Methods of controlling a tandem axle assembly in a vehicle, the tandem axle assembly including an inter-axle differential (IAD), one or more side gears, and a front tandem axle assembly having a pair of front tandem axle half shafts selectively connected to a pair of front tandem axle wheel hub assemblies. When a determined speed of the vehicle is greater or equal to a predetermined speed, the IAD may be locked, the tandem axle wheel hub assemblies may be disconnected from their respective tandem axle shafts, and/or the IAD may be moved out of engagement with the one or more side gears. When a determined speed of the vehicle is less than a predetermined speed, the IAD may be unlocked, the tandem axle wheel hub assemblies may be connected to their respective tandem axle shafts, and/or the IAD may be engaged with the one or more side gears.

A vehicle has an engine, a limited slip differential (LSD) mounted on an axle driven by the engine, and left and right wheels operably connected to the LSD. At least one parameter indicative of a riding condition of the vehicle is determined. A slippery driving condition is detected based on the at least one parameter. The LSD is selectively locked in response to the detection. The slippery driving condition is detected when a torque requested by a user is above a load line of the engine, upon successive wheel slips occurrences, and/or when a wheel slip is detected while a preload is applied to the LSD.

A driving force distribution apparatus includes an orthogonal gear pair constituted by a pinion gear shaft and a ring gear member, a casing that houses the orthogonal gear pair, an intermediate rotational member coaxially rotatable relative to the ring gear member, a clutch member configured to couple the ring gear member and the intermediate rotational member to each other, and first and second driving force adjustment mechanisms configured to adjust a driving force to be transmitted from the intermediate rotational member to first and second output rotational members. The ring gear member has a ring gear portion and a tubular portion. At two positions between which the ring gear portion is interposed in an axial direction, the tubular portion) is rotatably supported by a pair of bearings.

A powertrain for a vehicle includes an internal combustion engine and a transfer case. The transfer case includes a primary output shaft, an electric motor, and a planetary gear set. The primary output shaft receives engine torque from the internal combustion engine. The electric motor includes a rotor and a stator. The planetary gear set includes a sun gear rotatably fixed to the rotor, a ring gear, planet gears arranged radially between and engaging the sun gear and the ring gear, and a planet carrier coupled to the planet gears and rotatably fixed to the primary output shaft. The ring gear is selectively groundable for selectively transferring torque between the electric motor and the primary output shaft.

A vehicle includes a tandem axle system having an inter-axle differential and clutching assembly, a forward or first axle assembly, and a rear or second axle assembly. The inter-axle differential and clutching assembly includes a differential mechanism having first and second side gears and a clutch mechanism having a clutch member and an actuator assembly. At least one of the first axle assembly and the second axle assembly is in selective driving engagement with the inter-axle differential and clutching assembly.

A method of operating a drive-train of a vehicle having a drive engine, at least one drive axle and at least one further axle which can be drivingly connected by a pressure-controlled switching device. The switching device is acted upon by an opening pressure to disconnect the axle. When a service brake system of the vehicle is actuated, the axle is automatically connected by actuating the switching device, which is actuated as a function of a braking mode determined during actuation of the brake system, in such manner that when the brake system is actuated in a first braking mode, the switching device is actuated by a first control pressure to transmit a first torque, and if at least one parameter that characterizes the occurrence of a second braking mode is exceeded, the switching device is actuated by a second control pressure to transmit a second, higher torque.

Methods of controlling a tandem axle assembly in a vehicle, the tandem axle assembly including an inter-axle differential (IAD), one or more side gears, and a front tandem axle assembly having a pair of front tandem axle half shafts selectively connected to a pair of front tandem axle wheel hub assemblies. When a determined speed of the vehicle is greater or equal to a predetermined speed, the IAD may be locked, the tandem axle wheel hub assemblies may be disconnected from their respective tandem axle shafts, and/or the IAD may be moved out of engagement with the one or more side gears. When a determined speed of the vehicle is less than a predetermined speed, the IAD may be unlocked, the tandem axle wheel hub assemblies may be connected to their respective tandem axle shafts, and/or the IAD may be engaged with the one or more side gears.

A four-wheel-drive vehicle includes: a pump that is actuated by an electric motor; a friction clutch that has a plurality of clutch plates that are pressed by a piston that is movable by working oil discharged from the pump; a control device that controls the electric motor; front wheels, to which a drive force of an engine is always transferred; and rear wheels, to which the drive force of the engine is transferred in accordance with the fastening force of the friction clutch. When it is determined that the vehicle is in a high fastening force-requiring state in which it is necessary for the friction clutch to transfer a large drive force temporarily, the control device causes the electric motor to output torque that is larger than torque that the electric motor can continuously output.

A dual-motor transmission therefor, comprising a first and a second electric traction motor, a first gear arrangement, a second gear arrangement, and a summation box. The first gear arrangement includes a shaft and at least a first gear and a second gear, wherein each of the first and the second gears can be selectively engaged and disengaged with the shaft via a clutch, and the first gear arrangement supplies a first torque from the first motor to the summation box. The second gear arrangement includes a shaft and at least a first gear, wherein the first gear can be engaged and disengaged with the shaft via a clutch, and the second gear arrangement supplies a second torque from the second motor to the summation box, and the summation box is configured to combine the first and second torques and to output a combined output torque.

A control apparatus that controls a four-wheel drive vehicle in which a driving force is transmitted to rear wheels via a dog clutch, a propeller shaft, and a driving force transmission apparatus is configured to, when switching to a four-wheel drive mode, reduce a difference in rotation speeds of an intermediate rotational member and a ring gear member by a frictional force between a friction surface of a friction member, which is configured such that its rotation relative to the intermediate rotational member is restricted, and a target frictional slide surface of the ring gear member, and then couple the intermediate rotational member and the ring gear member by a clutch member in a state in which engagement forces of friction clutches configured to transmit the driving force between each of first and second output rotational members and the intermediate rotational member of the driving force transmission apparatus are set to engagement forces that allow their relative rotation.