Abstract: A torque transmission device is provided wherein a rotary housing is connected to one of front and rear drive shafts which respectively drive front and rear axles of a four-wheel drive vehicle, while a rotary shaft coaxially carried by the rotary housing is connected to the other of the front and rear drive shafts. The housing receives therein a multiple disc clutch device for transmitting rotational power between the housing and the shaft through friction engagement between alternately arranged outer and inner clutch discs which are respectively rotatable bodily with the housing and the shaft. The housing also receives an axially movable piston to press the clutch discs for friction engagement. An end wall of the housing or an end cap secured thereto and a facing end surface of the piston define an axially narrow circular chamber, within which a rotor with a plurality of radially extending blade portions provided with a pair of slanted surfaces is received to be rotated by the shaft.

Abstract: An apparatus for controlling the distribution of drive power in an all-wheel-drive motor vehicle which has main drive wheels, auxiliary drive wheels, and a drive power transmitting system for transmitting the drive power to the auxiliary drive wheels. The apparatus has a hydraulic pressure source, a hydraulic system, a hydraulic clutch disposed in the drive power transmitting system, which varies the drive power transmitted to the auxiliary drive wheels, depending on the hydraulic pressure supplied from the hydraulic pressure source to the hydraulic clutch through the hydraulic system, and a control system for controlling the ratio at which the drive power is distributed between the main and auxiliary drive wheels, through regulation of the hydraulic pressure supplied from the hydraulic pressure source to the hydraulic clutch.

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 control system for a four-wheel drive vehicle with a continuously variable transmission having a drive pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc, a driven pulley having a hydraulically shiftable disc and a hydraulic cylinder, and a pressure regulator valve for regulating pressure of oil supplied to the hydraulic cylinders. A hydraulic actuator is provided for engaging a transfer clutch for establishing four-wheel driving. The pressure regulator valve has a pressure level changing port to increase the pressure of oil supplied to the cylinders. A solenoid operated valve is provided for supplying the oil regulated by the pressure regulator valve to the hydraulic actuator and to the pressure level changing port or for draining the actuator and the port. An orifice is provided in an inlet side of the solenoid operated valve.

Abstract: A drive arrangement for a selectively engageable wheelset includes a clutch and a freewheel arranged in series, one behind the other, between a transmission and the selectively engageable wheelset. The clutch is designed as an overload release clutch, so that overloading of the drive to the selectively engageable wheelset is avoided when the freewheel is engaged. In addition, the clutch will permit interruption of the drive to the selectively engageable wheelset completely and as long as desired. The freewheel can be locked as a function of various operating conditions or upon demand.

Abstract: A plate for a viscous shear coupling has inner and outer peripheries and slots which extend partly across the radial dimension between the peripheries. Between each adjacent pair of slots is a land and this is deformed out of the general plane of the disc to provide oppositely inclined surfaces.

Abstract: A differential device having a central differential coaxially provided with an axle and a differential provided on the axle. The central differential has a differential case, a pair of pinion shafts, a pair of pinions rotatably mounted on the pinion shafts respectively, and first and second side gears engaged with the pinions. The pinion shafts are operatively connected to an output member of a transmission. The differential has a differential case operatively connected to the first side gear of the central differential, a pinion and a pair of side gears engaged with the pinion and secured to the axle, respectively. The second side gear of the central differential is operatively connected to the axle of the vehicle.

Abstract: A dog clutch mechanism for use as a clutch for switching drive power in a four-wheel-drive vehicle has a case, first and second rotatable shafts rotatably supported coaxially in the case for transmitting a relative torque between front and rear wheels of the vehicle, and a dog clutch comprising a dog piece having first dog teeth and fixedly mounted on the first rotatably shaft and a hub having second dog teeth capable of axially meshing with the first dog teeth and axially slidably mounted on the second rotatable shaft. The dog clutch is selectively engageable for transmitting the relative torque between the first and second rotatable shafts. The first and second dog teeth having respective meshing tapered surfaces for producing thrust forces acting on the hub and tending to move the hub in a direction away from the dog piece when the vehicle is braked while a relative forward torque is being transmitted between the first and second rotatable shafts through the dog clutch.

Abstract: In a four-wheel drive work vehicle selectively drivable in a standard four-wheel drive mode, an accelerated four-wheel drive mode and in a two-wheel drive mode, the invention provides an improved drive-mode switching operability through a linearly operable link mechanism for operatively connecting one operational system for directly operating a shift fork member with another operational system for operating the same via a cam member connected to a steering wheel.

Abstract: In a driving power transmission, an input shaft is coaxially rotatably carried in a closed cylinder housing, extending through an operating piston received therein. The operating piston is bodily rotatable with the housing and axially movable relative to the housing and the input shaft. The piston defines at opposite ends thereof a clutch chamber and an axially thin circular space. A multiple disc clutch operable by the piston is provided in the clutch chamber for selectively transmitting a torque from the input shaft to the housing acting as an output shaft. A rotor with diametrically opposite blades is received within the axially thin circular space and is rotatable bodily with the input shaft for compulsorily displacing silicon oil filled in the circular space, so as to generate a pressure therein when relative rotation occurs between the housing and input shaft.

Abstract: A torque distribution deciding control unit and an oil hydraulic clutch having opposite disks are provided. The clutch is disposed in a power transmitting system for four-wheel drive. One of disks is operatively connected to one of side gears of a central differential through a gear train and the other of the disks is operatively connected to the other side gear of the central differential through another gear train, whereby torque is transmitted to front and rear wheels at a distribution ratio. Loads on wheels such as weights on front and rear axles are detected. The control unit operates the clutch so as to distribute the torque at a ratio in accordance with loads on both axles.

Abstract: To restrict and further promote differential rotation between first and second output shafts, the power transmission apparatus for differentially transmitting a rotative power supplied to an input shaft to two output shafts comprises a differential gear mechanism coupled between the two output shafts; a multiplying mechanism associated with the differential gear mechanism, for detecting and multiplying a differential rotation; a motor coupled to the multiplying gear mechanism, for restricting or promoting the differential rotation by driving the multiplying gear mechanism in either direction; and a controller for controlling rotative direction and torque of the motor by adjusting supply voltage polarity and motor current magnitude. The multiplying mechanism is a strange gear mechanism or a planetary gear mechanism.

Abstract: A four-wheel drive vehicle comprises an engine and a power transmission system, including a shiftable change gear transmission having a power input shaft and a differential having front and rear output shafts and a biasing clutch, for driving the front and rear vehicle wheels. The differential, with biasing clutch disengaged, allows for differences in rotational speed between the front and rear wheels. Increased speed of one output shaft as may be caused by its' associated wheels slipping, results in decreased speed of the other output shaft. Conversely, decreased speed of one output shaft as may be caused by its' associated wheels being bogged down by mud, sand or deep snow, results in increased speed of the other output shaft. The degree of differential action may be determined from the known input shaft speed, the gear ratio engaged and an output shaft speed.

Abstract: A control system for a 4WD vehicle includes a transfer clutch capable of continuously varying a driving torque distribution ratio between front and rear axles, and a controller for producing a control signal to control the distribution ratio. In order to improve the stability of the vehicle during deceleration, the control system is provided with a sensor for sensing one or more of an engine speed, a throttle opening, a transmission gear ratio, a vehicle speed and other vehicle operating parameters affecting engine braking, and a controller section for controlling the distribution ratio in accordance with the amount of engine braking at a level which is higher enough than the level of 2WD to adequately distribute the engine braking force between the front and rear axles and which is lower enough than the 4WD level to allow the front and rear axles to rotate at different speeds.

Abstract: A motor vehicle comprises two driven axles, one of which is adapted to be driven by a drive train, which comprises a liquid friction coupling, which is preceded in said drive train by a clutch, which is adapted in a first position to cause the rear axle to be driven via said liquid friction coupling, in a second position to by-pass said liquid friction coupling and in a third position to disconnect said rear axle from said drive train. In a motor vehicle comprising a transmission comprising at least one cross-country or crawling gear the clutch is adapted to assume said second position under the control of a pick-up, which is associated with the cross-country gear or gears, a switching and control stage, and an actuator in response to the selection of the cross-country gear or one of the cross-country gears. That actuation is independent of the position previously assumed by the clutch. The clutch will remain in that position until a road gear is selected in the transmission.

Abstract: A control system for a 4WD vehicle includes a drive system for directly transmitting a torque to primary drive wheels such as rear wheels, and transmitting a torque to secondary drive wheels such as front wheels through a torque distributing transfer clutch, a group of sensors for determining a front and rear wheel speed difference, an engine condition such as a throttle opening, and a vehicle speed, and a control unit for controlling the engagement force of the transfer clutch. Normally, the control unit employs a first control mode based on the front and rear wheel speed difference. In rapid acceleration to start the vehicle, the control unit replaces the first mode by a second mode in which the clutch engagement force is increased in accordance with the engine condition such as the throttle opening independent of the wheel speed difference, and thereby prevents undesired spin of the primary drive wheels without delay.

Abstract: In a power transfer mechanism including an input shaft arranged to be applied with drive torque from a prime mover of a motor vehicle, a first output shaft arranged coaxially with the input shaft for drive connection to a first set of drive axles and a second output shaft arranged in parallel with the first output shaft for drive connection to a second set of drive axles, a planetary gearset of the double pinion type is mounted on the first output shaft to transfer the drive torque from the input shaft to the first and second output shafts, the planetary gearset including a ring gear in drive connection to the input shaft, a sun gear in drive connection to the first output shaft and a planet carrier for drive connection to the second output shaft, a limited-slip differential in the form of a viscous fluid coupling is disposed between the ring gear and planet carrier to limit differential action between the first and second output shafts, and a drive train for drive connection between the planet carrier and th

Abstract: A vehicle equipped with four-wheel drive has a transfer case including a center-differential which delivers driving power to both front and rear axle assemblies when needed and is shiftable between a two-wheel and a four-wheel drive mode of operation and between a differential-locked and a differential-unlocked drive mode of operation. A free wheeling drive mechanism with a clutch member is incorporated in an output shaft of an axle differential in association with wheels non-driven in the two-wheel drive mode of operation and is adapted to disconnect when the vehicle is in the two-wheel drive mode of operation. A controller causes a forced drive mode shift of the center-differential from the four-wheel differential-underlined drive mode of operation either to the four-wheel differential-locked or to the two-wheel drive mode of operation when the disconnection of the free-wheeling drive mechanism is detected while the vehicle is in the four-wheel differential-unlocked drive mode of operation.

Abstract: A torque distribution deciding control unit, a planetary gear device as a central differential and an oil hydraulic clutch having opposite disks are provided on a motor vehicle. The clutch is disposed between output members of the planetary gear device, whereby torque is transmitted to front and rear wheels at a distribution ratio decided by clutch torque of the clutch. The control unit operates the clutch so as to distribute the torque at a ratio in accordance with slipping of the front or rear wheels with respect to each other so as to reduce the torque for the slipping wheels.

Abstract: The invention relates to a fluid friction coupling (1) with a housing (2) and a hub (4) rotatably received within the housing. The interior (11) of the housing is divided into a main chamber (22) and a receiving chamber (23). Only the main chamber (22) is occupied by inner plates (8) and outer plates (6) of the coupling. The two chambers (22, 23) are separated by separating plates (18, 19). However, the separating plates (18, 19) comprise closable apertures (24) each of which is associated with a slide (25). The closing slides (25) open the apertures (24), thereby providing a passage between the two chambers (22, 23) when a certain rotational speed is exceeded. As a result, the possibility of a transfer of the coupling (1) into the hump mode is reduced at high rotation speeds.

Abstract: A torque distribution deciding control unit, a planetary gear device as a central differential and an oil hydraulic clutch having opposite disks are provided on a motor vehicle. The clutch is disposed between output members of the planetary gear device, whereby torque is transmitted to front and rear wheels at a distribution ratio decided by clutch torque of the clutch. The control unit operates the clutch so as to distribute the torque at a ratio in accordance with slipping of the front or rear wheels so as to reduce the torque for the slipping wheels.

Abstract: In a vehicle having a pair of left and right coaxially disposed wheels operatively coupled together via a differential gear which serves to restrict an increase in the difference in rotational speed between the wheels, a method to carry out anti-lock control of both the wheels concurrently during braking operation by utilizing a higher one of the wheel speeds thereof. This enhances braking efficiency and only one control channel is required for the wheels.

Abstract: A power transmission apparatus suitable for use with a four wheel drive apparatus of an automobile which can prevent production of rattling noises of a driving system and occurrence of a swerving phenomenon of the automobile. The apparatus includes a cam ring connected to a first rotary shaft and a rotor connected to a second rotary shaft and accommodated for rotation in the cam ring to define a pump chamber therebetween and is designed to transmit driving force between the first and second rotary shafts in accordance with a pressure of working fluid in the pump chamber which is produced in response to rotation of the first and second rotary shafts relative to each other. The apparatus comprises a frictional force applying mechanism interposed between the first and second rotary shafts for applying predetermined frictional force between them to assure stabilized transmission of torque between the first and second rotary shaft.

Abstract: A system for controlling distribution of drive forces from a drive source unit to front and rear wheels of a four-wheel drive motor vehicle includes drive force distributing means for transmitting the drive forces to the front and rear wheels at a continuously variable distribution ratio, first speed detecting means for detecting a rotational speed (Nf) of the front wheels, second speed detecting means for detecting a rotational speed (Nr) of the rear wheels, and control means for calculating a slip ratio (S) of the rear wheels to a road on which the motor vehicle is running based on the rotational speeds (Nf, Nr) of the front and rear wheels, calculating a distribution ratio between the drive forces to be distributed to the front and rear wheels based on the slip ratio (S), and controlling the drive force distributing means to transmit the drive forces from the drive source unit to the front and rear wheels according to the distribution ratio.

Abstract: A viscous shear coupling comprises a housing and a hub rotatable within the housing. Plates are splined to the housing and plates to the hub, there is a pair of plates splined to the hub between each two adjacent plates splined to the housing. The plates in pairs splined to the hub have convergent apertures therein, each aperture converging in a direction away from that radial face of the plate which is adjacent to the other plate of the pair.

Abstract: A control system for a full time four wheel drive vehicle having a transfer case including a planetary gear differential and an electromagnetically actuated clutch assembly for biasing torque between the front and rear drive wheels in response to signals from the control system. The control system includes apparatus for detecting wheel slip and a device, responsive to the detection of wheel slip for calculating a maximum torque level to be established by the clutch assembly as a function of the total torque delivered to the transfer case and for programming clutch torque application over a predetermined time period and in a manner biasing torque through the differential to eliminate wheel slip.

Abstract: A control system for a 4WD vehicle includes a drive system for directly transmitting a torque to primary drive wheels, and transmitting a torque to secondary drive wheels through a torque distributing clutch, at least one sensor for determining a front and rear wheel speed difference, at least one sensor for determining a lateral acceleration, and a control unit for controlling the engagement force of the clutch. When the primary wheel speed is lower than the secondary wheel speed, the control unit holds the clutch engagement force equal to zero to improve the steering response until the absolute value of the wheel speed difference reaches a predetermined level, and increase the clutch engagement force in accordance with the absolute value of the wheel speed difference to improve the vehicle stability after the absolute value of the wheel speed difference exceeds the predetermined level.

Abstract: A method and an apparatus for controlling a 4-wheel drive system of a motor vehicle having front wheels and rear wheels and a power transmission. The 4-wheel drive system includes a differential control clutch having input and output elements which are rotatable relative to each other with a controlled amount of engagement therebetween, so as to control a ratio of distribution of a torque from the power transmission to front and rear wheels. When it is determined that the power transmission is commanded to be shifted from a first gear position to a second gear position whose speed ratio is different from that of the first gear position, the differential control clutch is temporarily placed in a fully disengaged position thereof for a predetermined time duration. With the clutch placed in the fully disengaged position upon each shifting operation of the transmission to the second gear position, the separated friction surfaces of the clutch may be lubricated to maintain high durability of the clutch.

Abstract: An engine and transmission arrangement for a four wheel drive vehicle comprises an engine arranged to extend substantially along a longitudinal center line of the vehicle. A gearbox receives power from the engine and a torque splitting device is connected to an output of the gearbox so as to pass part of the power to a rear final drive and part of the power to a front final drive. The front final drive and the rear final drive each includes a drive shaft which extends substantially along the longitudinal center line of the vehicle and at least a part of one of the drive shafts extends above a substantial portion of the engine.

Abstract: A differential motion limiting device, for a power transmission device for four wheel drive vehicle, to regulate differential motion of a center differential device includes a wet-type multi plate clutch and an hydraulic actuator. And a switching valve is attached to an oil passage to the hydraulic actuator. In normal running condition, a switching valve is in connecting condition, and a hydraulic pressure being varied by driving conditions is applied to a hydraulic actuator. Under this condition, the clutch is slippingly engaged by certain engaging force so that torque, per certain ratio, is transmitted to the front and the rear wheels. In high speed condition, such as the maximum speed state like an overdrive, or a vehicle speed more than 100 km/h, sensors detect such state, then the switching valve is switched, and the clutch is released. As a result, lubrication oil is flowed between friction plates and separators of the clutch to release heat therefrom.

Abstract: A central differential for a four-wheel drive motor vehicle is provided on a pair of axles for right and left drive wheels. The differential has a tubular member secured to a final gear of a transmission, a pair of carriers one of which is connected to the drive wheels and the other carrier is operatively connected to the other drive wheels. A pair of annular side gears are securely provided on the tubular member, and an annular center gear rotatably mounted on the tubular member between the side gears. A pair of planetary gears are rotatably supported in the corresponding carrier. Each planetary gear comprises a pair of planet pinions, one of which is engaged with the side gear and the other is engaged with the center gear.

Abstract: A central differential for a four-wheel drive motor vehicle is provided on a pair of axles for right and left drive wheels. The differential has a cylindrical differential case connected to a final gear of a transmission, a pair of carriers provided in the differential case one of which is connected to the drive wheels and the other carrier is operatively connected to the other drive wheels. A pair of annular side gears are securely provided in the differential case, and an annular center gear rotatably mounted in the differential case between the side gears. A pair of planetary gears are rotatably supported in the corresponding carrier. Each planetary gear comprises a pair of planet pinions, one of which is engaged with the side gear and the other is engaged with the center gear.

Abstract: A drive arrangement for a four wheel drive vehicle is equipped with a planetary gear set for driving the front wheels which can operate in either direct drive or with a speed increase and which is shifted according to the steering angle .beta. sensed at the front pair of wheels. To avoid an excessively high jump in speed during the transition from direct drive to the increased speed mode, the planetary gearset is gradually shifted, i.e., the planetary gear clutch and/or brake are allowed to slip in proportion to the steering angle .beta..

Abstract: A method of and system for controlling a torque distribution over four wheels of four-wheel drive vehicle when the vehicle is making a turn. When an outer wheel revolution speed is higher than an inner wheel revolution speed, a differential action limiting force is decreased or weakened and a torque distribution ratio, viz., a ratio of a portion of torque distributed toward the front wheels (secondary driving wheels) to the remaining portion of torque distributed toward the rear wheels (primary driving wheels), is decreased. When the inner wheel revolution speed is higher than the outer wheel revolution speed, the differential acting limiting force is increased or strengthened and the torque distribution ratio is increased.

Abstract: A driving power transmission device having a clutch provided between a first shaft and a second shaft relatively rotatable to each other for transmitting a driving power is provided, wherein a housing to which the first shaft is connected and a piston provided in the housing for actuating the clutch define a cylindrical space in order to receive a plurality of blades rotatable with the second shaft. High viscous fluid is filled within the cylindrical space defined by the housing and the piston. Each of the blades has a convexly curved side surface and a concavely curved side surface located at opposite sides in rotational direction. When the first shaft rotates faster than the second shaft, the convexly curved side surfaces of the blades compulsorily displaces the high viscous fluid within the space in order to generate a pressure actuating the clutch through the piston. In this forward torque transmission, the tranmissive torque becomes relatively large.

Abstract: A clutch (1) including an inner part (3) and an outer part (4) having races (6 and 5) respectively between which are arranged rollers (4). The rollers are arranged in a cage (7) which is in two parts (8 and 9) which are connected by leaf springs (10). One part (8) of the cage may be operated upon by a brake (11) to retard it relative to the other part of the cage thus to cause the rollers to skew and jam between the races and thus transmit torque between the inner and outer member. The clutch may be associated with a viscous shear coupling (18) and the combination may be used in the driveline of a motor vehicle.

Abstract: An active torque distribution controller for the wheels of a motor vehicle detects a longitudinal acceleration and a side acceleration to which the vehicle is subject. Based on these longitudinal and side accelerations, a running mode which the vehicle is involved in is detected, and a torque distribution ratio of a portion of torque delivered to the front wheels to the remaining portion to the rear wheels and a differential limiting force are varied in response to a predetermined control schedule for the running mode detected.

Abstract: A differential limiting torque control system for a vehicle includes a differential limiting clutch provided in a differential, a sensing section including sensors such as an accelerator position sensor, and sensors for sensing speeds of left and right front wheels and left and right rear wheels, and a control unit controlling a differential limiting torque of the differential limiting clutch in accordance with an accelerator opening degree of movement, a left and right drive wheel speed difference, and a drive wheel slip which is represented, for example, by a front and rear wheel speed difference, in such a manner that the differential limiting torque is held equal to a difference obtained by subtraction whose subtrahend is a quantity proportional to the drive wheel slip, and whose minuend is a sum of a quantity proportional to the accelerator opening degree and a quantity proportional to the left and right drive wheel speed difference.

Abstract: A transfer case for a vehicle having full time four-wheel drive includes an interaxle differential connected to the output of a transmission and driving coaxial driveshafts, each connected to a different axleshaft. One of the driveshafts supports a chain sprocket driveably connected by a chain belt to a driveshaft coaxial with the input shaft and output drive shafts. The differential includes a center driving disc, a housing connected to the input, two friction disc clutches each connected to one of the output driveshafts, driven discs connected to input pressure plates associated with each of the disc clutches, a ball drive assembly for engaging and disengaging the friction disc according to the relative angular position of the pressure plates, and a coiled compression spring urging the clutches to an engaged state.

Abstract: A full time-four-wheel-drive vehicle in which front and rear wheels are always connected to each other through a torque transmission coupling includes an engine; a transmission, a first differential which is driven through the transmission to drive one of a front and a rear wheel systems; a second differential which is drivingly connected to the other of the systems; and a torque transmission coupling which includes an input shaft which is drivingly connected to the transmission and the first differential, an output shaft which is drivingly connected to the second differential, an oil pump which is driven by the relative rotation between the input shaft and the output shaft to generate oil pressure corresponding to the speed of the relative rotation, and a friction clutch mechanism which engages the input shaft and the output shafts with each other by the oil pressure generated by the oil pump.

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 predetermined slip threshold is exceeded. Below a predetermined vehicle road speed, the electronic control utilizes a pulse counting technique to determine whether or not an excessive slip condition occurs. Above the predetermined speed, the control compares the front and rear output shafts speeds to determine whether there is excessive slippage. During the first portion of the clutch engagement period, the clutch is fully engaged while, during the last portion, a partial clutch engagement signal is generated to cause the clutch to gradually move from a fully engaged condition to a fully disengaged condition. The length of time the clutch is engaged can be a function of the vehicle road speed.

Abstract: A torque transmitting assembly comprises a first rotary element including internal cam surfaces, a second rotary element disposed in the first rotary element, the second rotary element including a rotor containing a plurality of radially outwardly opening pressure chambers facing the cam surfaces, and a hydraulic mechanism for transmitting a ratio of the input torque from one of the first rotary element and the second rotary element to the other in response to rotation speed of the second rotary element and also to differential rotation occurring between the first rotary element and the second rotary element.

Abstract: In an arrangement for the control of the power transmission of a four-wheel drive vehicle, a main driving axle is driven directly and an auxiliary driving axle is driven via a continuously controllable longitudinal clutch by an internal combustion engine via a clutch-transmission unit. From a desired performance and the speed of the vehicle, a desired traction force of all the wheels is determined. From this desired traction force, and by a distribution factor that is dependent on operating driving parameters, the control quantity is obtained for the control of the longitudinal clutch. In addition, the longitudinal clutch can be controlled alone or in combination with the control quantity by an additional control quantity obtained by squaring of a speed difference at the longitudinal clutch.

Abstract: An all-wheel driven motor vehicle capable of operating in an understeering or an oversteering condition comprises a front axle, a rear axle, and an interaxle differential comprising a planetary gear system, a releasable coupling, and a liquid friction coupling. The planetary gear system includes an input member connected to the motor of the vehicle, a first output member connected to the front axle, and a second output member connected to the rear axle. The releasable coupling interconnects the first and second output members. The liquid friction coupling is disposed between the first output member and the front axle. The three-torque transmitting members of the planetary gear system are selected so that when the releasable coupling is disengaged, the vehicle operates in an understeering condition under normal running conditions.

Abstract: In a drive coupling unit suitable for use in an four-wheel drive unit for motor vehicles of the type wherein a torque is transmitted via a fluid pressure produced depending on a difference in rotational speed between two rotating shafts, each working fluid supply passage and a corresponding check valve disposed therein are arranged to interconnect one of two intake/discharge ports in each respective pump chamber with a tank in which a working fluid is retained. With this construction, an improved response characteristic of the check valves and a substantial reduction of the overall size of the drive coupling unit can be attained.

Abstract: A transfer device for a four-wheel drive vehicle has a transfer shaft rotatably mounted by first and second bearings and a transfer gear rotatably mounted on the transfer shaft between the bearings. A coupling device is provided outside the first bearing for engaging the transfer gear with the transfer shaft, and a bevel gear is secured to the transfer shaft at a portion outside of the second bearing.

Abstract: A four-wheel drive vehicle having a front- and rear-wheel engaging mechanism designed to enable differential limiting means provided between the front and rear wheels to be controlled over the range from the direct coupling position to the disengaged position through the slip region by the control of the degree of engagement. The vehicle is provided with engaging means for driving the front- and rear-wheel engaging mechanism at a set degree of engagement, detecting means for detecting a running condition, and control means for setting a degree of engagement to control the engaging means. The control means has reference data concerning degrees of engagement respectively corresponding to various running conditions, and sets a degree of engagement selected from the reference data in accordance with the detected running condition. Thus, it is possible to engage the front- and rear-wheel engaging mechanism in such a manner as to prevent the occurrence of tight corner braking while avoiding slipping.

Abstract: A four-wheel drive vehicle has an engine output shaft; a transmission having an input shaft connected to the output shaft and an output shaft connected through a transmission mechanism to the input shaft; a drive gear meshed with an output gear connected to the output shaft of the transmission; a front wheel side power transmitting mechanism; a rear wheel side power transmitting mechanism; a center differential mechanism coaxial with the drive gear and having an input member connected to the drive gear, a first output member connected to the front wheel side power transmitting mechanism, and a second output member connected to the rear wheel side power transmitting mechanism; a front differential gear coaxial with the center differential mechanism and connected to the first output member of the center differential mechanism; a power converting gear mechanism for converting a rotation about a first axis to a rotation about a second axis being perpendicular to the first axis to transmit power to the rear side p

Abstract: In order to be able to use a four-wheel drive of a motor vehicle for different vehicle types without significant changes, it is combined into a compact drive unit. For that purpose, a four-wheel-locking mechanism and a free-wheel device with by-pass clutch are arranged adjacent one another and coaxially to one another inside of a housing surrounding the same which is adapted to be flangedly connected to an axle housing of the motor vehicle.

Abstract: A four wheel driving power transmission is provided which is interposed between an input shaft and an output shaft in a driving power transmitting system for the wheels of a four wheel drive car. The transmission is provided with a member in association with one of the input shaft and the output shaft and a cylindrical casing in association with the other. The casing seals therein a working fluid in a fluid-tight manner and houses a fluid pressure pump operating by relative rotation of the casing with respect to the shaft, a piston actuated by discharge pressure of the pump, and a sliding clutch for engaging the shaft with the cylindrical casing through operation of the piston.