The present invention relates to a clutch (100) comprising: a rotatable housing (101); a fixed hub (201) internal to the housing (101) and a movable hub (202) axially mounted onto the fixed hub (201); a plurality of discs (204) interposed between the fixed hub (201) and the movable hub (202). The fixed hub (201) and the movable hub (202) axially slide, getting farther or closer so as to transmit a variable axial load onto the discs (204), to selectively transmit a torque. The clutch (100) further comprises a pressure plate assembly (208) for controlling the variable axial load, including a centrifugal assembly (210) comprising: a rotatable mass holder (211) and a plurality of mass elements (212) radially disposed. Each mass element (212) comprises a pivot (301) and is configured for a displacement (1002) by pivoting under centrifugal effects. The mass elements (212) are thus configured for exerting an axial thrust within the pressure plate assembly (208), to bring the movable hub (202) closer to the fixed hub (201), so as to increase the variable axial load and allowing the clutch (100) (automatic) engagement. Each mass element (212) comprises a main body (302) and a column element (303) which connects the pivot (301) with the main body (302).

A clutch device includes first frictional elements and second frictional elements connectable to the first frictional elements. The clutch device has a hub connected to a first part of the second frictional elements, a movable contact plate connected to a second part of the second frictional elements, a disengaging plate for actuating the contact plate, and a pressure disk. A first bolt extends through the pressure disk and includes a first end attached to the disengaging plate, and a second end attached to the contact plate. A compression spring is positioned between the first end and the pressure disk. A leaf spring is joined to the contact plate and to the hub. A first centrifugal unit is arranged to move the pressure disk in the axial direction against the compression spring to clamp the first and second frictional elements when a first speed of rotation is reached.

A power transmission device has a back torque transmission cam that brings driving clutch plates 6 and driven clutch plates 7 into press contact with each other. A second clutch member 4b is moved when a rotational force is input to a first clutch member 4a via the output shaft 3. The pressure member 5 is located at a non-actuation position. A torque transmission portion transmits a rotational force transmitted to the second clutch member 4b to the first clutch member 4a not via the back torque transmission cam.

A power transmission device has a back torque transmission cam that brings driving clutch plates 6 and driven clutch plates 7 into press contact with each other. This occurs by moving a second clutch member 4b when a rotational force is input to a first clutch member 4a, via the output shaft 3. A pressure member 5 is located at a non-actuation position. A back torque transmission cam can hold abutment between an interlocking member 9 and weight member 8 by moving the second clutch member 4b in a direction of being brought into proximity to the interlocking member 9.

A clutch assembly includes an output shaft extending along an axis and output teeth. A movable component is disposed adjacent to the output component. The movable component includes drive teeth and an annular engagement weight track including a groove circumscribing the axis. The movable component is movable between an engaged position, wherein the drive teeth are drivingly engaged with the output teeth, and a disengaged position, wherein the drive teeth are not engaged with the output teeth. An input component is disposed adjacent to the movable component. The input component includes engagement weight pockets. Spherical engagement weights are disposed in each engagement weight pocket. The groove has a generally uniform radial cross section across its circumference.

A centrifugal clutch for a drive train of a motor vehicle includes an input part, an output part, a friction unit, a counterpressure plate, a shifting device, and a snap ring. The output part is arranged coaxially and rotatably in relation to the input part and includes a leaf-spring core with a fixing element. The friction unit includes first friction elements connected to the input part and second friction elements connected to the leaf-spring core. The second friction units are arranged in alternate layers with the first friction elements in an axial direction. The shifting device is arranged to clamp the first friction elements and the second frictional elements against the counterpressure plate for frictional engagement in response to a centrifugal force. The fixing element extends through the counterpressure plate. The counterpressure plate is fixed to the fixing element by the snap ring.

A centrifugal clutch for a drive train of a motor vehicle includes an input part, an output part, a friction unit, a counterpressure plate, a shifting device, and a snap ring. The output part is arranged coaxially and rotatably in relation to the input part and includes a leaf-spring core with a fixing element. The friction unit includes first friction elements connected to the input part and second friction elements connected to the leaf-spring core. The second friction units are arranged in alternate layers with the first friction elements in an axial direction. The shifting device is arranged to clamp the first friction elements and the second frictional elements against the counterpressure plate for frictional engagement in response to a centrifugal force. The fixing element extends through the counterpressure plate. The counterpressure plate is fixed to the fixing element by the snap ring.

A friction clutch for a drivetrain includes an input shaft, an output shaft, a compressible friction pack including a normally closed spring system, and an actuating device. The compressible friction pack is for transmitting a torque between the input shaft and the output shaft in a closed state of the friction clutch. The actuating device is for producing an axial actuating force to compress the compressible friction pack. The actuating device includes an opening spring for exerting an opening force, a centrifugal mass unit including a ramp, and a switching element including a counterpart ramp. The centrifugal mass unit is movable through a radial travel at a predetermined rotational speed of the input shaft. The ramp and the counterpart ramp form a ramp pairing with a ramp gradient to convert the radial travel into the axial actuating force acting counter to the opening force to compress the compressible friction pack.

During movement of a mass of a centrifugal clutch a radially inner position to a radially outer position and a resulting increase in torque transmitted from an input gear to an output shaft, a power transmission apparatus includes a first torque region where the apparatus restricts operation of a pressing assist cam and a second torque region where the apparatus allows operation of the pressing assist cam.

During movement of a mass of a centrifugal clutch a radially inner position to a radially outer position and a resulting increase in torque transmitted from an input gear to an output shaft, a power transmission apparatus includes a first torque region where the apparatus restricts operation of a pressing assist cam and a second torque region where the apparatus allows operation of the pressing assist cam.