Abstract

A centrifugal clutch having an interlocking combination of shoes and stop pins includes compression biasing springs that are adjustable with tamper-free locking, using reversible spring biased wedges that smoothly transition between selected low-gain and high gain engagements within a desired narrow speed range. The clutch also includes a hub, a rotatable drum having a circularly cylindrical inside surface, and a plurality of shoes, each shoe including a rigid metallic shoe member and a lining. A stop pin is interposed between lock portions of each adjacent pair of the shoes for blocking the shoe members from moving radially outwardly into contact with the inside surface of the drum and for preventing separation of the shoes in the event of axial disengagement or structural failure of the drum during high-speed operation of the clutch. The compression biasing springs include a plurality of stacked spring washers assembled on the stop pins with respective adjustment nuts. A wedge member having oppositely inclined wedge surfaces slides in a slot of each shoe, for torque transmission in opposite rotational directions. The wedge surfaces can be asymmetrical for facilitating adjustment of a torque-speed characteristic of the clutch.