condition dependent torque, which is dependent on a specified vehicle operating condition, is calculated. Vehicle operating conditions are monitored to produce a command signal when a 4WD control is demanded.

Abstract: Provided is a transfer case having an integrated planetary gear assembly is operably installed between an input member and first and second output members and constructed in a compact dual-planetary arrangement having dual sun gears and dual planet gears that are journally supported from a carrier. The planetary gear assembly is axially slidable relative to the input and output members to a number of positions for establishing various drive modes. Included among the drive modes is a two-wheel with on-demand four-wheel drive high-range mode. In this arrangement, the carrier is driven by the input member, and the first output is engaged with the carrier for providing two-wheel drive output. The carrier is further coupled to the input member of a torque coupling device. The torque coupling device is operable to sense relative rotation between the first and second output members and to deliver torque to the second output member in response to a loss of traction at the first output member.

Abstract: In a vehicle including a torque distributing device for distributing the torque of an engine to left and right driving wheels, a feed-forward control system determines a lateral distribution torque T.sub.1 from an engine torque T.sub.E, a number Ne of revolutions of the engine, a vehicle speed V and a steering angle .theta., and a feed-back control system determines a feed-back torque T.sub.F from a target yaw rate Y determined from the vehicle speed V and the steering angle .theta. and an actual yaw rate Yaw. A final distribution torque T is determined by adding the lateral distribution torque T.sub.1 and the feed-back torque T.sub.D at a predetermined ratio, and an actuator is driven to distribute the engine torque to the left and right driving wheels on the basis of the final distribution torque T.

Abstract: A torque split control apparatus for use with 4WD type vehicle. The drive from the engine is transmitted to the primary drive wheels of the vehicle and to the secondary drive wheels of the vehicle through a torque distributing clutch capable of varying a torque transmitted to the secondary drive wheels. First and second control gains are calculated. The first control gain is inversely proportional to the vehicle lateral acceleration. The second control gain is inversely proportional to the vehicle lateral acceleration. The second control gain is smaller than the first control gain. A start indication signal is produced when the vehicle is starting. A target torque is calculated. The target torque is proportional to the first control gain and to the wheel speed difference in the presence of the start indication signal. The target torque is proportional to the second control gain and to the wheel speed difference in the absence of the start indication signal.

Abstract: An on demand vehicle drive system monitors vehicle performance and operating conditions and controls torque delivery to the vehicle wheels. The system includes a plurality of speed and position sensors, a transfer case having primary and secondary output shafts driving primary and secondary axles and a microcontroller. The sensors include a vehicle speed sensor, a pair of primary and secondary drive shaft speed sensors, and brake and driveline status sensors. The transfer case includes a modulating electromagnetic clutch controlled by the microcontroller which is incrementally engaged to transfer torque from the primary output shaft to the secondary output shaft. When the speed of either the front or the rear drive shafts overruns, i.e., exceeds, the speed of the other drive shaft by a predetermined value related to the vehicle speed, indicating that wheel slip is present, clutch current is incrementally increased to increase clutch engagement and torque transfer to the secondary axle.

Abstract: A clutch device for controlling transmitted torque in a vehicle comprises a first friction clutch including multiple clutch disks, a hub, a clutch drum and a pressing ring; a second friction clutch including multiple clutch disks, a clutch drum, a cam ring and an electromagnet; a cam mechanism; and a spring. A part of the thrust force is cancelled by energizing force of the spring to shift an operating point of the first friction clutch to a high torque side. A range where only the second friction clutch operates becomes wider. Therefore, change in the torque of the second friction clutch relative to change in operating force is decreased. This contributes to an accurate torque control. In accordance with the function of this clutch device, features of front wheel drive and 4WD vehicles are obtained so that fuel consumption can be decreased and road ability can be improved. Further, straight running performance of a vehicle can be achieved and a tight corner braking phenomenon can be avoided.

Abstract: A drive mechanism for an electric car which has a plurality of motors arranged in a drive mechanism case which, in turn rotatably supports a shaft at two points. This shaft transmits the rotation generated by the motors to drive shafts for rotation of the wheels to run the car. The motors are composed of stators having armature cores and coils, and rotors. The stators are fixed in the drive mechanism case and the rotors are supported by the shaft. Since this shaft is rotatably supported at two points by the drive mechanism case, accurate centering of the rotor is maintained.

Abstract: A torque distribution control device includes two rotational speed differential responsive type control couplings each having various transfer torque characteristics which differ in the ratio of a transfer torque to a rotational speed differential. The control device selects one of the torque transfer characteristics in response to a signal supplied thereto. When turning the outer wheel side control coupling is supplied with a signal for selecting the transfer torque characteristic that produces a maximum transfer torque for a given rotational speed differential, and the inner wheel side control coupling is supplied with a signal for attaining a non-slip rotational speed differential and for selecting the transfer torque characteristic that produces a transfer torque equal to that produced by the outer wheel side control coupling when the non-slip rotational speed differential is obtained.

Abstract: Construction equipment is often provided with the same size tires on both the front and the rear of the machine to maintain commonality of tire sizes and to simplify the drivetrain configuration. The present invention provides a smaller pair of tires on one end of a machine than the pair of tires that are positioned on the opposite end. In doing so, the overall height of the end of the machine having the smaller tires is reduced. This lowers the center of gravity of the machine to improve operating stability of the machine. In addition, the reduced height makes that portion of the vehicle more accessible and thereby enhances serviceability.

Abstract: A differential control system for restrictively controlling a differential, which has electromagnetically controlled clutches disposed between differentially driven shafts, is electromagnetically controlled to lock and unlock the driven shafts. The control system has a controller for restrictively applying a locking current to the differential to lock and unlock the clutches in accordance with control modes manually selected.

Abstract: A four-wheel drive vehicle control system has a differential mode control device which operates in at least a first mode, in which differential action of a differential is variably restricted between an unlocked state and a locked state according to driving conditions, and a second mode, in which the differential is forcibly locked. The first and second modes are manually selected by the driver.

Abstract: A rotation transmitting device has an input shaft coupled to the transmission of the engine of a four-wheel drive vehicle and an output shaft coupled to the rear wheel differential. The input and output shafts are mounted rotatably and concentrically relative to each other. An outer ring is rotatably mounted around the input shaft and a cage is rotatably mounted between the opposed surfaces of the input shaft and the outer rink and formed with a plurality of pockets. Engaging elements are mounted in the pockets and adapted to engage the opposed surfaces when the cage and the input shaft rotate relative to each other. Resilient members are mounted in the pockets to keep the engaging elements out of engagement with the opposed surfaces. The cage and the output shaft are coupled to the input shaft with a gap left therebetween in the direction of rotation so as to be rotatable to,ether. The input and output shafts are kept in a neutral position of the above gap by a retaining member.

Abstract: A transaxle for a drive system of a vehicle including a midship transversely mounted engine. The transaxle comprising a transmission, a differential mechanism for differential action between a set of rear wheels of the vehicle, and a transfer case for transferring drive torque to a set of front wheels of the vehicle. The transmission has a main shaft extending transversely with respect to a logitudinal direction of the vehicle. Disposed rearwardly of the main shaft is the differential mechanism, while disposed forwardly of the main shaft is the transfer case. Drive torque from the main shaft is transferred via two power flows to a differential case of the rear differential mechanism and to an input shaft of the transfer case.

Abstract: A driving torque distribution control system for a four wheel drive vehicle includes a torque distributing clutch provided in a drive path for the front wheels, and a controller for controlling a driving torque transmitted to the front wheels through the clutch, in accordance with a corrected front and rear wheel speed difference which is a difference resulting from subtraction of a dead band from a sensed actual front and rear wheel speed difference. In order to improve the controllability near the cornering limits of the vehicle without deteriorating the driving ability in a low lateral acceleration cornering operation, the controller sets the dead band so that the dead band increases as the lateral acceleration of the vehicle increases.

Abstract: A power transmission apparatus for vehicle capable of obtaining a plurality of transmission characteristics by moving spools of variable throttle member 6 according to controlling current flowing to a driving coil 7 by steps, wherein a spool chamber 60 housing a first and second spools 61, 62 therein is communicated with discharge side of a vane pump 3 according to first and second communicating holes 54, 55. And by controlling current flowing to the driving coil 7 by steps, two kinds of magnetic fields, intense and weak are formed in the spool chamber 60. In the case where the first spool 61 moves to the position where it is contacted with the inside end of the spool chamber 60 by the action of the weak magnetic field, it closes an opening end of one communicating hole 54, and in the case where the second spool 62 moves to the position where it is contacted with the first spool 61, it opens an opening end of the other communicating hole 55.

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.

Abstract: An electromagnetic clutch driven steerable drive axle system for a four-wheel drive vehicle, such as a front mount mower, including a rotary power source, a driven front axle, a mechanical rear axle converting power from the rotary power source into tractive power at a set of wheels attached thereto, a steering mechanism connected to the rear wheels, an electromagnetic clutch between the power source and mechanical rear axle, and a transducer which provides input representative of the turning and/or tractive power status of the mower to a microprocessor which may send current to the clutch. Having a plurality of frictional clutch disks, the clutch selectively transmits driving power to the secondary axle based on input current applied by the microprocessor. With the disks separated, the rotary power source and steerable axle are uncoupled. The rear wheels are allowed to freewheel, reducing skidding during turns in forward and reverse.

Abstract: An all-wheel drive for a motor vehicle has a first transmission line which starts out from a change-speed gearbox and leads to the rear axle and a second transmission line branching off from the first transmission line and leading to the front axle. The second transmission line can be connected by a permanently acting all-wheel locking system as a function of the rotational speed difference between the drive shaft and the output shaft of the all-wheel locking system. In the first transmission line, a separating coupling is inserted behind the branch-off point to the second transmission line, this separating coupling being operable as a function of parameters of the motor vehicle.

Abstract: A transfer case for a vehicle having a pair of front wheels and a pair of rear wheels and capable of all-wheel or two wheel drive has an input shaft connected to a carrier of a planetary gear differential having a ring gear connected to a first output shaft for driving a first pair of wheels and a sun gear connected to a second output shaft for driving a second pair of wheels. A clutch is provided on the planetary gear differential for selectively locking the first and second output shafts together for concurrent rotation when the planetary gear differential clutch is engaged, thereby providing all-wheel drive. A brake is provided for selectively preventing the second output shaft from rotating so that when the second output shaft brake is applied and the planetary gear differential clutch is disengaged, the first output shaft will rotate at an overdrive gear ratio relative to the rotational speed of the input shaft, thereby providing two-wheel drive at an overdrive gear ratio.

Abstract: In a four-wheeled buggy which has a pair of front wheels and a pair of rear wheels and a seat arranged around the middle of the vehicle to enable the rider to operate the vehicle in a sitting posture thereon, a pair of right and left main frames are two-dimensionally bent upwardly at the forward sections thereof and adapted to support at the front ends thereof a front wheel axle so as to prevent a front wheel driving device from hitting ground. The rearward sections of the main frames extend horizontally rearwardly to define a lowermost height from ground and are adapted to support a power unit behind the seat close to the rear wheels so as to obtain mass concentration.

Abstract: A viscous shear coupling for distributing torque between front and rear axles of an all-wheel drive vehicle is provided which comprises a housing, a set of inner blades interdigitating with a set of outer blades, the inner and outer blades being axially spaced apart from each other and axially slidably mounted within the housing, a viscous liquid located within the housing, an adjusting piston within the housing which is axially displaceable so as to adjust the axial distance between adjacent inner and outer blades. The viscous shear coupling further includes a control pressure circuit for delivery of a control pressure fluid to the adjusting piston, a control valve for regulating the delivery of the control pressure fluid to the adjusting piston, and a control device (e.g., a microprocessor) which calculates a desired adjusting piston speed based on driving conditions and adjusts a valve current delivered to the control valve in order to obtain the desired adjusting piston speed.

Abstract: A transmission system having a power input shaft for connection to a power source and two coaxial differentially driven outputs located substantially parallel to and spaced from the input shaft. The power input shaft is operatively connecting the driven outputs to simultaneously drive the driven outputs in response to rotation of the power input shaft.

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 torque distribution control device for a four-wheel drive vehicle includes a rotational speed differential responsive type control coupling combined with a front differential of a front wheel drive line. The control coupling has a variable orifice for varying its torque transfer characteristic and thereby varying distribution of engine torque between front and rear wheels. The orifice opening of the variable orifice varies depending upon a variation of a lateral acceleration of the vehicle, e.g., the orifice opening increases as the lateral acceleration increases.

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: Vehicular acceleration is sensed and used to set and/or modify at least two of a plurality of control sensitivity values in a manner which increases one with respect to the other and thus avoids the situation wherein a limited amount of servo power is wasted by futile operation of a servo powered arrangement which cannot produce a large control effect under the instant operating conditions and enables an adequate amount servo power to be directed to the operation of a different arrangement which can be effective.

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: A drive wheel torque control system for a vehicle includes control means for controlling a variable differential motion limiting device provided between drive wheels to distribute a predetermined LSD torque from a racing drive wheel to a nonracing drive wheel. The control means includes vehicle speed determining means for determining a vehicle speed from a follower wheel spaced, drive wheel speed determining means adapted to select a smaller one of the drive wheel speeds as a drive wheel speed, when the inner-side wheel in turning movement is racing, and to select a larger one of the drive wheel speeds, when the outer-side wheel in turning movement is racing, and torque determining means for determining the LSD torque from the vehicle speed and the drive wheel speed.

Abstract: The invention provides a drive train for propelling a vehicle capable of being used for transporting ore, coal or broken rock in underground mining operations. The vehicle has front and rear wheelsets, each comprising a right and left side wheel. The drive train comprises drive apparatus such as an electrically driven motor for delivering torque to at least a front wheel and rear wheel on one side of the vehicle. A torque sharing apparatus in the form of an epicyclic gear arrangement is interposed between the motor and the wheels, and operable to share torque delivered by the motor between the front and rear wheels while permitting them to rotate at different speeds in relation to each other. Front and rear transfer apparatus comprising gear trains co-operating with the epicyclic gear arrangement are provided for transferring torque to the front and rear wheels respectively.

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 motor vehicle has a pair of main drive road wheels, a pair of auxiliary drive road wheels, and a differential disposed between the auxiliary drive road wheels, the main and auxiliary drive road wheels serving as the front and rear road wheels of the motor vehicle. An apparatus for driving the front and rear road wheels includes a speed increasing device disposed in a power transmission path leading to the differential between the auxiliary drive road wheels, detecting means for detecting a speed of travel of the motor vehicle and a steering variable, and control member for enabling the speed increasing device by predicting a turn of the motor vehicle based on the detected speed and the detected steering variable.

Abstract: The present invention provides a motor vehicle traction control system for providing on-demand four-wheel drive under certain tractive and operational conditions. The present invention is operable for disabling the on-demand four-wheel drive feature upon the vehicle operator subsequently shifting into the four-wheel drive mode.

Abstract: The present invention provides a motor vehicle traction control system for providing on-demand four-wheel drive under certain tractive and operational conditions. The traction control system permits the vehicle operator to choose between operation in the conventional two-wheel drive and four-wheel drive mode or the "on-demand" four-wheel drive mode. Moreover, the traction control system is operable for disabling the on-demand four-wheel drive feature upon the vehicle operator subsequently shifting into either of the two-wheel drive and the four-wheel drive modes.

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 driving force transmission device for a vehicle has a homokinetic joint having an outer ring and a clutch device having an outer ring coupled to the outer ring of the homokinetic joint. An input shaft is rotatably inserted in the outer rings. A cage is rotatably mounted between opposed surfaces of the outer rings and the input shaft. The cage has pockets. Engaging elements are mounted in the pockets. They are adapted to engage the opposed surfaces when the input shaft and the cage rotate relative to each other either clockwise or counterclockwise. Elastic members are mounted in the pockets to keep the engaging elements in a not-engaged position. The cage and the input shaft are coupled together with a gap extending in the direction of rotation formed therebetween so as to be rotatable together. A differential member are mounted on the cage or the input shaft to produce a difference in rotation therebetween.

Abstract: A power transmission device for converting a four wheel drive vehicle is disclosed. The device utilizes the existing highway gear ratios available on standard front wheel drive vehicles. By incorporating an additional gear ratio for both the front and rear wheels, the lower gear ratios desired by off-road users are provided.

Abstract: An ideal lateral acceleration is calculated based on vehicle speed and steering angle, and an actual lateral acceleration is calculated based on a lateral acceleration detected by a lateral G sensor. A breakaway point of tires is determined by comparing the actual lateral acceleration with the ideal lateral acceleration. A differential operation of a central differential is controlled by restricting the differential operation in accordance with a determined breakaway point and the difference between the ideal lateral acceleration and the actual lateral acceleration.

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: An active torque-split control system for actively controlling a distribution of driving torque applied to front and rear wheels in a four-wheel drive vehicle employing a transfer device including a transfer clutch for varying said driving torque distribution depending on the operating state of the vehicle, comprises sensors for monitoring the operating state, and a torque-split controller for switching from a normal torque-split control mode to a rigid torque-split control mode only when the controller determines that the vehicle is operated in a warning region closer to a critical state.

Abstract: A central differential has first and second output members for distributing power of an engine through a transmission to front and rear wheels respectively, and has a third output member for controlling distribution of the power. A first friction clutch is operatively connected to the second and third output members for restricting differential operation of the central differential and for controlling distribution of the power to the front and rear wheels. A second friction clutch is operatively connected to the second output member and either of the front or rear wheels. The first friction clutch is disposed at the innermost position and the second friction clutch is disposed around the first friction clutch so as to effectively transmit and distribute power to each wheel in compact and simple structure.

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: A power train includes a transmission having transmission shafts, with axes of rotation parallel to a crankshaft of an engine. The transmission shafts extend in a transverse direction of a vehicle. A drive axle is connected to drive wheels of the vehicle , and a drive axle differential differentially drives the drive wheels through the drive axle. A center differential is provided to differentially drive the front and rear drive wheels. The drive axle has an axis of rotation placed below and parallel to the axis of rotation of the transmission shafts. The drive axle differential and center differential are disposed side by side in the transverse direction of the vehicle body on, and in alignment with, the axis of rotation of the drive axle. The drive axle differential is located closely adjacent to the transmission in the transverse direction.

Abstract: The present invention relates to a vehicle four wheel drive torque transfer case having a friction clutch which is selectively engaged when it is desired to place the transfer case in a four wheel drive operating mode. The transfer case includes an input shaft which is connected to supply torque to a rear output shaft. A multi-disc friction clutch is connected between the input shaft and a front output shaft for supplying torque to the front output shaft. A planetary gear assembly includes a sun gear, a carrier a planet carrier connected to the input shaft, and a ring gear coupled to drive the front output shaft. The multi-disc clutch is interposed between the sun gear and the ring gear and is engaged to inhibit any rotation of the planet carrier relative to the ring gear and thereby transfer torque to the front output shaft. The planetary gear assembly functions as a .sctn.'torque multipler" and this reduces the torque capacity requirements for the clutch.

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 differential limiter for a vehicle is provided with a hydraulic multi-disc clutch for limiting a differential operation between at least two wheels, an inhibitor switch for detecting a gear position of a transmission mechanism, and controller for changing a differential limiting force by the clutch in accordance with a change in transmission position detected by the inhibitor switch.

Abstract: A power transmitting system for a four-wheel drive vehicle includes a first hydraulic pump driven interlockingly with the rotation of front wheels, a second hydraulic pump driven interlockingly with the rotation of rear wheels, and a hydraulic clutch for connecting the front wheels and rear wheels. The hydraulic clutch is adapted to be brought into an engaged state by an increase in oil pressure based on the difference between the amount of oil discharged from one of the hydraulic pumps and the amount of oil drawn into the other hydraulic pump. The hydraulic clutch, first hydraulic pump and second hydraulic pump are arranged in that sequence from the front toward rear of the vehicle on an axis extending longitudinally of the vehicle to maximize the air cooling effect on the hydraulic clutch and minimize the length of oil passages between the two hydraulic pumps.

Abstract: A power transmission system for a four-wheel drive vehicle, comprising an engine for directly driving a primary driven axle, and a torque transmission device for transmitting drive torque from the primary driven axle to a secondary driven axle as required, according to a difference in the rotational speed between the front and rear axles, and the torque transmitted between the front and rear axles is reduced for a given difference in the rotational speed between the front and rear axles as a vehicle speed is increased. Thereby, the unnecessary burden of load on the rear axle members is reduced. Preferably, the torque transmission device comprises a structure for limiting the upper limit of the torque which can be transmitted to the secondary driven axle.

Abstract: The present invention provides a motor vehicle traction control system for providing on-demand four-wheel drive under certain tractive and operational conditions. The present invention is operable for disabling the on-demand four-wheel drive feature upon the vehicle operator subsequently shifting into the four-wheel drive mode.

Abstract: A transfer device is provided for distributing the output of a transmission to front wheels and rear wheels of the vehicle through a front power train and a rear power train. The output shaft of the transmission is operatively connected to the rear power train. The transfer device has a drive gear rotatably mounted on an output shaft of the transmission and engaged with a driven gear in the front power train, a fluid operated multiple-disk friction clutch having a drive drum and a driven drum. The driven drum is secured to the drive gear and the drive drum is secured to the output shaft. The output shaft of the transmission and the drive gear are arranged to be changed with an output shaft and a drive gear for the front power train which are engaged with each other, and an input member of the rear power train is arranged to be secured to the drive drum.