Patent ID: 7857541

Claim:
A composite apparatus comprising: a first unit comprising a hook portion comprising: a first hook including a branch extending upward at a longitudinal front end of the first hook and a camming surface, the branch including a front-end side face inclined downward toward the front end of the first hook; a bracket comprising a biasing member attached thereto; a hinge rotatably coupling the first hook to the bracket of the hook portion, the biasing member of the bracket biasing the first hook towards a rear end of the first unit; and a fixed pin abutting the first hook adjacent the camming surface; wherein the pin and the camming surface are configured to move the first hook from an upper position to a lower position when the bracket is moved in a forward direction by an external force against the bias of the biasing member and to move the first hook; from an upper position to a lower position when a forward external force is applied to the bracket and to move from the lower position to the upper position when the external force is removed, wherein a displacement between the upper position and the lower position is greater than a height of the branch; and a second unit connectable to the first unit, the second unit comprising a hook receptacle portion comprising: an abutting member configured to be pushed forward by the front end of the first hook to disconnect the second unit from the first unit when the first hook moves toward the lower position; and a first hook receptacle configured to engage the branch prior to movement of the first hook toward the lower position and to move with the abutting member to disengage from the branch when the first hook moves toward the lower position.