A centrifugal brake system for retarding shaft backspin includes a brake drum, a brake hub attachable to the shaft and two or more brake shoes mounted on the hub for braking engagement with the drum. A mechanical linkage transfers the generated braking force from the brake shoes to the hub and permits radial displacement of the brake shoes relative to the hub, upon rotational shifting of the hub relative to the brake shoes between deactivated and activated positions. In the deactivated position of the hub, the brake shoes are maintained in a radially inward, disengaged position. In the activated position, the brake shoes are radially displaceable by centrifugal force from the disengaged position to a radially outward, engaged position, wherein the brake shoes are in braking engagement. The rotational shifting of the hub is achieved through frictional drag between the brake shoes and the brake drum.