Provided is a socket which includes: an outer socket, an inner socket arranged to face an inner periphery of the outer socket, a coil spring (urging member) configured to urge the inner socket toward one end of the outer socket, and a lock/unlock mechanism configured to restrict the inner socket displaced toward the other end of the outer socket against an urging force of the coil spring from being rotated with respect to the outer socket.

Provided is a socket which includes: an outer socket, an inner socket arranged to face an inner periphery of the outer socket, a coil spring (urging member) configured to urge the inner socket toward one end of the outer socket, and a lock/unlock mechanism configured to restrict the inner socket displaced toward the other end of the outer socket against an urging force of the coil spring from being rotated with respect to the outer socket.

A locking device has a collar body, a roller cage, multiple rollers, and a clamping set. The collar body has a chamber formed inside the collar body and multiple concave recesses formed in an inner periphery of the collar body. The roller cage is mounted in the chamber. The clamping set has multiple clamping blocks annularly disposed within the roller cage. Each one of the multiple clamping blocks is curved and has multiple second concave recesses formed in an outer peripheral surface of the clamping block. The multiple rollers are rotatably mounted to the roller cage and are respectively received by the multiple first concave recesses and the multiple second concave recesses. Each one of the multiple rollers is rotatable along a corresponding one of the multiple first concave recesses and a corresponding one of the multiple second concave recesses.

A locking device has a collar body, a roller cage, multiple rollers, and a clamping set. The collar body has a chamber formed inside the collar body and multiple concave recesses formed in an inner periphery of the collar body. The roller cage is mounted in the chamber. The clamping set has multiple clamping blocks annularly disposed within the roller cage. Each one of the multiple clamping blocks is curved and has multiple second concave recesses formed in an outer peripheral surface of the clamping block. The multiple rollers are rotatably mounted to the roller cage and are respectively received by the multiple first concave recesses and the multiple second concave recesses. Each one of the multiple rollers is rotatable along a corresponding one of the multiple first concave recesses and a corresponding one of the multiple second concave recesses.