US Patent 7021347 Snow chain for vehicle wheels

A snow chain to be mounted on a tire has a connection set having a plurality of planks, each of which has an arch portion and a connection portion. A radial chain set has a plurality of radial chains having ends coupled with the planks respectively. A main chain is coupled with distal ends of the radial chains, wherein the main chain has a hook device to connect opposite ends of the main chain into an annular form. A coupling assembly set has a plurality of coupling devices to tighten two of the planks, each of which has a rotary member and two connection member movably mounted on the rotary member.