A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying and discharging hydraulic pressure to and from the chambers, and first and second oil paths communicating the valve with the chambers. The second surface has a larger area for receiving hydraulic pressure than that of the first surface. The method includes controlling the friction plates to change from the disengaged state to the engaged state. Controlling the friction plates includes adjusting the hydraulic pressure to a first instruction pressure in a first period in response to a gear shift command, and to a second instruction pressure in a second period.

A vehicle includes a transmission having a fluid pump, a high pressure fluid circuit, a low pressure fluid circuit, and an accumulator. The vehicle also includes a controller that is programmed to, in response fluid demand exceeding a capacity of the pump, isolate the low pressure circuit from the pump. The controller is also programmed to, in response to vehicle speed exceeding a threshold while the low the pressure circuit is isolated from the pump, discharge the accumulator into the high pressure circuit.

In a sleeve, two input ports are formed as ports that receive a discharge pressure of an electromagnetic pump, and a drain port connected to a drain oil passage is formed on the same circumference as that on which the input port is formed, so as to have a smaller opening area than the input port and an output port connected to an oil passage. The axial length of the second land is set so that the input port can be closed by the second land when a signal pressure is equal to or higher than a set pressure, and that the input port and the drain port can be closed by the second land when the signal pressure is lower than the set pressure.

A dual clutch-type transmission control device is provided which improves the accuracy with which transmission torque is learned. A dual-clutch transmission includes a clutch apparatus having a first clutch and a second clutch, a first input shaft, a second input shaft, a counter shaft, an output shaft, an auxiliary transmission portion including a first input gear pair and a second input gear pair, a main transmission portion including an output gear pair, and learning modules and the learning modules shift the main transmission portion into a neutral state, disengage both the first and second clutched generate a torque change in an engine by keeping the engine running at a predetermined revolution number, engaging partially one of the first and second clutches and thereafter engaging the other clutch gradually partially and learn an amount of change of torque associated with the torque change as transmission torque of the other clutch.

An assembly for actuating a double-acting shift cylinder of a shift assembly of an automatic transmission of a motor vehicle includes a hydraulic fluid reservoir having a motor-driven hydraulic pump and two control valves that are each connected to a pressure supply line of the hydraulic pump and to a return line to the hydraulic fluid reservoir. The shift cylinder has two pressure chambers that are each connected to one of the control valves. The control valves each connect one pressure chamber of the shift cylinder to the pressure supply line of the hydraulic pump or to the return line to the hydraulic fluid reservoir. The actuating assembly includes at least one pressure-limiting valve that connects the pressure supply line to the return line if a hydraulic over-pressure is present. The control valves can be 3/2-directional valves having integrated pressure-limiting valves.

A method of controlling an automatic transmission is provided. The automatic transmission includes a piston having first and second surfaces opposite from each other, friction plates, engaging and disengaging hydraulic pressure chambers for supplying and discharging hydraulic pressure and directing the piston to push the friction plates to be engaged and disengaged, a hydraulic pressure control valve for supplying and discharging hydraulic pressure to and from the chambers, first and second oil paths communicating the valve with the chambers, and a pressure reducing valve disposed in the second oil path and for preventing hydraulic pressure of the disengaging hydraulic pressure chamber from exceeding a given set pressure. The second surface has a larger area for receiving hydraulic pressure than an area of the first surface for receiving hydraulic pressure. The method includes changing the given set pressure according to information regarding a state of the automatic transmission.

A hydraulic arrangement for a vehicle transmission includes a hydraulic system path leading to a hydraulic system circuit with a system pressure, a hydraulic lubrication path leading to a hydraulic lubrication circuit with a lubrication pressure, and a branching point connected to an output side of the system and lubrication paths. A variable displacement pump or a pump combination includes at least two fixed displacement pumps hydraulically connected to an input side of the branching point, and a variable displacement pump or at least one fixed displacement pump are hydraulically connected to the output side of the branching point and integrated into the hydraulic system path.

A fast valve actuation system for an automatic vehicle transmission includes a pair of spring-biased shift valves. Solenoids control the application of pressurized hydraulic fluid to the head of each of the shift valves. Each shift valve has at least one port that is coupled to a fluid chamber of a torque transferring mechanism of an automatic transmission. The position of each of the shift valves determines whether its ports are connected with fluid pressure. Fluid passages connect the head of each shift valve to the spring pocket of the other shift valve.

An enhanced control system for an electronic automatic transmission enables the transmission to operate in a full neutral idle, a reverse lock-out, and an inching mode. These functions improve the mileage and durability of the operation of the transmission. They also enable the inching mode for use especially in industrial applications.

A working machine includes a prime mover, a traveling device, a traveling motor configured to output power to the traveling device, a speed shifting valve configured to shift an output speed of the traveling motor between a first speed and a second speed faster than the first speed, an actuation valve configured to change a hydraulic pressure applied to the speed shifting valve, a first fluid passage fluidly connected to the speed shifting valve so that hydraulic fluid having the hydraulic pressure to be applied to the speed shifting valve flows through the first fluid passage, a drain fluid passage fluidly connected to the first fluid passage, a brake shiftable between a braking state to brake the traveling motor and a braking releasing state to release the braking, and a controller configured or programmed to control the actuation valve and the brake, and being capable of activate a warm-up mode. The controller, when activating the warm-up mode, is configured or programmed to shift the brake into the braking state, and control the actuation valve so as to make the hydraulic pressure to be applied to the speed shifting valve equal to or greater than a value corresponding to the second speed.