US Patent 7712298 Chain plate structure

A chain plate structure includes a first outer link plate and a second outer link plate, and each of which includes a first/second through hole, a first/second connection hole, a first/second trough and a first/second engaging trough at two sides of the first/second connection hole. A first/second rib extends from an inner periphery of the first/second engaging trough and at least one first/second protrusion extends from the first/second rib. When the first and second outer link plates are connected to each other, the gap between two adjacent inner link plates of a chain is less than 2.3 mm.