A power transmission device has a pressure member 5, drive-side clutch plates, driven-side clutch plates, a clutch spring 10, a separate receiving member 11, and a back-torque limiting cam. A radially-outside restricting portion restricts radially-outward movement of the receiving member 11 relative to the pressure member 5. This maintains clearance t between a side surface 11d of the receiving member 11 and an inner peripheral wall 4e of a clutch member 4.

A power transmission apparatus includes a clutch connected to an output shaft to rotate a wheel of a vehicle, and a clutch pressure plate movable between an operating position where driving and driven clutch plates are pressed against each other so as to enable transmission of a driving force of an engine to the wheel and a non-operating position where a pressing force exerted on the driving and driven clutch plates is released so as to cut off transmission of the driving force of the engine to the wheel. One of the driven clutch plates is attached to a second clutch, and another is attached to the clutch pressure plate. The clutch pressure plate includes an oil flow passage through which oil flows to the driven clutch plate attached to the clutch pressure plate.

A power transmission device has an interlocking member 9 moving a pressure member 5 from an inactive position to an active position. A release spring (m) applies an urging force, while allowing movements of the interlocking member 9 and the pressure member 5, until drive-side clutch plates 6 and driven-side clutch plates 7 reach an engaged state before the drive-side clutch plates 6 and the driven-side clutch plates 7 are pressed against each other. A clutch spring 11 is compressed in a process where the interlocking member 9 moves after the drive-side clutch plates 6 and the driven-side clutch plates 7 have reached the engaged state. The clutch spring applying a press-contact force between the drive-side clutch plates 6 and the driven-side clutch plates 7 while allowing movements of the interlocking member 9 and the pressure member 5. The set load of the clutch spring 11 is set to be smaller than the maximum load of the release spring (m).

Provided is a clutch device configured so that close contactability between a cam surface of a center clutch and a cam surface of a pressure clutch can be improved and torque transmission can be stabilized accordingly. The clutch device (100) includes a center clutch (105) and a pressure clutch (112). The center clutch (105) includes center-side cam portions (107), a pressure clutch slide portion (106), and a lifter plate slide portion (110). The pressure clutch (112) includes pressure-side cam portions (114), a lifter plate (116), and a second center clutch slide portion (113). The lifter plate (116) includes first center clutch slide portions (120). A clearance (C2) between the second center clutch slide portion (113) and the pressure clutch slide portion (106) is set greater than a clearance (C1) between the first center clutch slide portion (120) and the lifter plate slide portion (110).

A power transmission device has a clutch member, a pressure member 5, a weight member 8, an interlocking member 9 and a bearing holding member C coupled to an activation member 10. The bearing holder member C holds a bearing B1 interposed between the activation member 10 and the pressure member 5. The bearing holding member C has a cylindrical member with one open end. An open end portion Ca is fit into and attached to a recessed portion 4d formed in a first clutch member 4a.

A power transmission device has an interlocking member 9 moving a pressure member 5 from an inactive position to an active position. A release spring (m) applies an urging force, while allowing movements of the interlocking member 9 and the pressure member 5, until drive-side clutch plates 6 and driven-side clutch plates 7 reach an engaged state before the drive-side clutch plates 6 and the driven-side clutch plates 7 are pressed against each other. A clutch spring 11 is compressed in a process where the interlocking member 9 moves after the drive-side clutch plates 6 and the driven-side clutch plates 7 have reached the engaged state. The clutch spring applying a press-contact force between the drive-side clutch plates 6 and the driven-side clutch plates 7 while allowing movements of the interlocking member 9 and the pressure member 5. The set load of the clutch spring 11 is set to be smaller than the maximum load of the release spring (m).

A clutch apparatus is provided which includes a center clutch and a pressure clutch that can hold a clutch plate without falling off of the clutch plate and also prevent a reduction in strength. A clutch apparatus 100 includes a center clutch 105 and a pressure clutch 112, which hold clutch plates 104 placed facing friction plates 103 that are rotationally driven by a driving shaft. The center clutch 105 includes a center-side mating portion 108 mating with internal teeth of the clutch plate 104. In addition, the center-side mating portion 108 includes a protruding tooth 110. The pressure clutch 112 includes a pressure-side mating portion 116 mating with internal teeth of the clutch plate 104. In addition, the pressure-side mating portion 116 includes a run-off 117. The protruding tooth 110 extends over the run-off 117 of the pressure-side mating portion 116, as one of spline teeth forming the center-side mating portion 108.

Provided is a clutch device configured so that different desired torque values can be set without influence between assist torque and slipper torque. A clutch device 100 includes a center clutch 105 holding clutch plates 104 arranged facing friction plates 103 to be rotatably driven by a drive shaft, and a pressure clutch 111. The center clutch 105 includes center-side assist cam surfaces 106a and center-side slipper cam surfaces 106b. The pressure clutch 111 includes pressure-side assist cam surfaces 112a and pressure-side slipper cam surfaces 112b. A contact surface between the center-side assist cam surface 106a and the pressure-side assist cam surface 112a and a contact surface between the center-side slipper cam surface 106b and the pressure-side slipper cam surface 112b are formed at different positions in a radial direction.

A clutch device includes a clutch center holding output-side rotating plates alternately arranged with input-side rotating plates, and a pressure plate movable toward or away from the clutch center. The pressure plate includes pressure-side fitting teeth holding the output-side rotating plates. The clutch center includes center-side fitting teeth holding the output-side rotating plates. In a half-clutch state, a portion of one of the center-side fitting teeth overlap with a portion of one of the pressure-side fitting teeth when seen in the radial directions of an output shaft.

A hub unit for a clutch of a vehicle with a handlebar has both a servo function when closing and a slipper function via the sliding motion of at least one pin along respective inclined and facing tracks. The hub unit includes a hub connected to an output shaft of a vehicle engine and having an axis of rotation, a plurality of guides rigidly connected to the hub, an axial stop rigidly connected to the hub, a disc pressure flange movable in a direction parallel to the guides, and at least one spring. The hub defines at least a first track and a second track facing in an axial direction and arranged in a direction not parallel to the axis of rotation. The disc pressure flange includes at least one pin projecting in a substantially radial direction and arranged in contact with the first track and the second track.