A slip control system for an off-road vehicle includes a control system configured to output a signal indicative of a first action if a magnitude of slippage of the off-road vehicle relative to a soil surface is greater than a first threshold value and less than or equal to a second threshold value. Furthermore, the control system is configured to output a signal indicative of a second action, different than the first action, if the magnitude of slippage is greater than the second threshold value.

A slip control system for an off-road vehicle includes a control system configured to output a signal indicative of a first action if a magnitude of slippage of the off-road vehicle relative to a soil surface is greater than a first threshold value and less than or equal to a second threshold value. Furthermore, the control system is configured to output a signal indicative of a second action, different than the first action, if the magnitude of slippage is greater than the second threshold value.

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 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 driving force control apparatus for controlling a driving force to be transmitted to a wheel includes a processor. The processor is configured to set, when the wheel is idled, a control amount of the driving force to be transmitted to the wheel based on a vehicle acceleration.

A transfer case and transmission are designed to permit the transmission hydraulic control system to control a range selection coupler and a torque on demand clutch in the transfer case. Two pressure circuits are transmitted from the transmission to the transfer case: a high range circuit and a low range circuit. The low range circuit is pressurized to engage low range while the range circuit is pressurized to engage high range. The torque on demand clutch is controlled by whichever of these circuits has the higher pressure. Lubrication is provided to a front section of the transfer case via the transmission output shaft, with the fluid returning to the transmission sump through a drainback passageway. The rear portion of the transfer case has a segregated sump. A control strategy is employed to partially fill front section of the transfer case with fluid in preparation for vehicle towing.

A transfer case and transmission are designed to permit the transmission hydraulic control system to control a range selection coupler and a torque on demand clutch in the transfer case. Two pressure circuits are transmitted from the transmission to the transfer case: a high range circuit and a low range circuit. The low range circuit is pressurized to engage low range while the range circuit is pressurized to engage high range. The torque on demand clutch is controlled by whichever of these circuits has the higher pressure. Lubrication is provided to a front section of the transfer case via the transmission output shaft, with the fluid returning to the transmission sump through a drainback passageway. The rear portion of the transfer case has a segregated sump. A control strategy is employed to partially fill front section of the transfer case with fluid in preparation for vehicle towing.

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 clutch control device is provided for a four-wheel drive vehicle for transmitting drive force to the rear wheels. The clutch control device includes a dog clutch and a friction clutch, and a controller that controls the engagement and disengagement of the dog clutch and the friction clutch. In this clutch control device, the four-wheel drive hybrid vehicle includes a disconnected, two-wheel drive mode and a connected, four-wheel drive mode. When a driver's foot is lifted off an accelerator in a low-speed region when the connected, four-wheel drive mode is selected, the 4WD control unit maintains the connected, four-wheel drive mode while the brakes are not depressed, and shifts the mode to the disconnected, two-wheel drive mode when the brakes are depressed.

A vehicle, system and method of operating the vehicle. A sensor measures a dynamic parameter of the vehicle. A processor determines a lateral force on a first tire based on the dynamic parameter of the vehicle, determines a longitudinal force on the first tire that achieves a maximal grip of the first tire for the lateral force, and adjusts a first torque on the first tire in order to achieve the determined longitudinal force at the first tire.