Abstract: A pair of pawl assemblies is mounted on a shaft. Each pawl assembly includes a pawl, an arm and a hub. The arm is attached to the hub by a pivot, and a spring biases the arm toward the hub. The pawl attaches to the end of the arm, and the surface of the pawl has several teeth pointed in the direction of rotation. A brake drum made of two halves is bolted together around the shaft and pawl assemblies. The inner surface of the drum has teeth designed to mesh with the teeth on the pawls. A brake lining band fits around the brake drum in a groove formed along the circumference of the brake drum. The brake lining band attaches to adjustable mounting hardware, which is secured to a fixed surface. When the rotational speed of the shaft exceeds a safe level, the teeth on the pawls engage the teeth in the brake drum, causing the drum to turn against the brake lining band. The friction of turning the drum slows the shaft to a full stop.