This invention relates to a locking device of the type known as a deadlock, which has a locking member mounted in a housing for movement to and from a locking position and retaining means for preventing the locking member from being pushed back from the locking position.

Conventional deadlocks are bulky and complex. Furthermore, it is usually possible to force back the locking member of a conventional deadlock by applying a force sufficient to overcome the shearing or bending resistance of a comparatively weak component of the retaining means.

The present invention substantially overcomes this problem by providing an elongate retaining element which engages, along substantially the whole of its 1 ength, etween the locking member and a lateral wall of the housing, thereby occupying only a small space and preventing forcing of the locking member by virtue of the high resistance of the elongate retaining element to deformation by transverse forces distributed along the whole of its length.

Accordingly, the present invention provides a locking device comprising a housing, a locking member mounted in the housing and guided between lateral walls of the housing for movement to and from a locking position in which it projects from

the housing, and an elongate retaining element mounted within the housing between one of its lateral walls and the locking member, the longitudinal axis of the retaining element extending transversely to the direction of movement of the locking member, and in which, when the locking member is in its locking position, the retaining element is laterally movable to and from a retaining position in which one longitudinal edge portion of the retaining element cooperates with an elongate

abutment provided in a recess in the locking member and the other longitudinal edge portion cooperates with a substantially parallel elongate abutment provided in a recess in the said one lateral wall, so as to prevent the locking member from being forced away from its locking position into the housing.

The longer length of mutual contact of the abutments and the retaining element, the greater the resistance of the element to force applied to the locking member. Preferably, the elongate retaining element extends over at least a major part of the corresponding dimension of the locking member. The retaining element may be made in one piece or subdivided into two or more pieces, and the pieces may be spaced apart along its length; this can facilitate assembly of the locking device.

In the preferred embodiment, the two abutments face each other when the locking member is in the locking position. In this arrangement, an attempt to force the locking member compresses the retaining element between the abutments. The element, which may be mounted on the locking member or, preferably, on the lateral wall, is preferably oblique to the lateral wall in the retaining position, thereby producing a wedging effect if the locking member is urged into the housing. Alternatively, an arrangement can be envisaged in which the abutments face away from each other and the longitudinal edge portions of the retaining element are constituted by flanges which cooperate with the abutments so that, if an attempt is made to force the locking member, the retaining element is put under tension transversely to its length.

The movement of the retaining element to and from its retaining position is preferably (but not necessarily) pivotal movement and it is preferable for the element to be hinged adjacent one of the abutments, conveniently the abutment in the housing wall. In one embodiment, resiliently deformable material is interposed between the retaining element and one or both of the abutments, in order to dissipate impacts which might be applied to the locking device in an attempt to force the

locking member away from its locking position. The deformable material may be carried by the retaining element and/or the abutment(s).

The retaining element may be urged into its retaining position by spring means and may be moved out of its retaining position by release means which may conveniently be combined with means for moving the locking member out of its locking position. The locking member may be rotated to and from its locking position, e.g. it may be a hook bolt, but preferably it moves rectilinearly. The locking member may be urged into its locking position by spring means, e.g. it may be a roller bolt or latch bolt. In this case it will be advantageous to arrange for the retaining element to be moved into its retaining position automatically when the locking element engages a rebate in a striking plate for example. This can be achieved by providing an actuating element- projecting from the housing adjacent the locking member and holding the retaining element out of its retaining position, the actuating element being actuable (e.g. by a striking plate) to release the retaining element.

Movement of the locking member out of its locking position can be provided by any convenient operating means, e.g. actuated by a mechanical, magnetic, or other key or by electrical means such as a microswitch. Preferably, the operating means is arranged within the length of the locking member, so that the space occupied by the locking device can be minimised. The retaining element preferably, but not necessarily, lies between the locking means and the projecting part of the locking member, for the same reason. A preferred operating means .comprises a rotary member comprising a first element for moving the retaining element out of its retaining position and a second element for moving the locking member out of its locking position.

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Since the locking device is simple in construction, using only a small number of moving parts, it can be made as small as desired, the only effective limitation being the required size of the locking member and operating mechanism for any particular application. By making the retaining element extend over substantially the whole of the width of the locking member, the device can be provided with great resistance to forcing, even if the housing is greatly reduced in size compared.with conventional locks. Accordingly, it is highly suitable for use not only on doors, particularly security doors, but also on windows, cupboard doors, drawers, and cases, for example. It is to be noted that a separate retaining element may be provided on each side of the locking member., if desired.

In a preferred embodiment of locking device the housing is connected to a first leaf through which the locking member projects in its locking position, the first leaf being hinged to a second leaf along one longitudinal edge portion, the second leaf being acted upon by the locking member so that, when the locking member is in its locking position, the second leaf is at an acute angle to the first leaf and its free longitudinal edge portion is capable of engaging' an elongate step (e.g. provided in a door-post). In this way, great resistance to breaking-open of the locking device when the said edge portion is engaged can be achieved by making the hinged leaves sufficient long.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic horizontal section through a locking device, with its locking member in the locking position;

Figure 2 is a schematic vertical section corresponding to Figure 1;

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Fi ure 3 is a view similar to Figure 1, but with the locking member withdrawn;

Figure 4 is a schematic vertical section corresponding to Figure 3;

Figures 5 to 8 are similar to Figures 1 to 4, respectively, but show another embodiment of the locking device;

Figure 9 is a fragmentary side view of a retaining element in another embodiment;

Figure 10 is a fragmentary perspective view of a modified locking device;

Figure 11 is a horizontal section corresponding to Figure 10;

Figure 12 is a fragmentary perspective view of a retaining element in another embodiment;

Figures 13 and 14 are fragmentary horizontal sections corresponding to Figure 12, with the locking member in the locking position and the withdrawn position respectively;

Figures 15 and 16 are similar views of another embodiment of retaining element;

Figure 17 is an exploded perspective view of a locking device with a modified housing; and

Figure 18 is a graph of load against deflection during testing of a locking device.

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The locking device illustrated in Figures 1 to 4 has a housing 1, preferably of metal such as hardened steel, which is to be received in a mortice in a door, for example. The housing

1 may be as small as 3 cm x 3 cm x 1 cm, for example, but can of course be of any desired size depending on the required strength of the locking device. A locking member in the form of a sliding bolt 2 is guided between lateral walls 3,4 of the housing 1 for movement between a locking position (Figures 1 and 2) in which the bolt 2 projects from the housing and a withdrawn position (Figures 3 and 4) in which it lies substantially wholly within the housing. The bolt 2 is preferably of metal such as hardened steel or brass with hardened steel inserts. •

A retaining element in the form of a metal flange 6 whose length is preferably equal to the width (height) of the bolt

2 is mounted in the housing 1 between its lateral wall 3 and the bolt 2. One edge of the flange 6 is hinged at 7 as shown (or by a pin or pivot points), adjacent to an elongate abutment 3 in a recess 9 in the wall 3 capable of accommodating the flange 6. With the bolt 2 in its locking position (Figures 1 and 2) the flange 6 is urged by a spring 11 (or a series

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of springs spaced along it) to a retaining position (as shown) in which it extends obliquely to the wall 3 (preferably at an angle less than 30°, e.g. 20° or less) and its free edge cooperates with an abutment or step 12 in the bolt 2 so as, to prevent the bolt from being forced back into the housing. Resiliently deformable material (e.g. rubber or resilient plastics) may be applied to the abutment 8, the abutment 12, -or one or both of the abutting surfaces of the flange 6, to dissipate impacts.

To release the retaining flange 6 and withdraw the bolt 2, a rotary member 13 (which may form part of an operating means such as a cylinder lock or other means actuated by an electrical, magnetic, optical, or mechanical code) is turned clockwise (Figure 2). In the drawings the arrows indicate the movements which are about to occur. The meπter 13 has a first element 14 which moves freely within a cavity 16 in the bolt 2 and comes in contact with the flange 6, pushing it into the recess 9. Immediately after, a second element 17 on the rotary member 13 bears against a cam surface 18 in the bolt 2 and pushes the bolt back into its withdrawn position (Figures 3 and 4).

The bolt 2 is moved to its locking position by turning the rotary member 13 anticlockwise, so that the first element 14 initially releases the flange 6 (which is, however, held in the recess 9 by the bolt 2, as seen in Figure 3) and then the second element 17 bears against a cam surface 19 in the bolt 2 and pushes the bolt into its locking position while the flange 6 is simultaneously urged into engagement with the abutment 12 by the spring 11.

in the locking device illustrated in Figures 5 to 8 (which is basically similar to the above-described device), the bolt 2 is a roller bolt (as shown in full line - but with

the roller omitted for clarity) or a latch bolt (as indicated in broken line at 21) and is urged into the locking position (Figures 5 and 6) by two compression springs 22 contained in blind longitudinal bores 23 in the bolt and guided by pins 24 fixed to the rear wall 26 of the housing 1.

When the bolt 2 is engaged in a rebate in a striking plate (not shown) an actuating element 27 adjacent the bolt is pushed (by the striking plate) into the housing 1 against the action of a spring 28 also guided by a pin 29 fixed to the rear housing wall 26. In this position (Figure 6), a recess 31 (Figure 7) in the actuating element 27 lies adjacent the retaining flange 6 (which in this case is extended below the bolt 2) and allows the flange to be urged into engagement with the abutment 12 by the spring 11.

The bolt 2 is withdrawn by the rotary member 13 in the manner described previously.

Figure 9 illustrates an alternative way of mounting the retaining element or flange 6. Here the flange has integral pins 33 received in blind bores in- the lateral wall 3 of the housing. The upper and lower ends 34 of the flange 6 slope slightly inwards away from the pins 33, so as to reduce friction or entering and leaving the recess 9. Two resiliently deformable strips 36 are interposed between the flange 6 and the abutment or step 8, with a space between them which accommodates a coil spring 37, one end 38 of which engages behind the flange 6 to urge it into the retaining position, while the other end (not shown) is fixed.

The locking device illustrated in Figures 10 and 11 is a modification of either one of the locking devices described above and substantially upgrades side pressure resistance. The housing 1 is shown mounted in a mortice in a wooden member 41 which may be a door or the face of a drawer. A piano-type

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hinge 42 has a first leaf 43 which is fixed to the member 41 (and therefore to the housing 1). The bolt 2 is bifurcated and its limbs 2a, 2b have aligned holes 44a, 44b through which a pin 46 passes. The bolt 2, in its locking position, projects 5 through the leaf 43 and acts on the second leaf 47 to place it at an acute angle to the first leaf 43 so that its free longitudinal edge portion 48 engages an elongate step 49 provided by a striking plate 51 mounted in a fixed frame merrier 52. The pin 46 in the bolt 2 passes through a bracket 10 53 on the leaf 47 so that the leaf 47 is pulled clear of the step 49 when the bolt 2 is withdrawn.

In the locking device shown in Figures 12 to 14 the retaining element 6 is of square section and is urged out of the recess 9 by a pair of upper and lower leaf springs 54 behind it. 15 An element 56 on the periphery of the rotary member 13 acts on a ramp surface 57 of the element 6 so as to push it into the recess 9 in order to allow the bolt 2 to be withdrawn (Figure 14).

In the locking device shown in Figures 15 and 16, the elongate 0 retaining element 6 and the recess 9 have the cross-sectional shape of a major segment of a circle. The element 6 is pivoted on an axis 58 passing through the centre of the circle.

Figure 17 illustrates two possible modifications to the housing 1 of the locking device. The housing has two flanges 68 5 extending from opposite edges of the end of the housing which is to be exposed at the open end of a mortice, each flange being in contact over the major part of its area with a resiliently deformable material 69 which is to be sandwiched between the flange and the member in which the mortice is provided.

0 The resiliently deformable material 69, which may be rubber, synthetic rubber, plastics material such as nylon, a visco-elastic material (e.g. a visco-elastic adhesive), or cork, for example,

tends to dissipate impacts if the locking device is violently attacked.

Resiliently deformable material 72, preferably in the form of a sleeve, encompasses the housing 1 and is in contact with its walls over substantially the whole of the length of the housing. The operating mechanism of the locking device is accessible through an aperture 73. As well as serving as a shoc -absorbing element to combat assault blows, the sleeve also helps to hold the housing 1 together if it is put under stress from a jemmy or crow-bar. The sleeve is preferably of tough plastics material such as nylon, polyvinyl chloride, or polyurethane.

Referring now to Figure 18, a locking device similar to that described with reference to Figures 1 to 4 was seated in a supporting block of wood and was tested to failure under an end load applied to the locking member or bolt projecting in the locking position. The load L was plotted against the displacement D (Fig. 18) and gave the failure load F as 25.85 kN (2.59 ton-force). It should be noted that the deformation measured aloπg ^' the horizontal axis of the graph includes not just that of the locking device itself, but also that of the wooden supporting block and the brackets with which the device was attached to the block.

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