A pump operation piston biased by a neutral spring mechanism and a larger volume operation spring biased by a larger volume operation spring in a larger volume direction operatively move pump and motor volume adjusting members, respectively, is provided. A first pressure control valve commonly controls supply-discharge of pressure oil that presses the pump operation piston in a first slide direction and the motor operation piston in a smaller volume direction. A second pressure control valve controls supply-discharge of pressure oil that presses the pump operation piston in a second slide direction. Biasing forces of the neutral spring mechanism and the larger volume operation spring are so set that, after the pump operation piston is moved in the first slide direction by a predetermined distance, the motor operation piston starts moving.

A pump operation piston biased by a neutral spring mechanism and a larger volume operation spring biased by a larger volume operation spring in a larger volume direction operatively move pump and motor volume adjusting members, respectively, is provided. A first pressure control valve commonly controls supply-discharge of pressure oil that presses the pump operation piston in a first slide direction and the motor operation piston in a smaller volume direction. A second pressure control valve controls supply-discharge of pressure oil that presses the pump operation piston in a second slide direction. Biasing forces of the neutral spring mechanism and the larger volume operation spring are so set that, after the pump operation piston is moved in the first slide direction by a predetermined distance, the motor operation piston starts moving.

A hydrostatic traction drive includes a first hydraulic machine that is coupled to a drive unit. The first hydraulic machine is hydraulically arranged in a hydraulic circuit with a second hydraulic machine. The second hydraulic machine has a drive shaft that is connected in a rotationally fixed fashion to a lockable differential. The traction drive has a control unit that is configured so as to control at least one measure for traction control as a function of a rotational speed of the second hydraulic machine. The at least one measure includes one or more of a measure for detecting a loss of traction and a measure for overcoming the loss of traction. A method for controlling the traction drive includes eliminating a loss of traction of the traction drive with use of the control unit as a function of the rotational speed of the second hydraulic machine.

A hydrostatic traction drive includes a first hydraulic machine that is coupled to a drive unit. The first hydraulic machine is hydraulically arranged in a hydraulic circuit with a second hydraulic machine. The second hydraulic machine has a drive shaft that is connected in a rotationally fixed fashion to a lockable differential. The traction drive has a control unit that is configured so as to control at least one measure for traction control as a function of a rotational speed of the second hydraulic machine. The at least one measure includes one or more of a measure for detecting a loss of traction and a measure for overcoming the loss of traction. A method for controlling the traction drive includes eliminating a loss of traction of the traction drive with use of the control unit as a function of the rotational speed of the second hydraulic machine.

A hydrostatic traction drive for a vehicle with a hydrostat includes a hydraulic pump, a hydraulic motor, and an electronic control unit. The hydraulic pump has an adjustable stroke volume, and includes an adjustment device configured to adjust the adjustable stroke volume. The hydraulic motor is arranged with the hydraulic pump in a hydraulic circuit, in particular a closed hydraulic circuit. The electronic control unit is configured to exclusively control the hydrostat so that the traction drive is controllable without knowledge or control of specific components thereof. The electronic control unit has a defined interface configured to pass a target value for an operating parameter of the hydrostat to the electronic control unit.

A hydraulic system according to the present invention includes a rotational shaft, a hydraulic rotor supported by the rotational shaft so as to be incapable of relative rotation, an output adjuster varying a volume of the hydraulic rotor, a control shaft tilting the output adjuster, a drive motor operating the control shaft around the axis, a drive shaft disposed on a reference axis same as the axis of the control shaft and operably driven around the axis by the drive motor, a deceleration mechanism decelerating rotary power input from the drive shaft and outputs the decelerated rotary power toward the control shaft, and a housing accommodating the hydraulic rotor, the output adjuster, and the deceleration mechanism, wherein the deceleration mechanism has a hypocycloid-type deceleration mechanism disposed on the reference axis.

A hydraulic system according to the present invention includes a rotational shaft, a hydraulic rotor supported by the rotational shaft so as to be incapable of relative rotation, an output adjuster varying a volume of the hydraulic rotor, a control shaft tilting the output adjuster, a drive motor operating the control shaft around the axis, a drive shaft disposed on a reference axis same as the axis of the control shaft and operably driven around the axis by the drive motor, a deceleration mechanism decelerating rotary power input from the drive shaft and outputs the decelerated rotary power toward the control shaft, and a housing accommodating the hydraulic rotor, the output adjuster, and the deceleration mechanism, wherein the deceleration mechanism has a hypocycloid-type deceleration mechanism disposed on the reference axis.

A method teaches a control function, preferably a characteristic curve, of a hydrostatic motor of a traction drive of a work machine when in drive mode. The traction drive is provided with the hydrostatic motor and a hydrostatic pump, which is hydraulically connected to the hydrostatic motor. The method includes setting a pivot angle of the hydrostatic motor while taking into account a desired velocity of the work machine when in the drive mode, and checking whether predefined conditions are met. If the predefined conditions are met and a current velocity differs from the desired velocity, the method includes correcting the control function of the hydrostatic motor by taking into account a difference between the desired velocity and the current velocity. At least one value of the corrected control function of the hydrostatic motor is taught during the correcting.

The controller determines whether the vehicle is in a shuttle motion from the operating position of the forward/reverse travel operating member and the actual traveling direction of the vehicle. The controller determines a target braking force when the vehicle is in the shuttle motion. The controller determines at least one of a target displacement of the travel pump and a target displacement of the travel motor based on the target braking force.

The controller determines whether the vehicle is in a shuttle motion from the operating position of the forward/reverse travel operating member and the actual traveling direction of the vehicle. The controller determines a target braking force when the vehicle is in the shuttle motion. The controller determines at least one of a target displacement of the travel pump and a target displacement of the travel motor based on the target braking force.