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 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.

A centrifugal clutch mechanism of a clutch device includes a holder to hold weights movable between radially inward positions and radially outward positions, springs to urge the weights in a radially inward direction, a pressure-contact structure movable in an axial direction of an output shaft by movement of the weights from the radially inward positions to the radially output positions to put input-side rotating plates and output-side rotating plates into pressure contact with each other, and urging structures between the holder and the pressure-contact structure in the axial direction of the output shaft, the urging structures urging the weights held by the holder in the axial direction of the output shaft and permitting the weights to move in a radial direction.

A centrifugal clutch mechanism of a clutch device includes a holder to hold weights movable between radially inward positions and radially outward positions, springs to urge the weights in a radially inward direction, a pressure-contact structure movable in an axial direction of an output shaft by movement of the weights from the radially inward positions to the radially output positions to put input-side rotating plates and output-side rotating plates into pressure contact with each other, and urging structures between the holder and the pressure-contact structure in the axial direction of the output shaft, the urging structures urging the weights held by the holder in the axial direction of the output shaft and permitting the weights to move in a radial direction.