Hydraulic control device for an automated dual clutch transmission having first and second clutches with first and second sub-transmissions and also a gear shifting system. The hydraulic control device has a regulating unit that predetermines at least one regulated pressure and/or one regulated volume flow for actuating the first and second clutches and shifting system. The hydraulic control device has a switching device that is arranged between the regulating unit and the clutches or the shifting system, switching the regulated pressure or volume flow to the clutches or the shifting system. The regulating unit includes a first regulating valve and a second regulating valve that is connected to an oil pressure supply having a system pressure regulator and an electric oil pump.

A vehicle power transmission device includes a forward first clutch between an engine and an input shaft of a continuously variable transmission, and a second clutch between an output shaft of the continuously variable transmission and driving wheels. When the hydraulic fluid of the hydraulic pump is not supplied to the first disconnection device and the second disconnection device, a dragging torque generated in the second disconnection device is larger than a dragging torque generated in the first disconnection device.

Disclosed is a hydraulic pressure supply system of a dual clutch transmission for a vehicle in which by independently configuring a low pressure supply route and a high pressure supply route, the hydraulic pressure supply system can enable a low hydraulic pressure that is generated in a hydraulic pump for a low pressure to be supplied to a gear lubrication device and a clutch cooling/lubrication device and enable a low hydraulic pressure that is generated in a hydraulic pump for a high pressure to be supplied to a gear control device and a clutch control device.

A hydraulic system including a hydraulically actuated clutch, a hydraulically actuated shifting piston, and a pressure source for actuating the clutch as well as the shifting piston. The movement of the shifting piston also controls a valve function which serves to open a connection from the pressure source to the clutch only when the shifting piston has reached one of its end positions.

A bulldozer includes a steering clutch, a steering brake, a hydraulic pump that discharges a lubricating oil, a first lubricating oil supply path, a second lubricating oil supply path, a third lubricating oil supply path, and a flow amount switching valve disposed on the second lubricating oil supply path. The first lubricating oil supply path supplies a portion of the lubricating oil discharged by the hydraulic pump to the steering clutch The second lubricating oil supply path supplies a portion of the lubricating oil discharged by the hydraulic pump to the steering brake. The third lubricating oil supply path supplies, to the steering brake, a portion of the lubricating oil that has passed through the steering clutch. The flow amount switching valve switches an amount of the lubricating oil supplied to the steering brake.

To provide a device to facilitate protection of a clutch while minimizing degradation of the torque transmission performance. A hydraulic clutch for drive power distribution is provided between a drive power source and auxiliary driving wheels, and a commanded torque is determined depending on the travel situation. The hydraulic pressure corresponding to the commanded torque is supplied to the hydraulic clutch. The surface temperature of the clutch is estimated (detected). The device generates a limiting value to limit the commanded torque when the difference in rotation between input and output shafts of the clutch is not less than a predetermined threshold and the commanded torque is not less than a predetermined value and performs control so as to increase the limiting value with an increase in the surface temperature of the clutch.

A transmission includes an input shaft coupled to a prime mover, a countershaft, main shaft, and an output shaft, with gears between the countershaft and the main shaft. A shift actuator selectively couples the input shaft to the main shaft by rotatably coupling gears between the countershaft and the main shaft. The shift actuator is mounted on an exterior wall of a housing including the countershaft and the main shaft. An integrated actuator housing is operationally coupled to the shift actuator and a linear clutch actuator. The linear clutch actuator is a self-adjusting actuator, and the transmission includes a self-adjusting clutch.

One solenoid valve included in a hydraulic pressure control device has at least two functions among the following (1) to (6) functions, (1) switching a state of a two-way clutch, (2) switching a state of a parking lock mechanism, (3) switching the supply of hydraulic pressure to a first brake that is put into an engaged state when a gear stage selected when driving of a vehicle starts is set, (4) controlling a line pressure adjustment valve so that a decrease in a line pressure is prevented when the temperature of a hydraulic fluid is a first predetermined temperature or higher, (5) preventing the occurrence of a creep phenomenon in a neutral range when the temperature of the hydraulic fluid is a second predetermined temperature or lower, and (6) boosting a line pressure by performing switching to another linear solenoid valve when the line pressure adjustment valve has failed.

A bulldozer includes a steering clutch, a steering brake, a hydraulic pump that discharges a lubricating oil, a first lubricating oil supply path, a second lubricating oil supply path, a third lubricating oil supply path, and a flow amount switching valve disposed on the second lubricating oil supply path. The first lubricating oil supply path supplies a portion of the lubricating oil discharged by the hydraulic pump to the steering clutch The second lubricating oil supply path supplies a portion of the lubricating oil discharged by the hydraulic pump to the steering brake. The third lubricating oil supply path supplies, to the steering brake, a portion of the lubricating oil that has passed through the steering clutch. The flow amount switching valve switches an amount of the lubricating oil supplied to the steering brake.

A transmission includes an input shaft coupled to a prime mover, a countershaft, main shaft, and an output shaft, with gears between the countershaft and the main shaft. A shift actuator selectively couples the input shaft to the main shaft by rotatably coupling gears between the countershaft and the main shaft. The shift actuator is mounted on an exterior wall of a housing including the countershaft and the main shaft. An integrated actuator housing is operationally coupled to the shift actuator and a linear clutch actuator. The linear clutch actuator is a self-adjusting actuator, and the transmission includes a self-adjusting clutch.