A pin tumbler lock is a type of lock mechanism, typically used in cylinder locks, in which pins of varying lengths must be aligned in order to allow a lock plug cylinder to rotate. The pin tumbler cylinder lock comprises a housing having a cylindrical bore in which the lock plug cylinder is removably inserted. The lock plug cylinder contains a plurality of openings that are initially positioned beneath and aligned with a plurality of chambers in the housing. Each pin chamber contains a pin stack, which consists of at least: a key pin, located entirely within the lock plug cylinder; a driver pin, located partially within the cylinder and partially within the chamber, for preventing the cylinder from rotating; and, a compression spring, located within the chamber. When a correct key is inserted to the lock plug cylinder, the peaks and valleys of the key raise and lower the pin stack as appropriate, so as to situate the driver pins entirely within the chamber, thereby allowing the lock plug cylinder to rotate. In more complicated locks, additional pin stack elements may be present, such as spacer pins.
Malfunctions of a pin tumbler lock can take various forms. One example of a common malfunction is a chamber jam, wherein one or more components of the pin stack get stuck within the chamber of a lock housing. In this case, the only way of repairing the jam is to remove the lock plug and then remove the pin stack components through the empty cylindrical bore. Due to the small space of the bore, and the 90 degree angle of the chamber with respect to the bore, there exist difficulties when trying to remove the pin stack components from the chamber. Therefore, the lock is often discarded and replaced to avoid the difficulties involved with attempting to fix it.
The inventor of the present invention is aware of a single prior art lock that superficially appears similar to the novel lock of the present invention, however, upon inspection, the prior art lock is quite dissimilar to the present invention in both form and function.
U.S. Pat. No. 5,921,122 to Lin, discloses a device for preventing the upper pin tumblers from falling while replacing the lock plug. A lock is disclosed comprising a number of longitudinally spaced holes in communication with the lower end of an associated upper chamber. A fork device having a number of branches is removably insertable into an associated hole to support the associated upper pin tumbler during replacement of the lock plug. The longitudinally spaced holes are bored in the housing at a 90 degree angle with respect to the associated chamber (see FIG. 5). Additionally, the holes must intersect with the shear (or, split) line of the lock for separating the upper pin tumblers from the lower pin tumblers. According to the present invention, as described herein below, the holes in the housing intersect with corresponding chambers between the upper and lower ends of the chamber, and are preferably angled away from the lower end of the chamber, and towards the upper end of the chamber.
It is therefore an object of the present invention to provide a novel lock for enabling a chamber jam to be easily repaired.
It is an additional object of the present invention to provide a novel lock that may be formed out of a conventional prior art lock.
It is yet an additional object of the present invention to provide a tool for forming the novel lock of the present invention.
Additional objects and advantages of the present invention are described in detail herein below.