Motorcycle safety hub

In a motorcycle safety mechanism for automatically changing from a primary operative mode to a secondary failure mode upon any malfunction leading to a stoppage in the drive train, the combination of:

• a rotatable driven plate mounted integrally with the rear wheel brake drum hub assembly of the motorcycle,
• a friction disc supported by the driven plate,
• a plurality of spring-loaded driving dogs each pivotally mounted on a boss of the rear wheel axle of the motorcycle,
• a rotatable driving plate mounting the rear wheel driving sprocket and mounted rotatably relative to the driven plate,
• an annular clutch plate mounted on the driving plate and having a plurality of circularly-arranged equispaced ramps inwardly inclined in the direction of normal rotation and each terminating in a dog receiving stop,
• adapted and arranged while the mechanism is in primary operative mode for the preclusion of relative rotation of the driven and driving plates with the dogs each in confrontation with a respective stop and while in a state of seizure in a secondary failure mode for the dogs to be withdrawn from the respective stops under the influence of the reversed input torque and led across the stops allowing free wheeling between the plates.