A hydrostatic transmission implements a braking system, in which at least one adjustable traction motor acting as a pump is supported via a closed circuit on an adjustable axial piston machine acting as a motor, which in turn is supported on an internal combustion engine. Since the internal combustion engine should not be rotated at excessive revolution rates, a control unit adjusts the swivel angle of the axial piston machine during braking. The axial piston machine is load-sensitive, as a relationship between the control pressure and the revolution rate and the pivot angle of the machine consists of a pressure difference between the two working lines of the closed circuit. Using a pre-control, a swivel angle of the axial piston machine is set during braking, and the swivel angle is corrected by a revolution rate controller, such that a target revolution rate is obtained on the combustion engine.

A hydrostatic transmission implements a braking system, in which at least one adjustable traction motor acting as a pump is supported via a closed circuit on an adjustable axial piston machine acting as a motor, which in turn is supported on an internal combustion engine. Since the internal combustion engine should not be rotated at excessive revolution rates, a control unit adjusts the swivel angle of the axial piston machine during braking. The axial piston machine is load-sensitive, as a relationship between the control pressure and the revolution rate and the pivot angle of the machine consists of a pressure difference between the two working lines of the closed circuit. Using a pre-control, a swivel angle of the axial piston machine is set during braking, and the swivel angle is corrected by a revolution rate controller, such that a target revolution rate is obtained on the combustion engine.

A hydraulic system of a work machine includes a first hydraulic device to operate in a first operation mode while pressure of hydraulic oil supplied from a hydraulic pump via a first oil passage is equal to or higher than a first pressure threshold. The hydraulic oil in the first oil passage is to be discharged via a second oil passage. A pilot check valve is provided in the second oil passage and has a pilot port to receive a pilot pressure of the hydraulic oil. The pilot check valve is closed to stop discharging the hydraulic oil in the first oil passage through the second oil passage while the pilot pressure is lower than the fourth pressure threshold. The pilot check valve is opened while the pilot pressure is higher than or equal to the fourth pressure threshold. The first hydraulic device is a ride control device.

A system is disclosed. The system may include a first hydraulic variator including a first hydraulic pump and a first hydraulic motor. A first actuator may be linked to the first hydraulic pump. The first actuator may be associated with a feedback link configured to control pressure supplied to the first actuator, via a control valve, according to the displacement of the first hydraulic pump. The system may include a second hydraulic variator including a second hydraulic pump and a second hydraulic motor. A second actuator may be linked to the second hydraulic pump and configured to control a pressure within the second hydraulic variator to correspond to a pressure within the first hydraulic variator. The system may include a controller configured to provide a first signal to the first hydraulic variator relating to a speed and a second signal to the second hydraulic variator relating to a torque.

A system is disclosed. The system may include a first hydraulic variator including a first hydraulic pump and a first hydraulic motor. A first actuator may be linked to the first hydraulic pump. The first actuator may be associated with a feedback link configured to control pressure supplied to the first actuator, via a control valve, according to the displacement of the first hydraulic pump. The system may include a second hydraulic variator including a second hydraulic pump and a second hydraulic motor. A second actuator may be linked to the second hydraulic pump and configured to control a pressure within the second hydraulic variator to correspond to a pressure within the first hydraulic variator. The system may include a controller configured to provide a first signal to the first hydraulic variator relating to a speed and a second signal to the second hydraulic variator relating to a torque.

A hydraulic device includes a braking device to brake a traveling device and release braking of the traveling device, a traveling pump to drive the traveling device with pressure of operation fluid, a brake-operation valve to control operation fluid flowing to the brake device, a traveling operation valve to control operation fluid flowing to the traveling pump, a first discharge fluid tube to discharge operation fluid flowing through the brake-operation valve, the first discharge fluid tube being connected to the brake operation valve, and a second discharge fluid tube to discharge operation fluid flowing through the traveling operation valve, the second discharge fluid tube being connected to the traveling operation valve. The traveling operation valve has a set pressure that is set to be higher than a brake set pressure set by the brake operation valve.

A hydraulic device includes a braking device to brake a traveling device and release braking of the traveling device, a traveling pump to drive the traveling device with pressure of operation fluid, a brake-operation valve to control operation fluid flowing to the brake device, a traveling operation valve to control operation fluid flowing to the traveling pump, a first discharge fluid tube to discharge operation fluid flowing through the brake-operation valve, the first discharge fluid tube being connected to the brake operation valve, and a second discharge fluid tube to discharge operation fluid flowing through the traveling operation valve, the second discharge fluid tube being connected to the traveling operation valve. The traveling operation valve has a set pressure that is set to be higher than a brake set pressure set by the brake operation valve.

A hydraulic system of a work machine includes a first hydraulic device to operate in a first operation mode while pressure of hydraulic oil supplied from a hydraulic pump via a first oil passage is equal to or higher than a first pressure threshold. The hydraulic oil in the first oil passage is to be discharged via a second oil passage. A pilot check valve is provided in the second oil passage and has a pilot port to receive a pilot pressure of the hydraulic oil. The pilot check valve is closed to stop discharging the hydraulic oil in the first oil passage through the second oil passage while the pilot pressure is lower than the fourth pressure threshold. The pilot check valve is opened while the pilot pressure is higher than or equal to the second pressure threshold. The first hydraulic device is an operation control valve.

A displacement volume setting device of a hydrostatic variable displacement axial piston unit includes an input device for providing a displacement command. Displacement volume adjusting means set the tilt angle of a displacement element according to the displacement command. A linkage element has an input coupling element connected to the input device, an output coupling element connected to the displacement volume adjusting means, and a connecting element. The input coupling element and the output coupling element are connected by the connecting element which is elastically deformable if a force resulting from the high pressure level present at the hydrostatic axial piston unit and acting on the output coupling element exceeds a predetermined threshold value. Also disclosed is a hydrostatic variable displacement axial piston unit.

A displacement volume setting device of a hydrostatic variable displacement axial piston unit includes an input device for providing a displacement command. Displacement volume adjusting means set the tilt angle of a displacement element according to the displacement command. A linkage element has an input coupling element connected to the input device, an output coupling element connected to the displacement volume adjusting means, and a connecting element. The input coupling element and the output coupling element are connected by the connecting element which is elastically deformable if a force resulting from the high pressure level present at the hydrostatic axial piston unit and acting on the output coupling element exceeds a predetermined threshold value. Also disclosed is a hydrostatic variable displacement axial piston unit.