Pin tumbler locks have been known for many years, and are one of the most common types of locks employed.
Referring now to FIG. 1A, there is shown a fully assembled pin tumbler lock, referenced 10, as known in the art. Lock 10 includes a shell 11 having formed therein central cylindrical opening 12, also referred to herein merely as the “cylinder,” in which is located a plug 13. Shell 11 further has formed therein a set of chambers 14, each of which is a radially extending bore adapted to receive therein a pin stack which includes first, second and third pin stack elements, respectively referenced 16, 17 and. 19. First pin stack element 16 is a compression spring, second pin stack element 17 is a driver pin, and third pin stack element 19 is a key pin.
As seen, the key pin 19 is outermost, and is supported on the driver pin 17, which is seated in turn on the compression spring 16, which assists in forcing the key pin 19 across a shear line (not shown) and into the keyway formed in the plug 13, so as to block rotation thereof within the cylinder 12. In this position, the lock cannot be opened without a key. As known, the driver pins are of uniform length, while the key pins are of different lengths.
Throughout the present specification and claims, unless specified otherwise, the term “pin stack element” is employed to mean any of the pin stack elements.
When a pin tumbler lock malfunctions, the plug and pin stacks must be removed so that all faulty elements of the pin stacks can be replaced. The position of the chambers relative to the opening of the shell requires special tools in order to be able to properly position the renewed pin stacks within their chambers, due partially to the fact that the chambers are radial to the cylindrical opening within the shell, and must be fully inserted—including the springs which tend to force the pins across the shear line—in order to facilitate insertion of the plug.
A further requirement with regard to the maintenance of pin tumbler locks concerns the need to ‘recode’ the locks from time to time by replacing the key pins. This is a time consuming and sometimes complicated process, and it is often more convenient simply to replace the entire lock mechanism. Clearly this is wasteful, and it would thus be desirable to be able to recode a pin tumbler lock quickly and simply.
There exist various tools and devices for reloading locks, and the following is a list of publications representative of the art:
U.S. Pat. No. 3,217,699 to Maese, entitled Method and Means for Assembling Lock Tumblers and Springs in Lock Cylinders and Plugs; U.S. Pat. No. 3,664,007 to Schlage, entitled Cylinder Loading Tool; U.S. Pat. No. 4,675,994 to Detloff, entitled Locksmith's Tool for Installing Spring and Driver Pins into Pin Tumbler Locks; U.S. Pat. No. 5,628,109 to Neuman, entitled Lock Cylinder Maintenance Tool; and U.S. Pat. No. 6,021,655 to Labbe et al, entitled Interchangeable Core Lock Repinning Apparatus.
USPTO Backgrounds
USPTO Backgrounds