JP2000302370A - Rail inverting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rail inverting device capable of keeping the safety in work, reducing the labor, saving the personnel and labor, and improving the efficiency. SOLUTION: The rail inverting device comprises an inverting panel 3 in which a plurality of claw members 2 to be inserted in both sides of a rail web portion 1b from one end of a rail 1 are mounted on a front surface in an off-centered manner from a specified distance from the axis 4 of inversion, a support member 5 to rotatably support the axis 4 of inversion of the inversion panel 3, and an inverting means 7 which is arranged on the support member 5 to invert the inversion panel 3, and the rail is inverted by the claw members 2 around the axis 4 of inversion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rail reversing device used for handling rails at railroad bases, such as when moving or transporting rails, or when replacing rails on railroad tracks.

[0002]

2. Description of the Related Art Standard rails have a standard weight of 60 kg / m and a length of 25 m for a first-class line, and have 50 kg / m and 40 kg / m for a local line. In each case, the standard length is 25 m. These rails are stored in advance at a railway base or the like, and when necessary, transshipment or unloading is performed, loaded on a bogie or the like, and transported to a destination or the like.

[0003] To transport rails to a railway base or the like, the rails are arranged side by side on a transport wagon with the flanges of the rails facing down and the heads facing upward (hereinafter referred to as the upright state). A rail having a head facing downward and a flange portion facing upward (hereinafter, referred to as an inverted state) is inserted into the gap between the upright rails and placed in parallel, and a horizontal girder is placed thereon. It is placed at appropriate intervals, and the upright rail and the inverted rail are combined and placed on the cross beam in the same manner as described above, and this is sequentially repeated to be transported in a state of being stacked in a plurality of stages. You. (See FIG. 1C).

When reloading or unloading rails, a portal crane is used, and wire ropes are hung at a plurality of locations in the longitudinal direction of the rails and suspended on hooks of the crane for transportation. In order to hang the wire rope on the rails stacked as described above, it is necessary to separate the rails on a trolley or the like, or to return the posture of the fallen object to the upright state.

Conventionally, the work of separating the rail and changing the posture to the upright state has been performed manually by an operator holding a crowbar or the like by hand.

[0006]

Since the rails are heavy and long, usually four workers are separated from each other at both ends in the longitudinal direction of the rails to perform the above-mentioned work. Labor saving and efficiency improvement are demanded.

The present invention has been developed to meet the above-mentioned demands, and has as its object to provide rails capable of improving work safety, labor reduction, labor saving, and efficiency improvement. An inversion device is provided.

[0008]

In order to achieve the above object, a rail reversing device according to the present invention is characterized in that a plurality of claw members which can be inserted from one end of a rail into both side surfaces of a rail web portion are eccentric by a predetermined distance from a reversal center axis. Reversing plate mounted on the front
A support member rotatably supporting a reversing center axis of the reversing plate; and reversing drive means disposed on the support member for reversing the reversing plate. It is characterized by being inverted by a member. With this configuration, when the rail is inverted, the entire device is arranged on one end side of the rail, the claw member is inserted into the web portion of the rail, and the inversion driving unit is driven. As a point of emphasis, the rail can be inverted by leverage.

The position of the reversing center axis of the reversing plate is set at one end of a flange portion of a rail for reversing. Thus, the inversion by the lever action of the rail can be reliably performed.

In addition, the reversing drive means has an edge section between the reversing plate and the reversing board so as to allow a reversing operation in the reversing direction due to the weight of the rail. In this case, during the reversing operation of the rail, when the center of gravity of the rail passes on the reversing center axis, the rail is rapidly reversed in the reversing direction at a speed higher than the driving speed by the reversing driving means due to the rotational moment due to its own weight. To prevent adverse effects such as shock due to a sudden change in the load on the inversion driving means.

Further, the present invention is characterized in that the reversing plate and the supporting member are provided with an index for displaying the initial phase of the claw member with respect to the rotation direction of the reversing center axis and a marker member.
With this configuration, the phase of the claw member of the reversing plate with respect to the support member can be easily confirmed, and the work of inserting the rail into the web portion can be smoothly performed.

A positioning recess and a positioning projection are provided on the reversing plate and the supporting member in correspondence with the index and the marking member, and the positioning projection and the positioning recess can be elastically disengaged from each other. In this case, the initial phase of the claw member of the reversing plate with respect to the support member is reliably determined and held by the reversing drive means.

Further, when the initial phase of the claw member is set symmetrically with respect to a vertical line perpendicular to the inversion center axis, the right end of the stacked row of rails is inverted to the right, and the left end is Can be easily turned to the left and work efficiency can be improved.

In the case where the support member can be mounted on the tip of an arm of a power shovel, the apparatus can be quickly moved closer to a place where rails are stacked, and can be inverted. The power of the driving means can be easily taken out from the power shovel body.

Further, the support member can be swung freely within a predetermined angle range around a vertical axis between the support member and a mounting board mounted on the tip of the arm of the power shovel, and is always held at a neutral position by a spring. In the case of interposing a mechanism that causes the excavator to approach the loading position of the rail and insert the claw member into the web portion of the rail by a power shovel, even if the approach direction is not parallel to the longitudinal direction of the rail, When the tip of the claw member enters the web portion of the rail, the posture can be automatically corrected so that the entire device is along the rail only by pushing in thereafter.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a side view showing a schematic configuration of an embodiment of a rail reversing device according to the present invention.
(B) is a schematic perspective view showing a relationship between a claw member and a rail of the present apparatus, (C) is a side view showing a loaded state and an inverted state of the rail, FIG. 2 is an enlarged longitudinal sectional side view of a main part of the present invention apparatus, FIG. 3 is a partial cross-sectional plan view of the apparatus of the present invention, FIG. 4A is a front view of the apparatus of the present invention, FIG. 4B is a front view of the positioning means for the initial phase of the claw member, and FIG. FIG. 5 is an explanatory view of the reversing operation of the rail by the device of the present invention.

In FIG. 1, 1 is a rail, 2 is a claw member,
3 is a reversing board, 4 is a reversing central axis, 5 is a supporting member, 6 is a mounting board, 7 is a reversing drive means, 8 is a vertical axis which is a swing center, 9 is a power shovel body, 10 is an arm, and 11 is a boom. , 12 are links, 13, 14, and 15 are hydraulic cylinders, and 16 is a rail loading table such as a bogie.

The rail 1 is, as shown in FIG.
A wide flange portion 1a is provided at a lower portion.
a web portion 1b rising from the center in the width direction of a.
A head 1c is formed on the upper part of the web portion 1b.
As shown in FIG. 1C, the rail 1 is mounted on a rail loading table 16 such as a trolley or a cradle with the head 1c facing upward with the flange 1a of the rail 1 facing downward (hereinafter referred to as an upright state). Side by side and aligned side-by-side with a head 1
The rail 1 having the flange 1a facing upward (hereinafter, referred to as an inverted state) with the c facing downward is inserted into the gap between the rails 1 and 1 in the upright state, and is placed in parallel, and the horizontal girder material is placed thereon. (Not shown) are placed at appropriate intervals, and the rails 1 in the upright state and the rails 1 in the inverted state are placed on the cross beams in the same manner as described above.
Are placed in combination, and this is repeated sequentially to be stored in a plurality of stages.

In taking out the rails 1 as described above, work such as separating the rails 1 on the rail loading table 16 and, when returning a fallen one to the upright state, lowering the upright one, etc. After that, the wire rope is hung, lifted by a crane, transported, and unloaded, transshipped, or loaded. The apparatus of the present invention is used for the work of separating the rail 1 and changing the attitude of the rail 1, and the configuration will be described below based on an embodiment shown in the drawings.

The apparatus according to the present invention comprises: a reversing plate 3 having a plurality of claw members 2 which can be inserted into both side surfaces of a web portion 1b from one end of a rail 1 eccentrically at a predetermined distance from a reversing center axis 4 and attached to the front surface; A reversing force transmitting member 20 for rotatably supporting the reversing center axis 4 of the reversing plate 3; and a reversing drive means 7 for reversing the reversing plate 3 with respect to the supporting member 5, the reversing center axis being provided. With the fulcrum 4 as a fulcrum and the claw member 2 as a power point, the rail 1 is inverted from one end thereof by the inversion driving means 7 by leverage.

The claw member 2 is separated on both sides so that it can be inserted into both side surfaces of the web portion 1b from one end of the rail 1, and is mounted and supported on the reversing plate 3 in a cantilever state. This claw member 2
The four rails are arranged in a square at equal intervals in the vertical and horizontal directions so as to easily correspond to the four postures (described later) of the rail 1. The tip of the claw member 2 is tapered to facilitate insertion of the rail 1 into the web portion 1b, and has a square cross section, but may have a rectangular, circular, semicircular, triangular, or other shape. .

The support structure of the reversing plate 3 is basically rotatably supported by the reversing force transmitting member 20 via the reversing center shaft 4. In the embodiment shown in FIG. An annular bearing inner ring 17 is fixed to the front surface.
An annular bearing outer ring 18 is concentrically rotatably mounted on the outer peripheral side of the bearing via a ball 19, and a disc-shaped reversing force transmitting member 20 is fixed to the front surface of the bearing outer ring 18. A bearing bush 3a is press-fitted into a boss cylindrical portion 20a at the center of 20.

The center boss cylindrical portion 20a of the reversing force transmitting member 20 is formed to extend rearward toward the inner space of the bearing inner ring 17, and the reversing plate 3 and the reversing center shaft 4 are integrally fitted. A positioning plate 21 is fixed to the rear end of the reversing center shaft 4 with a bolt 23 via a holding plate 22.

The positioning plate 21 also serves as a stopper for preventing the reversing plate 3 from coming off the central boss cylindrical portion 20a of the reversing force transmitting member 20, and serves as a positioning member for the reversing plate 3 with respect to the support member 5. (Details will be described later).

The reversing drive means 7 includes a hydraulic motor 7a attached to a part of the support member 5, a speed reduction mechanism 7b connected to the hydraulic motor 7a, and an output shaft 7 of the speed reduction mechanism 7b.
and a pinion 7d mounted on the outer ring 18 of the bearing outer ring 18. The pinion 7d is engaged with an annular external gear 18a formed on the outer peripheral surface of the bearing outer ring 18, thereby selecting the reversing force in the reversing force transmitting member 20 in the forward and reverse directions. It is configured to be able to communicate in a targeted manner.

The reversing force transmitting member 20 has a structure shown in FIG.
As shown in FIG. 5, two projections that engage with each other via a marginal section (play interval) over a predetermined range in the reversing direction of the reversing plate 3 in order to allow the reversing operation in the reversing direction due to the weight of the rail 1. 20b and 20c are formed symmetrically at 180 ° intervals.

Next, a mechanism for positioning the reversing plate 3 with respect to the support member 5 will be described. As shown in FIGS. 2 and 3, the positioning mechanism includes a positioning plate 21 fixed to the rear end of the reversing plate 3 and a positioning member 24 mounted on the support member 5.
Consists of

The positioning plate 21 has a structure shown in FIG.
As shown in FIG. 7, V-shaped positioning recesses 21a to 21d are formed at predetermined positions (laterally symmetrical with respect to a perpendicular perpendicular to the inversion center axis). Then, the positioning members 24 are installed at predetermined positions (two symmetrical positions at 180 ° intervals) of the support member 5 corresponding to the V-groove-shaped positioning concave portions 21a to 21d. The positioning member 24 installed on the support member 5 is formed of a ball plunger as shown in FIG. 3 and FIG. 4C, and a ball 24a corresponding to a convex portion is elastically pressed outward by a spring 24b. The position of the reversing plate 3 with respect to the support member 5, particularly the initial position of the claw member 2 of the reversing plate 3, is elastically removably fitted into one of the positioning concave portions 21 a to 21 d of the positioning plate 21. One of the phases is positioned and held.

Then, the reversing plate 3 and the supporting member 5 are
As shown in FIG. 4A, an index portion 3b for displaying the initial phase of the claw member 2 with respect to the rotation direction of the reversal center axis 4 and marker members 25a to 25d are provided. The indicator 3b and the marker members 25a to 25d are coated with a different color from the other members, in particular, a paint such as red or yellow which is conspicuous and attracts attention. The shovel body 9 can be visually checked from the driver's seat. This configuration makes it possible to easily confirm the phase of the claw member 2 of the reversing plate 3 with respect to the support member 5 and to smoothly insert the rail 1 into the web portion 1b.

Next, a mounting structure to the power shovel will be described. As shown in FIGS. 1, 2 and 3, the support member 5 rotates a mounting board 6 for mounting the tip of an arm 10 of a power shovel and a link 12 through a vertical axis 8 within a predetermined angle range. It is installed as possible. This allows the support member 5 to freely swing around the axis of the vertical shaft 8 within a predetermined angle range. Then, damper mechanisms 26a and 26b which are always held at a neutral position by a spring are arranged at symmetrical positions around the vertical axis 8 and are interposed between the support member 5 and the mounting board 6. With this configuration, when the power shovel moves the device closer to the loading position of the rail 1 and inserts the claw member 2 into the web portion 1b of the rail 1, the approach direction is not parallel to the longitudinal direction of the rail 1. However, if the tip of the claw member 2 enters the web portion 1b of the rail 1, there is a slight play in the left and right direction of the tip of the arm 10, so that the rest of the device is merely pushed in so that the entire device follows the rail 1. Can automatically correct the posture.

The power shovel has a main body 9 rotatably mounted on a crawler device 9a. A boom 11 is mounted on a front surface of the main body 9 so as to be vertically movable by a cylinder 15. 14
The mounting board 6 of the device of the present invention is pivotally attached to the tip of the arm 10 by a front and rear arm.
Is mounted so that it can move up and down. The hydraulic motor 7a of the reversing drive means 7 of the apparatus of the present invention is supplied with hydraulic pressure from a hydraulic unit provided in the power shovel body 9, and is controlled by a hydraulic valve switching operation means of a tip attachment provided in the power shovel body 9. Is used to control the forward and reverse rotation directions and the amount of rotation.

The embodiment of the apparatus of the present invention has the above-described configuration, and the operation thereof will be described next. In FIG. 5, when the left end rail 1 ′ is turned to the left by the apparatus of the present invention, the rail 1 ″ in the inverted state immediately to the right is also turned to the left together, and the two-dot chain line is caused by its own weight rotational moment from the middle. The rail 1 ', 1 "rolled over in this manner is turned upright by rotating one 1' to the right (clockwise) and the other 1" to the left (counterclockwise). The rail at the right end in Fig. 5 is reversed in a rotationally symmetrical relationship, and has two similar rollover states, and the same applies to other rails.

Therefore, the operation performed by the apparatus of the present invention is the case where the rail 1 in the upright state at the left end is rotated leftward (counterclockwise) as shown by a chain line in FIG. Operation a) and a case where the vehicle is rotated rightward (clockwise) from the rollover state indicated by the chain line to return to the erect state (operation b).
In FIG. 1 (C), the rail 1 in the upright state on the right side
(Right-handed clockwise) to roll over (operation c), and roll the rail 1 in the rolled state left (counterclockwise) to return to the upright state (operation d). It is. Hereinafter, this will be described.

First, in operation a, as shown by a solid line in FIG. 4A, the index portion 3b of the reversing board 3 is moved to the marker members 25a to 25a.
One of the rails 1 in the upright state is operated by operating the arm 10 of the power shovel body 9 as shown in FIGS. The claw member 2 is inserted into the web portion 1b from
4A, the reversing force transmitting member 20 is rotated to the left (counterclockwise) in FIG. 4A, and the reversing force transmitting member 20 is rolled over as shown by the chain line on the left side in FIG. In this case, since the reversal center axis 4 is set at one end (the end on the reversal direction side) of the flange portion 1a of the rail 1 to be reversed, the rail 1 is used as the fulcrum about the reversal center axis 4 and the claw member 2 is provided. Can be reversed by leverage as a power point. Also, when the center of gravity of the rail 1 passes on the reversal center axis 4 during this reversing operation, the rail 1 rapidly rolls to the left due to its own weight rotational moment. In order to allow this operation and not to adversely affect the reversing drive means 7 side, a marginal section (see FIG. 4A) is provided between the reversing plate 3 and the reversing force transmitting member 20. A play section) is formed.

Next, in the operation b, the index portion 3b of the reversing board 3 is moved to a position matching the mark 25b among the marker members 25a to 25d and positioned. This state is shown in FIG.
The angle is set so that the four claw members 2 can be just inserted into the web portion 1b of the rail 1 in the rolled state as shown by the chain line on the left side of FIG. As a result, the claw member 2 can be inserted from one end of the rail 1 in a state in which the claw member 2 has been rolled to the left, and thereafter, the reversing force transmitting member 20 is moved by the reversing drive means 7 in FIG. (Clockwise)
When the rail 1 is turned leftward, the rail 1 can be turned upside down by leverage using the inversion center axis 4 as a fulcrum and the claw member 2 as a point of force. Also in this case, when the center of gravity of the rail 1 passes on the reversing center axis 4 during the reversing operation, the rail 1 quickly rises rightward due to its own weight rotational moment. In order to allow this operation and not to adversely affect the reversing drive means 7, the position between the reversing plate 3 and the reversing force transmitting member 20 shown in FIG.
(A) is formed.

In operation c, the index portion 3b of the reversing board 3 is moved to a position corresponding to 25c among the marker members 25a to 25d and positioned. This state is shown in FIG.
4 to the web portion 1b of the rail 1 in the upright state on the right side of
The angle is set so that the two claw members 2 can be inserted just. As a result, the claw member 2 can be inserted into the erect rail 1 from one end thereof. Thereafter, when the reversing force transmitting member 20 is rotated right (clockwise) in FIG.
With the rail 1 in the upright state and the reversal center axis 4 as a fulcrum,
The pawl member 2 can be turned over to the right side by being inverted by leverage as a power point. Also in this case, when the center of gravity of the rail 1 passes on the reversal center axis 4 during the reversal operation,
The rail 1 rapidly rolls to the right due to its own weight rotational moment. In order to allow this operation and not to adversely affect the reversing drive means 7 side, a marginal section (see FIG. 4A) is provided between the reversing plate 3 and the reversing force transmitting member 20. Play interval) is formed.

Further, the operation d is performed in accordance with the operation of the index portion 3b of the reversing board 3.
Is moved to a position corresponding to 25d among the sign members 25a to 25d and positioned. This state corresponds to the web portion 1b of the rail 1 which is in a rolled state on the right side of FIG.
In addition, the angle is set so that the four claw members 2 can be inserted exactly. As a result, the claw member 2 can be inserted from one end of the rail 1 which is in a rolled state to the right. After that, the reversing force transmitting member 2 is
By rotating 0 in FIG. 4 (A) to the left (counterclockwise), the rail 1 that is in a rollover state to the right can be returned to an upright state. Also in this case, when the center of gravity of the rail 1 passes on the reversal center axis 4 during the reversal operation,
The rail 1 quickly rises to the right due to its own weight rotational moment. In order to allow this operation and not to adversely affect the reversing drive means 7 side, a marginal section (see FIG. 4A) is provided between the reversing plate 3 and the reversing force transmitting member 20. Play interval) is formed.

The positioning of the initial phase of the claw member 2 of the reversing plate 3 for performing these four operations is shown in FIG.
(C) and the positioning plate 21 and the positioning member 24 shown in FIG. Therefore, it should be understood that the subscripts (ad) given to the four positioning recesses 21a to 21d of the positioning plate 21 correspond to the four operations described above. In FIG. 4B, the left and right angles α and α and β and β are equal.

The operation of the apparatus of the present invention is as described above. The support member 5 is provided with appropriate sensor means for automatically detecting the phase of the reversing plate 3 and the phase of the reversing force transmitting member 20.
The determination of the phase may be automatically performed.

[0040]

According to the first aspect of the present invention, when the rail is inverted, the entire device is disposed at one end of the rail, the claw member is inserted into the web portion of the rail, and the inversion driving means is driven. Using the reversal center axis as a fulcrum and the claw member as a power point, the rail can be reversed by leverage. Further, according to the second aspect of the present invention, it is possible to surely perform the reversal by the lever action of the rail.

According to the third aspect of the present invention, when the center of gravity of the rail passes over the reversal center axis during the reversal operation of the rail, the rail is rotated by its own weight at a speed higher than the driving speed of the reversing drive means. It is possible to allow the vehicle to rapidly roll or stand forward in the reverse direction, thereby preventing an adverse effect such as an impact due to a sudden change in the load on the reverse drive means.

Further, according to the invention of claim 4, the phase of the claw member of the reversing plate with respect to the support member can be easily confirmed, and the work of inserting the rail into the web portion can be smoothly performed.

According to the fifth aspect of the present invention, the initial phase of the claw member of the reversing plate with respect to the support member is reliably determined and held by the reversing drive means.

Further, according to the invention of claim 6, it is easy to invert the right end of the stacked row of rails to the right and to invert the left end of the row to the left, thereby improving work efficiency. .

Further, according to the invention of claim 7, it is possible to quickly move the present apparatus to the place where the rails are piled up by using the mobility of the power shovel, and to turn over. The power of the driving means can be easily taken out from the power shovel body.

According to the eighth aspect of the present invention, when the power shovel moves the apparatus close to the loading position of the rail and inserts the claw member into the web portion of the rail, the approach direction is parallel to the longitudinal direction of the rail. Even if not, if the tip of the claw member enters the web portion of the rail, the posture can be automatically corrected so that the entire device follows the rail by simply pushing in the rest. Therefore, it is possible to provide a rail reversing device that enables safety, labor reduction, labor saving, and efficiency improvement of this kind of rail reversing work.

[Brief description of the drawings]

1A is a side view showing a schematic configuration of an embodiment of a rail reversing device according to the present invention, FIG. 1B is a schematic perspective view showing a relationship between a claw member of the device and a rail, and FIG. The side view which shows the loading state of a rail, and an inversion state.

FIG. 2 is an enlarged vertical sectional side view of a main part of the device of the present invention.

FIG. 3 is a partial cross-sectional plan view of the device of the present invention.

4A is a front view of the apparatus of the present invention, FIG. 4B is a front explanatory view of a positioning means for an initial phase of a claw member, and FIG.

FIG. 5 is an explanatory view of a reversing operation of the rail by the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rail 2 Claw member 3 Reversing board 4 Reversing center axis 5 Supporting member 6 Mounting board 7 Reversing drive means 8 Vertical axis which becomes the center of swinging 9 Power shovel body 10 Arm 11 Boom 12 Link 13, 14, 15 Hydraulic cylinder 16 Dolly, etc. Rail loading table

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shogo Inoue 23-3 Ikedanakacho, Neyagawa-shi, Osaka F-term in Oyodo Komatsu Co., Ltd. (Reference) AE02 AE21 AE38 BB15 BE01 FD09 FG01 FG09

Claims (8)

[Claims] 1. A reversing plate in which a plurality of claw members which can be inserted into both side surfaces of a rail web portion from one end of a rail are eccentrically mounted by a predetermined distance from a reversing center axis and mounted on the front surface, and the reversing center axis of the reversing plate is rotated. A supporting member that supports the reversible plate, and a reversing drive unit disposed on the supporting member for reversing the reversing plate, wherein the rail is reversed around the reversing center axis by the claw member. Features rail reversing device. 2. The rail reversing device according to claim 1, wherein the position of the reversing center axis of the reversing plate is set at one end of a flange portion of the rail for reversing the position. 3. The method according to claim 1, wherein the reversing drive means is provided between the reversing board and the reversing board so as to allow a reversing direction rolling operation due to the weight of the rail.
3. The rail reversing device according to claim 1, wherein the rail reversing device has an edge cutting section. 4. The reversing plate and the supporting member are provided with an index for displaying an initial phase of the claw member with respect to the rotation direction of the reversing central axis and a marker member. The rail reversing device according to item 1. 5. A positioning recess and a positioning projection are provided on the reversing plate and the support member in correspondence with the index and the marking member, and the positioning projection and the positioning recess can be elastically disengaged from each other. The rail reversing device according to claim 4, characterized in that: 6. The rail reversing device according to claim 5, wherein an initial phase of the claw member is set symmetrically with respect to a perpendicular perpendicular to a reversal center axis. 7. The power shovel according to claim 1, wherein the support member is attachable to an end of an arm of a power shovel.
7. The rail reversing device according to any one of claims 6 to 6. 8. The support member can be freely swung around a vertical axis within a predetermined angle range between the support member and a mounting board attached to the tip of an arm of a power shovel, and is always held at a neutral position by a spring. The rail reversing device according to any one of claims 1 to 7, further comprising a mechanism for causing the rail to be interposed.