IMPROVEMENTS IN OR RELATING TO BRIDGES

Abstract

A deployable bridge carried on or by a vehicle, the bridge being movable from a stowed position to a deployed position, in which a bridge launch mechanism is provided and has only a single actuator.

Claims

1-16. (canceled)

17. A launch and recovery mechanism for a deployable bridge, wherein said mechanism has only a single actuator, said single actuator powers and controls bridge deployment using a launch sequence, in which bridge recovery is powered and controlled by said single actuator, and in which bridge recovery is achieved by the reverse of said launch sequence.

18. A launch and recovery mechanism as claimed in claim 17, in which the mechanism comprises a stowage pallet.

19. A launch and recovery mechanism as claimed in claim 18, in which the stowage pallet is pivotably connectable to a vehicle so as to be rotatable about a single point and the bridge is pivotably connected to the pallet.

20. A launch and recovery mechanism as claimed in claim 17, said launch and recovery mechanism being provided on or by a vehicle.

21. A launch and recovery mechanism as claimed in claim 17, said launch and recovery mechanism being provided on or by a trailer.

22. A launch and recovery mechanism as claimed in claim 17, wherein said mechanism has only a single degree of freedom and achieves bridge launch with said single actuator which does not require a sequencing control mechanism.

23. A launch and recovery mechanism as claimed in claim 17, in which said single actuator is a linear actuator

24. A launch and recovery mechanism as claimed in claim 23, in which said linear actuator comprises long powered leadscrew.

25. A launch and recovery mechanism as claimed in claim 17, further comprising a bridge interface probe.

26. A mobile bridge system comprising a deployable bridge, the bridge being movable from a stowed position to a deployed position, the system comprises a bridge launch and recovery mechanism, the launch and recovery mechanism consisting of a single actuator, said single actuator powers and controls deployment of the bridge using a launch sequence, and bridge recovery is powered and controlled by the single actuator, and in which bridge recovery is achieved by the reverse of said launch sequence.

27. A mobile bridge system as claimed in claim 26, in which the mechanism is provided on or by a vehicle.

28. A mobile bridge system as claimed in claim 27, in which the vehicle is a military vehicle.

29. A mobile bridge system as claimed in claim 27, in which the vehicle is a trailer which can be towed and/or pushed by a powered vehicle.

30. A mobile bridge system as claimed in claim 26, in which the mechanism comprises a stowage pallet.

31. A mobile bridge system as claimed in claim 30, in which the stowage pallet is pivotably connectable to a vehicle so as to be rotatable about a single point and the bridge is pivotably connected to the pallet.

32. A mobile bridge system as claimed in claim 26, in which the bridge comprises two or more bridge sections.

33. A mobile bridge system as claimed in claim 26, in which the or at least one bridge section is inverted during deployment.

34. A mobile bridge system as claimed in claim 26, in which the or at least one of the sections is stored upside down and flipped the right way up during deployment.

35. A method of deploying a bridge from a vehicle or a vehicle trailer, comprising the steps of: i) providing a mobile bridge system comprising a deployable bridge, the bridge being movable from a stowed position to a deployed position, the mobile bridge system comprises a bridge launch and recovery mechanism, the bridge launch and recovery mechanism having only a single actuator, said single actuator powers and controls deployment of the bridge using a launch sequence; ii) deploying said bridge across an obstacle; and iii) detaching the vehicle from the deployed bridge and moving the vehicle or vehicle trailer aside to allow traffic to pass.

36. A method as claimed in claim 35, in which once all of the traffic has crossed, the vehicle crosses the deployable bridge itself and reattaches to said deployable bridge on the other side, in which bridge recovery is powered and controlled by said single actuator, and in which bridge recovery is achieved by the reverse of said launch sequence.

Description

DEVICE OPERATION

[0085] FIG. 1 shows the bridge folded and stowed on the transporting trailer. The bridge is impaled onto a bridge interface probe (15) which is a standard military bridging feature and is supported on a bridge support (11). The vehicle (6) and trailer (9) chassis' both sit on sprung suspensions which connect to wheels/tyres (4) & (5).

[0086] FIG. 2 shows the start of the bridge launch procedure. A single linear actuator takes the form of a long powered leadscrew (20) which in this embodiment runs horizontally and the whole length of the trailer and is an integral part of the trailer chassis (9). The pivot joint 13 is connected to the lead screw so can be moved the whole length of the trailerfrom front to back of the trailer chassis or from left to right in these figures. As the leadscrew moves the pivot (13) to the right, it pushes the connecting link (12) rearwards. This causes the bridge stowage pallet (10), Bridge (16, 17, 18) and the bridge interface probe (15) to pivot around the joint (3). Referring back to FIG. 1 briefly, it is significant that the line drawn along the axis of the connecting link (21) is below the pivot joint (I) so the connecting link is trying to rotate the bridge interface probe anticlockwise. The pivot (14) is arranged to bare down upon the bridge stowage pallet so that it cannot rotate anticlockwise from this location so the whole assembly is forced to rotate around pivot (3) and lift up as shown in FIG. 2.

[0087] In all the subsequence figures showing the launching sequence the leadscrew continues to move the pivot (13) to the right.

[0088] In FIG. 2, even after the line along the connecting rod axis (22) passes above the pivot (I) the mechanism continues to rotate as an assembly (bridge, bridge pallet, interface probe) about pivot (1) because the bridge mass and centre of gravity (24) provides sufficient anticlockwise moment to exceed the clockwise moment provided by the connecting link.

[0089] In FIG. 3 the stowage pallet has rotated sufficiently that it's extreme end touches the ground and becomes a supporting foot. The stowage pallet cannot rotate much beyond this point.

[0090] In FIG. 4 the bridge and interface probe start to rotate about pivot 1 because the stowage pallet is prevented from further rotation. The bridge lifts off its support (11).

[0091] In FIG. 5 the bridge is starting to unfold. This might be caused by a connected mechanical system (discussed in optional features below), by a hydraulic system (common in service) or by some other means. The bridge C of G is still to the left of the supporting foot, the connecting rod is in compression pushing the bridge up and the weight of the bridge is bearing down on the supporting foot and on the trailer.

[0092] In FIG. 6 the bridge centre of gravity (23) has moved to the right of the supporting foot. The connecting rod is now in tension so it is lifting the trailer chassis. FIG. 5 showed the trailer suspension compressed (the wheels are above the chassis lower edge), in FIG. 6 the trailer suspensions have extended (the wheels are below the trailer chassis lower edge). As the bridge deploys further, there might be a danger that the trailer chassis lifts sufficiently or that the foot depresses into soft ground such that the supporting foot over rotates under the chassis. A rotation stop (19) is provided to prevent this. In FIG. 5 the stowage pallet is not quite touching the rotation stop, in FIG. 6 it is. In this design, the trailer mass can be minimised because the see-saw can be balanced by a vertical force generated at the trailer to vehicle hitch lifting the rear of the vehicle. The vehicle suspension extends accordingly (the vehicle rear wheel can be seen extended slightly from the vehicle chassis.

[0093] FIG. 7 shows the same situation progressed a little further. The rear of the vehicle is lifting more and its rear suspension is extending further. If the vehicle is very lightweight its rear end may be lifted clear of the ground and the see-saw may collapse. However, by adding chain (7) the possibility of this happening can be avoided.

[0094] FIG. 8 shows the most highly loaded position with the bridge just about to land. In this position the chain (7) has been pulled tight so the see-saw is trying to lift the whole mass of the vehicle, not just it's rear end.

[0095] FIG. 9 shows the bridge on the ground (or crossing a gap). The mechanism is no longer supporting the bridge and has unloaded. Vehicle and trailer suspensions has returned to their normal positions and the chain (7) is slack. The vehicle and trailer combination can now move forwards (to the left in the figure) which will disengage the interface probe from the bridge.

[0096] Bridge recovery is achieved by reverse of bridge launch sequence.

[0097] Optional Features

[0098] The system could be fitted directly onto a vehicle rather than on a trailer

[0099] The chain (7) may not be required if the vehicle is sufficiently heavy.

[0100] The system can launch single piece bridges or two (or more) piece scissor bridges.

[0101] When launching scissor bridges (as shown in this embodiment), the bridge opening could preferably be powered and controlled by the single actuator of the bridge launch mechanism. Scissor bridges currently in service typically have an integral hydraulic cylinder used to open and close them. This is connected to the bridge launching vehicle by a quick connect/disconnect hydraulic hose connection. During the launch, the launching vehicle supplies hydraulic oil to the bridge cylinder which extends or contracts and possibly via cables and pulleys opens the bridge from its folded arrangement to its deployed shape. This has several disadvantages. The hydraulic connections which are made and broken during each launch/recover must be kept clean to avoid contamination of the oil which can damage hydraulic systems leading to their failure. The supply of the oil needs to be timed accurately to ensure the bridge opens/closes at the correct time. Numerous vehicles may launch numerous bridges which will result in cross contamination of oil present in the vehicles and the bridges. Hydraulic oil need periodic renewal and this cross contamination makes it impossible to know when this should occur. Hydraulic oil viscosity varies with temperature and can be excessively viscous at very low temperature.

[0102] A warm vehicle recovering a cold bridge will have to circulate oil of very different temperature and viscosity which may require more complex valves or controls. Thus an optional addition to the single actuator bridge launch mechanism described here is a scissor bridge with integral leadscrew instead of the traditional hydraulic cylinder. This leadscrew may be powered via a direct mechanical power take of (PTO) drive from the launching mechanism. The whole system is thus mechanically geared together and the timing of the sequence is thus fixed to the operation of the single powering actuator.

[0103] Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention.