Abstract: Described herein is a hydraulic servo suitable for friction coupling elements in automatic transmissions. The hydraulic servo of the invention is compact in construction and easy to assemble, including an annular drum rotatably or fixedly mounted in an automatic transmission case, a piston provided in a predetermined position of the drum, a return spring provided on the piston, and a connecting member for connecting the return spring and the piston, characterized in that the piston is provided with a guide sleeve at the tip end of one end face thereof for guiding one end of said connecting member.

Abstract: Described herein is a hydraulic servo suitable for friction coupling elements in automatic transmissions. The hydraulic servo of the invention is compact in construction and reduced particularly in axial dimensions, and essentially comprises: an annular drum rotatably or fixedly mounted in a transmission case and having a press-formed annular plate member with an first cylinder portion and a second cylinder member joined to the first cylinder portion by fully encircling welding; a piston fitted between the first cylinder portion and the second cylinder member; and a reaction area formed by extending the annular plate member of the drum radially inward to support return springs.

Abstract: The transmission of the invention is capable of attaining a plurality of shift ranges by locking and releasing one or more elements of a gear mechanism to a casing of the transmission or by connecting and releasing the elements with the input shaft, the output shaft or into and out of engagement with each other. The control system for controlling the action of the elements of the gear set is a hydraulic control system having friction elements which achieve a higher speed range and a lower speed range of the transmission upon actuation by servo valves. An additional servo valve is included to work in opposition to one of the other servo valves and communicates with another of the servo valves. A communication control valve is disposed in a hydraulic line which communicates with another of the servo valves and with the servo valve acting in opposition so as to control the communication between these valves in response to a signal pressure developed by a signal pressure valve.

Abstract: A control apparatus in an automatic transmission includes first and second shift valves which are independently actuable to define four distinct states corresponding to four speed ranges of the transmission. In the first state, neither valve participates in achieving the first range. In the second state, only the first valve participates in achieving the second range. In the third state, only the second valve participates in achieving the third range. In the fourth state, both valves participate in locking a lock-up clutch by being fluidly interconnected by an interconnecting passage so as to define a signal pressure passage which conducts a signal pressure to a lock-up relay valve to implement a locking of the lock-up clutch.

Abstract: A control system for an automatic transmission equipped with a plurality of friction engaging devices for attaining a plurality of shift ranges by locking the elements of a gear mechanism, which is disposed between an input shaft and an output shaft, to a case, by bringing the elements into and out of engagement with the input shaft or output shaft, or into and out of engagement with each other, said friction engaging devices including a first friction engaging device (C2) which takes part in achieving a reverse shift, and a second friction engaging device (B2) which participates in achieving parking and reverse the control system includes an electronic control circuit means which controls the timing of the actuation of the first and second friction engaging devices upon shifting from parking to reverse range so as to mitigating shock upon gear shifting.

Abstract: In a hydraulic control system for an automatic transmission for vehicles having a pump being driven by the engine of the vehicle for generating a pressure of pressurized fluid in the hydraulic control system, and a pressure regulator valve for regulating the pressure of pressurized fluid supplied from the pump in keeping with an input signal pressure varying in accordance with the cruising condition of the vehicle, a pressure relief valve is provided in the input fluid passage of the regulator valve for relieving the pressure when the input signal pressure exceeds a predetermined level.

Abstract: A hydraulic governor pressure generator including a governor body fixedly mounted on a rotational shaft, a governor valve movably mounted in a cavity of the governor body in the radial direction with respect to the rotational shaft according to centrifugal force acting thereon, an input oil passage and an output oil passage provided in the governor body communicating with each other through a clearance between the inner peripheral wall surface of the governor body and the outer peripheral wall surface of the governor valve and at least one pocket provided in each one of the input and output oil passage and recessed in a direction away from the rotational center of the rotational shaft to collect therein particles of swarf of foreign material in the working oil in the input and output passages.

Abstract: The shift valve operates in response to a governor pressure counteracting a throttle pressure and in response to a detent pressure used in a kickdown operation. The valve is capable of shifting up from a first speed range to a second speed range as well as shifting down from second speed to the first speed under control of the shift valve. The 1-2 shift valve comprises a spool having a pressure bearing surface adapted to receive either the throttle pressure or the detent pressure. In the first speed position, the spool closes off the detent line pressure and receives the throttle pressure on the pressure bearing surface. On the other hand, at the second speed position, the spool closes off the throttle pressure line and receives the detent pressure on the pressure bearing surface.