Telescopic undercarriage

Abstract

To enable proper and simple performance of expanding and retracting operations without mistaking a procedure.SOLUTION: A lower part running body includes: a connection mechanism connecting a pair of side frames 110, 110 movable between an expanded position and a retracted position with a truck frame 107; and a side cover 132 and a center cover 131 covering its periphery. The connection mechanism has a connection pin 122 that changes a connection state via a re-inserting operation. The side cover 132 has a first opening 10 that enables re-inserting operations at both positions to be performed by opening a first opening / closing cover 11. The center cover 131 has a second opening 20 that enables a re-inserting operation at both positions to be performed by opening a second opening / closing cover 21. The two covers are configured such that the second opening / closing cover 21 cannot be opened unless the first opening-closing cover 11 is opened at both positions.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The disclosed technology relates to a lower traveling body of a hydraulic excavator or the like, and relates to a telescopic lower traveling body in which the crawler width is telescopic. [Background technology]

[0002] The applicant has previously proposed this type of undercarriage (Patent Document 1). The technology disclosed herein relates to an improvement of that undercarriage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-284988 Summary of the Invention [Problem to be solved by the invention]

[0004] 1 shows a lower traveling body 102 (hereinafter also referred to as a conventional machine) disclosed in Patent Document 1. The lower traveling body 102 includes a track frame 107 and a pair of side frames 110, 110 located on both the left and right sides of the track frame 107. Although not shown, an upper body is mounted on the track frame 107 so as to be rotatable via a swivel bearing.

[0005] As shown in Figure 2, a pair of axles 109 extend outward from both the front and rear of the track frame 107. These axles 109 are slidably inserted into axle insertion holes 111 in the left and right side frames 110. Although not shown, each side frame 110 supports a crawler in a rotatable manner.

[0006] Hydraulic motors 114 are provided at one end of the side frames 110. The crawlers are driven by these hydraulic motors 114 and are configured to revolve around the side frames 110. As shown in FIG. 2, a swivel joint 115 is provided in the center of the bearing base 108 to which the slewing bearing is fixed. Hydraulic pipes 116 extending from the swivel joint 115 are connected to each hydraulic motor 114 in order to supply pressure oil to each hydraulic motor 114.

[0007] As shown by the white arrows in Fig. 1, the left and right side frames 110 are configured to be movable left and right. This allows the pair of side frames 110, 110 to be switched between a position (extended position) where the distance between the left and right crawlers (crawler distance) is maximum, and a position (retracted position) where the distance between the crawlers is minimum. The left side of Fig. 1 shows the retracted position, and the right side of Fig. 1 shows the extended position. Typically, the extended position is used for work, and the retracted position is used for transportation.

[0008] A coupling mechanism is provided on the undercarriage 102 to couple both side frames 110, 110 to the truck frame 107 in each of the extended and retracted positions. The coupling mechanism is located on the drive side of the undercarriage 102 (the side where the hydraulic motor 114 is located).

[0009] Specifically, the connecting mechanism is located near the end of the truck frame 107 and is provided between the left and right side frames 110, 110. As shown in Fig. 1, the periphery of the connecting mechanism is covered with a protective cover 130. As shown in Fig. 3, the connecting mechanism has a connecting link 120, a link connecting member 125, and a connecting pin 122.

[0010] The connecting links 120 are made of steel plates extending inward from each side frame 110, and are arranged in pairs at the front and rear (four in total). The ends of the connecting links 120 are provided with pin holes (extended position pin holes 123) for connection in the extended position. The middle parts of the connecting links 120 are provided with pin holes (reduced position pin holes 124) for connection in the retracted position.

[0011] The link connecting member 125 is made up of a member that connects the connecting links 120 by sandwiching them from above and below, and is provided to protrude from each axle 109. The link connecting member 125 is formed with a pin hole of the same diameter (extended position superimposed pin hole 126) that overlaps with the extended position pin hole 123 in the extended position, and a pin hole of the same diameter (reduced position superimposed pin hole 127) that overlaps with the reduc- ed position pin hole 124 in the reduc- ed position, aligned in the left-right direction.

[0012] The link connecting member 125 is provided with cylindrical pin receiving portions 128 that protrude upward from the periphery of each of the expanded position superimposing pin hole 126 and the contracted position superimposing pin hole 127. A pair of U-shaped notches 128a are formed facing each other at the top of these pin receiving portions 128, 128.

[0013] The connecting pin 122 is made of a cylindrical member that fits into each of the above-mentioned pin holes 123, 126, 124, and 127. The connecting pin 122 is inserted into each of the overlapping pin holes 123, 126 (124, 127) by inserting it into the pin receiving portion 128 from above. A handle 122a formed by bending a rod material is provided on the top of the connecting pin 122.

[0014] By aligning the direction of the connecting pin 122 and inserting it into the pin receiving portion 128, the handle 122a fits into the notch 128a, and the connecting pin 122 is configured to be properly inserted into each of the pin holes 123, 124. The connecting pin 122 properly inserted into each of the pin holes 123, 124 is prevented from coming out by the retaining pin 129.

[0015] 3 shows the state of the connecting pin 122 in the expanded position. In the expanded position, the expanded position pin hole 123 of the connecting link 120 and the expanded position overlap pin hole 126 of the link connecting member 125 are vertically overlapped, so the connecting pin 122 is inserted into and fitted into both of these pin holes 123 and 126.

[0016] On the other hand, since the retracted position pin hole 124 and the retracted position overlapping pin hole 127 do not overlap vertically, even if the connecting pin 122 is inserted into its pin receiving portion 128, the connecting pin 122 does not enter the retracted position pin hole 124. The connecting pin 122 is supported by the retracted side pin receiving portion 128 and stands on the connecting link 120, as shown by the two-dot chain line in the lower diagram of Figure 3.

[0017] Conversely, in the retracted position, the retracted position pin hole 124 of the connecting link 120 and the retracted position overlapping pin hole 127 of the link connecting member 125 overlap vertically, so the connecting pin 122 is inserted into and fits into both of these pin holes 124, 127. On the other hand, the expanded position pin hole 123 and the expanded position overlapping pin hole 126 do not overlap vertically, so even if the connecting pin 122 is inserted into its pin receiving portion 128, the connecting pin 122 will not enter the expanded position pin hole 123. The connecting pin 122 is supported by the expanded side pin receiving portion 128 and stands on the connecting link 120.

[0018] 1 and 4, the periphery of the connecting mechanism is covered with a protective cover 130. The protective cover 130 has a center cover 131 that covers the side of the truck frame 107 and side covers 132 that cover the sides of the left and right side frames 110. The hydraulic piping 116 is routed along the connecting mechanism, and is also housed inside the protective cover 130.

[0019] The center cover 131 is made of a rectangular cylindrical member that is open on the side facing each side frame 110. Each side cover 132 is made of a member that covers the inside of the side frame 110 and the part that protrudes inward from the side frame 110. An opening (receiving opening 132a) that receives the end of the center cover 131 is formed in the protruding part of each side cover 132.

[0020] As a result, when the crawler width is expanded or contracted, the center cover 131 is configured to enter the side cover 132 through the receiving opening 132a as it moves from the expanded position to the contracted position.

[0021] As shown in Fig. 4, a side opening 141 is formed on the top surface of each side cover 132 so that the connecting pin 122 can be inserted and replaced from above when the side cover 132 is in the retracted position. This side opening 141 is covered by an openable and closable side opening cover 141a. One end of the openable side cover 141a is attached to the side frame 110 in a rotatable manner. The side opening 141 can be opened by loosening the thumbscrew N1 and rotating the openable side cover 141a.

[0022] A center opening 142 is formed on the top surface of the center cover 131 to allow the connecting pin 122 to be inserted and replaced from above. This center opening 142 is covered by an openable and closable center opening cover 142a. The center opening cover 142a is detachably attached to the center cover 131 with a thumbscrew N2. The center opening 142 can be opened by loosening the thumbscrew N2 and removing the center opening cover 142a.

[0023] (Crawler spacing expansion / contraction operation) Figure 4 shows the procedure for shortening the crawler spacing. The worker loosens the thumbscrew N2 and removes the center opening cover 142a. By opening the center opening 142, the upper part of the link connecting member 125 is exposed, making it possible to replace the connecting pin 122. The worker then loosens the thumbscrew N1 and rotates the side opening cover 141a, thereby opening the side opening 141.

[0024] In the illustrated example, the side frame 110 is in the extended position, so the connecting pin 122 is inserted into both the extended position pin hole 123 and the extended position overlap pin hole 126. After removing the retaining pin 129, the handle 122a is grasped and the connecting pin 122 is pulled upward. Then, as shown in the lower diagram of Figure 4, the connecting pin 122 is replaced with the pin receiving portion 128 on the retracted side.

[0025] After that, the side frame 110 is moved inward, causing the connecting pin 122 to slide along the upper surface of the connecting link 120, and when it reaches the retracted position, the retracted position pin hole 124 and the retracted position overlap pin hole 127 overlap, so that the connecting pin 122 automatically drops into these pin holes 124, 127.

[0026] The handle 122a is fitted into the notch 128a and the retaining pin 129 is attached. The operation to shorten the crawler spacing is then completed by closing the side opening cover 141a and the center opening cover 142a. To lengthen the crawler spacing, simply perform the reverse operation.

[0027] (Issues with expanding and contracting crawler spacing) As shown in FIG. 4, when performing an operation to shorten the crawler spacing, it is necessary to open both the side opening cover 141a and the center opening cover 142a before moving the side frame 110 as a procedure.

[0028] That is, when the side frame 110 is moved toward the track frame 107, the center cover 131 is configured to fit into the side cover 132. Therefore, as shown in an enlarged view in the lower part of FIG. 4, the upper surface of the side cover 132 is located higher than the upper surface of the center cover 131.

[0029] In contrast, after replacement, the connecting pin 122 stands on the connecting link 120, and the upper part of the connecting pin 122 (here, the handle 122a) protrudes above the upper surface of the side cover 132.

[0030] Since the connecting pin 122 cannot be replaced unless the center opening cover 142a is opened, there is no possibility that the worker will forget to open the center opening cover 142a. In contrast, the connecting pin 122 can be replaced without opening the side opening cover 141a, so there is a possibility that the worker will forget to open the side opening cover 141a. If the side frame 110 is moved while forgetting to open the side opening cover 141a, the connecting pin 122 will collide with the side cover 132 (side opening cover 141a) and be damaged.

[0031] Therefore, the technology disclosed here allows workers to properly and easily perform the operation to expand or contract the crawler spacing without making any mistakes in the procedure. [Means for solving the problem]

[0032] The disclosed technology relates to an extendable undercarriage in which the crawler width is extendable.

[0033] The lower running body includes a track frame, a pair of side frames located on both the left and right sides of the track frame to support a pair of crawlers and configured to be movable left and right between an extended position at which the width between the crawlers is maximum and a retracted position at which the width is minimum, a connecting mechanism connecting each of the side frames to the track frame, and a protective cover that covers the periphery of the connecting mechanism.

[0034] The protective cover has a side cover that covers the side frame side and a center cover that covers the side of the truck frame and fits into the side cover as it moves from the extended position to the retracted position. The connecting mechanism has a connecting pin that changes the connecting state by a replacement operation from above at each of the extended position and the retracted position.

[0035] The side covers are covered with first opening / closing covers and have a first opening on their upper surfaces that enables the replacement operation in both the extended position and the retracted position by opening the first opening / closing cover, and the center cover is covered with a second opening on its upper surface that enables the replacement operation in both the extended position and the retracted position by opening the second opening / closing cover.The second opening / closing cover cannot be opened unless the first opening / closing cover is opened in both the extended position and the retracted position.

[0036] That is, in this undercarriage, the side covers have a first opening on their upper surfaces that allows replacement operation in both the extended position and the retracted position by opening the first opening cover. The center cover also has a second opening on its upper surface that allows replacement operation in both the extended position and the retracted position by opening the second opening cover. The second opening cover cannot be opened unless the first opening cover is opened in both the extended position and the retracted position.

[0037] Therefore, unless both the first opening in the side cover and the second opening in the center cover are open, the connecting pin cannot be replaced in either the extended or retracted position. Even if the first opening cover is open in both positions, the second opening cover cannot be opened unless the first opening cover is also open, so there is no chance that an operator will forget to open the second opening cover. This eliminates the risk of moving the side frame while forgetting to open the second opening cover, reliably preventing the connecting pin from colliding with the side cover and causing damage.

[0038] Since it only restricts the order in which the two covers are opened and closed, there is no need to add any new parts, which is also cost-effective. Workers can easily and properly adjust the crawler spacing without making any mistakes.

[0039] For example, the second opening / closing cover may be opened and closed by swinging it upward, and the first opening / closing cover may be configured to overlap the second opening / closing cover in both the extended position and the retracted position.

[0040] With this configuration, the first and second opening / closing covers only need to be partially overlapped. This extremely simple modification can achieve the excellent effects described above. Each cover can be opened and closed by swinging it upward, making it easy to use.

[0041] For example, the second opening / closing cover may be opened and closed by operating a predetermined opening / closing operation part, and the first opening / closing cover may be configured to overlap the opening / closing operation part in both the extended position and the retracted position.

[0042] This configuration also makes it possible to achieve the above-mentioned excellent effects with extremely simple modifications.

[0043] The second opening / closing cover may be held closed by a magnet.

[0044] This eliminates the need for thumbscrews, bolts, or other components that can be lost when removed, making the cover easier to handle. Magnets also help reduce the height, making it easier to stack covers.

[0045] The connecting pin after replacement in both the extended position and the retracted position may be positioned in a range where the first opening / closing cover and the second opening / closing cover overlap when both are closed.

[0046] As described above, the connecting pin after replacement protrudes above the top surface of the side cover. Therefore, if the connecting pin after replacement is positioned so that it is in the area where the first and second opening / closing covers overlap when both covers are closed, the covers will hit the top of the connecting pin and will not close when you try to close them.

[0047] If a worker accidentally closes these covers in the middle of work, there is a risk of damage, but this can be reliably prevented. [Effects of the Invention]

[0048] According to the disclosed technology, an operator can appropriately and easily extend or retract the crawler spacing without making any mistakes in the procedure, thereby making it easier to handle the telescopic lower traveling structure. [Brief explanation of the drawings]

[0049] [Figure 1] FIG. 10 is a diagram illustrating the structure of a conventional machine. [Figure 2] FIG. 10 is a diagram illustrating the structure of a conventional machine. [Figure 3] FIG. 10 is a diagram illustrating a connection mechanism of a conventional machine. [Figure 4] FIG. 10 is a diagram for explaining a problem with a conventional machine. [Figure 5] 1 is a schematic diagram showing the structure of a lower traveling body to which the disclosed technology is applied. [Figure 6] 1A and 1B are schematic diagrams showing the extended position (upper diagram) and the retracted position (lower diagram). [Figure 7] FIG. 2 is a schematic perspective view showing the structure of a protective cover. [Figure 8] 10A and 10B are diagrams illustrating an operation procedure from an expanded position to a contracted position. [Figure 9] 10A and 10B are diagrams illustrating an operation procedure from an expanded position to a contracted position. [Figure 10] 10A and 10B are diagrams illustrating an operation procedure from an expanded position to a contracted position. [Figure 11] 10A and 10B are diagrams illustrating an operation procedure from a contracted position to an expanded position. [Figure 12] 10A and 10B are diagrams illustrating an operation procedure from a contracted position to an expanded position. [Figure 13] 10A and 10B are diagrams illustrating an operation procedure from a contracted position to an expanded position. DETAILED DESCRIPTION OF THE INVENTION

[0050] Hereinafter, embodiments of the disclosed technology will be described in detail with reference to the accompanying drawings. However, the following description is merely exemplary in nature and does not limit the present invention, its applications, or its uses.

[0051] <Overall structure of the lower running body> 5 and 6 show an example of a lower running body to which the disclosed technology is applied. The basic configuration of this lower running body is the same as that of the conventional machine (the lower running body of the above-mentioned Patent Document 1). Therefore, the same names and symbols are used for the components that have the same explanation as the conventional machine, and the explanation is omitted or simplified. The components that have different explanations from the conventional machine are explained using different names or symbols.

[0052] This undercarriage 102 constitutes the lower part of a work machine such as a hydraulic excavator, a crane, or a demolition machine. The undercarriage 102 includes a track frame 107 and a pair of side frames 110, 110 located on both the left and right sides of the track frame 107. Although not shown, an upper body is mounted on the track frame 107 so as to be able to rotate freely via a slewing bearing.

[0053] In this lower traveling body 102, as in the conventional machine, the axles 109 of the track frame 107 are slidably inserted into axle insertion holes 111 of the left and right side frames 110, 110. As shown imaginarily by the two-dot chain line, a crawler 1 is rotatably supported on each side frame 110. One end of each side frame 110 is provided with a hydraulic motor 114 connected to hydraulic piping 116 extending from a swivel joint 115 (shown only in the conventional machine).

[0054] As shown in Fig. 6, the left and right side frames 110 are configured to be movable in the left-right direction. This allows the pair of side frames 110, 110 to be switched between a position (extended position, upper diagram in Fig. 6) where the distance between the left and right crawlers 1, 1 (crawler distance) is maximum, and a position (retracted position, lower diagram in Fig. 6) where the crawler distance is minimum. Note that Fig. 5 shows a state in which the pair of side frames 110, 110 are located in the extended position (state during work).

[0055] In this lower traveling body 102, the connecting mechanism is also located near the end of the track frame 107, between the left and right side frames 110. The periphery of the connecting mechanism is covered with a protective cover 130. As with the conventional machine, the connecting mechanism also has a connecting link 120, a link connecting member 125, and a connecting pin 122 (see FIG. 3).

[0056] For example, as shown on the left side of the upper view of Fig. 6, a pin hole (expanded position pin hole 123) for connection at the expanded position is provided at the tip portion of the connecting link 120. A pin hole (reduced position pin hole 124) for connection at the contracted position is provided at the middle portion of the connecting link 120. As shown in Fig. 3, the link connecting member 125 is provided with pin holes (expanded position superimposed pin hole 126, contracted position superimposed pin hole 127) and a pin receiving portion 128.

[0057] As with conventional machines, the periphery of the connecting mechanism is covered with a protective cover 130. The protective cover 130 has a center cover 131 that covers the side of the truck frame 107 and side covers 132 that cover the sides of the left and right side frames 110. The hydraulic piping 116 is routed along the connecting mechanism, and is also housed inside the protective cover 130.

[0058] (protective cover) As shown in the enlarged view of Fig. 5 and Fig. 7, the center cover 131 is made of a rectangular cylindrical member that is open on the side facing the track frame 107. Each side cover 132 is made of a member that covers the inside of the side frame 110 and the portion that protrudes inward from the side frame 110. A receiving opening 132a that receives the end of the track frame 107 is formed in the protruding portion of each side frame 110.

[0059] As a result, when the crawler width is expanded or contracted, the center cover 131 is configured to enter the side cover 132 through the receiving opening 132a as it moves from the expanded position to the contracted position.

[0060] Unlike conventional models, an improved side opening 10 (first opening) is formed on the upper surface of each side cover 132 to allow the connecting pin 122 to be inserted and removed from above in both the extended and retracted positions. The improved side opening 10 is formed by cutting out the tip portion of the side cover 132.

[0061] The improved side opening 10 is covered by an openable and closable improved side opening cover 11 (first openable cover) made of steel plate. Unlike conventional models, one side of the improved side opening cover 11 is attached to the side cover 132 via a hinge in a swingable state. A handle 12 is attached to the other side (the swing end side) of the improved side opening cover 11.

[0062] A first magnet 13 is attached to the edge of the improved side opening 10, more specifically to the edge on the swing end side of the improved side opening cover 11. The improved side opening cover 11 is held in a closed state by the first magnet 13. The improved side opening 10 can be opened by holding the handle 12 and pulling the improved side opening cover 11 upward, causing the improved side opening cover 11 to swing. When the improved side opening cover 11 is returned to its original position, it is attracted by the first magnet 13 and the improved side opening cover 11 is closed, and this state is maintained.

[0063] Unlike conventional models, an improved center opening 20 (second opening) is also formed on the top surface of the center cover 131 to allow the connecting pin 122 to be inserted and removed from above in both the extended and retracted positions. The improved center opening 20 is formed by cutting out an end of the center cover 131. This improved center opening 20 is also covered by an openable and closable improved center opening cover 21 (second opening cover) made of steel plate.

[0064] Unlike conventional models, the improved center opening / closing cover 21 has one side attached to the center frame via a hinge so that it can swing. The other side (the swing end side) of the improved center opening / closing cover 21 has a circular insertion hole 22 (an example of an opening / closing operating part) that functions as a handle.

[0065] A second magnet 23 is attached to the edge of the improved center opening 20, more specifically to the edge on the swing end side of the improved center opening cover 21. The improved center opening cover 21 is held in a closed state by the second magnet 23. The improved side opening 10 is opened by inserting a finger into the insertion hole 22 and pulling the improved center opening cover 21 upward, thereby swinging the improved center opening cover 21. When the improved center opening cover 21 is returned to its original position, it is attracted by the second magnet 23 and the improved center opening cover 21 is closed, and this state is maintained.

[0066] By forming the improved side opening 10 and the improved center opening 20 by cutting out, these openings 10, 20 can be arranged closer together than by drilling holes. Also, this method is easier to process than drilling holes.

[0067] By holding the improved center opening / closing cover 21 with the second magnet 23 and forming the insertion hole 22, the end of the center cover 131 can easily fit into the opening of the side cover 132. In other words, the height of the improved center opening / closing cover 21 from the top surface of the center cover 131 can be reduced. Therefore, the center cover 131 can be inserted into the side cover 132 with a small gap.

[0068] The lower running body 102 is configured such that the improved center opening / closing cover 21 cannot be opened unless the improved side opening / closing cover 11 is opened in both the extended position and the retracted position.

[0069] In this embodiment, as shown in the enlarged view of Figure 5, in the extended position, the improved side opening cover 11 is configured to overlap the improved center opening cover 21. The improved side opening cover 11 is also configured to overlap the insertion hole 22.

[0070] Specifically, when the center cover 131 is in the extended position where it protrudes furthest from the side cover 132, a portion of the swing end of the improved center open-close cover 21 is recessed under the improved side open-close cover 11. Therefore, an operator cannot open the improved center open-close cover 21 without opening the improved side open-close cover 11. The insertion hole 22 is also located under the improved side open-close cover 11, and the area above the insertion hole 22 is covered by the improved side open-close cover 11. Therefore, an operator cannot see or operate the insertion hole 22 unless he or she opens the improved side open-close cover 11.

[0071] In the retracted position, the center cover 131 is recessed further into the side cover 132 than in the extended position. As a result, in the retracted position, most of the improved center opening / closing cover 21 is recessed under the improved side opening / closing cover 11, and the area above the insertion hole 22 is also completely covered by the improved side opening / closing cover 11. Therefore, in both the extended position and the retracted position, the improved center opening / closing cover 21 cannot be opened unless the improved side opening / closing cover 11 is opened.

[0072] As a result, when performing an operation to extend or shorten the crawler spacing, it is possible to reliably prevent forgetting to open the improved openable side cover 11. The operation to extend or shorten the crawler spacing can be performed appropriately and easily.

[0073] As long as the improved center opening / closing cover 21 overlaps the improved side opening / closing cover 11, the improved center opening / closing cover 21 does not have to overlap the insertion hole 22. Also, it is preferable that the improved side opening / closing cover 11 itself overlaps the improved center opening / closing cover 21 and the insertion hole 22, but the improved side opening / closing cover 11 may be expanded by providing a protruding portion that protrudes from the improved side opening / closing cover 11 or by attaching a separate member such as a plate or rod, and the expanded portion may overlap the improved center opening / closing cover 21 and the insertion hole 22.

[0074] <Crawler spacing expansion / contraction operation> Next, the procedure for expanding and contracting the crawler spacing in the lower traveling structure 102 will be specifically described.

[0075] (extended to retracted position) 8, 9, and 10 show the operating procedure for moving the pair of side frames 110, 110 from the extended position to the retracted position. Figure 8(a) corresponds to the area surrounded by the dashed line L in Figure 6 (the state in which the improved side opening / closing cover 11 is open).

[0076] To move the pair of side frames 110, 110, it is necessary to change the connection state of the connection mechanism. Specifically, it is necessary to replace the connection pin 122 at the extended or retracted position. To do this, it is necessary to open at least the improved center opening / closing cover 21. In the case of this lower running body 102, the improved center opening / closing cover 21 cannot be opened unless the improved side opening / closing cover 11 is also opened.

[0077] The worker first opens the improved side opening cover 11 as shown in Figure 8(a). The improved side opening cover 11 can be easily opened by pulling up the handle 12 against the attractive force of the first magnet 13. No tools are required, and the operation can be performed simply and in a short time. By opening the improved side opening cover 11, the entire improved center opening cover 21 is exposed, and the insertion hole 22 can also be accessed.

[0078] Next, the worker opens the improved center opening / closing cover 21. By pulling up the insertion hole 22 against the attractive force of the second magnet 23, the improved center opening / closing cover 21 can also be easily opened. This exposes the upper part of the link connecting member 125, as shown in Figure 8(b). The connecting pin 122 is inserted into the extended position pin hole 123 and the extended position overlap pin hole 126.

[0079] After removing the retaining pin 129, the operator lifts the handle 122a and pulls out the connecting pin 122 from the expanded position pin hole 123 and the expanded position superimposed pin hole 126. Then, as shown in FIG. 9(c), the operator replaces the connecting pin 122 with the retracted side pin receiver 128. After replacement, the connecting pin 122 stands on the connecting link 120.

[0080] The replaced connecting pin 122 is positioned in the overlapping area of ​​the improved side opening cover 11 and the improved center opening cover 21 when both are closed, as shown by the two-dot chain line in (c) of Figure 9. The upper part of the replaced connecting pin 122 protrudes above the side cover 132 and the center cover 131 (see the enlarged view in Figure 4).

[0081] Therefore, even if an attempt is made to close the improved side opening / closing cover 11 or the improved center opening / closing cover 21 in this state, these opening / closing covers 11, 21 will hit the upper part of the connecting pin 122 and will not be able to close. If an operator accidentally closes the improved side opening / closing cover 11 or the improved center opening / closing cover 21 in the middle of work, there is a risk of damage, but this method can reliably prevent such a problem.

[0082] The worker moves the side frame 110 inward with the improved side opening cover 11 and the improved center opening cover 21 open. Then, as shown in Figure 9(d), when the side frame 110 reaches the retracted position and the retracted position pin hole 124 and the retracted position overlap pin hole 127 overlap, the connecting pin 122 drops into these pin holes 124, 127 under its own weight and fits into them.

[0083] As shown in Figure 10(e), the worker fits the handle 122a into the notch 128a, and then attaches the retaining pin 129 to the connecting pin 122. Then, as shown in Figure 10(f), the improved center opening / closing cover 21 is closed. Finally, the improved side opening / closing cover 11 is closed, completing the process of moving the pair of side frames 110, 110 from the extended position to the retracted position.

[0084] (retracted position to extended position) 11, 12, and 13 show the operating procedure for moving the pair of side frames 110, 110 from the retracted position to the extended position. Figure 11(g) shows the improved side opening / closing cover 11 in the retracted position with the cover open.

[0085] In Figure 11(g), the state in which the improved side opening cover 11 is closed is shown by a two-dot chain line. In this state, almost the entire improved center opening cover 21 is located below the improved side opening cover 11. Therefore, in order to open the improved center opening cover 21, the improved side opening cover 11 must be opened first. The worker then opens the improved center opening cover 21 as shown in Figure 11(h).

[0086] This exposes the upper portion of the link connecting member 125. The connecting pin 122 is inserted into the contracted position pin hole 124 and the contracted position overlap pin hole 127.

[0087] After removing the retaining pin 129, the operator lifts the handle 122a and pulls out the connecting pin 122 from the retracted position pin hole 124 and the retracted position overlapping pin hole 127. Then, as shown in FIG. 12(i), the operator inserts the connecting pin 122 into the expansion-side pin receiver 128. At this time, the connecting pin 122 stands on the connecting link 120.

[0088] As is clear from the drawings, the replaced connecting pin 122 is positioned in the area where the improved side opening cover 11 and the improved center opening cover 21 overlap when both are closed. As described above, the upper part of the replaced connecting pin 122 protrudes above the side cover 132 and the center cover 131.

[0089] Therefore, even if an attempt is made to close improved side opening / closing cover 11 or improved center opening / closing cover 21 in this state, these opening / closing covers will hit the upper part of connecting pin 122 and will not be able to close. If an operator accidentally closes improved side opening / closing cover 11 or improved center opening / closing cover 21 in the middle of work, there is a risk of damage, but this method reliably prevents such a problem.

[0090] The worker moves the side frame 110 outward with the improved side opening cover 11 and the improved center opening cover 21 open. Then, as shown in Figure 12(j), when the side frame 110 reaches the extended position and the extended position pin hole 123 and the extended position overlap pin hole 126 overlap, the connecting pin 122 drops into these pin holes 123, 126 under its own weight and fits into them.

[0091] As shown in Figure 13(k), the worker fits the handle 122a into the notch 128a, and then attaches the retaining pin 129 to the connecting pin 122. Then, as shown in Figure 13(l), the improved center opening / closing cover 21 is closed. Finally, the improved side opening / closing cover 11 is closed, completing the process of moving the pair of side frames 110 from the retracted position to the extended position.

[0092] In this way, with the undercarriage to which the disclosed technology is applied, workers can properly and easily extend and retract the crawler spacing without making any mistakes in the procedure, making the telescopic undercarriage easier to handle.

[0093] The disclosed technology is not limited to the above-described embodiment, and includes various other configurations. For example, in the embodiment, the opening / closing operation portion is the insertion hole 22, but it may be a thumbscrew, a bolt, or the like.

[0094] Also, the improved side opening / closing cover 11 is shown as a type that swings upward to open, but it may be a type that can be attached and detached by loosening a thumbscrew, as in the conventional model, or a sliding type. Similarly, the improved center opening / closing cover 21 may be a type that can be attached and detached by loosening a thumbscrew, or a sliding type.

[0095] If the improved side opening cover 11 or the improved center opening cover 21 is a type that swings upward to open, the opening direction may be either forward, backward, left, or right. This can be selected depending on the specifications of the undercarriage in which the disclosed technology is employed. [Explanation of symbols]

[0096] 1 crawler 10 Improved side opening (first opening) 11 Improved side opening cover (first opening cover) 12 Handle 13 First Magnet 20 Improved center opening (second opening) 21 Improved center opening cover (second opening cover) 22 Insertion hole 23 Second Magnet 102 Undercarriage 107 Truck Frame 108 Bearing stand 109 Axle 110 Side Frame 111 Axle insertion hole 114 Hydraulic motor 115 Swivel joint 116 Hydraulic piping 120 connecting links 122 connecting pin 122a Handle 123 Extended position pin hole 124 Pin hole for reduced position 125 Link connecting member 126 Extended Position Overlap Pin Hole 127 Reduced position overlap pin hole 128 Pin receiving part 128a Notch 129 Retaining pin 130 Protective Cover 131 Center cover 132 Side cover 132a Receiving opening 141 Side opening 141a Side opening cover 142 Center opening 142a Center opening cover N1, N2 thumbscrews

Claims

1. A telescopic lower traveling body in which the crawler width is expandable and contractible, The truck frame and a pair of side frames positioned on both the left and right sides of the track frame to support a pair of crawlers, and configured to be movable in the left-right direction between an expanded position where the width between the crawlers is maximized and a contracted position where the width between the crawlers is minimized; a connecting mechanism that connects each of the side frames to the truck frame; a protective cover that covers the periphery of the connecting mechanism; Equipped with The protective cover is a side cover that covers a side of the side frame; a center cover that covers a side of the truck frame and that fits into the side covers as it moves from the extended position to the retracted position; and the coupling mechanism has a coupling pin that changes the coupling state by a replacement operation from above at each of the extended position and the retracted position, the side cover has a first opening on an upper surface thereof, the first opening being covered with a first opening cover and enabling the replacement operation in both the extended position and the retracted position by opening the first opening cover; the center cover has a second opening on its upper surface, the second opening being covered by a second opening cover and enabling the replacement operation in both the extended position and the retracted position by opening the second opening cover; The lower traveling body is configured such that the second opening / closing cover cannot be opened unless the first opening / closing cover is opened in both the extended position and the retracted position.

2. The undercarriage according to claim 1, The second opening / closing cover is opened and closed by swinging it upward, The first opening / closing cover is configured to overlap the second opening / closing cover in both the extended position and the retracted position.

3. The undercarriage according to claim 1 or 2, the second opening / closing cover is opened and closed by operating a predetermined opening / closing operation part, The first opening / closing cover is configured to overlap the opening / closing operation unit in both the extended position and the retracted position.

4. The undercarriage according to claim 2 or 3, The second openable cover is held in a closed state by a magnet.

5. The undercarriage according to claim 1, A lower running body in which the connecting pin after replacement in both the extended position and the retracted position is positioned in the range where the first opening / closing cover and the second opening / closing cover overlap when both the first opening / closing cover and the second opening / closing cover are closed.

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