A locking cam stop conducts rotation from a driving part, such as a tire ring, to a driven part, such as a rotary dryer or kiln. The device utilizes clamping cams with logarithmic profiles to secure the tire ring without welding or direct attachment, only frictional force. The cams provide immediate, powerful holding force in the desired direction, while allowing free counter-rotation when necessary. The device utilizes a tension link to maintain sufficient contact with the tire ring, ensuring that the cams will engage and hold the tire ring when necessary.