US Patent 7174756 Padlock

A padlock comprises: a casing; a shackle having a free first end and a second end, the second end being pivotally connected to the casing; a locking mechanism received within the casing and limiting the axial movement of the second end of the shackle; a latching tube received and operative to be moved within the casing; and a stop member driven by the latching tube so as to be moved between a first position where the first end of the shackle can be rotated by using the second end thereof as a center of rotation, and a second position where the stop member prevents the first end of the shackle from moving, and the shackle and the casing co-define a closed loop.