GB2553408A

GB2553408A - Locking mechanism

Info

Publication number: GB2553408A
Application number: GB1709590.2A
Authority: GB
Inventors: Matthew Corbett Brian; Dain Fletcher Tracy
Original assignee: Spire Manufacturing Ltd
Current assignee: Spire Manufacturing Ltd
Priority date: 2016-06-16
Filing date: 2017-06-16
Publication date: 2018-03-07
Anticipated expiration: 2037-06-16
Also published as: GB201709590D0; GB2553408B; GB201610492D0

Abstract

A locking mechanism has a first and second oppositely driven drive bars 14 each driving a respective locking bolt 20 in a direction perpendicular to extend from an aperture 36 in a housing 12. The drive bars have angled guides 42 which engage with angled guides 44 on the bolts such that sliding movement of the drive bars is converted to perpendicular movement of the locking bolts to extend/retract from the housing. The drive bars may include serrated connectors 16 for coupling to further locking mechanisms. Preferably locking bolt aperture 36 includes a wide section 50 and a narrower section 52 and the locking bolt includes a thin section 56 and a thicker section 54 such that a two stage movement of the locking bolt is produced, first to extend the bolt out of the housing and second movement to slide laterally. The first and second drive bars may be identical as may be the locking bolts.

Description

(71) Applicant(s):

Spire Manufacturing Limited

Union Street, WEST BROMWICH, B70 6DB,

United Kingdom (72) Inventor(s):

Brian Matthew Corbett Tracy Dain Fletcher

1709590.2 |_NT ci_:

E05C 9/04 (2006.01) E05C 9/18 (2006.01)

16.06.2017 (56) Documents Cited:

GB 2351316 A EP 2206860 A2 (58) Field of Search:

INT CL E05B, E05C

Other: EPODOC, WPI, Patents Fulltext (74) Agent and/or Address for Service:

Fairfield IP Limited

South Lynn Gardens, London Road, Shipston on Stour, Warwickshire, CV36 4ER, United Kingdom (54) Title of the Invention: Locking mechanism Abstract Title: Locking mechanism (57) A locking mechanism has a first and second oppositely driven drive bars 14 each driving a respective locking bolt 20 in a direction perpendicular to extend from an aperture 36 in a housing 12. The drive bars have angled guides 42 which engage with angled guides 44 on the bolts such that sliding movement of the drive bars is converted to perpendicular movement of the locking bolts to extend/retract from the housing. The drive bars may include serrated connectors 16 for coupling to further locking mechanisms. Preferably locking bolt aperture 36 includes a wide section 50 and a narrower section 52 and the locking bolt includes a thin section 56 and a thicker section 54 such that a two stage movement of the locking bolt is produced, first to extend the bolt out of the housing and second movement to slide laterally. The first and second drive bars may be identical as may be the locking bolts.

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LOCKING MECHANISM

FIELD OF THE INVENTION

This invention relates to a locking mechanism. The invention is particularly suitable for locking a panel against movement relative to its fixed (outer) frame.

BACKGROUND TO THE INVENTION

The following description and disclosure is for convenience directed to hinged window panels, though it will be understood that the invention is equally applicable to other hinged panels such as doors, and to sliding panels such as patio windows or doors. The window panel may be connected to its frame by butt hinges or by friction stays (for example).

A hinged window has a closed condition within its surrounding frame, with only a small air gap between the window panel and frame. A locking mechanism is provided to secure the window panel in the closed condition. In practice, the air gap between the window panel and frame is sealed by resilient seals fitted to the window panel and/or frame and the locking mechanism acts to compress the seal(s) to minimise the likelihood of draughts when the window panel is closed.

The window panel can be secured in its closed condition at one position (single point locking) or at more than one position (multi-point locking). A common locking mechanism can be used to operate multi-point locks simultaneously.

Many window panels have glazing surrounded by a largely hollow (extruded) profile. It is common to fit the locking mechanism within the hollow profile.

The locking mechanism can control the position of a locking bolt having a bolt tip which in its locked position projects across the air gap to engage within or behind a fixed keeper.

The locking mechanism can (alternatively or additionally) comprise an espagnolette locking mechanism driving one or more locking bars along the locking edge of the window panel. The locking bars carry one or more locking bolts which can move along the locking edge behind correspondingly-located keepers mounted to the frame. An espagnolette locking mechanism having a locking bar carrying a plurality of locking bolts is disclosed in GB 2 072 740, for example. Each of the locking bolts can be made more secure by having an enlarged head locatable into an undercut-keeper, such as those of GB 2 161 208.

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Some espagnolette locking mechanisms have two locking bars which move in opposing directions, and a variant of those mechanisms takes advantage of the opposing movement by connecting the locking bars to shoot bolts which project beyond the corners of the window panel (i.e. beyond the ends of the locking edge).

An espagnolette locking mechanism suitable for use with a multi-point locking arrangement is disclosed in GB 2 297 796. In that disclosure, linear movement of two locking bars along the locking edge is converted into transverse movement of two locking bolts (i.e. towards and away from the locking edge) by cooperating angled guides of the locking bolts and the locking bolt housing. In the non-locking condition the locking bolts are completely withdrawn and do not project into the air gap between the window panel and frame, allowing the size of the air gap to be minimised. In addition, the mechanism drives the two locking bolts to move along the locking edge in opposing directions, which allows a single keeper to be engaged by two oppositely-moving locking bolts, resulting in a very secure locked condition.

The locking bolts of GB 2 297 796 undergo a two-stage movement, the first stage being angled relative to the locking edge, the angled movement having a component along the locking edge and a component perpendicular to the locking edge. During the second stage the locking bolts move with their respective locking bar parallel to and along the locking edge. This two-stage movement allows the enlarged heads of the locking bolts to locate behind under-cut keepers so as to maximise the security in the locked condition.

SUMMARY OF THE INVENTION

Notwithstanding the practical and commercial benefits of the locking mechanism of GB 2 297 796, the inventors have appreciated certain drawbacks which the present invention seeks to reduce or avoid.

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According to the present invention there is provided a locking mechanism having a housing, a first locking bar mounted at least partially in the housing, a second locking bar mounted at least partially in the housing, the housing having actuator means adapted to communicate rotary movement of an operating handle in use into opposing longitudinal movement of the first and second locking bars, a first locking bolt and a second locking bolt mounted in the housing, the housing having first and second locking bolt openings through which the respective locking bolts can project from the housing, the first locking bar having a set of angled guides which engage angled guides of the first locking bolt, the second locking bar having a set of angled guides which engage angled guides of the second locking bolt, the angled guides being configured to convert longitudinal movement of the locking bars into transverse movement of the locking bolts.

Each locking bar is provided with a set of angled guides for its locking bolt, which provides a number of advantages. Firstly, by a suitable arrangement of the actuator means the first and second locking bars can be identical so that the number of different components needing to be manufactured is reduced. Secondly, the first and second locking bolts can also be identical, further reducing the number of components. Thirdly, the locking mechanism can be made symmetrical with the locking bolts mounted between the locking bars; the locking bolts can therefore lie in the same plane and the forces acting upon the keeper and upon the locking bolt housing as the locking bolts are moved in use is entirely in compression or tension and there are no unbalanced twisting forces which might damage some of the componentry. Fourthly, allowing the locking bolts to be located between the locking bars provides additional support for the locking bolts during movement and greater security during use.

In relation to the first of these advantages, it will be understood that in the locking mechanisms of the prior art arrangement of GB 2 297 796, one of the locking bars is driven to move longitudinally by the main gear whilst the other locking bar is driven to move in the opposite direction by a pinion gear mounted between racks of the first and second locking bars; the first locking bar therefore has a io significantly different form to the second locking bar.

In relation to the third of these advantages, it will be understood that in the locking mechanisms of the prior art arrangement of GB 2 297 796, the angled guides are located on the housing walls, resulting in the first locking bolts lying between the first locking bar and one housing wall, and the second locking bar lying between the first locking bar and the other housing wall. The locking bolts do not therefore lie on the same (central) plane of the housing as in the present invention. Forces acting upon the locking bolts during movement (particularly into engagement with the keeper) are therefore necessarily unbalanced and can cause a twisting force upon the mechanism componentry.

In relation to the fourth of these advantages, with the prior art locking mechanism of GB 2 297 796 each locking bolt necessarily engages the housing wall. If an attempt was made to disable the locking mechanism by forcing the locking bolts out of a keeper, the forces acting upon the locking bolts are opposed directly by the housing wall. With the present invention on the other hand those forces are opposed directly by the locking bars and indirectly by the housing walls, providing an additional layer of material to oppose the forces.

Also, because the angled guides are located on the locking bars rather than the housing walls, the form of the housing walls can be simplified. In some embodiments, the housing is formed from two components which are secured together to provide the housing walls; the two components can be identically formed so as to reduce the number of different components.

Furthermore, because the angled guides are located on the (moving) locking bars rather than the (fixed) housing walls, the transverse movement of the locking bolts can be perpendicular to the locking edge. In preferred embodiments in which the locking bolts undergo two-stage movement, movement of the locking bolt in the first stage can be substantially perpendicular to the movement in the second stage.

It will be understood that two-stage substantially perpendicular movement minimises the length of the locking bolt housing. This in turn minimises the length of the window panel profile which needs to be recessed or routed to accommodate the housing and also reduces the material required for the housing.

It furthermore minimises the length of the keeper and reduces the material required for the keeper.

Desirably, each locking bolt has a first-thickness section and a second-thickness section, the first-thickness section being of greater thickness than the second20 thickness section. Desirably also, the locking bolt openings in the housing have a first-width section and a second-width section, the first-width section being wider than the second-width section. The first-width sections of the locking bolt openings are at least as wide as the first-thickness section of the locking bolts so that a respective first-thickness section can be accommodated in the first-width section of the locking bolt opening. The second-width sections of the locking bolt openings are at least as wide as the second-thickness sections of the locking bolts so that a respective second-thickness section can be accommodated in the second-width section of the locking bolt opening. Importantly, however, the second-width sections of the locking bolt openings are too narrow to accommodate the first-thickness sections of the locking bolts. Such an arrangement can ensure that the first stage of movement of each locking bolt is controlled by the first-thickness section of the locking bolt passing through the first-width section of the locking bolt opening, and can ensure that the transverse movement is substantially perpendicular to the locking edge. The second stage of movement can be controlled by the second-thickness section of the locking bolt entering the second-width section of the locking bolt opening.

Preferably, the cooperating angled guides are configured to cause the first and second locking bolts to move towards each other as they move outwardly of the housing. The designer can determine the orientation of the angled guides, and therefore whether the angled guides drive the bolts towards each other or away from each other as the locking bolts move outwardly of the housing. This is not possible with GB 2 297 796.

Desirably, each of the locking bars extends alongside both of the locking bolts, so that the first and second locking bolts both lie between the first and second locking bars. The first locking bar can therefore drive the first locking bolt to move and can also support the second locking bolt, and vice versa. The first locking bar can have a channel to accommodate the second locking bolt (and vice versa), the channel acting to guide and/or support the second locking bolt during its movement. Desirably also, the first and second locking bars are identically formed.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

Fig. 1 is an exploded view of the components of the locking mechanism;

Fig.2 is a side view of a locking bolt of the locking mechanism;

Fig.3 is a view of the assembled locking mechanism in an unlocked condition;

Fig.4 is a view of the locking mechanism in an intermediate condition; and

Fig.5 is a view of the locking mechanism in the locked condition.

DETAILED DESCRIPTION

The locking mechanism 10 has a housing 12 which in this embodiment is formed from two housing components 12A and 12B which are identical. The housing components 12A and 12B are made as zinc castings but other materials may be io used, and other embodiments of locking mechanism according to the present invention can use pressed or forged housing components. Also, in other embodiments of the invention the housing components are not identical.

The housing 12 accommodates most of a first locking bar 14A and most of a second locking bar 14B. In this embodiment the first and second locking bars 14A and 14B are also identical but that is not necessarily the case. Each of the locking bars has a connector 16 which lies outside of the housing 12 and is adapted to cooperate with further locking bars or shoot bolts which lie along the locking edge of the panel (not shown) to which the locking mechanism 10 is mounted for use, in known fashion.

Notwithstanding that the panel is not shown in the drawings, a skilled person will appreciate that the housing 12 is suitable for fitment into the hollow profile of a window panel or the like, the longitudinal axis A-A of the fitted housing 12 being parallel with the locking edge of the window panel in known fashion. Typically, the housing 12 is inserted into the hollow profile through an opening which has been cut or routed through the profile wall, the housing being inserted in the direction INS shown in Fig.4. When inserted, the connectors 16 will be accessible for fitment of the further locking bars or shoot bolts, as desired. (The references to further locking bars and shoot bolts is not limiting, but generally further locking bars will terminate before the corners of the window panel and provide multiple locking bolts along the locking edge, whereas shoot bolts will project beyond the corners of the window panel.)

Whilst the locking mechanism 10 is therefore an espagnolette locking mechanism suited to multi-point locking by virtue of the connectors 16, in other embodiments the locking bars terminate within the housing and do not include connectors; such a locking mechanism relies only upon the locking bolts 20 as described below. Whether or not the locking mechanism includes connectors such as 16, and whether those connectors are fitted to further locking bars or to shoot bots in use, are not relevant to the present invention.

io In common with many espagnolette locking mechanisms, the housing 12 has actuator means adapted to communicate rotary movement of an operating handle (not shown) into opposing longitudinal movement of the first and second locking bars 14A,B. Specifically, the operating handle is connected to the housing 12 by way of a square-section bar (not shown) which fits into the opening 22 of actuator gear 24. The gear teeth 28 of the actuator gear 24 engage the primary rack 26 of the first locking bar 14A. The first locking bar 14A has a secondary rack 30A which is engaged by two actuator pinions 32, the pinions 32 also engaging the secondary rack 30B of the second locking bar 14B. Whilst the secondary rack 30B of the second locking bar 14B is only partially visible in Fig.1, as above stated the first and second locking bars are identical, and so the secondary rack 30B of the second locking bar 14B is identically configured and positioned to that of the first locking bar 14A. It will also be understood that whilst the second locking bar 14B has a primary rack which is identical to that of the first locking bar 14A, that primary rack is redundant as it does not engage the teeth 28 of the actuator gear

24; the primary rack of the second locking bar 14B merely slides across the flat, part-circular, face of the actuator gear 24 which is visible in Fig. 1. It is preferable (but clearly not essential) to include a redundant primary rack for the second locking bar 14B so that the locking bars 14A,B can be identical and therefore interchangeable.

A first locking bolt 20A and a second locking bolt 20B are mounted in the housing. Again, the locking bolts 20A,B are identical but that is not necessarily the case. The locking bolt 20A is shown in side view in Fig.2.

The housing 12 has a face plate 34 with a first locking bolt opening 36A and a second locking bolt opening 36B, and through which the respective locking bolts

20A,B can project from the housing 12. In this embodiment the locking mechanism has a cover plate 40 which covers the face plate 34 and also covers the connectors 16 in the unlocked condition of Fig.3; the cover plate 40 is intended to be the final component fitted to the locking mechanism, after the further locking bars/shoot bolts (if any) have been fitted to the connectors 16. The cover plate 40 is not required for the present invention, however, and can be io omitted from certain embodiments.

The first locking bar 14A has a set of angled guides 42A which cooperate with angled guides 44A of the first locking bolt 20A. The angled guides 44A are only partially visible in Figs. 1 and 2, but are identical to the angled guides 44B of the second locking bolt 20B which are visible in Fig. 1. The angled guides 44B of the second locking bolt 20B cooperate with angled guides 42B of the second locking bar 14B (the angled guides 42B being only partially visible in Fig.1).

The angle a between the guides and the longitudinal axis A-A is in this embodiment 45° but it will be understood that other angles can be used, depending upon the transverse movement required for the locking bolts 20A,B for a given longitudinal movement of the locking bars 14A,B. The angle a can in other embodiments be in the range 30° to 60° for example.

It will be understood that the angled guides 42A,B and 44A,B convert longitudinal movement of the locking bars 14A,B (in the direction A-A) into transverse movement of the locking bolts (the direction T shown in Fig.3). Specifically, movement of the first locking bar 14A outwards of the housing 12 (i.e. to the left as drawn in Figs. 1 and 3) is converted to movement of the first locking bolt 20A outwards of the housing 10 (i.e. towards the top of the page in Figs. 1 and 3), and similarly for the second locking bar 14B and second locking bolt 20B.

It will be understood that in the assembled locking mechanism 10 the locking bolts 20A,B lie between the locking bars 14A,B and are engaged by both locking bars. In addition to the cooperation between the angled guides 42A,44A and 42B,44B respectively, the second locking bolt 20B slides across and along the surface 38 of the second locking bar 14A, and vice versa. Though not present in the embodiment shown, the first and second locking bars can have a respective channel to guide and support the second and first locking bolts respectively during movement.

io It will also be understood that in the assembled locking mechanism 10 the locking bolts 20A,B lie on the same (central) plane of the housing 12, and remain on that plane throughout their range of movement. Importantly, the forces acting upon the locking bolts 20A,B (and upon the keeper, not seen) during locking and unlocking movements are entirely compressive or tensile and act along the longitudinal axis A-A; there are no offset or unbalanced forces which might cause twisting movement and consequential strain and wear to the componentry.

Importantly also, a portion of a locking bar 14A,B and a portion of a housing component 12A,B lie to each side of the locking bolts 20A,B and provide additional support to the locking bolts if attempts are made to forcibly remove the locking bolts from a keeper.

As seen in Fig.1, the locking bolt openings 36A,B each have a wider section 50 and a narrower section 52. As seen in Fig.2, each locking bolt 20A,B has a thicker section 54 and a thinner section 56. In common with many prior art locking bolts, the locking bolts 20A,B each have a further enlarged head 60 which can locate behind an under-cut section of the keeper, in known fashion.

The wider section 50 of the locking bolt openings 36A,B is wide enough to accommodate the thicker section 54 of the locking bolt 20A,B, so that (as seen in

Fig.3) the locking bolts 20A,B can be substantially fully retracted into the housing where they are almost flush with the cover plate 40. It will be understood that if further retraction of the locking bolts is desired, the locking bolt openings in the cover plate 40 and in the face plate 34 can be made large enough to accommodate the enlarged head 60 of the locking bolt, enabling the locking bolts to be retracted to a position in which they are flush with the cover plate.

Importantly, the narrower section 52 of each of the locking bolt openings 36A,B is too narrow to accommodate the thicker section 54 of its locking bolt 20A,B. During the first stage of opening movement therefore, the first locking bolt 20A is prevented from following the leftwards movement (as drawn) of the first locking bar 14A and instead is caused by the angled guides 42A,44A to move outwardly io of the housing 12 into the intermediate position of Fig.3. Similarly, the second locking bolt 20B is caused to move outwardly to the intermediate position by the corresponding rightwards movement (as drawn) of the second locking bar 14B.

The length of the wider sections 50 (i.e. in the direction of the longitudinal axis A15 A) is arranged to be only slightly greater than the corresponding dimension of the thicker sections 54 of the locking bolts 20, so that the first stage of movement of the locking bolts is along the direction T substantially perpendicular to the longitudinal axis A-A.

In the intermediate position of Fig.3, the step 58 between the thicker section 54 and thinner section 56 of each locking bolt 20 has just passed through the face plate 34 (and cover plate 40). The narrower section 52 of each of the locking bolt openings 36A,B can accommodate the thinner sections 56 of the respective locking bolt 20, so that further leftwards movement of the first locking bar 14A (as drawn) causes corresponding leftwards movement of the first locking bolt 20A (i.e. along the direction of the longitudinal axis A-A) as the thinner section 56 of the locking bolt 20A enters and moves along the narrower section 52 of the locking bolt opening 36A (and likewise for the second locking bolt 20B). The locking bolts 20 therefore undergo a second stage of movement, in the direction A-A, to the locked condition of Fig.4.

The locking bolts 20 undergo a similar two-stage movement during movement from the locking condition to the unlocking condition. Initially, as the first locking bar 14A moves to the right (as drawn) from the locked position of Fig.4, the thicker section 54 of the locking bolt 20A cannot enter the narrower section 52 of the locking bolt opening 36A and the locking bolt 20A is caused to move in the direction A-A to the intermediate position of Fig.3. In that position, the locking bolt

20A has reached the right hand end (as viewed) of the locking bolt opening 36A.

Continued rightwards movement of the locking bolt 20A, by virtue of the angled guides 42A,44A causes the locking bolt 20A to move along the direction T to the unlocked position of Fig.2. Similarly for the locking bolt 20B.

io It will be understood that in this embodiment each locking bar 14 extends past the actuator gear 24, i.e. the actuator gear 24 lies between the connector 16 and the angled guides 42 of each locking bar 14. That is not necessarily the case, however, and in other embodiments the angled guides of each locking bar lie between the actuator gear and the connector.

Locking mechanisms in which the locking bolts 20A,B move towards each other between the intermediate and locking positions (such as that shown in the drawings) are preferred. It will be understood that in other embodiments it can be arranged that the locking bolt 20A is driven by the locking bar 14B and vice versa, so that the locking bolts are configured to move away from each other as they move from the intermediate position to the locked position. Such alternative arrangements will require a larger keeper, however, and are therefore not preferred.

The (substantially) perpendicular two-stage movement, and in particular the first stage of movement being (substantially) perpendicular to the longitudinal axis AA, has the particular advantage that the length of the housing 12 (i.e. in the direction of the longitudinal axis) can be minimised. This reduces the size of the housing components 12A,B and thereby reduces the material required. It also reduces the length of the opening needing to be cut or routed into the hollow profile, and therefore minimises the weakening of the profile which can result from such routing.

It will be understood that the sets of angled guides 42, 44 can comprise a chosen number of aligned guide rails and channels. In the embodiment shown the set of angled guides 42 comprises two guide rails separated by a single guide channel, and the set of angled guides 44 comprises two guide channels separated by a single guide rail. More (or fewer) channels and rails can be provided in each set, as desired.

Claims

1. A locking mechanism having a housing, a first locking bar mounted at least partially in the housing, a second locking bar mounted at least partially in the

5 housing, the housing having actuator means adapted to communicate rotary movement of an operating handle in use into opposing longitudinal movement of the first and second locking bars, a first locking bolt and a second locking bolt mounted in the housing, the housing having first and second locking bolt openings through which the respective locking bolts can io project from the housing, the first locking bar having a set of angled guides which engage angled guides of the first locking bolt, the second locking bar having a set of angled guides which engage angled guides of the second locking bolt, the angled guides being configured to convert longitudinal movement of the locking bars into transverse movement of the locking bolts.

2. The locking mechanism according to claim 1 in which the first and second locking bars are identical.

3. The locking mechanism according to claim 1 or claim 2 in which the first and

20 second locking bolts are identical.

4. The locking mechanism according to any one of claims 1-3 in which each of the locking bars extends beyond both of the locking bolts.

25 5. The locking mechanism according to claim 4 in which the locking bolts are located between the locking bars.

6. The locking mechanism according to claim 5 in which the locking bolts are located at the same longitudinal plane.

7. The locking mechanism according to claim 5 having a central longitudinal plane, in which the locking bolts are located at the central longitudinal plane.

8. The locking mechanism according to any one of claims 1-7 in which the housing is formed from two housing components which are identically formed.

5 9. The locking mechanism according to any one of claims 1-8 in which each locking bolt has a first-thickness section and a second-thickness section, the first-thickness section being of greater thickness than the second-thickness section.

io 10. The locking mechanism according to claim 9 in which each locking bolt opening has a first-width section and a second-width section, the first-width section being wider than the second-width section.

11. The locking mechanism according to claim 10 in which the first-width section

15 of the lock bolt opening is at least as wide as the first-thickness section of the locking bolt, in which the second-width section of the locking bolt opening is at least as wide as the second-thickness section of the locking bolt, and in which the thickness of the first-thickness section of the locking bolt is greater than the width of the second-width section.

12. The locking mechanism according to claim 11 in which each of the lock bolt openings has a length in the direction of the longitudinal axis, and in which each of the first-thickness sections of the locking bolts has a length in the direction of the longitudinal axis, the length of the lock bolt openings and the

25 length of the first-thickness section being approximately the same.

13. The locking mechanism according to any one of claims 1 -12 in which the first and second locking bolts move towards each other as they move outwardly of the housing.

14. The locking mechanism according to any one of claims 1-13 in which each locking bar has a connector to which a further locking bar or shoot bolt can be connected in use.

15. The locking mechanism according to claim 14 in which in which the actuator means includes at least one pinion gear which is driven to rotate in use by longitudinal movement of the first locking bar and which drives the second

5 locking bar to move in the opposing longitudinal direction, the first locking bar and the second locking bar each having a secondary rack in engagement with the pinion gear(s), the secondary rack being located between the connector and the angled guides of that locking bar.

io 16. The locking mechanism according to any one of claims 1 -15 in which the first and second locking bars each move in the direction of the longitudinal axis of the locking mechanism, and in which the angle between the angled guides and the longitudinal axis is in the range 30° to 60°.

15 17. The locking mechanism according to claim 16 in which the angle is 45°.

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