GB2458893A

GB2458893A - Gate with hook bolt assembly

Info

Publication number: GB2458893A
Application number: GB0805802A
Authority: GB
Inventors: Stuart Kenneth Parker
Original assignee: Surelock McGill Ltd
Current assignee: Surelock McGill Ltd
Priority date: 2008-03-31
Filing date: 2008-03-31
Publication date: 2009-10-07
Anticipated expiration: 2028-03-31
Also published as: GB0805802D0; GB2458893B

Abstract

A hook bolt assembly with a plurality of hook bolts 140, the hook bolts coupled to a common drive bar 130, the hooks arranged to rotate between thrown and retracted positions by the drive bar and the drive bar having a pin 135. A rotating drive cam 110 is provided having a drive aperture within which is disposed the drive bar pin 135 such that the drive cam bears on the pin to drive the drive bar. Preferably two hooks are provided, both rotating in the same direction. There may be two drive cams 110 (210 Fig 6b) rotating independently, each with apertures that engage with the drive bar pin. The apertures in the drive cams are preferably sized such there is a lost motion between the pin and drive cam. A slide plate 170 may be provided to engage with a lock mechanism, the slide plate may be biased into a position that locks the movement of the drive cam. An extendable gate including the hook bolt assembly is also disclosed.

Description

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HOOK BOLT ASSEMBLY

Technical Field

The present invention relates to a hook bolt assembly having two or more hook bolts. In a particular embodiment a twin hook bolt lock assembly is provided. The present invention also relates to a gate including the hook bolt lock assembly.

Background Art

Figure 1 shows an entrance way 10 closed by a pair of trellis gates 12. In the position shown, each trellis gate 12 is extended such that the laths 14 of the trellis gate space apart the vertical struts 16 of the gate. When the gate is opened, the laths 14 pivot bringing the vertical struts closer together to allow the gate to be stored in a small space, for example at the side of the entrance way 10.

The advantage of the trellis gate is that it may be stored in a smaller space than a solid gate that is hinged or sliding, and is hence, particularly useful for entrance ways in confined spaces or having large number of persons passing through, for example, at the entrance or exit of stations of the London Underground.

Similarly, concertina gates may be used to close entrance ways as these fold up into a small space when the gate is opened.

In some embodiments the gates are arranged to run in tracks provided across the floor and ceiling of the entrance way.

Conventionally, trellis and concertina gates of this kind are secured closed using bolts 18 driven into receiver holes in the floor and ceiling of the entrance way. The bolts 18 may be driven from a lock mechanism 20 located around the mid-point of the end of the gate. Alternatively, a local lock mechanism may be placed at the top and bottom of the gate with each bolt being driven separately.

A problem with the above mentioned lock assembly and trellis or concertina gate is that because the gate is not rigid, the end of the gate may not remain vertical when the gate is opened or closed. In particular, the end of the gate will tilt and slide at an angle to the vertical. This makes simultaneous alignment of the bolts 18 with the receivers in the floor and ceiling difficult. Where no tracks are provided to guide the gate, alignment of a single bolt with a receiver may even be difficult.

On occasions that have required gates of the above kind to be locked, but it has not been possible to lock the gates using the floor and ceiling bolt and receiver arrangement, a chain and padlock is sometimes used. However, this prevents persons opening the gates and leaving through the entrance, for example during evacuation in the event of a fire.

Therefore, it is desirable to provide a lock assembly which can be used to secure closed gates of the above kind, but that can also be opened from the inside in the event of a fire.

Summary of the Invention

The present invention provides an extendable gate, such as a trellis gate or concertina gate, having a fixed end and an extending end, the fixed end being attached to a frame, the extending end being provided with a bolt assembly, wherein the bolt assembly is provided with a plurality of hooks arranged to rotate and secure the gate in an extended position.

The hooks, which may alternatively be known as hook bolts, may be arranged to secure the extending end to the frame by hooking into a keeper provided in the frame. The hooks may alternatively be arranged to secure the extending end by hooking in to a keeper provided on a second extendable gate. The keeper may alternatively be known as a receiver.

The present invention also provides a hook bolt assembly, comprising: a plurality of hook bolts arranged to rotate between thrown and retracted positions; a common drive bar coupled to the hook bolts and arranged to drive the hook bolts between the thrown and retracted positions; and a rotating drive cam having a drive aperture within which is disposed a pin extending from the drive bar, such that the drive cam bears on the pin to drive the drive bar.

The drive aperture may be sized such that there is lost motion between the pin and drive cam resulting in return motion of the pin after throwing or retracting the hook bolts not bearing on the drive cam. By lost motion we mean that the two parts are not always directly coupled and may move with some freedom. When the hook bolts are thrown or retracted, the drive cam will be at one extreme of movement.

When the drive cam is turned in the opposite direction no movement of the drive pin and hooks will occur because of the lost motion between the drive aperture and drive pin.

Then after the lost motion is completed continued turning of the drive cam will again result in the drive aperture bearing on the surface of the drive aperture and moving the hook bolts to the opposite position.

The drive aperture may be a closed aperture.

There may be provided a second drive cam having a second drive aperture within which is disposed the pin, such that the second drive cam bears on the pin to drive the drive bar, wherein the second drive cam rotates independently of the first drive cam.

The second aperture may be sized such that there is lost motion between the pin and second drive cam resulting in return motion of the pin after throwing or retracting the hook bolts not bearing on the second drive cam.

The hook bolt assembly may further comprise a slide plate, or slider, rnoveable between a first position in which rotation of the drive cam is restrained, and a second position in which rotation of the drive cam is free, the slide plate being biased towards the first position.

The hook bolt assembly may further comprise a locking cam arranged to drive the slide plate towards the second position. The locking cam may be part of a key cylinder, or may be a separate unit that is driven by the tang of a key cylinder.

The hook bolt assembly may further comprise a second slide plate moveable between a first position in which rotation of the second drive cam is restrained, and a second position in which rotation of the second drive cam is free, the second slide plate being biased towards the first position.

The hook bolt assembly may additionally comprise a second locking cam arranged to drive the second slide plate towards the second position.

The hook bolt assembly may include at least one key cylinder arranged to rotate the locking cam under operation of a matching key.

The hook bolt assembly may additionally comprise a biasing arm coupled to the drive bar, the biasing arm arranged to bias the drive bar to urge the hook bolts towards the thrown or retracted position.

Brief Description of the Drawings

Embodiments of the present invention, along with aspects of the prior art, will now be described with reference to the accompanying drawings, of which: Figure 1 illustrates a trellis gate closing an entrance way; Figure 2a shows a two hook bolt assembly and receiver in isometric projection; Figure 2b shows the two hook bolt assembly in isometric proj ection; Figures 3a and 3b show two different isometric projection views of the hook bolt assembly with a housing plate removed; Figure 4 is a plan view of the drive cam; Figure 5a shows a view of the inside of the hook bolt assembly with the hook bolts in the thrown position; Figure 5b shows a view of the inside of the hook bolt assembly with the hook bolts in the retracted position; Figure 6a is a view of the inside of the hook bolt assembly showing the drive cams and slide plates at their centre (or rest) position; Figure 6b is a view of the inside of the hook bolt assembly showing the first drive cam driven to retract the hook bolts; Figure 7a is a view of the inside of the hook bolt assembly showing the first slide plate and key cylinder in the unlocked position; Figure 7b is a view of the inside of the hook bolt assembly showing the first slide plate and key cylinder in the locked position; and Figures 8a, 8b and 8c show schematic plan views of the slide plate, key cylinder, and boss of the drive cam in the unlocked position (a), locked position (b), and unlocked with drive cam rotated (C)

Detailed Description of the Preferred Embodiments

The hook bolt assembly described herein has a pair of hook bolts, that is bolts that are in the shape of hooks and that pivot when thrown. The hooks when thrown latch over a keeper bar in a receiver. The hook bolt assembly may be provided on a gate, such as a trellis or concertina gate.

The receiver may be disposed on another gate or fitted in a frame in which the gate is also fitted.

There are a number of embodiments of hook bolt assembly. In a first embodiment, the hook bolts may be thrown or retracted by the operation of turning a handle on either side of the assembly. A key cylinder may also be provided on each side to allow the handle which drives a drive cam to be locked to prevent the hook bolts being thrown or retracted.

In another embodiment, two drive cams are provided to allow independent operation from either side of the assembly. That is, a first drive cam operated by a first handle on a first side of the assembly may be locked by turning a key cylinder. But on the second side the second drive cam is not locked because it has a separately lockable key cylinder thereby allowing the second drive cam and handle to turn freely even though the first side is locked.

Thus, in this position the hook bolts can be driven from the second side but not the first.

In some embodiments the second key cylinder may be omitted such that the second drive cam can always be rotated to throw or retract the hook bolts.

Figure 2a shows a hook bolt assembly 100 and receiver assembly 300. Figure 2b shows the hook bolt assembly alone.

The hook bolt assembly 100 and receiver 300 can be fitted to a gate, door, and other types of opening leaf. The receiver assembly 300 is particularly suitable for fitting in a wall, door frame, or other fixed object surrounding the gate. The receiver or bolt assembly may alternatively be fitted to the gate or frame surrounding the gate.

The receiver assembly 300 comprises a strike plate 310 with receiver holes 320 for receiving hook bolts of the assembly 100. The receiver holes 320 are each provided with a casing 330 extending away from and perpendicular to the strike plate 310. Each casing 330 may enclose the volume swept through when the hook bolt is thrown. In one embodiment, the keeper bar has a U-shaped cross-section. In the embodiment shown in figure 2a, the receiver assembly includes two receiver holes 320 each having a corresponding casing 330. Each receiver hole 320 is provided for a single hook bolt. In alternative embodiments, different numbers of hook bolts may be used. Optionally, a single casing may be used to enclose the volumes swept through when all of the hook bolts are thrown.

Figure 2a shows a keeper bar 340 in each casing 330.

The keeper bar 340 spans from one side of the casing 330 to the other, and may be fitted through holes on the casing 330. When a hook bolt is thrown, the hook of the bolt pivots over and around the keeper bar 340 such that the hook bolt cannot be pulled from the receiver assembly 300.

The hook bolt assembly, as shown in figures 2a and 2b, comprises a face plate 102 (also known as a fore-end plate) and two housing plates 104, 106. These three parts together make up the housing of the bolt assembly 100. The two housing plates may also be known as the main body.

Figures 3a and 3b show the inside of the bolt assembly 100 when one of the housing plates 106 has been removed.

These two figures show the bolt assembly with the hook bolts in the thrown position. The housing plate 106 is formed with a face bent at right angles to attach to the face plate 102.

Between the two housing plates 104 and 106 is carried the mechanism of the hook bolt assembly.

The mechanism comprises a drive cam 110 which is arranged to pivot about an axis 112. The drive cam 110 has a hole 114 for receiving a spindle. In the embodiment shown, the hole is square to receive a spindle which has a square cross-section. Other shapes of holes and spindle may be used. The spindle (not shown in the figures) is arranged to be driven by a handle (also not shown in figures) . The drive cam 110 has a lobe that extends away from the axis 112, the lobe itself being extended to have two ends with a drive aperture 118 there between. The drive cam 110 may be considered to be based on a triangular shape but with rounded corners and the pivot axis 112 located towards one of the vertices of the triangle.

Figure 4 shows the drive cam 110. The drive cam 110 has a boss 120 surrounding the hole 114. The boss 120 has a shape derived from a circle but with two parallel flats 122 added. The flats 120 are perpendicular to the elongate direction of the cam but parallel to the drive aperture 118 in the lobe of the cam.

A drive bar 130 extends between two hook bolts 140, as shown in figures 3a and 3b. Optionally, (and as shown in figures 3a and 3b) two drive bars may be used, both extending from one hook bolt to the other. The hook bolts are coupled to the drive bars at pivots 144. The hook bolts are attached to the housing plate 104 at a further pivot 142.

In the embodiment shown in figures 3a and 3b, the hook bolts 140 have a rectangular shape with a channel cut towards the end of one of the long sides of the rectangle to form the hook. Some of the corners of the rectangle are rounded.

The face plate 102 comprises slots 103 through which the hook bolts 140 protrude when in the thrown position.

Attached to the drive bar 130, or extending between the two drive bars 130 if two drive bars are provided, is a drive pin 135. The drive pin 135 extends into the drive aperture 118 of the drive cam 110.

In some embodiments, a biasing arm 150 may optionally be provided. The biasing arm 150 is attached to the housing plate 104 at a pivot, and comprises an arm with a rod 152 attached at the opposite end of the arm to the pivot. The rod 152 locates in a slot 154 in the drive bar 130. The biasing arm 150 is itself biased by the action of a coiled -10 -spring 156, although other types of spring and biasing means may be used. The coiled spring 156 is arranged such that as the biasing arm moves from a first position to a second position, the spring extends and then retracts again. The first and second positions are separated by about around 90°. The first and second positions being those where the spring 156 is unextended or at it least extension. In the embodiments shown in figures 3a and 3b, the coiled spring 156 is attached to the biasing arm at a point close to the rod 152 (shown in figure 6a) . The other end of the coiled spring 156 is attached to the housing by a retaining pin located distant from the rod 152.

Figures 5a and 5b show the hook bolt assembly 100 with the hook bolts 140 in thrown and retracted positions respectively. These figures, and also figure 3a and 3b, show an embodiment comprising two drive cams 110 which can be driven independently from separate handles on either side of the hook lock assembly. The details of this embodiment will be described later.

There follows a description of the operation of the mechanism in moving the hook bolts from the thrown to the retracted position. Starting from figure 5a with the hook bolts 140 in the thrown positions, the drive cam 110 is rotated about the axis 112, for example by turning a handle locating on a spindle (not shown) inserted through hole 114 in the drive cam 110. As the drive cam is rotated, the surface of the drive aperture 118 bears against drive pin attached to the drive bar 130. As the drive cam 110 rotates, the drive pin 135 moves longitudinally to move the drive bar 130 in a direction parallel to its length. In figures 5a and 5b this movement of the drive bar 110 is towards the top right of the page. The movement of the drive -11 -bar 110 provides a turning force on the hook bolts 140 to rotate them about their pivots 142 as shown in figure 5b.

The continued rotation of the drive cam 110 results in the hook bolts being moved to their retracted positions. To move the hook bolts 140 to their retracted positions requires the drive cam 110 (and as a result the spindle and handle) to be turned approximately 450 This will be in the clockwise direction for the side of the assembly shown on top in figures 5a and 5b.

As the drive cam 110 is turned and the hook bolts moved from the thrown position a biasing force is exerted by the biasing arm 150. This biasing force reduces as the drive cam moves beyond the mid point between thrown and retracted positions. Thus, the biasing arm 150 is arranged to bias the hook bolts towards the thrown and retracted positions. This provides the advantage of holding the hook bolts in either position when the turning force of the drive cam 110 is removed.

After turning the drive cam 110 to move the hook bolts, the drive cam 110 and handle (not shown) will be returned to the starting position, shown in figure 5a, by the action of a return spring located between the handle and its housing.

Alternatively, the return spring may be located to act directly on the drive cam. The resulting return force on the handle and drive cam will return the handle and drive cam to the start position. Because the drive cam may be rotated clockwise or anti-clockwise, the start position may also be known as a medial or centre position.

From the retracted position, to throw the hook bolts 140 the handle is required to be turned in the opposite direction as for throwing the bolts 140. In the arrangement shown in figures 5a and 5b, the drive cam 110 should be -12 -rotated in the anticlockwise direction by approximately 45°.

At the starting position of having the hook bolts 140 in the retracted position, the drive pin 135 will bear against the opposite end surface of the drive aperture 118 to that when retracting the bolts. In an embodiment such as that shown in figures 5a and 5b, this will be the surface at the top of the aperture. Again after turning the handle and drive cam 110, these will be returned to the starting position shown in figure 5a by the action of a spring.

Figures 6a and 6b show the operation of the drive cam in more detail. As can be seen, the aperture of the drive cam 118 is larger than the size of the drive pin 135 such that at some positions the drive cam 118 can move without moving the drive pin. For example, the drive cam can be returned to its middle or rest position without moving the drive pin. This partial freedom of movement is known as lost motion.

The drive cam 110 can be locked to prevent it being rotated.

The additional components shown in figures 6a and 6b that are provided for locking the drive cam 110 will now be described.

Figure 6a shows slide plate 170 located to partially cover the drive cam 110. The slide plate 170 includes an aperture 172. The aperture 172 is an enclosed slot with a rectangular shape at the one end 174 and a circular shape at the other end 176, thereby providing an aperture that is similar in shape to a keyhole. The diameter of the circular portion of the aperture is slightly larger than the diameter of the boss 120 of the drive cam 110 such that the boss 120 protrudes into the circular portion 176. The rectangular portion of the aperture has a width that is slightly larger -13 -than the dimension across the flats 122 of the drive cam 110. This allows the slide plate 170 to slide to receive the boss 120 of the drive cam 110 when the drive cam is oriented with flats 122 parallel to the aperture.

As shown in figures 6a and 6b, the aperture is located towards one end of the slide plate 170. At the other end of the slide plate a drive surface 178 is provided. The drive surface 178 is arranged to be driven by key cylinder 180.

More specifically, the key cylinder 180 has a cam 182 which rotates when a key is inserted in the cylinder and turned.

It is this cylinder cam 182 that bears against the drive surface 178 of the slide plate 170.

The key cylinder 180 may be any commercially available replaceable cylinder, such as the Scandinavian oval key cylinder. The key cylinder 180 is fixed to the housing plate 104 or 106 by screws or other fasteners placed in to holes 108 (see figure 3a) in the housing plate.

The drive surface 178 of the slide plate 170 is comprised of two parts, one formed at an angle to the other such that one part is similar to an internal chamfer. At both ends of the drive surface 178 are provided with lips to limit rotation of the cam cylinder 182.

The slide plate 170 is biased towards the key cylinder by the action of a spring 186. The spring may be a coiled spring, lever spring or other biasing means. In the present embodiment the spring 186 is a lever spring. A first end of the lever spring 186 is supported against a first pin provided in the housing. The second end of the lever spring 186 pushes against the slide plate 170. The middle of the lever spring is bent around a second pin thereby providing the spring with a fulcrum about which the lever force is derived. The end of the spring 178 that pushes against the -14 -slide plate 170 is provided with a channel into which the slide plate locates. In the embodiment shown in figures 6a and 6b, the first pin acts to support the lever spring 186, and may also act as an anchor point for spring 156 used to bias the biasing arm 150 described above.

The slide plate 170 has two small slots 179. These are to be found around the middle and toward the drive surface end of the slide plate. The small slots 179 have rounded ends. Each slot carries a guide pin 188 which guides the slide plate 170 as it moves.

The operation of the slide plate and key cylinder will now be described with reference to figures 7 and 8.

The slide plate 170 operates to lock the drive cam 110 in position. The movement of the slide plate 170 is determined by rotation of the key cylinder.

Upon insertion of the correct key into key cylinder 180, the key may be turned causing the cylinder cam 182 to rotate. From a starting point shown in figures 7a and 8a, the lobe of the cam of the key cylinder bears against a first end of the drive surface 178 of the slide plate 170.

In this position, the boss 120 of the drive cam 110 is within the circular part 174 of the aperture 172 of the slide plate 170 and the drive cam 110 is free to rotate to drive the hook bolts 140 between the thrown and retracted positions, as shown in figures 6b and Sc.

As the key cylinder 180 is turned the lever spring 186 causes the slide plate 170 to slide. The key cylinder may be turned through an angle of around 90°. As shown in figures 8a and 8b this is in the anticlockwise direction, but will be reversed if the other side of the lock assembly is viewed. As the key cylinder is rotated, the lobe of the cylinder cam moves along the first part of the drive surface -15 - 178. Up to about the mid-point of the rotation, the slide plate 170 moves by only a small amount because the shape of the drive surface approximates to the arc swept out by the movement of the cylinder cam lobe. After the mid point, the drive surface 178 is flat (and horizontal as shown in figure 8b), and thus the slide plate moves upward against the cam lobe under the bias of the lever spring 186. The movement of the slide plate 170 is guided by guide pins 188 in slots 179. The rotation of the key cylinder 180 causes the slide plate to move towards the key cylinder by around 6-10 mm, and preferably by around 8 mm. As shown in figure 8b, the boss 120 of the drive cam 110 is now partly within the circular part 176 of slide plate aperture 172, but also partly within the rectangular part 174 of the slide plate aperture. In this position, the drive cam 110 cannot rotate because the flats 122 of the boss 120 are clamped by the aperture of the slide plate thereby locking the drive cam 110.

To release the drive cam 110, the key cylinder 180 is rotated in the opposite direction (clockwise in figure 8) pushing the slide plate downwards (as shown in figure 8) against the bias of the spring 186 away from the key cylinder 180. When the key cylinder 180 is fully turned back to the end of the drive surface 178 the boss 120 will no longer be clamped by the rectangular part 174 of the slide plate 170. The drive cam 110 can then turn because the boss is located within the circular part 176 of the aperture 172 as shown in figure 8c.

In the embodiments described above, when the slide plate 170 locks the drive cam 110 to prevent it from rotating, the hook bolts 140 cannot be rotated and remain in either of the thrown or retracted position.

Above we have described operation of the lock assembly comprising one drive cam, one slide plate, and one key cylinder and a number of other components. However, as shown in the figures two drive cams, two slide plates, and two key cylinders may be provided. There follows a description of such an embodiment.

Figures 5 and 6 show a twin bolt hook lock assembly comprising two drive cams, two slide plates, and two key cylinders. The two drive cams are both able to drive the drive bar and hook locks, but can be locked independently using the two key cylinders. This allows the leaf, gate or door to which the lock assembly is fitted to be secured independently from each side. This means, for example, that the side of the gate facing the outside can be locked to prevent persons from opening the gate, whereas the side of the gate facing inside can be left unlocked to allow persons to open the gate in an emergency.

Figure 6b shows the two drive cams and two slide plates most clearly. Housing plates 104 and 106 (the latter not shown in figure 6b) have sandwiched there between the two drive cams 110 and 210, and the two slide plates 170 and 270. The first slide plate 170 faces against housing plate 102, and the second slide plate 270 faces against housing plate 104. The two slide plates 170, 270 are spaced apart by two drive cams 110 and 210. Guide pins 188 may also be used to space apart the slide plates by having a central portion of greater diameter than the portion located in guide slots 179. Both drive cams 110, 210 have bosses 120, 220 which protrude in to the aperture (172 in the first slide plate, aperture in the second slide plate not shown) of each slide plate. The two drive cams 110, 210 lie parallel to each other and may be spaced apart by a collar (not shown) which -17 -also retains the drive cams to rotate about the same axis 112. The drive cams both have a drive aperture 118, 218 in which the drive pin 135 attached to the drive bar 130 bears.

Each slide plate 170, 270 has a drive surface 178, 278 against which a cylinder cam 182, 282 of the respective key cylinders 180, 280 is driven. The two key cylinders 180, 280 are co-axial. The first key cylinder 180 is attached to housing plate 106 by screws, bolts or other fastening means.

The second key cylinder 280 is attached to housing plate 104 by similar means. The two key cylinders 180, 280 may arranged to butt directly back to back or may be spaced apart by a disc or ring. Alternatively, instead of two key cylinders being used, a double cylinder can be used provided it has two cams which can be rotated independently.

The two slide plates 170, 270 are biased by lever springs 186, 286 respectively. The bias pushes the slide plates towards the key cylinders.

Operation of the bolt assembly with twin drive cams will be described below.

As mentioned above, each of the two drive cams 110, 210 is arranged to rotate about the same axis 112. From the position shown in figure 6a, each drive cam may be rotated clockwise or anticlockwise by around 45°. Both drive cams have a hole (114 in first drive cam, not shown in second drive cam) for receiving a spindle (not shown) to rotate the drive cam, each of which may be driven by a handle (not shown). Because the drive cams may be driven independently, any spindle that is used should extend from a handle through the hole in the drive cam 110, 210. If a collar is used to space apart the drive cams, as described above, the collar may include a disc so as to space apart the ends of the two spindles.

-18 -As described above, when the first drive cam 110 is rotated the surface of the drive aperture 118 bears against the drive pin 135. The drive cam is driven linearly in the direction of the drive bar 130 as shown in figure 6b. When the drive cam 110 is rotated clockwise, the hook bolts 10 are moved to the retracted position. After turning the drive cam 110 it is returned to its start position shown in figure 6a by the action of a return spring. To move the hook bolts to the thrown position the drive cam is rotated in the opposite direction.

The apertures 118, 218 in drive cams 110, 210 should be long enough that when one of the drive cams is moved to throw or retract the hook bolts thereby moving the drive pin, and the other drive cam is at its centre or rest position (as shown in figure 6a), this other drive cam is not moved because the drive pin moves within its aperture.

Thus, there should be lost motion between the drive cam and drive pin. The apertures 118, 218 should also be wide enough to accommodate movement of the drive pin as the drive cam rotates. That is, as the drive cam rotates, the drive pin will move longitudinally resulting in some radial movement of the pin relative to the cam.

As shown in figure 6b the aperture in the second drive cam 210 allows the drive pin 135 to move freely when driven by the first drive cam 110. Thus, either drive cam may be used to independently move the drive pin 135 thereby throwing or retracting the hook bolts. In figure 7b, the first slide plate 170 has been moved to the locked position by turning the first key cylinder 180. As a result, the slide plate has moved toward the key cylinder resulting in the aperture 172 of the slide plate clamping the flats 122 on the boss 120 of the drive cam thereby preventing the -19 -drive cam from being rotated. However, second drive cam 210 and slide plate 270 operate independently of the first cam and side plate 170. Second drive cam 210 may still be operated even though the first drive cam 110 is locked. Thus rotating the second drive cam will move the drive pin up or down depending on the direction of rotation of the drive cam thereby throwing or retracting the hook bolts as required.

Only when both key cylinders are in the position shown in figures 7b and 8b (or the mirror position, if viewed from the opposite side of the lock assembly) will the hook bolts be unable to be moved.

In some embodiments, one of the key cylinders may be removed or replaced with a blank. For example, if the first key cylinder 180 is removed, a handle provided with a spindle can be used to turn the drive cam 110, but the handle cannot be locked. In this case, the hook bolts can always be thrown or retracted by turning this handle.

However, operation of the second drive cam 210 and key cylinder 280 is as described above and requires the key cylinder 280 to be in the correct position allowing the drive second drive cam to turn.

There follows a summary of the embodiments described above. Other embodiments not yet described but that are based on those described above are also mentioned. In one embodiment, the lock assembly may include a single drive cam, slide plate and key cylinder which may be operated from one side of the lock only. The presence of the key cylinder and slide plate allows the drive cam to be locked preventing movement of the hook bolts. Alternatively, the single drive cam may driven by a handle on both sides, but that can be locked on one side only. In another alternative embodiment, a double key cylinder may be used such that the single cam -20 -may be operated from both sides and locked from both sides.

In these embodiments, the hook bolts are not able to be independently operated from the two sides of the lock.

Embodiments having two drive cams and two slide plates will now be summarised. The first slide plate is drivable from a first side of the lock assembly, the drive cam being lockable suing the key cylinder on the first side of the assembly. A similar arrangement may also be provided on the second side of the lock assembly to allow independent movement of the hook bolts and in which the second drive 210 cam is independently lockable from the first drive cam 110.

This is the embodiment shown in many of the drawings, for example, in figures 5, 6 and 7. As described above, in another embodiment, the second key cylinder may be removed or a blank fitted to prevent the hook bolt arrangement being locked. This arrangement is the preferred arrangement for a gate, for example, at the entrance to a London Underground station. This will allow the gate to be locked and access restricted by throwing the hook bolts into the receiver and the key cylinder being turned from outside of the gate facing the outside of the building. Whereas the side of the lock on the gate facing the inside of the building has only a handle for throwing and retracting the hook bolts and there is no key cylinder to lock the slide plate and drive cam. This arrangement means that person inside the building can escape by turning the handle and the handle and drive cam cannot be locked inside.

In another embodiment, because there is only one key cylinder, the second slide plate is omitted, but both drive cams are retained. This provides an assembly that is lockable from one side only, whereas from the other side a -21 -handle may freely operate to throw and retract the hook bolts.

Although the first embodiments described above relates to a lock assembly having a single drive cam and slide plate and may contain additional features not mentioned in the description of the lock assemblies having two drive cams and slide plates, such as the biasing arm 150, this does not mean they are excluded from such embodiments and may be included in these embodiments having two drive cams.

The person skilled in the art will readily appreciate that various modifications and alterations may be made to the above described hook bolt assembly without departing from the scope of the appended claims, for example, the hook bolt assembly may be provided with more or less than two hook bolts. The number of hooks may also be varied for example, by coupling the drive bar to additional hooks spaced along its length. Variations in the actual shapes of the parts such as the drive cam and slide plate may also be made without diverging from the general scope of the present invention.

Claims

-22 -CLAIMS: 1. An extendable gate, such as a trellis gate or concertina gate, having a fixed end and an extending end, the fixed end being attached to a frame, the extending end being provided with a bolt assembly, wherein the bolt assembly is provided with a plurality of hooks arranged to rotate and secure the gate in an extended position.
2. The extendable gate of claim 1, wherein the hooks are arranged to secure the extending end to the frame by hooking into a keeper provided in the frame.
3. The extendable gate of claim 1, wherein the hooks are arranged to secure the extending end by hooking in to a keeper provided on a second extendable gate.
4. A hook bolt assembly, comprising: a plurality of hook bolts arranged to rotate between thrown and retracted positions; a common drive bar coupled to the hook bolts and arranged to drive the hook bolts between the thrown and retracted positions; and a rotating drive cam having a drive aperture within which is disposed a pin extending from the drive bar, such that the drive cam bears on the pin to drive the drive bar.
5. The hook bolt assembly of claim 4, wherein the drive aperture is sized such that there is lost motion between the pin arid drive cam resulting in return motion of the drive cam after throwing or retracting the hook bolts not bearing on the drive pin.

-23 -
6. The hook bolt assembly of claim 4 or claim 5, wherein the drive aperture is a closed aperture.
7. The hook bolt assembly of any of claims 4 to 6, further comprising a second drive cam having a second drive aperture within which is disposed the pin, such that the second drive cam bears on the pin to drive the drive bar, wherein the second drive cam rotates independently of the first drive cain.
8. The hook bolt assembly of claim 7, wherein the second aperture is sized such that there is lost motion between the pin and second drive cam resulting in return motion of the second drive cam after throwing or retracting the hook bolts not bearing on the drive pin.
9. The hook bolt assembly of any of claims 4 to 8, further comprising a slide plate moveable between a first position in which rotation of the drive cam is restrained, and a second position in which rotation of the drive cam is free, the slide plate being biased towards the first position.
10. The hook bolt assembly of claim 9, further comprising a locking cam arranged to drive the slide plate towards the second position.
11. The hook bolt assembly of claim 9 or claim 10, further comprising a second slide plate rnoveable between a first position in which rotation of the second drive cam is restrained, and a second position in which rotation of the second drive cam is free, the second slide plate being biased towards the first position.

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12. The hook bolt assembly of claim 11, further comprising a second locking cam arranged to drive the second slide plate towards the second position.
13. The hook bolt assembly of any of claims 10 to 12, further comprising at least one key cylinder arranged to rotate the locking cam under operation of a matching key.
14. The hook bolt assembly of claim 13, comprising two key cylinders, the first arranged to rotate the first locking cam, and the second arranged to rotate the second locking cam.
15. The hook bolt assembly of any of claims 9 to 14, wherein at least one of the drive cams has a boss which locates in an aperture of the first or second slide plate.
16. The hook bolt assembly of claim 16, wherein the drive aperture of at least one of the slide plates is a slot with two parallel surfaces, the boss of the at least one drive cam having two parallel surfaces, and when the slide plate is at a first position, the boss is at least in part within the slot and the parallel surfaces of the slide plate restrain movement of the boss.
17. The hook bolt assembly of claim 15 or claim 16, wherein the aperture of at least one of the slide plates has an arcuate surface, the boss of the at least one drive cam also has an arcuate surface, and when the drive cam is rotated the boss rotates freely within the arcuate surface of the slide plate.

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18. The hook bolt assembly of any of claims 4 to l7, wherein the drive aperture of the drive cam is elongate in a direction orthogonal to the radius of the cam.
19. The hook bolt assembly of any of claims 4 to 18, wherein the drive cam comprises a hole for receiving a spindle for rotationally driving the drive cam.
20. The hook bolt assembly of any of claims 4 to 19, wherein there are two hook bolts, one coupled to each end of the drive bar.
21. The hook bolt assembly of any of claims 4 to 20, wherein rotation of the at least one drive cam in a first direction throws the hook bolts, and rotation of the at least one drive cam in a second direction retracts the bolts.
22. The hook bolt assembly of any of claims 4 to 21, wherein the at least one drive cam is biased such that after rotation the drive cam returns to its position before rotation.
23. The hook bolt assembly of any of claims 9 to 22, wherein the slide plate is biased by a leaf spring.
24. The hook bolt assembly of any of claims 4 to 23, further comprising a biasing arm coupled to the drive bar, the biasing arm biasing the drive bar to urge the hook bolts towards the thrown or retracted position.

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25. A hook bolt system, comprising the hook bolt assembly of any of claims 4 to 24, and further comprising a keeper arranged to receive the hook bolts.
26. The hook bolt system of claim 25, further comprising a gate within a frame, the hook bolt assembly attached to the gate and arranged to secure the gate when the hook bolts are thrown into the keeper.
27. The hook bolt system of claim 26 wherein the gate is the extendable gate of any of claims 1 to 3.
28. A hook bolt assembly substantially as herein described with reference to figures 2 to 8 of the accompanying drawings.
29. A hook bolt system including an extendable gate substantially as herein described with reference to the accompanying drawings.319917, M. MDE