CRAWLER BRIDGE

Abstract

A crawler bridge (10) having a bridge section (12) for bridging across opposite sides of a gap G. The bridge section (12) being connected to a support structure (14) which has a pair of elongate beams (16,17), that are spaced apart and generally parallel. The beams (16,17) each including leading and trailing feet (18,19). The bridge section (12) is attached to the beams (16,17) for relative movement forward and backward along the beams (16,17) and vertically up and down. The crawler bridge (10) has a first mode of operation when the leading and trailing feet 18,19 of the beams (16,17) are in engagement with a ground surface, in which the bridge section (12) is supported by the support structure (14) elevated above the ground surface and is movable forward and backward along the beams (16,17) and vertically up and down. The crawler bridge (10) has a second mode of operation when the bridge section (12) has been moved downward relative to the beams (16,17) and into engagement with a supporting surface, in which the leading and trailing feet (18,19) of the beams (16,17) are lifted away from the supporting surface and the beams (16,17) are movable forward and backward relative to the bridge section (12) and vertically up and down relative to the bridge section (12).

Claims

1. A crawler bridge having: a. a bridge section for bridging across opposite sides of a gap, b. the bridge section being connected to a support structure, c. the support structure including a pair of elongate beams that are spaced apart and generally parallel, the beams each including leading and trailing feet that extend downwardly from the beams for engagement with a ground surface, d. the bridge section being attached to the beams for relative movement forward and backward along the beams and vertically up and down relative to the beams, e. the crawler bridge having a first mode of operation when the leading and trailing feet of the beams are in engagement with a ground surface, in which the bridge section is supported by the support structure elevated above the ground surface and is movable forward and backward along the beams and vertically up and down relative to the beams, and f. the crawler bridge having a second mode of operation when the bridge section has been moved downward relative to the beams and into engagement with a supporting surface, in which the leading and trailing feet of the beams are lifted away from the supporting surface and the beams are movable forward and backward relative to the bridge section and vertically up and down relative to the bridge section.

2. A crawler bridge according to claim 1, the support structure including arms that extend from the bridge section into engagement with the beams and the arms including a drive arrangement to drive the bridge section relative to the beams.

3. (canceled)

4. (canceled)

5. (canceled)

6. (canceled)

7. A crawler bridge according to claim 2, the arms being telescopic for lifting and lowering the bridge section.

8. (canceled)

9. (canceled)

10. A crawler bridge according to claim 1, the bridge section including a deck which has an upper surface for travel over the bridge section.

11. A crawler bridge according to claim 1, the bridge section including leading and trailing feet for engagement with a ground surface.

12. (canceled)

13. A crawler bridge according to claim 1, the bridge section including a deck and rails that extend from opposite ends of the deck to overlie the ground surface on either side of a gap when the bridge section is in position bridging the gap.

14. A crawler bridge according to claim 13, the deck including a pair of rails on either side of the deck.

15. A crawler bridge according to claim 14, ends of the rails forming leading and trailing feet.

16. A crawler bridge according to claim 13, an upper surface of the deck being at generally the same level as the lower surface of the rails so that with the lower surface of the rails extending to rest on the ground surface on either side of a gap, the upper surface of the deck is close to the ground surface on either side of the gap.

17. A crawler bridge according to claim 13, sections of the rails that extend beyond the leading and trailing ends of the deck being offset from the feet of the beams.

18. A crawler bridge according to claim 13, the feet of the beams including openings to allow sections of the rails that extend beyond the leading and trailing ends of the deck to extend through the feet.

19. A crawler bridge according to claim 1, the bridge section including a plurality of beams that extend generally perpendicular to the lengthwise direction of the beams.

20. (canceled)

21. A crawler bridge according to claim 1, the bridge section being steerable.

22. A crawler bridge according to claim 21, the bridge section including a steering facility that can be brought into engagement with a ground surface to turn the crawler bridge to the left or right.

23. A crawler bridge according to claim 22, the steering facility being a steering plate that is part of or overlies a bottom or underneath of the bridge section and which engages the ground surface when the bridge section engages the ground surface.

24. A crawler bridge according to claim 23, the steering plate being engageable with the ground surface and shiftable relative to the beams, to alter the orientation of the beams to change the direction of travel of the crawler bridge.

25. A crawler bridge according to claim 1, further including a walkway.

26. (canceled)

27. A method of operating a crawler bridge according to claim 1, the method including moving the crawler bridge along a tunnel excavation by utilising the first and second modes of operation.

28. A method according to claim 27, including moving the crawler bridge towards a gap in a ground surface by successive activation of the first and second modes of operation to place the bridge section adjacent the gap, then activating the second mode of operation to traverse the beams across the gap relative to the bridge section to place the leading feet of the beams on the opposite side of the gap, then activating the first mode of operation to traverse the bridge section along the beams and to align the bridge section over the gap, then lowering the bridge section to bridge across the gap.

29. A method according to claim 28, including activating the second mode of operation to traverse the beams to position the leading and trailing feet of the beams substantially equidistantly on opposite sides of the gap.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order that the invention may be more fully understood, some embodiments will now be described with reference to the figures in which:

[0038] FIG. 1 is a perspective view from above of a crawler bridge according to one embodiment of the present invention.

[0039] FIG. 2 is a perspective view from below of the crawler bridge of FIG. 1.

[0040] FIG. 3 is a detailed view of an arm of the crawler bridge of FIG. 1.

[0041] FIG. 4 is an end view of the crawler bridge of FIG. 1.

[0042] FIG. 5 is a side view of the crawler bridge of FIG. 1.

[0043] FIGS. 6 to 11 illustrate a sequence of operation of the crawler bridge of FIG. 1 as applied to a roadway having a gap.

DETAILED DESCRIPTION OF THE DRAWINGS

[0044] FIG. 1 illustrates a crawler bridge according to one embodiment of the present invention. The crawler bridge 10 includes a bridge section 12 and a support structure 14. The support structure 14 supports the bridge section 12 as will become apparent hereinafter.

[0045] The support structure 14 includes a pair of elongate beams 16 and 17 that are formed as I-beams having upper and lower flanges connected by a central web. The beams 16 and 17 each have leading and trailing feet 18 and 19 that extend downwardly from the generally horizontal beams 16 and 17. Bottom ends of the feet 18 and 19 that are remote from the connection of the feet 18 and 19 with the beams 16 and 17 are provided for engagement with a ground surface of the tunnel, which can be a road deck or road surface for example. The designation of the feet as being leading or trailing is relevant for travel of the crawler bridge 10 in one direction. As the crawler bridge 10 can travel forward and back, the feet can be leading or trailing dependent on the direction of travel.

[0046] The bridge section 12 is attached to the beams 16 and 17 and is suspended therefrom. In FIG. 1, the bridge section 12 is suspended from the beams 16 and 17 by four arms 20 to 23, which form part of the support structure 14. As the arms 20 to 23 are identical, only the arm 20 is shown in more detail in FIG. 3. From this, it can be seen that the arm 20 connects to a box structure 24 that extends about the beam 16 and the box structure includes a sleeve 26 that accepts a post 28, which is an upper end of the arm 20. The post 28 can shift within the sleeve 26, relative to the sleeve 26 so that the sleeve and post represent a telescopic arrangement. The shifting movement is driven by a pneumatic strut 30. The post, sleeve and strut arrangement is repeated or duplicated on the opposite side of the beam 16, although it is mostly obscured in FIG. 3. The pair of struts 30 associated with each of the arms 20 to 23 provides an equal lifting or lowering load between the sleeves 26 and the posts 28.

[0047] Further evident in FIG. 3 is the upper set of rollers 32 which roll along the upper flange surface 34 of the beam 16. As shown in FIG. 4, the arms 20 to 23 further include lower rollers 36 to roll along the downwardly facing surface of the lower flange of the beams 16 and 17. The upper rollers 32 bear the major weight of the bridge section 12 in the first mode of operation where the bridge section is suspended from the beams 16 and 17 for movement along the beams, whereas the lower rollers 36 bear the major weight of the beams 16 and 17 in the second mode of operation where the beams 16 and 17 are lifted from the ground surface for movement relative to the bridge section 12.

[0048] To drive the bridge section 12 along the length of the beams 16 and 17, a pair of driven rollers 38 are associated with each of the arms 22 and 23. The rollers 38 are each driven by an electric motor 40 and the drive is by frictional engagement between the rollers 38 and the flange surface 34 of the beams 16 and 17.

[0049] To maintain separation between the arms 20 and 22, and 21 and 23, rods 42 extend between the arms on each side of the beams 16 and 17.

[0050] A bottom end of the arms 20 to 23 connects to the bridge section 12. The arms 20 to 23 extend on opposite sides of rails 46 and 48 and can connect to the rails 46 and 48 as well. The rails 46 and 48 are also formed I-beams, having top and bottom flanges connected by a central web.

[0051] The bridge deck 44 of the bridge section 12 has a continuous upper surface, formed over a series of I-beam planks 50 which are shown in the underneath view of the crawler bridge 10 of FIG. 2. The planks 50 connect to the bottom flange of the rails 46 and 48 and extend generally perpendicular to the lengthwise extent of the beams 16 and 17.

[0052] As clearly shown in FIG. 4, a pedestrian walkway 52 extends from one side of the bridge section 12 and includes an upstanding handrail, fence or barrier 54.

[0053] It will be understood from the foregoing description, that by virtue of the arms 20 to 23 being movable along or relative to the beams 16 to 17, that the bridge section 12 can shift forward and backwards relative to the feet 18 and 19 of the beams 16 and 17. As described above, this is a first mode of operation of the crawler bridge 10 in which, with the leading feet 18 and trailing feet 19 engaged on a ground surface, the struts 30 of the arms 20 to 23 can raise the bridge section 12 away from the ground surface to allow freedom of movement of the arms 20 to 23 and thus the bridge section 12 along the beams 16 and 17.

[0054] However, in a second mode of operation, the struts 30 can lower the bridge section 12 into engagement with the ground surface and continuing activation of the struts 30 will lift the beams 16 and 17 away from the ground surface. In that condition, the beams 16 and 17 can move relative to the arms 20 to 23 and the bridge section 12 forwards and backwards relative to the bridge section 12. These two forms of relative movement between the arms 20 to 23 and the bridge section 12 is facilitated in both cases by the driven rollers 38.

[0055] It can be seen in FIGS. 1 and 2, that the rails 46 and 48 extend beyond the lengthwise ends 56 and 58 of the bridge section 12. These extensions are provided to rest on either side of a gap which has been bridged by the bridge section 12. These extensions can extend or pass through openings 60 in the feet 18 and 19 of the beams 16 and 17 during relative movement of the bridge section 12 and the beams 16 and 17, to ensure maximum travel of the bridge section 12 relative to the beams 16 and 17.

[0056] Operation of the crawler bridge 10 through the first and second modes of operation is illustrated in FIGS. 6 to 11. Each of these figures shows a roadway 62 that is formed with a gap G that has a lengthwise dimension of 7.2 m. The gap G can be the opening of a void beneath the roadway 62 that can be from 2 m to 3 m deep. The gap G can be provided to facilitate construction of cross passages between adjacent tunnels. Clearly, such a gap G will prevent vehicles and pedestrians from moving from one side of the roadway 62 to the other side unless a bridge is formed over the gap G.

[0057] FIG. 6 shows the crawler bridge 10 in place on the left-hand side of the roadway 62. The terms left-hand and right-hand side will be used in the discussion of FIGS. 6 to 11 but it will be clear that the crawler bridge 10 is not restricted to movement in the direction shown in FIGS. 6 to 11. Moreover, the roadway 62 can be a road deck or a ground surface inside a tunnel. In the condition shown in FIG. 6, the bridge section 12 is in contact with the upper surface of the roadway 62. In the condition shown in FIG. 6, with the bridge section 12 in contact with the roadway 62, extension of the struts 30 lifts the beams 16 and 17 so that the feet 18 and 19 are lifted away from the surface of the roadway 62 as shown.

[0058] To initiate the first mode of operation of the crawler bridge 10 to shift the bridge section 12 towards the gap G, the beams 16 and 17 are lowered by action of the struts 30 to bring the feet 18 and 19 into engagement with the roadway 62. Continued activation of the struts 30 will lift the bridge section 12 away from the roadway 62 and suspend the bridge section 12 on the beams 16 and 17 above the roadway 62. In that condition, the bridge section 12 can the shift to the right along the beams 16 and 17 as shown in FIG. 7.

[0059] In the transition between FIGS. 6 and 7, it can be seen that the rail 46 extends through the foot 18 in FIG. 6, but in FIG. 7, the bridge section 12 and the rail 46 has shifted away from the foot 18 and now the rail 46 extends through the foot 19 (through the opening 60 of FIG. 2) to bring the bridge section 12 adjacent to the feet 18. This illustrates how the maximum travel of the bridge section 12 is obtained between the respective feet 18 and 19 of the beams 16 and 17.

[0060] In FIG. 7, the bridge section 12 cannot move any closer to the gap G in the roadway 62 as it is close to or even abutting against the feet 18. Thus, the struts 30 operate to lower the bridge section 12 into engagement with the roadway 62 and to lift the beams 16 and 17 away from the roadway 62. The beams can now be shifted relative to the bridge section 12 to the right, so that the feet 18 traverse over the gap to position them adjacent the roadway 62 on the opposite side of the gap G. This is the position shown in FIG. 8. In that position, the struts 30 can be activated to lift the bridge section 12 away from the roadway 62 to bring the feet 18 and 19 of the beams 16 and 17 into engagement with the roadway 62 on either side of the gap G. The bridge section 12 is then able to be moved to the right to position the bridge section 12 in alignment with the gap G and to be lowered over the gap G. This is the position shown in FIG. 9.

[0061] In FIG. 9, it can be seen that the extensions of the rail 46 to the left and right of the bridge deck 44 of the bridge section 12 rest against the roadway 62 on either side of the gap G, while the bridge deck 44 bridges across the gap G and provides a bridge for the passage of vehicles and personnel.

[0062] For structural stability, it is preferred that the beams 16 and 17 be shifted relative to the bridge section 12 once the bridge section 12 has been lowered to bridge the gap G as shown in FIG. 9. Thus, in the position shown in FIG. 9, the struts 30 are activated to lift the beams 16 and 17 away from the roadway 62 and the driven rollers 38 drive the beams 16 and 17 to position them substantially equidistantly on either side of the gap G. This is the position shown in FIG. 10, while FIG. 11 shows the beams 16 and 17 having been lowered so that the feet 18 and 19 engage the roadway 62.

[0063] For safety purposes, locking pins, one of which is shown at reference numeral 64 in FIG. 3 can be activated to engage between the sleeves 26 and posts 28, so that the bridge section 12 is held safely in place suspended from the beams 16 and 17 and with the rails 46 and 48 in bearing engagement with the roadway 62 on opposite sides of the gap G.

[0064] Once the bridging requirement for the gap G has been removed, the crawler bridge 10 can be shifted from the gap G utilizing a sequence which is similar to that shown in FIGS. 6 to 11. Firstly, any locking pins 64 would be disengaged and thereafter, the beams 16 and 17 would be lifted via the struts 30 and shifted to the right by the driven rollers 38. This would bring the feet 19 to the left-hand edge of the gap G, whereafter the beams 16 and 17 can be lowered and the bridge section 12 lifted to shift the bridge section 12 onto the roadway 62 on the right-hand side of the gap G. The beams 16 and 17 can then be lifted away from the roadway 62 and shifted further to the right and by this mechanism of one of the bridge section 12 and beams 16 and 17 being released from engagement with the roadway, moved to the right and being re-placed into engagement with the roadway, the crawler bridge 10 can slowly move (or crawl) along the roadway 62 and away from the gap G. Current estimates are that the crawler bridge 10 which is illustrated would have a speed of somewhere in the region of 4 m/min.

[0065] Some tunnel excavations include a cross passage site approximately every 120 m. For each cross passage site, a gap will be left in the road deck, roadway or tunnel floor, requiring a bridge for travel over and past the gap. In such an arrangement, the crawler bridge 10 would cover the 120 m spacing between gaps in approximately 30 minutes.

[0066] The crawler bridge 10 would likely be assembled within a tunnel, rather than being installed in the tunnel in an already assembled state. Thus, the components of the crawler bridge 10 could be loaded into the tunnel and then largely bolted or welded together for subsequent use. Conveniently, use of the crawler bridge 10 means that cranes or other types of lifting equipment are not required within a tunnel for placing and removing bridge sections and in particular, the present invention alleviates difficulties with having to lift and place a large and heavy bridge section from one side of a gap (because access to the opposite side of the gap is not available because of the gap). While this would be relatively easy to do outside of a tunnel environment, the lack of headspace within a tunnel means that heavy lifting machinery is often not appropriate for placement of bridge sections across roadway gaps.

[0067] Still further, it will be appreciated from FIG. 4, that when the crawler bridge 10 is not in use over a gap in a roadway, vehicles and personnel can nevertheless continue to drive through the crawler bridge and so it's presence within the tunnel does not create an obstacle to traffic within the tunnel. This is in contrast with a crane or other form of lifting equipment which is bulky and heavy and thus likely to form an unwanted obstruction to the passage of other equipment and activities that occur during tunnel excavation.

[0068] Certain terminology has been used herein for convenience in reference only and will not be limiting. For example, up, down, top, bottom, back, right, left, forward, backward, upward, and downward refer to the crawler bridge as orientated in the view being referred to and are not intended to be limiting on the scope of the claims of this application.

[0069] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.