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.

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 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).

An improved expanding friction disk for use in a clutch of a power transmission system. The improved expanding friction disk accommodates multiple clutch pack configurations including clutch packs utilizing novel improved friction disks, is compatible with wear liners and operates with reduced friction including a reduced difference between the static and dynamic coefficients of friction in the ramp mechanism.

An improved expanding friction disk for use in a clutch of a power transmission system. The improved expanding friction disk accommodates multiple clutch pack configurations including clutch packs utilizing novel improved friction disks, is compatible with wear liners and operates with reduced friction including a reduced difference between the static and dynamic coefficients of friction in the ramp mechanism.

A clutch apparatus is disclosed having concentrically spaced inner and outer clutches. The inner and outer clutches are coupled for rotation via a coupling ring. The present invention is well suited to a configuration wherein one of the clutches is dynamically actuated and one of the clutches is manually disengageable by the operator using a clutch lever. In this configuration, the operation of the clutch lever by the operator is unaffected by the dynamically actuated clutch. The concentric configuration of the clutches is beneficial in allowing the improved clutch to occupy a similar space compared to a traditional clutch mechanism.

A clutch apparatus is disclosed having concentrically spaced inner and outer clutches. The inner and outer clutches are coupled for rotation via a coupling ring. The present invention is well suited to a configuration wherein one of the clutches is dynamically actuated and one of the clutches is manually disengageable by the operator using a clutch lever. In this configuration, the operation of the clutch lever by the operator is unaffected by the dynamically actuated clutch. The concentric configuration of the clutches is beneficial in allowing the improved clutch to occupy a similar space compared to a traditional clutch mechanism.

A clutch (100) having: a fixed hub (201), a movable hub (202), a plurality of discs (204). 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). The clutch (100) has a pressure plate assembly (208) including a centrifugal assembly (210), having: a rotatable mass holder (211) and a plurality of mass elements (212) radially disposed. Each mass element (212) has a pivot (301) and is configured for a displacement (1002) by pivoting under centrifugal effects. The mass elements (212) are configured for bringing 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) has a main body (302) and a column element (303) which connects the pivot (301) with the main body (302).

A clutch (100) having: a fixed hub (201), a movable hub (202), a plurality of discs (204). 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). The clutch (100) has a pressure plate assembly (208) including a centrifugal assembly (210), having: a rotatable mass holder (211) and a plurality of mass elements (212) radially disposed. Each mass element (212) has a pivot (301) and is configured for a displacement (1002) by pivoting under centrifugal effects. The mass elements (212) are configured for bringing 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) has a main body (302) and a column element (303) which connects the pivot (301) with the main body (302).

A clutch (3) includes: a clutch housing (32) which is provided with a drive plate (33) to be movable in an axial direction; a clutch hub (34) which transmits a rotary motive power to an output shaft; a clutch sleeve (35) which is provided with a driven plate (36) to be movable in the axial direction; and a pressure disk (40) which biases the drive plate (33) and the driven plate (36) toward the clutch hub (34), further includes a back torque limiter (7) which moves the pressure disk (40) in a direction away from the clutch hub (34) when back torque is applied, and the clutch hub (34) is provided with a restricting apparatus which restricts movement of the pressure disk (40) in the direction away from the clutch hub (34) when a number of rotations of the output shaft is less than a predetermined value.