Apparatus for converting motion

Abstract

An assembly for converting motion comprises a first arm rotatable about a first fixed pivot; a second arm rotatable about a second fixed pivot, the second fixed pivot spaced apart from the first fixed pivot; a third arm pivotably connected to the second arm; a fourth arm pivotably connected at a first position thereon to the first arm and pivotably connected at a second position thereon spaced apart from the first position thereon to the third arm; a connecting arm extending between the first arm and the second arm, the connecting arm pivotably connected to the first arm and pivotably connected to the second arm; and a support arm pivotably connected to the fourth arm.

Claims

1. An assembly for converting motion, the assembly moveable between a retracted position and an extended position, the assembly comprising: a first arm rotatable at a first position on the first arm about a first fixed pivot; a second arm rotatable at a first position on the second arm about a second fixed pivot, the second fixed pivot spaced apart from the first fixed pivot; wherein the first and second fixed pivots are fixed in relation to one another; a third arm pivotably connected by a direct pivot connection comprising a pivot pin or axle at a first position on the third arm to the second arm at a second position on the second arm, the second position on the second arm spaced apart a fixed distance from the first position on the second arm; a fourth arm pivotably connected by a direct pivot connection comprising a pivot pin or axle at a first position on the fourth arm to a second position on the first arm spaced apart a fixed distance from the first position on the first arm and pivotably connected at a second position on the fourth arm spaced apart from the first position on the fourth arm to the third arm at a second position on the third arm spaced apart from the first position on the third arm; a connecting arm extending between the first arm and the second arm, the connecting arm pivotably connected by a direct pivot connection comprising a pivot pin or axle to a third position on the first arm disposed between the first and second positions on the first arm and pivotably connected by a direct pivot connection comprising a pivot pin or axle to a third position on the second arm; and a support arm pivotably connected by a direct pivot connection comprising a pivot pin or axle at a first position on the support arm to a third position on the fourth arm, the third position on the fourth arm being spaced from the first and second positions on the fourth arm and beyond the second position in a direction from the first position on the fourth arm to the second position on the fourth arm.

2. The assembly according to claim 1, wherein the length of the first arm is no greater than the distance between the first and second fixed pivots.

3. The assembly according to claim 1, wherein the length of the second arm is no greater than the distance between the first and second fixed pivots.

4. The assembly according to claim 1, wherein the length of the first and second arms is substantially the same.

5. The assembly according to claim 1, wherein the lengths of the first, second and third arms are substantially the same.

6. The assembly according to claim 1, wherein the third position on the second arm coincides with the second position on the second atm, such that the connecting arm is connected to both the second and third arms.

7. The assembly according to claim 1, further comprising a second support arm, the second support arm being pivotably connected at a first position on the second support arm to the support arm at a second position on the support arm, the second position on the support arm being spaced from the first position on the support arm.

8. The assembly according to claim 7, further comprising a third support arm, the third support arm pivotably connected at a first position on the third support atm to a second position on the second support arm.

9. The assembly according to claim 8, further comprising a fourth support arm, the fourth support arm pivotably connected at a first position on the fourth support arm to a second position on the third support arm.

10. The assembly according to claim 1, further comprising a fifth arm, the fifth arm pivotably connected at a first position on the fifth arm to the second arm at a fourth position on the second arm.

11. The assembly according to claim 10, further comprising a sixth arm, the sixth arm pivotably connected at a first position on the sixth arm to a second position on the fifth arm.

12. The assembly according to claim 11, wherein in the extended position the fifth and sixth arms extend in a substantially straight line.

13. The assembly according to claim 11, further comprising a supporting arm, the supporting arm pivotably connected at a first position on the supporting arm to the sixth arm at a third position on the sixth arm.

14. The assembly according to claim 10, further comprising a second connecting arm, the second connecting arm pivotably connected at a first position on the second connecting arm to the first arm at a fourth position on the first arm, and at a second position on the second connecting arm to the fifth arm at a third position on the fifth arm.

15. The assembly according to claim 14, further comprising a third connecting arm, the third connecting arm pivotably connected at a first position on the third connecting arm to the third arm at a third position on the third arm, and at a second position on the third connecting arm to the sixth arm at a second position on the sixth arm.

16. The assembly according to claim 1, wherein the movement of the third arm is limited to confine a point on the third arm to move in a straight line.

Description

(1) The principles and operation of the assembly of the present invention will be further explained by reference to the accompanying drawings, in which:

(2) FIG. 1 is a simplified diagrammatical representation of an assembly according to the present invention in the extended position;

(3) FIG. 2a is a side view of the assembly of one embodiment of the present invention in a retracted position;

(4) FIG. 2b is a side view of the assembly of FIG. 2a in a first partially extended position;

(5) FIG. 2c is a side view of the assembly of FIG. 2a in a second partially extended position;

(6) FIG. 2d is a side view of the assembly of FIG. 2a in a third partially extended position;

(7) FIG. 2e is a side view of the assembly of FIG. 2a in a fourth partially extended position;

(8) FIG. 2f is a side view of the assembly of FIG. 2a in an extended position;

(9) FIGS. 3a to 3f are perspective views of the assembly in the positions from the retracted position to the extended position and corresponding to FIGS. 2a to 2f;

(10) FIG. 4 is a simplified diagrammatical representation of an assembly according to a further embodiment of the present invention in the extended position;

(11) FIG. 5 is a simplified diagrammatical representation of an assembly according to a still further embodiment of the present invention in the extended position;

(12) FIG. 6a is a side view of the assembly of the assembly of FIG. 5 in a retracted position;

(13) FIG. 6b is a side view of the assembly of FIG. 6a in a first partially extended position;

(14) FIG. 6c is a side view of the assembly of FIG. 6a in a second partially extended position;

(15) FIG. 6d is a side view of the assembly of FIG. 6a in a third partially extended position;

(16) FIG. 6e is a side view of the assembly of FIG. 6a in a fourth partially extended position;

(17) FIG. 6f is a side view of the assembly of FIG. 6a in an extended position;

(18) FIGS. 7a to 7f are perspective views of the assembly in the positions from the retracted position to the extended position and corresponding to FIGS. 6a to 6f;

(19) FIGS. 8a to 8f are side views of the assembly of FIGS. 2a to 2f in an inverted orientation in positions from the retracted position to the extended position;

(20) FIGS. 9a to 9f are side views of the assembly of FIGS. 2a to 2f employed in an expandable seating assembly in positions from the retracted position to the extended position;

(21) FIGS. 10a to 10f are perspective views of the seating assembly of FIGS. 9a to 9f in the positions from the retracted position to the extended position and corresponding to FIGS. 9a to 9f;

(22) FIG. 11 is simplified diagrammatical representation of an assembly according to a further embodiment of the present invention in the extended position; and

(23) FIGS. 12a and 12b are perspective views of a bridge assembly comprising the assembly of FIG. 11.

(24) Turning to FIG. 1, there is shown a diagrammatical representation of an assembly of one embodiment of the present invention, generally indicated as 2. The assembly 2 is shown mounted to a fixed structure at a first fixed pivot 4 and a second fixed pivot 6. The fixed pivots 4, 6 are spaced apart and are fixed in relation to one another. In the embodiment shown in FIG. 1, the first and second fixed pivots are arranged on a vertical line.

(25) A first arm 8 is pivotally connected at a first position at one end to the first fixed pivot 4. A second arm 10 is pivotally connected at a first position at one end to the second fixed pivot 6. A third arm 12 is mounted at one end by a pivot connection 14 at the second end of the second arm 10.

(26) A fourth arm 16 is mounted at one end by a pivot connection 18 at the second end of the first arm 8. The fourth arm 16 is mounted at a second position thereon by a pivot connection 20 to the third arm at a second position on the third arm 12.

(27) A connecting arm 22 is mounted at one end by a pivot connection 24 to the first arm 8 at a third position on the first arm spaced from both the first and second positions thereon. The second end of the connecting arm 22 is mounted by a pivot connection to the second arm 10. In the embodiment shown in FIG. 1, the pivot connection between the connecting arm 22 and the second arm 10 is at the first end of the second arm and coincides with the pivot connection 14, such that the connecting arm is pivotally connected to both the second arm 10 and the third arm 12.

(28) As shown in FIG. 1, the fourth arm 16 extends in the distal direction (that is to the right in FIG. 1) beyond the third arm 12. The assembly of FIG. 1 further comprises a support arm 26. The support arm 26 is connected by a pivot connection 28 at one end thereof to the distal end of the fourth arm 16.

(29) The pivot connections between the arms may be formed by any suitable means, for example by pins extending through holes in the arms being pivotally joined.

(30) Movement of the first arm 8 about the first fixed pivot 4 and the second arm 10 about the second fixed pivot 6 causes the third arm 12 to move such that a point A on the third arm moves between a retracted position and an extended position. In moving between the retracted and extended positions, the point A describes a substantially straight line.

(31) A component to be moved can be connected to either or both the third arm 12 and the support arm 26. In particular, the point A on the third arm 12 and a point B on the support arm 26 may be connected, for example by a component to be moved, with the result that the points A and B lie on a straight line extending from the second fixed pivot 6. In the embodiment shown in FIG. 1, the line joining points A and B extends perpendicular to the line joining the first and second fixed pivots 4, 6.

(32) Turning now to FIGS. 2a to 2f, there is shown a sequence of drawings of a side view of an assembly of the embodiment of FIG. 1 in positions between a retracted position, shown in FIG. 2a, and an extended position shown in FIG. 2f. The components of the assembly of FIGS. 2a to 2g have been identified using the same reference numerals as used in relation to FIG. 1 and discussed above.

(33) The assembly in FIGS. 2a to 2f is supporting and moving a component 50 comprising three hingedly connected members 52, 54 and 56. The component 50 may be a support structure for providing support to one or more items to be moved and supported, with the items being connected to the component 50. Alternatively, the component 50 may itself be formed by the item to be moved and supported.

(34) The sequence of views of FIGS. 2a to 2f are shown in perspective view in FIGS. 3a to 3f.

(35) Referring to FIG. 2a, the assembly 2 is shown in a retracted position held within a frame 102, providing the mounting for the fixed pivots 4 and 6. The arms of the assembly are formed to lie within one another when in the retracted position of FIG. 2a. The form of the arms is shown in FIGS. 3a to 3f. In particular, it can be seen that the first, second and third arms and the support arm are each formed of a plurality of parallel arm members, allowing the arms to lie within one another in the retracted position. In this way, the assembly 2 occupies the minimum amount of space when in the retracted position.

(36) The assembly 2 is shown in FIG. 2b in a first partially extended position, with the third arm 12 having moved away from the fixed pivots 4, 6 and the frame 102, that is to the left as viewed in the figure. In the movement from the position of FIG. 2a to the position of FIG. 2b, the point A at the end of the third arm 12 is following a substantially straight line.

(37) FIG. 2c shows the assembly 2 in a second partially extended position, with the third arm 12 moved further away from the fixed pivots 4, 6. Again, point A on the third arm 12 is tracing a substantially straight line from its position in the retracted position of FIG. 2a.

(38) Similarly, FIGS. 2d and 2e shows the assembly 2 in third and fourth partially extended positions, with the third arm 12 still further from the fixed pivots 4, 6 and the point A on the third arm 12 still following a straight line path.

(39) FIG. 2f shows the assembly 2 in its extended position, that is with the third arm 12 at a position where the point A is at the end of the straight line path followed from the retracted position. The extended position is shown in perspective in FIG. 3f. As can be seen, the component 50 extends in a straight line from the second fixed pivot 6.

(40) FIGS. 2a to 2f and 3a to 3f show one example of a drive system to operate the assembly. In the embodiment shown in FIGS. 2a to 2f and 3a to 3f, the movement of the arms is driven by a drive mechanism, generally indicated as 110. The drive mechanism 110 comprises a motor 112 rotating a screw (not visible in the figures) extending within the frame 102. A slider 114 is moveable on the frame 102 and is connected to the screw, such that rotation of the screw by the motor moves the slider 114 up or down the frame 102. Drive arms 106 are pivotably connected at one end to the slider 114 and pivotably connected at the other end to the member 52. In the retracted position, shown in FIGS. 2a and 3a, the slider is positioned in the upper portion of the frame 102. Operation of the motor 112 draws the slider 114 downwards, as viewed in the figures, causing the drive arms 106 to urge the member 52 outwards, away from the frame 102. Reversing the direction of rotation of the motor 112 and the screw raised the slider 114 and draws the assembly into the retracted position.

(41) Referring to FIG. 4, there is shown a further embodiment of an assembly according to the present invention. The assembly 202 is shown mounted to a fixed structure at a first fixed pivot 204 and a second fixed pivot 206. The fixed pivots 204, 206 are spaced apart and are fixed in relation to one another. In the embodiment shown in FIG. 4, the first and second fixed pivots are arranged on a vertical line.

(42) A first arm 208 is pivotally connected at a first position at one end to the first fixed pivot 204. A second arm 210 is pivotally connected at a first position at one end to the second fixed pivot 206. A third arm 212 is mounted at one end by a pivot connection 214 at the second end of the second arm 210.

(43) A fourth arm 216 is mounted at one end by a pivot connection 218 at the second end of the first arm 208. The fourth arm 216 is mounted at a second position thereon by a pivot connection 220 to the third arm at a second position on the third arm 212.

(44) A connecting arm 222 is mounted at one end by a pivot connection 224 to the first arm 208 at a third position on the first arm spaced from both the first and second positions thereon. The second end of the connecting arm 222 is mounted by a pivot connection to the second arm 210. In the embodiment shown in FIG. 4, the pivot connection between the connecting arm 222 and the second arm 210 is at the first end of the second arm and coincides with the pivot connection 214, such that the connecting arm is pivotally connected to both the second arm 210 and the third arm 212.

(45) As shown in FIG. 4, the fourth arm 216 extends in the distal direction (that is to the right in FIG. 4) beyond the third arm 212. The assembly further comprises a first support arm 226. The first support arm 226 is connected by a pivot connection 228 at one end thereof to the distal end of the fourth arm 216. A second support arm 230 is connected at one end by a pivot connection 232 to the second end of the first support arm 226.

(46) The pivot connections between the arms may be formed by any suitable means, for example by pins extending through holes in the arms being pivotally joined.

(47) Movement of the first arm 208 about the first fixed pivot 204 and the second arm 210 about the second fixed pivot 206 causes the third arm 212 to move such that a point A on the third arm moves between a retracted position and an extended position. In moving between the retracted and extended positions, the point A describes a substantially straight line.

(48) A component to be moved can be connected to one or more of the third arm 212, the first support arm 226 and the second support arm 230. In particular, the point A on the third arm 212, a point B on the first support arm 226 and a point C on the second support arm 230 may be connected, for example by a component to be moved, with the result that the points A, B and C lie on a straight line extending from the second fixed pivot 206. In the embodiment shown in FIG. 4, the line joining points A, B and C extends perpendicular to the line joining the first and second fixed pivots 204, 206.

(49) Turning to FIG. 5, there is shown a diagrammatical representation of an assembly of a still further embodiment of the present invention, generally indicated as 302. The assembly 302 is shown mounted to a fixed structure at a first fixed pivot 304 and a second fixed pivot 306. The fixed pivots 304, 306 are spaced apart and are fixed in relation to one another. In the embodiment shown in FIG. 5, the first and second fixed pivots are arranged on a vertical line.

(50) A first arm 308 is pivotally connected at a first position at one end to the first fixed pivot 304. A second arm 310 is pivotally connected at a first position at one end to the second fixed pivot 306. A third arm 312 is mounted at one end by a pivot connection 314 at the second end of the second arm 310.

(51) A fourth arm 316 is mounted at one end by a pivot connection 318 at the second end of the first arm 308. The fourth arm 316 is mounted at a second position thereon by a pivot connection 320 to the third arm at a second position on the third arm 312.

(52) A first connecting arm 322 is mounted at one end by a pivot connection 324 to the first arm 308 at a third position on the first arm spaced from both the first and second positions thereon. The second end of the first connecting arm 322 is mounted by a pivot connection to the second arm 310. In the embodiment shown in FIG. 5, the pivot connection between the first connecting arm 322 and the second arm 310 is at the first end of the second arm and coincides with the pivot connection 314, such that the first connecting arm is pivotally connected to both the second arm 310 and the third arm 312.

(53) The fourth arm 316 extends in the distal direction (that is to the right in FIG. 5) beyond the third arm 312. The assembly further comprises a first support arm 326. The first support arm 326 is connected by a pivot connection 328 at one end thereof to the distal end of the fourth arm 316.

(54) A fifth arm 340 is connected at one end to the pivot connection 314 and extends in a distal direction from the first connecting arm 322. The second end of the fifth arm 340 is connected by a pivot connection 342 to a sixth arm 344 that extends further in the distal direction.

(55) A second connecting arm 346 extends from the pivot connection 318 on the first arm 308 to a pivot connection 347 on the fifth arm 340.

(56) Movement of the first arm 308 about the first fixed pivot 304 and the second arm 310 about the second fixed pivot 306 causes the third arm 312 to move such that a point A on the third arm moves between a retracted position and an extended position. In moving between the retracted and extended positions, the point A describes a substantially straight line.

(57) A third connecting arm 348 is pivotally connected to and extends from the point A on the third arm 312. The third connecting arm 348 is connected to a pivot connection 350 on the distal end of the sixth arm 344.

(58) Finally, a supporting arm 352 extends from the pivot connection 350 on the sixth arm 344.

(59) The pivot connections between the arms may be formed by any suitable means, for example by pins extending through holes in the arms being pivotally joined.

(60) A component to be moved can be connected to one or more of the third arm 312, the first support arm 326 and the supporting arm 352. In particular, the point A on the third arm 312, a point B on the first support arm 326 and a point C on the supporting arm 352 may be connected, for example by a component to be moved, with the result that the points A, B and C lie on a straight line extending from the second fixed pivot 306. In the embodiment shown in FIG. 5, the line joining points A, B and C extends perpendicular to the line joining the first and second fixed pivots 304, 306.

(61) Turning now to FIGS. 6a to 6f, there is shown a sequence of drawings of a side view of an assembly of the embodiment of FIG. 5 in positions between a retracted position, shown in FIG. 6a, and an extended position shown in FIG. 6f. The components of the assembly of FIGS. 6a to 6g have been identified using the same reference numerals as used in relation to FIG. 5 and discussed above.

(62) The assembly in FIGS. 6a to 6f is supporting and moving a component 380 comprising four hingedly connected members 382, 384, 386 and 388. The component 380 may be a support structure for providing support to one or more items to be moved and supported, with the items being connected to the component 380. Alternatively, the component 380 may itself be formed by the item to be moved and supported.

(63) The sequence of views of FIGS. 6a to 6f are shown in perspective view in FIGS. 7a to 7f.

(64) Referring to FIG. 6a, the assembly 302 is shown in a retracted position held within a frame 402, providing the mounting for the fixed pivots 304 and 306. The arms of the assembly are formed to lie within one another when in the retracted position of FIG. 6a. The form of the arms is shown in FIGS. 7a to 7f. In particular, it can be seen that the first, second, third, fifth and sixth arms and the support arms are each formed of a plurality of parallel arm members, allowing the arms to lie within one another in the retracted position. In this way, the assembly 302 occupies the minimum amount of space when in the retracted position.

(65) The assembly 302 is shown in FIG. 6b in a first partially extended position, with the third arm 312 having moved away from the fixed pivots 304, 306 and the frame 402, that is to the left as viewed in the figure. In the movement from the position of FIG. 6a to the position of FIG. 6b, the point A at the end of the third arm 312 is following a substantially straight line.

(66) FIG. 6c shows the assembly 302 in a second partially extended position, with the third arm 312 moved further away from the fixed pivots 304, 306. Again, the point A on the third arm 312 is tracing a substantially straight line from its position in the retracted position of FIG. 6a.

(67) Similarly, FIGS. 6d and 6e shows the assembly 302 in third and fourth partially extended positions, with the third arm 312 still further from the fixed pivots 304, 306 and the point A on the third arm 312 still following a straight line path.

(68) FIG. 6f shows the assembly 302 in its extended position, that is with the third arm 312 at a position where the point A is at the end of the straight line path followed from the retracted position. The extended position is shown in perspective in FIG. 7f. As can be seen, the component 380 extends in a straight line from the second fixed pivot 306, with the members 382, 384, 386 and 388 unfolded.

(69) The assembly of FIGS. 6a to 6f and 7a to 7f employs a drive mechanism having the same general configuration and mode of operation as described above with respect to FIGS. 2a to 2f and 3a to 3f.

(70) FIGS. 8a to 8f show the sequence of positions of the assembly of FIGS. 2a to 2f in an inverted orientation. The components of the assembly common to the embodiment of FIGS. 2a to 2f have been identified using the same reference numerals and are as described above.

(71) In this arrangement, the assembly is being used to extend and raise a component. The assembly arranged in this manner may be used to support a range of components, for example an expandable roof assembly or an expandable terrace. In the embodiment shown, the second arm 10 has been extended beyond the pivot connection 14 to provide additional support for the assembly and component. A wheel 76 is provided on the distal end of the extended second arm 10 and contacts the ground to provide additional support for the assembly and the component being moved.

(72) The assembly of the present invention may be used to deploy and support a wide range of components and structures. By way of example, FIGS. 9a to 9f show a side view of the assembly of FIG. 2a in an expandable seating assembly for use in a stadium, theatre, hall or the like.

(73) The expandable seating assembly, generally indicated as 802, comprises a plurality of seating units 804 supported on a pair of spaced apart, parallel assemblies 2 of the configuration of FIGS. 2a to 2f, as described hereinbefore. To provide additional support and facilitate moving the assembly, a wheel 86 is provided at the point A on the third arm 12.

(74) As can be seen in FIGS. 9a to 9f, the seating units 804 are mounted on the arms of the assemblies 2 so as to pivot and be foldable.

(75) Perspective views of the expandable seating assembly 802 corresponding to those of FIGS. 9a to 9f are shown in FIGS. 10a to 10f.

(76) Referring to FIG. 11, there is shown a further embodiment of an assembly according to the present invention. The assembly 902 is shown mounted to a fixed structure at a first fixed pivot 904 and a second fixed pivot 906. The fixed pivots 904, 906 are spaced apart and are fixed in relation to one another. In the embodiment shown in FIG. 11, the first and second fixed pivots are arranged on a vertical line.

(77) A first arm 908 is pivotally connected at a first position at one end to the first fixed pivot 904. A second arm 910 is pivotally connected at a first position at one end to the second fixed pivot 906. A third arm 912 is mounted at one end by a pivot connection 914 at the second end of the second arm 910.

(78) A fourth arm 916 is mounted at one end by a pivot connection 918 at the second end of the first arm 908. The fourth arm 916 is mounted at a second position thereon by a pivot connection 920 to the third arm at a second position on the third arm 912.

(79) A connecting arm 922 is mounted at one end by a pivot connection 924 to the first arm 908 at a third position on the first arm spaced from both the first and second positions thereon. The second end of the connecting arm 922 is mounted by a pivot connection to the second arm 910. In the embodiment shown in FIG. 11, the pivot connection between the connecting arm 922 and the second arm 910 is at the first end of the second arm and coincides with the pivot connection 914, such that the connecting arm is pivotally connected to both the second arm 910 and the third arm 912.

(80) As shown in FIG. 11, the fourth arm 916 extends in the distal direction (that is to the right in FIG. 10) beyond the third arm 912. The assembly further comprises a first support arm 926. The first support arm 926 is connected by a pivot connection 928 at one end thereof to the distal end of the fourth arm 916. A second support arm 930 is connected at one end by a pivot connection 932 to the first support arm 926, the pivot connection 932 spaced from the pivot connection 928. A third support arm 940 is connected by a pivot connect 942 at one thereof to the distal end of the second support arm 930. A fourth support arm 944 is connected at one end by a pivot connection 946 to the distal end of the third support arm 940.

(81) The pivot connections between the arms may be formed by any suitable means, for example by pins extending through holes in the arms being pivotally joined.

(82) Movement of the first arm 908 about the first fixed pivot 904 and the second arm 910 about the second fixed pivot 906 causes the third arm 912 to move such that a point A on the third arm moves between a retracted position and an extended position. In moving between the retracted and extended positions, the point A describes a substantially straight line.

(83) A component to be moved can be connected to one or more of the third arm 912, the first support arm 926, the third support arm 940, and/or the fourth support arm 944. In particular, the point A on the third arm 912, a point B on the first support arm 926, a point C on the third support arm 940 and a point D on the fourth support arm 944 may be connected, for example by a component to be moved, with the result that the points A, B, C and D lie on a straight line extending from the second fixed pivot 906. In the embodiment shown in FIG. 11, the line joining the points A, B, C and D extends perpendicular to the line joining the first and second fixed pivots 904, 906.

(84) Finally, turning to FIGS. 12a and 12b, there is shown a folding bridge assembly, generally indicated as 960. The bridge assembly 960 is shown in FIG. 12a in a partially extended position and in FIG. 12b in a fully extended position.

(85) The bridge assembly 960 comprises a generally vertical support assembly 962 in the form of a frame with an opening therethrough to allow access to and from the bridge. The bridge assembly 960 further comprises a plurality of bridge deck components 964a to 964d. The deck components are hingedly attached to the or each adjacent deck component, with the deck component 964a adjacent the support assembly 962 also being hingedly attached to the support assembly.

(86) The deck components 964a to 964d are supported and moved by a pair of support assemblies 966a, 966b each of the general configuration shown in FIG. 11 and described in detail above. The support assemblies 966a, 966b are mounted on opposing sides of the deck components 964a to 964d, as shown in FIGS. 12a and 12b. The deck components 964a to 964d are pivotally connected to the points A, B, C and D on the assembly shown in FIG. 11 and described above.

(87) A foldable counterbalance assembly 968 is mounted to the support assembly 962 and extends from the side opposite to that of the deck components 964a to 964d.

(88) The bridge assembly 960 is portable and may be transported to a required location, for example by a suitably sized lorry. In operation, the bridge assembly 960 is placed at the required location. The deck components 964a to 964d are deployed by operation of the support assemblies 966a, 966a and being unfolded from a retracted position to the extended position shown in FIG. 12b, to form the bridge.