Numerical combination replacement plug for cylinder locks

Claim 1

As a new article of manufacture, a plug for a cylinder type lock comprising: a hollow housing element including a planar front wall, a cylindrical side wall and a generally planar rear wall, said walls defining a cavity having a principal cylinder axis; a dial element including a first axially positioned shaft supported by said housing element for selective rotational and axial movement relative thereto, said shaft extending through an opening in said front wall at a front end thereof; a dial knob supported upon said front end of said first shaft, and a first medially positioned spur gear on said first shaft; a tumbler element carried by said housing element, and driven by said first shaft, said tumbler element including a plurality of planar circular tumbler members, each having an opening therein selectively alignable with corresponding openings in the other tumbler members and having pin means interconnecting the same for limited rotational relative movement; a bar member carried by said first shaft for axial movement thereon and freely rotatable relative thereto, said bar member being selectively positionable within aligned openings in said tumbler members, said bar member normally preventing outward axial movement of said shaft; a second motion output shaft element carried by said housing element, and having a second spur gear thereon selectively engagable with said first spur gear; whereby upon the dialing of a correct combination resulting in the alignment of said openings in said combination tumblers, said first shaft may be moved axially outwardly of said housing element to position said bar member within said openings, and engage said first and second spur gears for the transmission of rotary motion from said knob to said second shaft.