Locks – Operating mechanism – Key
Reexamination Certificate
1999-09-14
2001-08-14
Gall, Lloyd A. (Department: 3627)
Locks
Operating mechanism
Key
C070S395000, C070S398000
Reexamination Certificate
active
06272891
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to tumbler locks, more particularly, to a device for preventing a key from being inserted into a double-sided tumbler lock.
THE PRIOR ART
Tumbler locks have a variety of uses, the most prevalent being as building door locks and as automotive ignition and door locks. There are occasions when it is desired to prevent a tumbler lock from being opened, even by the correct key. For example, a worker is given a key to a room that is only to be used during normal business hours. Or a person is loaned a car, but is told not to open the trunk. Or a person renting a locker is behind in his/her rental payments. In all cases, the key will be able to open the lock at any time, but for some reason, the person in possession of the key is to be prevented from doing so.
Double-sided locks are becoming increasingly prevalent, particularly in motor vehicles. The position of the ignition switch on the steering column behind the steering wheel makes it difficult to see in order to orient the key. Double-sided locks have opposite sets of identical tumblers and use keys with identical cuts on each side so that the key can be inserted in either orientation and still work.
A number of devices have been developed over the years to prevent the correct key from opening a single-sided lock. Examples include U.S. Pat. No. 1,696,326 issued to Roethlisberger, U.S. Pat. No. 1,728,310 issued to Sundel, U.S. Pat. No. 2,068,936 issued to Unterberg, U.S. Pat. No. 3,408,842 issued to Barnes et al., U.S. Pat. No. 3,276,233 issued to Russell et al., and Japanese Pat. No. 52-15799 invented by Miyamae.
All of these devices will work on a double-sided lock. However, with the exception of Barnes et al., the convenience of being able to insert the keyway plug in either orientation is lacking because the extractor can only be used in one orientation relative to the plug. Consequently, one of the main advantages of using a double-sided lock disappears.
On the other hand, Barnes et al., in
FIG. 6
, discloses a keyway plug that can be used in a double-sided lock and the extractor can be used in either orientation. However, the plug of Barnes et al. has the problem in that it must be long enough to extend over all of the tumblers. If the outermost tumbler should drop in front of the plug, the plug could not be removed. The flat outer end of the plug would be caught against the tumbler and the flat end of the extractor could not be inserted past the tumbler.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a keyway plug for preventing the correct key from opening a double-sided tumbler lock while retaining the convenience of the double-sided lock of inserting the key in either orientation.
The keyway plug of the present invention provides a means for preventing the correct key from opening a double-sides tumbler lock, while overcoming the deficiencies of the prior art. A double-sided tumbler lock includes a cylindrical barrel that rotates within a shell, a keyway, and a series of identical tumblers on opposite sides of the keyway. The key has identical cuts on both sides and causes the tumblers to align, permitting the barrel to rotate.
The keyway plug of the present invention includes a plug and an extractor. The plug fits into the double-sided keyway to block entrance of a key. Its tip is similar to the tip of an ordinary key. A pair of arms extend from the tip along both sides of the keyway. Unlike the plugs of the prior art, the arms of the first embodiment of the plug do not have to extend across all of the tumblers. It is preferred that the arms be short enough that the outermost tumbler drop in front of the plug, hiding it from casual inspection. To overcome the problem of the prior art plugs where the outermost tumbler prevents the plug from being removed with the extractor, the end of the arms have a chamfer to push the outermost tumblers out of the way upon extraction.
A second plug embodiment is for use in a lock where the plug could be pushed out the other end. Unlike the first embodiment, the arms extend to the outermost tumblers, which drop into notches in the outer edge of the arms. The outer edge of the notches is vertical to prevent the tumblers from sliding out of the notches, thus keeping the plug from moving farther into the keyway.
A third plug embodiment is a combination of the first two embodiments, where one arm has a notch for the outermost tumbler and the other arm is short enough to allow the outermost tumbler to extend fully into the keyway.
An extractor is used to remove the plug from the keyway. The extractor includes a narrow finger, each edge of which includes a hook that mates with a matching hook in the inner edge of the plug arms. As the extractor is being inserted into the keyway, the leading surface of the hooks forces the plug arms against the tumblers. When the extractor and plug hooks become aligned, the tumblers push the plug back against the extractor, and when the extractor is pulled from the keyway, the hooks mate to pull the plug from the keyway.
Other objects of the present invention will become apparent in light of the following drawings and detailed description of the invention.
REFERENCES:
patent: 1696326 (1928-12-01), Roethlisberger
patent: 1728310 (1929-09-01), Sundel
patent: 1807540 (1931-05-01), Makranczy
patent: 2068936 (1937-01-01), Unterberg
patent: 2591652 (1952-04-01), Ziegliss
patent: 2662390 (1953-12-01), Michnoff et al.
patent: 3276233 (1966-10-01), Russel et al.
patent: 3408842 (1968-11-01), Barnes et al.
patent: 4120184 (1978-10-01), Gerlach
patent: 5950466 (1999-09-01), Moen
patent: 289878 (1986-09-01), None
patent: 52-15799 (1977-05-01), None
Gall Lloyd A.
Morse, Altman & Martin
LandOfFree
Keyway plug for double-sided keyways does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Keyway plug for double-sided keyways, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Keyway plug for double-sided keyways will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2482667