A vehicle having a four-wheel-drive system including an auxiliary portion that has an auxiliary driveshaft and drive means between the auxiliary driveshaft arranged to releasably connect a second group of wheels to the driveline via a releasable torque transmitting device. The releasable torque transmitting device is operable to allow slippage of the input portion with respect to the output portions, thereby to vary an amount of torque that is transmitted to the second group of wheels.

A transmission arrangement for the controllable distribution of a drive torque from an input element to at least one output element in an all wheel drive train of an all wheel drive motor vehicle, comprising an additional drive unit, a first transmission part region, the first transmission part region being drive-connected directly or indirectly to the additional drive unit, a second transmission part region, the first transmission part region being connected indirectly via the second transmission part region to the output element, and a selector element, it being possible for the selector element to be moved into three shifting positions, namely a first shifting position, in which the first transmission part region is drive-connected to the input element, a second shifting position, in which the first transmission part region is drive-connected to the second transmission part region, and a third shifting position, in which the first transmission part region is drive-connected neither to the input element nor to the second transmission part region.

A method for operating a vehicle is disclosed. The vehicle has at least one torque transmission device which when rotating splashes in a fluid, at least two axles each having at least two wheels and at least one controllable coupling device adapted for selectively coupling or decoupling the torque transmission device with at least one of the wheels. The method includes the steps of: in an operating state in which no torque is requested by a driver of the vehicle, decoupling with the control device the torque transmission device and the at least one wheel when a driving speed of the vehicle is greater than or equal to a predetermined speed threshold value and coupling with the control device the torque transmission device and the at least one wheel for torque transmission when the driving speed is smaller than the predetermined speed threshold value.

A method for operating a motor vehicle having a four-wheel drive and a drive unit, which can be switched on and off during travel, wherein the motor vehicle is driven by a torque provided by the drive unit, and the initially disengaged four-wheel drive is switched on, including: determining at least one limit torque which, while the four-wheel drive is switched off, can be transmitted from at least one wheel of the motor vehicle driven by the drive unit to the ground surface upon which the motor vehicle is travelling, while the slip between the at least one wheel and the ground surface falls below a specifiable threshold value.

A method for operating a motor vehicle having a four-wheel drive and a drive unit, which can be switched on and off during travel, wherein the motor vehicle is driven by a torque provided by the drive unit, and the initially disengaged four-wheel drive is switched on, including: determining at least one limit torque which, while the four-wheel drive is switched off, can be transmitted from at least one wheel of the motor vehicle driven by the drive unit to the ground surface upon which the motor vehicle is travelling, while the slip between the at least one wheel and the ground surface falls below a specifiable threshold value.

A method for controlling the safe operation of a rear axle of a set of combined axles powered by a motor vehicle, particularly for a vehicle designed to carry loads and which have 6×4, 8×4 or 10×4 type traction configurations, or tridem models formed by three drive axles. The method includes a set of steps and activities that ensure proper and safe operation of systems and mechanisms for uncoupling and raising a rear axle of a vehicle, and more specifically checking a status of certain operating parameters of the rear axle and of the vehicle itself in order to permit or prevent uncoupling and coupling, as well as raising and lowering of the rear axle of the vehicle.

A hydraulic circuit is disclosed for use with a powertrain having an engine, a transmission, and an output transfer group. The hydraulic circuit may have a first sump configured to collect fluid drained from the transmission, and a second sump configured to collect fluid drained from the output transfer group. The hydraulic circuit may also have a primary pump configured to draw fluid from the first sump and generate at least one flow of pressurized fluid directed to the transmission and to the output transfer group.

Even in the case where it is difficult to increase an engine torque (Te) during switching when a running is switched to a 4WD running or a 2WD running during a 2WD_d running, an alternative control section suppresses a fluctuation in the driving force of a four-wheel drive vehicle, hence it is possible to suppress a switching shock and an unnatural feeling of deceleration occurring during the switching to the 4WD running or the 2WD running.

Even in the case where it is difficult to increase an engine torque (Te) during switching when a running is switched to a 4WD running or a 2WD running during a 2WD_d running, an alternative control section suppresses a fluctuation in the driving force of a four-wheel drive vehicle, hence it is possible to suppress a switching shock and an unnatural feeling of deceleration occurring during the switching to the 4WD running or the 2WD running.

A vehicle differential disconnect assembly can include a differential case, a differential gear set, and a torque distribution device. The differential gear set is carried within the differential case. The torque distribution device transfers torque between the differential gear set and side shafts of the accompanying vehicle driveline. The torque distribution device can include a clutch pack and an actuator assembly. The clutch pack is located at a first side of the differential case relative to the differential gear set, and the actuator assembly is located at a second side of the differential case relative to the differential gear set. The actuator assembly has a mover that transmits movement to the clutch pack when the actuator assembly actuates and deactuates the clutch pack.