A driveline system comprising a prime mover configured to provide torque to at least a first group of wheels; an electric machine configured to provide torque to at least a second group of wheels; a torque transfer drive comprising a first side and a second side and configured to enable torque generated by the prime mover to be provided from the first side to the second side for provision to the second group of wheels; a first disconnect device configured to, in a first connect configuration, transmit torque from the prime mover to the first side of the torque transfer drive and, in a first disconnect configuration, prevent transmission of torque from the prime mover to the first side of the torque transfer drive; and a second disconnect device configured to, in a second connect configuration, transmit torque between the electric machine and the second side of the torque transfer drive and, in a second disconnect configuration, prevent transmission of torque between the electric machine and the second side of the torque transfer drive.

A method for controlling a vehicle driveline uses sensors to estimate a need for powering secondary wheels for each of a plurality of conditions. The estimates are scaled and the scaled estimates summed. Only primary wheels are powered when the summed estimates are less than a reference value. Both the primary and secondary wheels are powered when the summed estimates exceed the reference value.

Removable devices and systems for operating the four wheel drive (4WD) system of a tow vehicle having an electronically controllable part time 4WD system including a selectable 4WD low range mode are described. The removable device may comprise a first interface for coupling the removable device to a selector, the selector providing an indication of a desired operating mode for the 4WD system; a second interface for coupling the removable device to a controller-area network bus of the tow vehicle; a memory storing vehicle control codes; and at least one controller communicatively coupled to both the first interface and the second interface. The removable device, and system, may allow a vehicle operator to operate the tow vehicle in two-wheel drive low range mode.

A vehicle drive system, that can improve drive efficiency while maintaining vehicle stability, includes a step (S3, S105) in which a switch is made from 2WD to AWD on the basis of a cumulative slip point; a step (S12, S303) in which a switch is made from 2WD to AWD on the basis of a calculated lateral G; a step (S13, S109, S111) in which a switch is made from AWD to 2WD after the step (S3 or S105) under a first switching condition; and a step (S13, S306, S308) in which a switch is made from AWD to 2WD after the step (S12 or S303) under a second switching condition. The first switching condition and the second switching condition differ from one another.

A method for operating a vehicle having an all-wheel drive driveline with a disconnecting drive unit. The method conditions changing the operational state of the all-wheel drive driveline from a connected state to a disconnected state based in part on an operational state of a vehicle torque converter.

A vehicle includes a first axle, second axle, driveshaft, engine, clutch, and controller. The first and second axles are coupled by the driveshaft. The engine is configured to generate torque in the first axle. The clutch is configured to disconnect an output of the second axle. The controller is programmed to, responsive to a clutch release request that would result in an increasing commanded torque to the first axle being greater than a threshold, decrease an engine torque such that a first axle torque is less than the threshold.

Methods and systems are provided for operating a four-wheel drive powertrain of a vehicle. In one example, a method may comprise: in response to a desired shift from a four-wheel drive mode to a two wheel-drive mode: decreasing a transfer case torque output to a secondary driveline to a lower first level and disengaging a disconnect device of the secondary driveline; increasing the transfer case torque output from the lower first level to a higher second level over a duration; and after the duration, reducing the transfer case torque.

An all-terrain vehicle includes a frame including a front frame part and a separate rear frame part connected to the front frame part via frame joints. A surface is supported by one of the front frame part and the rear frame part. An engine is supported by the rear frame part and is positioned behind the seating surface. Front wheels operably coupled to the front frame part are drivingly coupled to the engine via a front drive unit. Rear wheels operably coupled to the rear frame part are drivingly coupled to the engine via a rear drive unit. A brake system is mounted to the frame and includes front wheel brakes and rear wheel brakes. The brake system further includes a brake modulator and a master brake cylinder operably connected to the brake modulator. The brake modulator is mounted to the front frame part.

A four-wheel drive vehicle includes front wheels, rear wheels to which a driving force of an engine is transmitted via a propeller shaft, a dog clutch that enables blocking of transmission of the driving force from the engine to the propeller shaft, and a multi-disc clutch that enables blocking of transmission of the driving force from the propeller shaft to the rear wheels. During two-wheel driving in which the transmission of the driving force through the dog clutch and the multi-disc clutch is blocked, an ECU in the four-wheel drive vehicle calculates an estimated driving force estimated to be transmitted to the front wheels based on a vehicle speed and an amount of acceleration operation. The ECU allows the multi-disc clutch to transmit the driving force when the estimated driving force is larger than a driving force threshold defined according to a slip limit torque for the front wheels.

An actuation system of a transfer case includes a face cam, a motor, a gear reduction assembly, and an intermediate rotating member. The face cam includes a first member and a second member, and rotation of the first member relative to the second annular causes the first member or the second annular member to displace axially relative to the other member for selective operation of a torque transfer mechanism of the torque transfer device. The gear reduction assembly includes a first planetary gear set that increases torque from the motor by a first ratio, and a second planetary gear set that increases torque from the first planetary gear set by a second ratio and is coaxial with the first planetary gear set and the motor. The intermediate rotating member is rotated by the gear reduction assembly and rotates the first annular member for selective operation of the torque transfer mechanism.