Rail joint

Abstract

To provide a rail that extends the operational life of a crane rail by reducing the wear rate in high stress areas at the joints and adding additional wear material above the rail at the joints. SOLUTION: A rail (13) supporting a trolley (14) of a gantry crane (10) has rail sections (18, 19) on opposite sides of a joint (17) with an end region (20) of a modified rail head profile that guides the wheels of the trolley (14) onto a ridge (23) that gradually exceeds the height (L1) of the rail head (27) as it approaches the joint (17). The ridge (23) then carries the wheels to the joint (17) where the transition from one rail section to the next takes place on a reinforced region. The load-bearing apex (A) of the ridge is located away from the side edge of the rail (13) and the end of each lug (21).

Description

[Technical field]

[0001] The present invention relates to joints between rails for carrying wheeled vehicles, particularly (but not exclusively) to joints between rails mounted on gantry cranes. [Background technology]

[0002] Gantry cranes are widely used in dockyards and other locations for loading and unloading containerized cargo. Typically, a gantry crane comprises a large chassis, with wheels for running along a first axis along the ground, and an elevated boom extending along an orthogonal second axis. The containers handled by the crane are supported by cables suspended vertically from a trolley that travels along the longitudinal axis of the boom. This trolley is usually equipped with wheels that run on parallel rails fixed to the support surface of the boom.

[0003] Gantry cranes for handling containers in dockyards may have a hinged boom that extends from the crane chassis across the width of the ship. It will be appreciated that the hinged boom can be raised to allow unhindered access to the dockside for the ship, which requires the provision of a joint in the rail. Typically, such a joint is provided as a lap joint between longitudinally disposed rail sections of the hinged and unhinged booms, with adjacent ends thereof overlapping to provide a smooth transition to the next rail section and avoid gaps.

[0004] The elongated rails used in gantry cranes have a base portion which rests on a support surface, an upwardly-facing central web which extends between the base portion and the head portion of the rail along which the trolley runs. The upper surface of the head portion of the rail curves upwardly from both side edges towards the center, and the wheels of the trolley are supported by a central region of the head portion which lies directly above the upwardly-facing web portion of the rail.

[0005] The problem with this arrangement is that because the ends of adjacent rail sections are cut longitudinally along this central area and cut down to the web to form the respective protrusions and recesses of the lap joint, the load of the trolley passing through the joint 100-200 times a day is shared along the longitudinally cut upward facing sides of the rail sections. Impacts from the wheels therefore cause wear and tear on one or both rail sections, which in turn cause stress fractures that lead to cracks progressing along the sides of the web and ultimately to failure. The damage caused to the joint means that the rails must be replaced every 5 to 7 years, sometimes sooner. Typically the rails are replaced along the entire boom, which is very expensive and takes the crane out of operation for long periods of time. Summary of the Invention

[0006] In light of the above, we have devised improvements relating to rail joints. According to a first aspect of the invention, there is provided a rail comprising a rail head defining an upper rail surface for supporting a wheeled vehicle and a base defining a lower rail surface for engaging a support structure. The rail is divided into first and second rail sections by the joint, adjacent end regions of the rail sections comprising a protrusion and a recess located on first and second opposite longitudinal sides, respectively. The protrusions of each rail section longitudinally overlap one another in use, with the protrusion of the first rail section extending into the recess of the second rail section and vice versa. The upper rail surface at each adjacent end region is truncated along one side edge by the recess and has an altered profile compared to the profile away from that end region. The altered profile of the upper rail surface at each adjacent end region includes an elongated ridge section extending longitudinally along the protrusion, the apex of which is located away from the side edge where the upper rail surface is truncated by the recess.

[0007] A joint may be formed between rail sections that extend along the inner and outer ends, respectively, of a gantry crane boom, which allows one rail section to rotate upwardly relative to the other rail section between a vertically aligned position in use and a biased position. Alternatively, the joint may be an expansion joint formed between permanently longitudinally aligned rail sections.

[0008] The present invention solves the aforementioned problems because the load of a trolley or other vehicle passing through the joint is borne along an elongated ridge section of the protruding outer end portion that is positioned away from the side edge where the upper rail surface is cut off by the recess. Thus, the forces on the recessed side of the rail are significantly reduced, thereby reducing the risk of wear or damage to one or both rail sections from impacts by the wheels.

[0009] An apex of each elongated ridge section may be located away from both of the opposing longitudinal side edges of the protrusion on which it is provided. Each elongated ridge section may extend along a center of the protrusion on which it is provided.

[0010] Adjacent end regions of the rail sections may have a projection extending from their respective inner ends and an elongated ridge section in each end region extending from the projection to the inner end such that the load of a trolley or other vehicle passing through the joint is borne by the elongated ridge section both before and after passing through the joint.

[0011] Each inner end may further include a short ridge section extending parallel to the elongated ridge section toward the rebate, wherein, in use, the short ridge section of each member extends to connect end-to-end with the elongated ridge section of the other member.

[0012] It is understood that the support web portion at the protruding outer end of the known joint is thinned by at least 50% where it is cut away to form the recess of the lap joint. Thus, the protruding outer end of the rail section is weakened, which further exacerbates the risk of failure of the joint. To solve this problem, the opposite side of the rail at the joint section includes a reinforcement material that extends between the head and base portions of the rail. This side material increases the cross-sectional area of ​​the rail between the base and head portions and strengthens the protruding outer end of the rail.

[0013] The stiffener may substantially close a recess extending longitudinally along each side of the rail remote from the joint.

[0014] The reinforcement may include strength members bolted or otherwise secured along opposite sides of the rail at the joint.

[0015] As trolleys and other vehicles pass through the joint, wear is inevitably caused to the upper surface of the rail. To extend the life and increase the strength of the joint, the apex of each ridge section may extend a significant portion above the upper surface of the rail away from the end region. The increased height of the ridge section allows it to withstand more wear and strengthens the joint.

[0016] Both ends of the ridge formed by the ridge section may taper downwardly towards the top surface of the rail away from the end regions to avoid an abrupt change in the level of the rail.

[0017] In one embodiment, the end regions of each rail section are integrally formed with the elongate rail member, for example, by machining or casting the ends of the rail member to a predetermined shape.

[0018] In another embodiment, each rail section includes an elongated rail member arranged end-to-end with a short rail end member, and the end regions of each rail section are integrally formed with the rail end member, for example, by machining or casting the ends of the rail end member to a predetermined shape.

[0019] It will be appreciated that it is much easier to form the ends of short rail members to a predetermined shape and that existing rails can be relatively easily repaired by cutting away the length of rail adjacent the joint and attaching a short rail end member.

[0020] In another embodiment, each elongated ridge section is provided on a capping member which is attached, for example by bolting or welding, to a complementary formation provided on an end region of the respective rail section.

[0021] In one embodiment, the complementary formations of each rail section are integrally formed with the elongated rail member, for example by machining or casting the ends of the rail member to a predetermined shape.

[0022] In another embodiment, each rail section includes an elongated rail member arranged end-to-end with a short rail end member, and the complementary formations of each rail section are integrally formed with the rail end member, for example, by machining or casting the end of the rail end member to a predetermined shape.

[0023] Each capping member may further include a short ridge section extending parallel to the elongated ridge section, such that, in use, the short ridge section of each member extends to connect end-to-end with the elongated ridge section of the other member.

[0024] A notch may extend between the parallel ridge sections of each capping member to one end of the capping member, and the rail section includes a finger that extends into the notch to help determine the position of the capping member, In this embodiment, the opposite end of the ridge provided by the ridge section may taper downwardly to a point below the top surface of the finger.

[0025] According to a second aspect of the present invention there is also provided a rail section for forming a rail as previously described.

[0026] Further, according to a third aspect of the present invention, there is provided a gantry crane as previously described, wherein the rail sections of each rail are provided on opposite sides of a hinge between the boom and the chassis of the crane.

[0027] Further, according to a fourth aspect of the present invention, there is provided a method of forming a rail as previously described, the method comprising mounting respective rail sections on opposite sides of a joint between two support structures.

[0028] In one embodiment, each rail section is formed by laying an elongated rail member and a short rail end member arranged end-to-end. A portion of the elongated rail member may be cut away and a short rail end member laid in its place.

[0029] In another embodiment, the capping members are secured, for example by bolting or welding in situ, to complementary formations provided in the end regions of the respective rail sections.

[0030] The complementary formations may be formed by machining or casting the end regions of the rail sections.

[0031] Embodiments of the present invention will now be described, by way of example only, with reference to the drawings in which: [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a side view of a gantry crane incorporating an embodiment of a rail in accordance with the present invention. [Figure 2A] FIG. 2 is a top perspective view from one side of a section of rail of the gantry crane of FIG. [Figure 2B] FIG. 2B is an enlarged view of an end region of the rail section of FIG. 2A. [Diagram 3] FIG. 2 is a top perspective view from one side of a joint between rail sections of the gantry crane of FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2A. [Diagram 5] FIG. 2B is a cross-sectional view taken along line VV in FIG. 2A. [Figure 6] 6A and 6B are exploded and assembled views of the outer ends of a rail section of an alternative embodiment of a rail according to the present invention. [Figure 7] 4 is a plan view of the region of the outer end of a rail section of an alternative embodiment of a rail according to the invention; FIG. [Figure 8] 1 is a bottom perspective view from one side of a proximal end of a rail end member of an alternative embodiment of a rail in accordance with the present invention; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Referring to Figure 1, a typical gantry crane 10 is shown and includes a large chassis 11 with wheels that run on rails fixed to the ground (e.g., dockside D) along a first axis. The gantry crane 10 includes an overhead boom 12 that extends along a second axis perpendicular to the first axis. Containers (e.g., C) handled by the gantry crane 10 are supported by cables that are suspended vertically from a trolley 14 that moves along the longitudinal axis of the boom 12.

[0034] The trolley 14 is fitted with wheels which run on the upper surface of a steel rail 13 which has its underside fixed to the support surface of the boom 12, for example using a clip as disclosed in our pending patent application GB2591259. The boom 12 of the gantry crane 10 is adapted to rotate at point P so that the outer end of the boom 12 can be raised to allow vessels to enter and leave the dockside D unhindered. A joint is provided in the rail 13 at point P to enable the boom 12 of the gantry crane 10 to be raised and lowered as desired, as will be explained below.

[0035] 2 to 5, each rail 13 is divided by a joint 17 into first and second rail sections 18, 19 which extend respectively along the inner and outer ends of the boom 12. The joint 17 allows the second rail section 19 to rotate, in use, between a longitudinally aligned position relative to the first rail section 18 and a raised position.

[0036] Each rail section 18, 19 extends from the joint 17 and includes a short rail end member 31 attached end-to-end to an elongated rail member 32. Each rail end member 31 includes an end region 20 of modified cross-sectional shape that is machined or cast to a predetermined shape. It will be appreciated that a traditional gantry crane rail 13 may be modified by cutting out the end section of the elongated rail opposite the joint and attaching the rail end member 31 in place. The elongated rail member 32 is of conventional shape and includes a base portion 26 having a lower rail surface 16 thereon, a head portion 27 having an upper rail surface 15 thereon, and a web-shaped support portion 28 extending between the base portion 29 and the head portion 27. The opposite longitudinal side of the elongated rail member 32 includes a longitudinally extending recess 30.

[0037] Adjacent end regions 20 of the short rail end members 31 each include a protrusion 21 and a recess 22 that are disposed on longitudinally opposite sides of each other. The protrusions 22 of each member 31 longitudinally overlap one another at joint 17 when the boom 12 is in the lowered (in-use) position, such that the protrusion 21 of one rail section 18 extends into the recess 22 of the other rail section 19, and vice versa.

[0038] The upper rail surface 15 in the end region 20 of each rail end member 31 is truncated along one side edge 25 thereof by a recess 22 to have a modified profile that differs from the profile of the upper rail surface 15 throughout the rail 13 away from the end region 20. The modified profile in each adjacent end region 20 of the rail sections 18, 19 includes a first elongated ridge 23 extending longitudinally along a protrusion 21. The first elongated ridge 23 has an apex A at the center of a given protrusion 21 and is spaced from the opposite longitudinal side edge of that protrusion 21.

[0039] Adjacent end regions 20 of rail sections 18, 19 also include inner ends 26 from which the respective protrusions 21 extend. Each inner end 26 of rail sections 18, 19 also includes a second ridge 24 that extends parallel to the first ridge 23 toward the recess 22. When the boom 12 is in the lowered (in-use) position, the second ridge 24 of each rail section (e.g., 18) extends to connect end-to-end with the first ridge 23 of the other rail section (e.g., 19).

[0040] The first ridge 23 of each end region 20 also extends from its convex portion 21 toward its inner end 26 along with a second ridge 24, which supports the load across the trolley 14 as it passes through the joint 17. The apex A of each ridge 23, 24 extends substantially to a level L1 that is higher than the level L2 of the upper rail surface 15 away from the end region 20. The increased height of the ridge section 23, 24 allows it to withstand more wear and strengthens the joint 17. The opposite end of the ridge 23, 24 tapers downward from the level L1 toward the level L2 of the upper rail surface 15 to avoid an abrupt change in the level of the rail 13.

[0041] The recesses 30 in the longitudinal sides of the rail 30 terminate short of each end region 20 of each rail end member 31 so that the ridges 23, 24 overlap an area of ​​completely solid steel that extends to the base 29, as shown in Figure 4. This increases the cross-sectional area of ​​the rail 13 and strengthens the protrusions 21. The cross-sectional shape of the proximal end of each rail end member 31 is the same as the elongated rail member 32 so that they can be welded in a conventional manner at point W.

[0042] In use, the load of the trolley 14 passing through the joint 17 is carried by the ridges 23, 24 over an elongated area extending along the centre of the projecting end 21 away from the inner edge where the upper rail surface 15 is cut away by the rebate 22. Thus, the forces on the rebate edge 25 of the rail 13 are significantly reduced, reducing the risk of wear and damage to one or both of the rail sections 18, 19 from an impact by the trolley 14.

[0043] 6A and 6B, in another embodiment, instead of forming the end region 20 of each rail section 18, 19 integrally with the rail, the shape of each end region is modified by attaching a capping member 33. The capping member 33 is attached to a complementary formation 34 formed in the end region 20 of the respective rail section, such as by bolting it to a shape that is machined or cast.

[0044] Each capping member 33 further includes an elongated first ridge 230 extending parallel to a second, shorter ridge 240, such that when the boom 12 is in the lowered (in-use) position, the second ridge 240 of one capping member 33 extends to connect end-to-end with the first ridge 230 of the other capping member 33.

[0045] A notch 35 extends between the first ridge 230 and the second ridge 240 at the inner end of the capping member 33, and rail sections 18, 19 include fingers 36 that extend into the notch 35 to fix the position of the proximal end of the capping member 33. An outer end of the capping member 33 has a pair of sockets 37 formed therein, and rail sections 18, 19 include a pair of raised tabs 38 that extend into respective sockets 37 to fix the position of the outer end of the capping member 33.

[0046] With the use of the capping members 33, existing joints can be repaired by simply machining the formations 34 into the existing rail. Because the recesses 30 in the longitudinal sides of the rail 13 extend the entire length of the rail, their end regions 20 can be strengthened by bolting or otherwise fastening reinforcing members 39 along the opposite longitudinal sides of the overlapping end regions 20 of the rail 13. The reinforcing members 39 ensure that the ridges 230, 240 overlap a complete area of ​​steel extending to the base 29, thereby effectively increasing the cross-sectional area of ​​the rail 13 and strengthening the protrusions 21. It will be appreciated that if the capping members 33 become worn or damaged, they can be easily replaced.

[0047] 7, in another embodiment, the bifurcated proximal end of each capping member 33 is provided with an end face 50 that is keyed to a distal end face 51 of formation 34 to prevent separation of the bifurcated ends 53. The underside of each capping member 33 includes a longitudinally extending formation 54 that engages a complementary formation (not shown) on the bottom surface of formation 34 to help maintain the position of capping member 33.

[0048] Typically, the rail section opposite the joint 17 is attached to an elongated rail pad (not shown) of elastomeric material. In the past, the rail pad had to be cut to shape or shortened at the joint, and these arrangements had drawbacks. To solve this problem, and referring to FIG. 8, the height H of the short rail end member 31 of each rail section 18, 19 of the present invention is substantially equal to the height of the elongated rail member 32 to which it is joined, plus the height of the underlying rail pad. In this way, the rail pad does not extend into the joint, and the increased height of the short rail end member 31 compensates for the height lost by the rail pad. To avoid stress on the weld W between the rail end member 31 and the elongated rail member 32, the underside of the proximal end of the rail end member 31 is provided with a rebate 55, which allows the rail pad located below the elongated rail member 32 to extend below the weld W, reducing the risk of stress caused by the rail pad terminating directly below the weld W.

[0049] The present invention provides a rail with a unique rail head profile at the joint 17, which guides the trolley wheels onto a surface that gradually exceeds the height of the rail head as they approach the joint. The wheels are then brought into the joint 17 and the transition from the next rail section (e.g. 18) to the next rail section (e.g. 19) is made on a transition area supported by both ridges 21. The transition area is located above the reinforced cross section of each ridge and the load bearing surfaces of the ridges are located away from the side edges of the rail and the ends of each ridge 21.

[0050] A rail according to the invention is simple in construction and relatively low cost, while reducing the wear rate at high stress areas of the joints and extending the service life of the crane boom rail by adding additional wear material above the rail at the joints.The invention reduces trolley vibration by guiding the wheels into a smooth, contoured rail head profile.

Claims

1. A rail having a rail head for supporting an upper rail surface of a wheeled vehicle, and a base having a lower rail surface for engaging a support structure, the rail being divided into first and second rail sections by a joint; Adjacent end regions of each rail section include a protrusion and a recess disposed on first and second opposed longitudinal sides, respectively; the convex portions of each rail section longitudinally overlap one another in use, with the convex portion of a first rail section extending into the concave portion of a second rail section, and vice versa; the top rail surface at each adjacent end region is truncated by a recess along an edge of the top rail surface and has an altered profile compared to the profile away from the end region; the modified profile of the upper rail surface at each adjacent end region includes an elongated ridge section extending longitudinally along the protrusion; an apex of the elongated ridge section is located away from a truncated edge of the top rail surface. A rail characterized by:

2. an apex of each elongated ridge section is disposed away from opposite longitudinal side edges of the protrusion on which the ridge section is disposed; 2. A rail according to claim 1.

3. The elongated ridge section extends along the center of the protrusion on which the ridge section is provided.

3. A rail according to claim 2.

4. each adjacent end region of the rail section further includes an inner end portion from which the protrusion extends; an elongated ridge section of each end region extending from the protrusion to the inner end; A rail according to any one of claims 1 to 3.

5. Each inner end further includes a short ridge section extending parallel to the elongated ridge section toward the recess; Each short ridge section extends to connect end-to-end with another elongated ridge section when the rail section is in the use position; 5. A rail according to claim 4.

6. The opposite side of the rail at the joint includes a reinforcing material extending between the rail head portion and the base portion. A rail according to any one of claims 1 to 5.

7. the reinforcing material closes a recess extending longitudinally along each side of the rail remote from the joint; 7. A rail according to claim 6.

8. The reinforcing material includes reinforcing members bolted or otherwise secured along opposite sides of the rail at the joint.

8. A rail according to claim 6 or 7.

9. an apex of each ridge extends to a level higher than the level of the upper rail surface away from said end region; A rail according to any one of claims 1 to 8.

10. an opposite end of the ridge provided by the ridge section tapers downwardly toward a surface of the upper rail remote from the end region; 10. A rail according to claim 9.

11. an end region of each rail section being integrally formed with the elongated rail member; A rail according to any one of claims 1 to 10.

12. Each rail section includes a short rail end member and an elongated rail member arranged end-to-end; an end region of each rail section being integrally formed with the rail end member; A rail according to any one of claims 1 to 10.

13. the ridge is provided on a capping member which is attached to a complementary formation provided on an end region of each rail section; A rail according to any one of claims 1 to 10.

14. the complementary formations of each rail section being integrally formed with the elongated rail member; 14. A rail according to claim 13.

15. Each rail section includes a short rail end member and an elongated rail member arranged end-to-end; the complementary formations of each rail section being integrally formed with the rail end member; 14. A rail according to claim 13.

16. Each capping member includes a fastening formation at an opposite end thereof for engaging a complementary fastening formation on a respective rail section; A rail according to any one of claims 13 to 15.

17. A rail section provided on a rail according to any one of claims 1 to 16.

18. A gantry crane equipped with a rail according to any one of claims 1 to 16, The rail sections of each rail are provided on opposite sides of a hinge between the boom and fixed parts of the crane. A gantry crane characterized by:

19. A method for forming a rail according to any one of claims 1 to 16, comprising the steps of: attaching each rail section to an opposite side of a joint between two support structures; A method comprising:

20. Each rail section is formed by placing a short rail end member end-to-end with an elongated rail member; A short rail end member of each section extends from opposite sides of the joint.

20. The method of claim 19 .

21. 21. The method of claim 20, wherein a section of the elongated rail member is cut away and a short rail end member is laid in its place.

21. The method of claim 20.

22. The capping members according to claim 13 are attached to complementary formations in the end regions of the respective rail sections.

20. The method of claim 19 .

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