Locks – Portable – Padlocks
Reexamination Certificate
1999-09-28
2001-01-23
Barrett, Suzanne Dino (Department: 3627)
Locks
Portable
Padlocks
C070S312000
Reexamination Certificate
active
06176109
ABSTRACT:
The present invention relates to a combination lock that is capable of providing a false feel against lock picking.
BACKGROUND OF THE INVENTION
Combination locks have been known for a long time, which are useful to prevent access to locked premises or removal of locked items by a person who does not know the preset combination code. A typical combination padlock has several (usually three to four) dials marked with numerals (usually “0” to “9”) and includes respective tumbler sleeves rotatable by the dials to unlocking positions according to the combination code for releasing the shackle.
For better protection against lock picking, certain combination padlocks have been designed to have a false feel feature, for example as disclosed in U.S. Pat. No. 5,715,709. Such a feature allows the shackle to move, or to have a tendency to move, slightly outwards when the dials are turned to certain positions other than the unlocking positions, thereby providing a false impression that those dials have been turned to the right, unlocking positions. The construction of this padlock requires the cutting of inclined recess slots (to permit the aforesaid slight shackle movement) at awkward positions difficult to gain access to, which is therefore difficult and thus expensive to manufacture.
The invention seeks to mitigate or at least alleviate such a problem by providing an improved combination lock of this type.
SUMMARY OF THE INVENTION
According to the invention, there is provided a combination lock comprising a body formed with a plurality of parallel slots and a bore intersecting with the slots to form co-axial apertures through the parts of the body immediately above and below each of the slots, each said aperture above a respective slot being formed with an unlocking groove, a plurality of dials received in the slots respectively, each of which is formed around its inner side with a ring of equi-angular recesses, an inverted J-shaped shackle having a longer limb extending into the bore and passing through the dials, and a plurality of tumbler sleeves supported co-axially on the shackle limb for individual rotation, each said sleeve having on its outer side a locking fin engageable with one of the recesses of the respective dial for rotation by the dial to reach an unlocking position aligned with the unlocking groove of the aperture above it such that the sleeve is movable into the aperture for unlocking the shackle, wherein the locking fin of at least one of the sleeves has an uppermost end which is formed with a step, and the aperture above it includes a false-feel groove apart from the unlocking groove for limited entrance by the uppermost end of the fin at a false-unlocking position, thereby giving a false impression that the respective sleeve has been rotated to the unlocking position.
It is preferred that the false-feel groove has a depth which is substantially half of that of the unlocking groove.
Preferably, the step has a depth of substantially 0.1 mm to 0.3 mm.
It is preferred that the locking fin of each of the sleeves has an uppermost end which is formed with a said step, and the respective aperture above it includes a said false-feel groove for co-operation with the uppermost end of the fin in the same manner.
It is further preferred that the unlocking and false-feel grooves extend over the entire length of the apertures in which they are formed, and are aligned with each other as between adjacent apertures.
In a preferred embodiment, said at least one sleeve has a number of stable angular positions corresponding to the number of the recesses in the respective dial, which include the false-unlocking position.
More preferably, the false-feel groove is positioned apart from the unlocking groove at an angle which is any integral multiple of 360° divided by the number of the stable angular positions for said at least one sleeve.
In a specific construction, the false-feel groove is positioned apart from either side of the unlocking groove at an angle of 72°.
The aforesaid combination lock may be in the form of a padlock.
REFERENCES:
patent: 1580573 (1926-04-01), Schara
patent: 3386271 (1968-06-01), Morin
patent: 3410121 (1968-11-01), Morin
patent: 3720082 (1973-03-01), Feinberg et al.
patent: 4444029 (1984-04-01), Remington
patent: 4733548 (1988-03-01), Ling
patent: 5125248 (1992-06-01), Ling
patent: 5520032 (1996-05-01), Ling
patent: 5715709 (1998-02-01), Lai
patent: 5953940 (1999-09-01), Ling
patent: 6029481 (2000-02-01), Lai
patent: 605018 (1948-07-01), None
patent: 636356 (1978-12-01), None
patent: 9111580 (1991-08-01), None
Barrett Suzanne Dino
Kwong Wah Lock Manufactory Ltd.
Rabin & Champagne, P.C.
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