- 1 MOVABLE FOOTBOARD FOR RAILWAY WAGON AND RAILWAY WAGON TECHNICAL FIELD [0001] The present application relates to the technology of railway wagons, in particular to a movable footboard for a railway wagon and a railway wagon. BACKGROUND [0002] The conventional footboards for the railway wagon are all of a whole welded structure. As shown in Figure 1, a footboard consists of an upper footboard body 1 and a lower footboard body 2 which are welded together. Two ends of the upper footboard body 1 are welded to one end of a mounting base 3, and the other end of the mounting base 3 is welded to an end portion of a wagon body 4, and the footboard has a fixed structure. When it is required to overhaul the wagon in a maintenance workshop, a bogie of the wagon is required to be detached from the wagon body and pushed out, so as to be disassembled for inspection and repair. Since multiple footboards are arranged at the end portion of the wagon body, the wagon body has to be lifted to a high position to avoid interference between the footboards and the bogie, which is not convenient for maintenance. SUMMARY [0003] An embodiment of the present application may provide a movable footboard for a railway wagon and a railway wagon, which may facilitate maintenance. [0004] A first aspect of the disclosure provides a movable footboard for a railway wagon. The footboard is of a ladder shape, and is formed by at least two U-shaped footboard bodies connected to one another end-to-end, a footboard body located at an upper portion of the footboard is an upper footboard body, and a footboard body located at a lower portion of the footboard is a lower footboard body, and a closed end of the upper footboard body is detachably connected to an open end of the lower footboard body, the closed end of the upper footboard body is located in the open end of the lower footboard body, and two lateral 7327275_1 (GHMatters) P96800.AU DENISET -2 sides of the upper footboard body are detachably connected to two lateral sides of the lower footboard body, both of the two lateral sides of the upper footboard body are provided with two circular mounting holes at a position near the closed end of the upper footboard body, and the two circular mounting holes are arranged in the height direction of the two lateral sides of the upper footboard body; both of the two lateral sides of the lower footboard body are provided with an elongated mounting hole arranged in the height direction of the two lateral sides of the lower footboard body; and the circular mounting hole and the elongated mounting hole are connected via a bolt assembly. [0005] A second aspect of the disclosure provides a movable footboard for a railway wagon, wherein the footboard is of a ladder shape, and is formed by at least two U-shaped footboard bodies connected to one another end-to-end, a footboard body located at an upper portion of the footboard is an upper footboard body, and a footboard body located at a lower portion of the footboard is a lower footboard body, and a closed end of the upper footboard body is detachably connected to an open end of the lower footboard body; the closed end of the upper footboard body is located in the open end of the lower footboard body, and two lateral sides of the upper footboard body are detachably connected to two lateral sides of the lower footboard body; and both of the two lateral sides of the upper footboard body are provided with two first mounting holes at a position near the closed end of the upper footboard body, and the two first mounting holes are arranged in the height direction of the two lateral sides of the upper footboard body; both of the two lateral sides of the lower footboard body are provided with at least two second mounting holes arranged in the height direction of the two lateral sides of the lower footboard body, and a distance between the two second mounting holes in each pair of the second mounting holes is equal to a distance between the two first mounting holes; and the first mounting hole and the second mounting hole are connected via a bolt assembly. [0006] The first mounting holes and the second mounting holes can each be of a circular structure. 7327275_1 (GHMatters) P96800.AU DENISET -3 [0007] As another embodiment, the open end of the lower footboard body has a flanging, and the flanging is detachably connected to a base of the upper footboard body. [0008] In the movable footboard for the railway wagon according to an embodiment of the present application, the footboard bodies are detachably connected, thus during the overhaul of a wagon body, when a bogie is required to be detached from the wagon body, the lower footboard body may be detached to avoid interference between the footboard body and the bogie, therefore it is not necessary to lift the wagon body via a lifting jack to avoid the interference, thus it is convenient for overhauling the wagon body. [0009] Another aspect of the disclosure provides a railway wagon is further provided in the present application, which includes a wagon body and footboards installed at end portions of the wagon body via a mounting base, the mounting base having one end fixed on the wagon body and the other end extending outwardly with respect to the wagon body, the footboard having a top fixedly connected to the outwardly extending end of the mounting base, and a bottom extending downwardly, wherein the footboard is in accordance with the first or second aspect, and an open end of an upper footboard body of the footboard is fixedly connected to the outwardly extending end of the mounting base. [0010] In the railway wagon provided in an embodiment of the present application, during the normal operation of the wagon, the upper footboard body and the lower footboard body are connected to form a long footboard to facilitate use. When the wagon is to be overhauled in a maintenance workshop, the upper footboard body may be detached from the lower footboard body, thus only the upper footboard body is fixed on the mounting base, which greatly reduces the length of footboard. Then, the wagon body can be lifted by the lifting jack to push out the bogie, thus it may not be necessary to lift the wagon body to a high position via the lifting jack, thereby facilitating overhauling the wagon body. DESCRIPTION OF THE DRAWINGS [0011] Embodiments of the disclosure will now be described, by way of example only, 7327275_1 (GHMatters) P96800.AU DENISET -4 with reference to the accompanying non-limiting drawings, in which: [0012] Figure 1 is a schematic view showing the structure of a footboard in the conventional technology; [0013] Figure 2 is an assembly drawing of a movable footboard and a mounting base according to a first embodiment of the present application; [0014] Figure 3 is an assembly drawing of a movable footboard and a mounting base according to a second embodiment of the present application; [0015] Figure 4 is a left view of Figure 3; [0016] Figure 5 is an assembly drawing of a movable footboard and a mounting base according to a third embodiment of the present application; and [0017] Figure 6 is an exploded schematic view of a movable footboard and a mounting base according to a fourth embodiment of the present application. DETAILED DESCRIPTION First Embodiment [0018] As shown in Figure 2, a movable footboard for a railway wagon is provided in the present application. The footboard is of a ladder shape, and is formed by at least two U-shaped footboard bodies connected to one another end-to-end. A footboard body located at an upper portion of the footboard is an upper footboard body 1, and a footboard body located at a lower portion of the footboard is a lower footboard body 2. A closed end 11 of the upper footboard body is detachably connected to an open end 22 of the lower footboard body. As one manner of the detachable connection, the closed end 11 of the upper footboard body and the open end of the lower footboard body 22 are connected via a bolt assembly 10. [0019] In the movable footboard for the railway wagon according to the present application, the upper footboard body 1 and the lower footboard body 2 are detachably connected, thus during the overhaul of a wagon body, when a bogie is required to be 7327275_1 (GHMatters) P96800.AU DENISET -5 detached from the wagon body, the lower footboard body may be detached to avoid interference between the footboard body and the bogie, therefore it is not necessary to lift the wagon body via a lifting jack to avoid the interference, thus it is convenient for overhauling the wagon body. [0020] In this embodiment, the footboard includes two footboard bodies. When the footboard includes three footboard bodies, the footboard has identical structure, and an open end of a lower footboard body in each two adjacent footboard bodies is detachably connected a closed end of an upper footboard body in the two adjacent footboard bodies. During the overhaul of the wagon body, the footboard bodies may be selectively detached. The detachable connection refers to bolt connection. The specific structure of the detachable connection is illustrated by the following two embodiments. [0021] In one manner of the first embodiment as shown in Figures 3 to 5, the closed end 11 of the upper footboard body is located in the open end 22 of the lower footboard body, and two lateral sides 13 of the upper footboard body are detachably connected to two lateral sides 23 of the lower footboard body. This structure may be realized by the following two preferred manners. Second Embodiment [0022] As shown in Figures 3 and 4, based on the first embodiment, both of the two lateral sides 13 of the upper footboard body are provided with two circular mounting holes 14 at a position near the closed end of the upper footboard body, and the two circular mounting holes 14 are arranged in the height direction of the two lateral sides of the upper footboard body 13. Both of the two lateral sides 23 of the lower footboard body are provided with an elongated mounting hole 24 arranged in the height direction of the two lateral sides 23 of the lower footboard body. The circular mounting hole 14 and the elongated mounting hole are connected via a bolt assembly 10. [0023] During the normal driving of the wagon, a top of the elongated mounting hole 24 of the lower footboard body and the two circular mounting holes 14 are cooperated with 7327275_1 (GHMatters) P96800.AU DENISET -6 each other and are connected via bolt assemblies. During the overhaul of the wagon, nuts connecting two footboard bodies are unscrewed, and the lower footboard body is moved upward by a distance, such that a bottom of the elongated mounting hole 24 cooperates with the two circular mounting holes 14, and then the nuts at two sides are screwed again. And the wagon body is lifted via the lifting jack to push out the bogie, and the height of the lifting jack at this time is far less than that of the lifting jack during the overhaul of the wagon with a whole welded footboard in the conventional technology, thus such structure is convenient for the overhaul of the wagon body. Third Embodiment [0024] As shown in Figure 5, based on the first embodiment, both of the two lateral sides 13 of the upper footboard body are provided with two first mounting holes 15 at a position near the closed end of the upper footboard body, and the two first mounting holes 15 are arranged in the height direction of the two lateral sides 13 of the upper footboard body. Both of the two lateral sides 23 of the lower footboard body are provided with at least four second mounting holes 25 arranged in the height direction of the two lateral sides 23 of the lower footboard body. Two of the second mounting holes 25 are arranged at a top of the lower footboard body, and the other two of the second mounting holes 25 are arranged at a bottom of the lower footboard body, and a distance between the two second mounting holes 25 located at the top of the lower footboard body is equal to a distance between the two second mounting holes 25 located at the bottom of the lower footboard body. The first mounting hole 15 and the second mounting hole 25 are connected via a bolt assembly. The first mounting holes 15 and the second mounting holes 25 are each of a circular structure. [0025] During the normal driving of the wagon, the two second mounting holes 25 at the top of the lower footboard body and the two first mounting holes 15 are cooperated with each other and are connected via bolt assemblies. During the overhaul of the wagon, nuts connecting two footboard bodies are unscrewed, and the lower footboard body is moved upward by a distance, such that the two second mounting holes 25 at the bottom of the lower 7327275_1 (GHMatters) P96800.AU DENISET -7 footboard body may cooperate with the two first mounting holes 15, and then the nuts at two sides are screwed again. And the wagon body is lifted via the lifting jack to push out the bogie, and the height of the lifting jack at this time is far less than that of the lifting jack during the overhaul of the wagon with a whole welded footboard in the conventional technology, thus such structure is convenient for the overhaul of the wagon body. Fourth Embodiment [0026] As shown in Figure 6, as one manner of the first embodiment, the open end 22 of the lower footboard body has a flanging 20, and the flanging 20 is detachably connected to a base 12 of the upper footboard body. The flanging 20 may be folded inwardly or outwardly with respect to the open end 22 of the lower footboard body. In this embodiment, the flanging 20 is folded outwardly with respect to the open end 22 of the lower footboard body. [0027] During the normal driving of the wagon, the flanging 20 on the lower footboard body and the base of the upper footboard body are connected via bolt assemblies. During the overhaul of the wagon, when the bogie is required to be detached from the wagon body, the nuts may be unscrewed to detach the lower footboard body from the upper footboard body so as to avoid interference between the footboard body and the bogie, therefore it is not necessary to lift the wagon body via a lifting jack to avoid the interference, thus it is convenient for overhauling the wagon body. Fifth Embodiment [0028] As shown in Figures 2 to 6, the present application also provides a railway wagon which includes a wagon body and footboards installed at end portions of the wagon body via a mounting base 3. The mounting base has one end 31 fixed on the wagon body, and the other end 32 extending outwardly with respect to the wagon body. A top of the footboard is fixedly connected to the outwardly extending end of the mounting base, and a bottom of the footboard extends downwardly. The footboard may be any one of the movable footboards for the railway wagon in the above embodiments. An open end of an upper footboard body is fixedly connected to the outwardly extending end of the mounting base. 7327275_1 (GHMatters) P96800.AU DENISET -8 [0029] In the railway wagon provided in the present application, during the normal operation of the wagon, the upper footboard body and the lower footboard body are connected to form a long ladder to facilitate use. When the wagon is to be overhauled in a maintenance workshop, the upper footboard body may be detached from the lower footboard body, or the lower footboard body may be moved upwardly by a distance to form a structure that the upper footboard body and the lower footboard body are sleeved together to form a short ladder. And then the wagon body is lifted by the lifting jack to push out the bogie, since the footboard is short, it is not necessary to lift the wagon body to a high position via the lifting jack, thus it is convenient for overhauling the wagon body. [0030] It should be noted that, the above embodiments are only intended for describing the technical solutions of the present application, and should not be interpreted as limitation to the present application. Although the present application is described in detail in conjunction with the above embodiments, it should be understood that, for those skilled in the art, modifications may be made to the technical solutions of the above embodiments, or equivalent substitutions may be made to part or all of the technical features in the technical solutions; and theses modifications and substitutions also fall into the protection scope of the present application defined by the claims. [0031] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. [0032] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. 7327275_1 (GHMatters) P96800.AU DENISET