A drive control system for a work vehicle is provided with a power transmission device that drives front wheels and rear wheels, a request determination unit, and a drive mode control unit. The power transmission device has a drive mode switching mechanism that performs drive mode switching between a four-wheel drive mode in which drive power is transmitted to front wheels and rear wheels and a two-wheel drive mode in which drive power is transmitted to only the rear wheels. The request determination unit determines a necessity for an increase in drive power on a contact area of the work vehicle, and outputs an increase request based on the determination result. The drive mode control unit outputs a drive mode switching request for switching to the four-wheel drive mode to the drive mode switching mechanism, in response to output of the increase request.

A method is provided for determining whether or not ground contact loss is imminent for wheel of a vehicle, the vehicle including a vehicle body having a vertical extension in a vertical direction, the wheel being allowed to be subjected to a relative vertical displacement, in the vertical direction, in relation to the vehicle body, the vehicle further being such that a maximum value of a vertical displacement of the wheel relative to the vehicle body is limited to a relative vertical displacement limit; the method including determining an actual relative vertical displacement of the wheel relative to the vehicle body, determining a limit margin as the difference between the actual relative vertical displacement and the relative vertical position limit, and determining that ground contact loss is imminent for a wheel if the limit margin is within a predetermined vertical threshold range.

In a method for controlling a traction system for a heavy road vehicle, the system includes a first mechanical propulsion system, a second hydraulic propulsion system, and a control unit. The method includes measuring a first parameter value, indicative of the rolling radius of a first traction wheel, measuring a second parameter value, indicative of the rolling radius of a second traction wheel, and the control unit using the first and second parameter values for determining a present relation between the rolling radii of the first and second traction wheels. The control unit provides an output signal based on the present relation to optimize the traction applied to the second traction wheel. A traction system and a heavy vehicle incorporating a traction system are also provided.

A vehicle traction control system for a vehicle, in which the vehicle has a prime mover, at least one wheel for providing tractive effort on a support surface, and a transmission having an input side operably coupled to the prime mover and an output side operably coupled to the at least one wheel, and in which the transmission has a controllable clutch pressure between the input side and the output side, includes a controller operable to monitor wheel slip of the at least one wheel. When wheel slip is detected the controller is operable to control the clutch pressure for modulating an output torque of the transmission for reducing the wheel slip. The clutch pressure can be controlled as a function of clutch slip.

A method of minimizing the occurrence of wheel slip in a traction vehicle includes a drivetrain, at least one wheel for providing tractive effort on a support surface, and a ground-engaging implement moveable relative to the support surface. The method includes estimating a first force acting against the ground-engaging implement, estimating a second force provided by the at least one wheel operable to move the vehicle on the support surface, and controlling the ground-engaging implement based on a difference between the first force and the second force.

A system for limiting engine torque of a four-wheel-drive motor vehicle, including an actuator that is controlled and configured to distribute the engine torque to the drive wheels, a computer calculating at least one variable characteristic of an operation of the vehicle, and a module for limiting the engine torque. In addition, the limitation system includes a mechanism for deactivating the module for limiting the engine torque according to the variable characteristic of the operation of the engine.

A traction control system configured to limit slip by a machine having a work implement including a machine motion sensor configured to determine a motion of the machine, a work implement unit configured to determine whether the work implement is in an operational state, a powertrain motion sensor configured to determine a motion of a powertrain component, and a machine powertrain controller configured to determine slip by comparing the motion of the machine to the motion of the powertrain component, wherein the machine powertrain controller is configured to command a torque reduction to the powertrain component when slip is determined.

A control apparatus for an electrically driven vehicle includes a electronic control unit and a dynamic power transmission mechanism. The electronic control unit is configured to control the dynamic power transmission mechanism to execute a slip control such that the speed of an electric motor is a higher speed than a speed of the electric motor at a time point and speed of a relative rotation in the fluid coupling increases, in a case of determining that the operating state of the electric motor enters the operating state in which the value of the heat load is the predetermined value or greater, the time point being a time point when the operating state of the electric motor enters the operating state in which the value of the heat load is the predetermined value or greater.

A control apparatus for a dynamic power transmission apparatus is provided. The dynamic power transmission apparatus includes a differential mechanism, an electric generator, an electric motor, and a fluid coupling. The electric motor is disposed at a position apart from a transmission path along which a dynamic power of an engine is transmitted to a driving wheel. The fluid coupling is disposed between the electric motor and the transmission path. The control apparatus includes an electronic controller configured to restrict a charge of an electric storage apparatus with an electric power generated by the electric generator, depending on a state of the electric storage apparatus, and control the fluid coupling to differentially rotate and to drive the electric motor by the electric power such that a dynamic power loss is generated in the fluid coupling, when restricting the charge of the electric storage apparatus.