Padlock

#1. Field of the Invention

#The present invention relates to a padlock and, more particularly, to a padlock in which the correct key is not allowed to be pulled out after the padlock is opened, so as to prevent the door of a building, especially of a warehouse, from being locked up while the key is left in the building.

#2. Description of Related Art

#FIG. 1 is an exploded perspective view of a first preferred embodiment of a padlock in accordance with the present invention;

#FIG. 2 is a transverse cross-sectional view showing the padlock of FIG. 1 in its closed position;

#FIG. 3 is a cross-sectional view taken along lines 3-3 in FIG. 2;

#FIG. 1 shows a first embodiment of a padlock in accordance with the present invention for locking the door of a building, especially a warehouse. The padlock includes a casing 1, a cylindrical tumbler 2 and a cylinder assembly 3.

#The casing 1 has an opening 11 defined therein for receiving both the cylindrical tumbler 2 and the cylinder assembly 3, with the assembly 3 retained in the opening 11 by means of a fastening 12, such as in the form of a screw. The casing 1 is further formed with a movable shackle 13 that defines a pair of curved notches 14 for partially receiving a pair of opposed balls 15, which is movable laterally in the opening The cylindrical tumbler 2, rotatably received in the opening 11 of the casing 1, has a periphery that defines a pair of curved grooves 21 (only one is shown) to receive the balls 15. The tumbler 2 is further formed with a neck 22 terminating in a butt 23, with a torsion spring 24 and a retainer ring 25 mounted around the neck 22. The torsion spring 24 is provided for urging the tumbler 2 to turn back to its original angular position within the opening 11, and the butt 23 is contoured as a sector less than half a round, preferably as a sector about a quart of a round which has an arched edge projecting from the periphery of the neck 22.

#Furthermore, the cylindrical tumbler 2 is provided with a detent 26 extending outward axially from a bottom end of the tumbler 2, for the purpose which is to be described hereinafter. In the illustrated embodiment, the detent 26 is configured as a pin partially fitted in a hole 27 defined in the bottom end of the tumbler 2.