Abstract: A frictional engagement device for an automatic transmission, by which an input shaft and an output shaft are engaged or disengaged by use of oil pressure. A casing connected to an input shaft and a first piston disposed in the casing define a first oil pressure chamber. The first piston is rotationally movable by predetermined angle and is axially movable by predetermined distance relative to the casing. A second piston disposed in the first piston defines a second oil pressure chamber with the first piston, and the second piston is axially movable relative to the first piston. Separator plates axially slidably connected to the first piston and clutch discs axially slidably connected to a hub which is fixedly connected to the output shaft are engaged by a displacement of the second piston by supplying pressurized oil to the second oil pressure chamber and/or to the first oil pressure chamber.

Abstract: A wet type clutch which has its piston moved by the difference of the pressure in two oil chambers at the two sides of the piston while shutting the communication between the two oil chambers with a friction member adhered to either of the piston or a front cover to be engaged by the piston. An annular groove for communicating with such one of the two oil chambers as will take a lower pressure when the clutch is applied is formed in the surface, to which the friction member is adhered, and/or the adhered surface of the friction member itself, to reduce the pressure acting to return the piston. A seal or high porosity material may also be used to reduce the oil pressure acting on the piston.

Abstract: A fluid coupling power transmission having a lockup clutch, in which a housing is formed by the shell of a pump impeller and a front cover integrally connected to the shell, in which a turbine runner facing the pump impeller is arranged in the housing, and in which the lockup clutch is disposed in the housing for transmitting a torque selectively between the housing and an output member integrated with the turbine runner.

Abstract: A fluid coupling power transmission is constructed such that a pump impel let and a turbine runner are arranged to face each other in a housing, to which torque is inputted, and such that a lockup clutch is disposed in the housing for transmitting the torque from the housing to the turbine runner.

Abstract: A torque converter wherein a fluid flow established by a pump impeller is fed to rotate a turbine runner, wherein a lock-up clutch to be engaged with and released from a first member integrated with the pump impeller is connected to an annular drive member, and wherein an annular driven member arranged to face the drive member and made rotatable relative to the drive member is connected to a second member integrated with the turbine runner, whereby torque is transmitted between the drive member and the driven member.

Abstract: A control system for use in an automatic transmission which is connected to an engine comprises: a fluid coupling for transmitting a torque between an input member and an output member; a lock-up clutch adapted to be selectively engaged with and released from the input member; and a variable capacity type viscous coupling arranged in series between the lock-up clutch and the output member.

Abstract: A fluid power transmission which comprises: a pump impeller; a turbine runner; a housing accommodating the pump impeller and the turbine runner; a lock-up clutch adapted to be engaged with and released from a front cover integrated with the pump impeller; and a viscous coupling including an annular drive member and an annular driven member for transmitting torque inbetween through viscous fluid. The drive member is connected to the lock-up clutch, whereas the driven member is connected to a hub which is integrated with the turbine runner. Further comprised is a second clutch which is engaged, after the lock-up clutch has been engaged, to connect the drive member and the driven member mechanically.

Abstract: A viscous clutch assembly includes a viscous coupling arranged for generating a viscous resistance force in response to relative rotation between a pair of coaxially arranged rotary members, a cam mechanism cooperable with the viscous coupling for converting the viscous resistance force into a thrust force, a friction clutch mechanism cooperable with the cam mechanism to be brought into engagement when applied with the thrust force from the cam mechanism for establishing the drive connection between the rotary members. One of the rotary member is in the form of a cylindrical outer casing and the other rotary member is in the form of an internal rotary member coaxially surrounded by the outer casing.

Abstract: A viscous clutch assembly adapted for installation in a torque transmission system for effecting a drive connection between a pair of rotary members coaxially arranged for relative rotation. The viscous clutch assembly includes a viscous coupling arranged for generating a viscous resistance force in response to relative rotation between the rotary members, a first cam mechanism cooperable with the viscous coupling for converting the viscous resistance force into a thrust force, a friction disc clutch arranged to be brought into engagement when applied the thrust force from the first cam mechanism for establishing the drive connection between the rotary members, and a second cam mechanism cooperable with the viscous coupling for increasing and decreasing the viscous resistance force in response to a difference in torque between the rotary members.

Abstract: A drive mechanism of the limited slip type having driving and driven members to be drivingly connected, wherein a friction clutch is operatively associated with the driving and driven members to drivingly connect the members in its engaged condition, and a fluid pump is arranged between the driving and driven members to be driven by relative rotation therebetween and located adjacent one side of the clutch, the fluid pump being movable in a direction to effect engagement of the clutch when applied at one side thereof with a discharge pressure thereof, and wherein a communication passage for fluid circulation is connected at one end thereof to a discharge port of the pump and at the other end thereof to a suction port of the pump, and a flow control valve is disposed in the communication passage to control an amount of fluid under pressure passing through the communication passage.

Abstract: A hydraulically operated friction clutch, having a driving and a driven rotary member frictionally engageable with each other, a movable member axially movable for frictional engagement of the driving and driven rotary members, and an actuator piston axially slidable by a pressure in a pressure chamber, for moving the movable member. The actuator piston has a control passage which communicates with the pressure chamber and a discharge passage. The clutch further has a shut-off valve disposed in operative association with the actuator piston and the movable member. The shut-off valve includes a closure member which is movable relative to the actuator piston and which has a first position for closing the control passage, and a second position for opening the control passage. The closure member is placed in the second position when the actuator piston has been moved to a predetermined ready-to-operate position which is a predetermined first distance away from the movable member.

Abstract: A control device for a hyudraulic friction clutch for a motor vehicle, wherein a piston is moved by a pressurized fluid supplied to a pressure chamber, to effect frictional engagement between driving and driven rotary members, and a proximity shut-off valve is disposed in the piston, for permitting the fluid to be discharged from the pressure chamber through a discharge passage when the piston has reached a ready-to-operate position from which the piston is moved to start the frictional engagement.

Abstract: An electromagnetic powder clutch of double-gap type comprising a first rotary member, a second rotary member and a labyrinth device. The first rotary member has a first friction surface, and a second friction surface which is disposed radially inwardly of and opposite to the first friction surface. The second rotary member of an annular shape incorporates therein an annular solenoid coil and has a wall thickness sufficient to accommodate the solenoid coil. The second rotary member is disposed between the first and second friction surfaces of the first rotary member, and has a radially outer friction surface opposite to the first friction surface and a radially inner friction surface opposite to the second friction surface.