Interlocking chain

An interlocking chain comprising at least a pair of reciprocally movable inner and outer chain members that engage with each other to unite when moving forward, and disengage from each other to separate when moving backward,

• the inner chain member and the outer chain member each being made up of a plurality of first link plates, each having a pair of first pin holes arranged along a reciprocating direction, and a plurality of second link plates, each having a pair of second pin holes arranged along the reciprocating direction, the first link plates and the second link plates being serially arranged and pivotably connected together by connecting pins passed through the first pin holes and the second pin holes, with the first pin hole on one side in each of the first link plates overlapping the second pin hole on another side in each of the second link plates that are adjacent in the reciprocating direction,
• the connecting pins of the inner chain member being spaced apart along the reciprocating direction by a first distance, the connecting pins of the outer chain member being spaced apart along the reciprocating direction by a second distance, the first distance being smaller than the second distance,
• at least one of the inner chain member and the outer chain member including specific link plate pairs of the first link plates and the second link plates adjoining each other in the reciprocating direction, whose combined plate thickness, measured in a chain width direction, is smaller in an interlocking portion where the inner chain member and the outer chain member engage than a combined plate thickness measured in the chain width direction in a connecting portion where the link plates are connected together by the connecting pins.