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.

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.

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.

A centrifugal clutch assembly. The clutch assembly has a cover adapted for connecting to a driving member extending along a central axis and a pressure plate coaxially mounted on the cover for axial movement relative to the cover. The assembly includes a friction disc adapted for connection to a driven member coaxially mounted adjacent the pressure plate. The assembly has a lever support mounted on and having a hardness greater than the pressure plate. The clutch assembly includes a lever pivotally mounted on the lever support and reacting against the cover to move the pressure plate into and out of engagement with the friction disc. The lever is shaped to apply more clamping force to the pressure plate as the clutch assembly turns faster about the central axis.

A centrifugal clutch assembly. The clutch assembly has a cover adapted for connecting to a driving member extending along a central axis and a pressure plate coaxially mounted on the cover for axial movement relative to the cover. The assembly includes a friction disc adapted for connection to a driven member coaxially mounted adjacent the pressure plate. The assembly has a lever support mounted on and having a hardness greater than the pressure plate. The clutch assembly includes a lever pivotally mounted on the lever support and reacting against the cover to move the pressure plate into and out of engagement with the friction disc. The lever is shaped to apply more clamping force to the pressure plate as the clutch assembly turns faster about the central axis.

A centrifugal friction clutch is provided which includes a first friction member to be fixed on a rotary shaft; a support portion to be fixed on the rotary shaft; a centrifugal device disposed on the support portion, the centrifugal device including a cam portion and a centrifugal arm extending the cam portion, the cam portion being rotating relative to the support portion when the centrifugal arm moves; and a friction connecting member disposed between the first friction member and the support portion. When the support portion rotates along with the rotary shaft, a free end of the centrifugal arm moves radially outwardly under a centrifugal force and drives the cam portion to rotate, the cam portion urges the friction connecting member toward the first friction member when the cam portion rotates.

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.