Expanding duck clutch of portable computer

A checking device of extension port on portable computer is prepared as setting rotary shaft unit at one side of hook unit, forming a spring by an elastic winding and a force exerting arm, setting elastic winding on rotary shaft of check hook to let rotary shaft be able to pivot-rotate in elastic winding, connecting force exerting arm of spring against with hook unit of check hook and setting hook-on surface and hook-release surface separately to be the first angle and the second angle at vertical direction of coordination surface between extension port and portable computer.