GB2229220A - Padlock; changing combination - Google Patents

Abstract

A combination wheel padlock has the combination wheels 50 mounted on a shaft 42 which is displaceable in padlock body 10 only when the correct combination has been set. Displacement of the shaft 42 by means of button 48 moves boss 72 clear of bolts 74, 76 so that the latter can move inwardly to release shackle 18; such inward movement of bolts 74, 76 is provided by virtue of action of spring 40 on shackle 18 via ejector pin 38. The release combination can be changed at will using a tool (80, Figure 4) inserted into the body 10 through holes 84. A rotatable cap 90 is provided over the holes (84) and can only be moved into a position in which the holes are exposed when the shackle 18 is in a released condition- arm 22 of shackle is then out of the path of movement of lever 96. Each wheel 50 is mounted on shaft 42 through intermediary of toothed members 52, 54. When lugs 66 on inner toothed members 52 are mutually aligned in axial groove 70 in shaft 42, shaft 42 can be moved axially. The inner toothed members 52 can be displaced relative to outer toothed members 54 by means of the code changing tool (80, Figure 4). Shaft 42 has an axial means 98 of smaller width than groove 70 to confuse a potential picker. <IMAGE>

Description

"PADLOCK" This invention relates to a padlock and is more particularly concerned with a padlock having a combination wheel release mechanism as opposed to a keyrelease mechanism.

According to the present invention, there is provided a padlock comprising a body; a shackle mounted in the body and movable between a locked position and a released position, said shackle having an arm which is pivotally and slidably mounted in the body; and a plurality of combination lock wheels rotatably mounted in the body and cooperating with the shackle to retain the latter in its locked position but permitting the shackle to be moved into its released position when the combination lock wheels are arranged in a predetermined combination of mutual angular orientations; wherein a shaft is mounted in the body for movement between first and second positions, the combination lock wheels are mounted on the shaft, an interengaging lug and recess arrangement is provided between the lock wheels and the shaft to prevent movement of the shaft into its second position except when said predetermined combination is set, and at least one member in the body cooperates with a formation on the shackle and a formation on the shaft to prevent movement of the shackle from its locked position into its released position when the shaft is in its first position, but to permit such movement of the shackle when the shaft is in its second position.

The above described arrangement can be very robust because it does not involve the mounting of the combination lock wheels on the shackle itself, so that force exerted on the shackle is not transmitted to the lock wheels.

In a preferred embodiment, each of the combination lock wheels is mounted on the shaft through the intermediary of a toothed element carrying part of the interengaging lug and recess arrangement, the toothed element engaging the respective combination lock wheel but being axially slidable, relative to the shaft to enable it to be disengaged from its associated lock wheel whereby the angular orientation of the combination lock wheel relative to the part of the interengaging lug and recess arrangement carried by the respective toothed element can be altered so as to enable said predetermined combination to be changed.

Preferably, the body has at least one hole therein to enable insertion of a tool therein to move the toothed elements out of engagement with the respective combination lock wheels whereby to permit the predetermined combination to be altered by orientation of the lock wheels in the chosen manner. It is preferred for said at least one hole in the body to be covered by a cap which can be rotated relative to the body to a position in which said at least one hole is exposed.

In a highly preferred embodiment, the cap is provided with a formation thereon which cooperates with the shackle to prevent the cap from being moved into the position in which said at least one hole is exposed when the shackle is in its locked position.

Preferably, the lug and recess arrangement includes a recess in the form of an axially extending groove in the shaft and a plurality of axially spaced peripheral grooves, and a lug associated with each combination lock wheel, said lug being engaged in a respective one of the annular grooves, and said axial groove receiving all of the lugs when the combination lock wheels are in said predetermined combination whereby movement of the shaft from its first position to its second position is permitted by movement relative to the wheels.

Most advantageously, a further axial groove is provided in the shaft, said further axial groove being slightly smaller than said lugs. Such a groove does not permit sliding movement of the shaft but provides an additional safeguard against a person trying to pick the lock by testing the "feel" of the combination lock wheels. It will be appreciated that, particularly when the combination lock wheels are worn, it may be possible to detect when the lug associated with the wheel is in an orientation in which it is aligned with the firstmentioned axial recess in the shaft. The provision of another axial groove is intended to give the false impression that the release orientation of the wheel has been achieved.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is an axial section through one embodiment of padlock according to the present invention, Fig. 2 is a section on the line 2-2 of Fig. 1, Fig. 3 is a section on the line 3-3 of Fig. 1, Fig. 4 is a section on the line 4-4 of Fig. 1 but additionally showing a combination changing tool, and Fig. 5 is an exploded side view showing parts of the padlock of Figs. 1 to 4.

Referring now to the drawings, the padlock comprises a body 10 formed of two intermediate parts 12 permanently secured together by top and bottom shells 14 and 16, respectively. The padlock includes a U-shaped shackle 18 having one arm 20 longer than the other arm 22. The arm 20 is received slidably and rotatably in a blind bore 24 defined by the intermediate body parts 12. The bore 24 opens onto the top of the body 10 through a coaxial aperture 26 in the top shell 14. At an intermediate region of the blind bore 24 there is provided a region 26 of reduced cross-section which is of a size just to receive slidably a reduced cross-section region 28 of the arm 20. The reduced cross-section region 28 terminates short of the free end of the arm 20 so that a boss 30 is defined there.Thus, the shackle is pivotally mounted in the body 10 and is also slidable relative thereto by a limited extent dictated by the permitted movement of the boss 30 between the blind end of the bore 224 and the reduced cross-section region 26.

The other arm 22 of the shackle 18 is engageable in a further bore 32 defined by the intermediate body parts 12. Grooves 34 and 36 having curved side edges are provided in the respective arms 20 and 22. The grooves 34 and 36 extend transversely with respect to the direction of extent of the arms 20 and 22 and lie opposite each other.

An ejector pin 38 provided in the bore 32 is urged upwardly against the free end of the arm 22 by a compression spring 40 when the arm 22 is in the position shown in Fig. 1.

Mounted in the body 10 between the bores 24 and 32 is a shaft 42 which is urged downwardly by a further spring 44 so that an abutment surface 46 is urged against a corresponding abutment surface at the base of the body 10. A push-button 48 is secured in the shaft 42 and is accessible on the underside of the body 10. The shaft has a series of four combination wheels 50 mounted thereon each through the intermediary of an inner toothed member 52 and an outer toothed member 54. Each wheel 50 is securely fixed to its respective outer toothed member 54 and bears a series of indicia 56 on its peripheral surface. In this embodiment, the indicia 56 take the form of the integers 1 to 8. For each of the indicia 56 there is provided a corresponding recess 58 in a raised annular rim 60. Part of the peripheral surface of each wheel 50 is exposed in a window 62 in the body 10 (see Fig. 3).A blade spring 64 formed of synthetic plastics material is provided in the body 10 and has a respective configurated blade for each wheel 50. Each blade engages against the surface of the rim 60 and provides, with the grooves 58 therein, a detent mechanism for releasably retaining each of the wheels 50 in an orientation corresponding to a respective one of the indicia 56 thereon being displayed in the window 62.

The teeth on the outer toothed member 54 mesh with the teeth on the respective inner toothed member 52.

However, axial displacement of the inner toothed member 52 relative to the respective outer toothed member 54 enables the teeth to be disengaged and thereby enables the wheel 50 and outer toothed member 54 to be rotated relative to the inner toothed member 52 to enable the angular orientation of the wheel 50 to be altered relative to the inner toothed member 52. The teethfiare arranged so that there are eight possible angular orientations corresponding to the number of indicia 56 on the respective wheel 50. The inner toothed member 52 has an inwardly projecting lug 66 (see Fig. 3). Each lug 66 is engaged in a respective annular groove 68 in the shaft 42 (see Fig.5). The annular recesses 68 are spaced apart axially of the shaft 42. The annular grooves 68 are, however, interconnected by a relatively wide axially extending groove 70 provided in the shaft 42. The axially extending groove 70 is of a size to accommodate the lugs 66 so that when all of the wheels 50 are moved into mutual angular orientations such that the lugs 66 are mutually aligned in the groove 70, the shaft 42 can be moved axially upon operation of the button 48 upwardly as viewed in Fig. 1 against the action of spring 44. In Fig. 1, the shaft 42 is shown in a first position in which a boss 72 at the upper end of the shaft 42 is aligned with respective rectangular bolts 72, 74. The bolts 72, 74 are slidable inwardly and outwardly relative to the axis of the shaft 42. In the position shown in Fig. 1, the bolts 74 and 76 are urged outwardly by boss 72 into engagement with the respective grooves 34 and 36 in the shackle 18. In this way, the shackle 18 is held in the position illustrated in Fig. 1, such position representing a locked position of the shackle 18.

When the wheels 50 are set in their release combination, i.e. the combination in which the lugs 66 are mutually aligned in the axial groove 70, the shaft 42 can be moved upwardly by push button 48 into a second position in which the boss 72 lies above the bolts 74 and 76 which are thus permitted to move inwardly. Such inward movement of the bolts 74 and 76 is provided by virtue of the action of spring 40 on the shackle 18 via ejector pin 38. Axial movement of the arms 20 and 22 causes an inward force to be exerted on the bolts 74 and 76 by virtue of the curved edges of the respective grooves 34 and 36. The ejector pin 38 continues to move the shackle 18 outwardly until the boss 30 has moved upwardly by the full extent possible, i.e. by a distance corresponding to the spacing between the blind end of the bore 24 and the reduced cross section region 26.When the shackle 18 is in this position, the arm 22 lies clear of the body 10, thus permitting the whole shackle 18 to be pivoted about the axis of arm 20 to enable the padlock to be engaged with or disengaged from a part or parts to be secured by the padlock. This represents the released position of the shackle 18.

When the lugs 66 are aligned in the axial groove 70, the inner toothed members 52 can be displaced relative to the outer toothed members 54 as described above. Such displacement is effected by means of a special code changing tool 80 (see Fig. 4). The code changing tool 80 has a pair of prongs 82 which engage in respective holes 84 provided in the body 10. The holes 84 are aligned with respective recesses 86 which pass either side of the boss 72 and terminate adjacent and in alignment with the inner toothed member 52 which is closest to the top of the padlock. Thus, axial displacement of the inner tooth members 52 (which are in mutual abutment) can be effected using the tool 80 by urging the blades 82 along the respective recesses 86 and into engagement with the nearest inner toothed member 52.However, such displacement can only occur when the lugs 66 are mutually aligned in the axial groove 70.

Thus, the release combination of the wheels 50 can only be changed when the release combination has been set on the wheels 50.

In order to prevent unwanted ingress of dirt etc into the body via the holes 84, a cap 90 is provided. The cap 90 is permanently secured to the body 10 but is rotatable relative thereto. The cap 90 has a pair of diametrically opposed cut-out regions 92 in its peripheral surface so that, when the cap 90 is correctly orientated, the holes 84 are exposed in the regions 92. The cap 90 can also be pivoted into a position in which small lugs 94 releasably engage in the holes 84 to retain the cover 90 in position. However, the cover 90 is provided with a projecting lever 96 which is so positioned relative to the cut-out regions 92 and relative to the shackle 18 that the cover 90 can only be moved into the position in which the holes 84 are exposed in the region 92 when the shackle 18 is in its released position and the arm 22 has been pivoted out of the path of movement of the lever 96.

In other words, the lever 96 has to be moved into a position in which it overlies the bore 32 before the cutout regions 92 are aligned with the respective holes 84.

This provides an added safeguard against attempts to "pick" the lock using a tool inserted down one of the recesses 86 with a view to gathering information by "feel" as to what might constitute the unlocking combination.

In order to provide a further safeguard against "picking" of the lock, the shaft 42 is provided with a further axial recess 98 therein (see Fig. 3). This axial recess 98 is of smaller width than the recess 70 and is of a size which is insufficient to accommodate the lugs 66.

Such recess 98 is provided to confuse a potential lock picker into thinking that the desired opening combination for a particular wheel may have been reached by feeling when the lug 66 appears to be engaged in the axially extending groove.

Claims (8)

1. ' A padlock comprising a body; a shackle mounted in the body and moveable between a locked position and a released position, said shackle having an arm which is pivotally and slidably mounted in the body; and a plurality of combination lock wheels rotably mounted in the body and cooperating with the shackle to retain the latter in its locked position but permitting the shackle to be moved into its released position when the combination lock wheels are arranged in a predetermined combination of mutual angular orientations; wherein a shaft is mounted in the body for movement between first and second positions, the combination lock wheels are mounted on the shaft, an interenging lug and recess arrangement is provided between the lock wheels and the shaft to prevent movement of the shaft into its second position except when said predetermined combination is set, and at least one member in the body cooperates with a formation on the shackle and a formation on the shaft to prevent movement of the shackle from its locked position into its released position when the shaft is in its first position, but to permit such movement of the shackle when the shaft is in its second position.

2. A padlock as claimed in claim 1, wherein each of the combination lock wheels is mounted on the shaft through the intermediary of a toothed element carrying part of the interengaging lug and recess arrangement, the toothed element engaging the respective combination lock wheel but being axially slidable relative to the shaft to enable it to be disengaged from its associated lock wheel whereby the angular orientation of the combination lock wheel relative to the part of the intergaging lug and recess arrangement carried by the respective toothed element can be altered so as to enable said predetermined combination to be changed.

3. A padlock as claimed in claim 2, wherein the body has a least one hole therein to enable insertion of a tool therein to move the toothed elements out of engagement with the respective combination lock wheels whereby to permit the predetermined combination to be altered by orientation of the lock wheels in the chosen manner.

4. A padlock as claimed in claim 3, wherein said at least one hole in the body is covered by a cap which can be rotated relative to the body to a position in which said at least one hole is exposed.

5. A padlock as claimed in claim 4, wherein the cap is provided with a formation thereon which cooperates with the shackle to prevent the cap from being moved into the position in which said at least one hole is exposed when the shackle is in its locked position.

6. A padlock as claimed in any preceding claim, wherein the lug and recess arrangement includes a recess in the form of an axially extending groove in the shaft and a plurality of axially spaced peripheral grooves, and a lug associated with each combination lock wheel, said lug being engaged in a respective one of the annular grooves, and said axial groove receiving all of the lugs when the combination lock wheels are in said predetermined combination whereby movement of the shaft from its first position to its second position is permitted by movement relative to the wheels.

7. A padlock as claimed in claim 6, wherein a further axial groove is provided in the shaft, said further axial groove being slightly smaller than said lugs.

8. A padlock substantially as hereinbefore with reference to the accompanying drawings.