JP5351122B2 - Construction machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction machine in which an opening formed in a cylinder cover storing a hydraulic cylinder can be covered by a protective cover so as to be freely opened and closed, the hydraulic cylinder driving a step body of a movable ladder into an expanded state and a storage state. <P>SOLUTION: A protective cover 32 which slides along a long hole 22b formed in the bottom face of a cylinder cover 21 is disposed in the cylinder cover 21. A first link member 11 which rotates a step body between an expanded state and a storage state is disposed so as to be rotatable around a shaft C<SB POS="POST">1</SB>by expansion/contraction of a hydraulic cylinder 4. The tip of a cylinder rod 4a is born by a supporting shaft 31 in the vicinity of a bending part 11c of the first link member 11, and an interlocking link 30 is provided such that its both ends are pivoted in the vicinity of the supporting shaft 31 and on a bracket 34 provided in the protective cover 32, respectively. The long hole 22b can be openably closed with the protective cover 32 by expansion/contraction of the hydraulic cylinder 4. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a construction machine including a movable ladder that moves up and down a moving passage of a vehicle body. In particular, the present invention relates to a construction machine having a drive mechanism that drives a step body of a movable ladder to an expanded state and a retracted state.

  In construction machines in which the cab is located at a high position, a structure provided with a ladder is employed to ascend and descend to a moving passage serving as a communication path to the cab. As the structure of the ladder, a fixed structure fixed to the construction machine or a movable structure that is movable between a stored storage position and an expanded position in use is employed.

  The movable ladder has a configuration in which the upper end of the step body provided with a step is supported by a rotating support shaft so that it can be rotated vertically between the expanded state during use and the stowed stowed state. Etc. are adopted. As a movable ladder that rotates in the vertical direction, a work vehicle (see Patent Document 1) related to the applicant of the present application has been proposed.

  The vehicle access system described in Patent Document 1 will be described as a conventional example in the present invention with reference to FIGS. In the vehicle access system shown in FIG. 11, a hydraulic cylinder 53 that drives the elevating ladder 50 to an expanded state and a retracted state is incorporated in the ladder support frame 52. A base end portion of the elevating ladder 50 and a bracket 56 provided at the distal end portion of the ladder support frame 52 are connected via a support shaft 51.

  The base end portion of the hydraulic cylinder 53 is supported via a pin 57 on a bracket (not shown) provided inside the ladder support frame 52. The tip of the cylinder rod 53a in the hydraulic cylinder 53 is connected to a lever-like member 54 provided at the base of the lifting ladder 50 via a pin 58.

  The extension movement of the hydraulic cylinder 53 can be converted into the rotation of the lifting ladder 50 via the lever-like member 54, and the lifting ladder 50 can be positioned at the storage position stored on the upper swing body 60 side. This storage position is indicated by a solid line. On the contrary, the lifting ladder 50 can be positioned at the use position protruding from the upper swing body 60 toward the ground by the contraction movement of the hydraulic cylinder 53. This use position is indicated by a two-dot chain line.

  As shown in FIG. 12, which is a sectional view taken along the line XII-XII in FIG. 11, when the hydraulic cylinder 53 is expanded and contracted, the hydraulic cylinder 53 is allowed to rotate around the pin 57. An opening 61a is formed on the bottom surface of the stored ladder support frame 52, and an opening 61b is formed on the surface of the ladder support frame 52 on the lift ladder 50 side.

JP 2010-133151 A

In the invention described in Patent Document 1, since the openings 61a and 61b are formed in the ladder support frame 52, when mud, stones, etc. are sprung up during traveling of the work vehicle, Or the like may enter the ladder support frame 52 from the openings 61a and 61b and damage the cylinder rod 53a.

  The present invention relates to a construction machine having a drive mechanism that drives a step body of a movable ladder to an expanded state and a retracted state, and an opening formed in a cylinder cover that houses a hydraulic cylinder of the drive mechanism, An object is to provide a construction machine that can be freely opened and closed.

The object of the present invention can be achieved by the inventions described in claims 1 to 5.
That is, in the construction machine according to the present invention, a step body that is rotatably provided on the vehicle body,
A drive mechanism for driving the step body into an expanded state and a retracted state,
The drive mechanism connects a hydraulic cylinder having a base end pivotally supported by the vehicle body, the vehicle body and the step body, and pivotally supports the vehicle body and the step body respectively. And a link mechanism that pivotally supports the tip of the cylinder rod of the hydraulic cylinder and rotates the step body by the expansion and contraction of the hydraulic cylinder, and stores and covers the hydraulic cylinder so as to expand and contract the hydraulic cylinder. A cylinder cover formed with an opening that allows rotation of the cylinder rod around the base end portion,
The opening includes an opening formed on a surface of the cylinder cover on the side of the step body, and a long hole formed in communication with the opening and along a longitudinal direction of the cylinder rod, and opens and closes the long hole. The main feature is that the protective cover that is freely closed is slidably disposed along the elongated hole in conjunction with the expansion and contraction of the hydraulic cylinder.

  In the present invention, an interlocking link is disposed between the link member pivotally supported by the vehicle body and the protective cover in the link mechanism, and one end side of the interlocking link pivotally supports a tip of the cylinder rod. The main feature is that it is pivotally supported in the vicinity of the portion of the link member, and the other end side of the interlocking link is pivotally supported by a bracket provided on the protective cover.

  Further, according to the present invention, the protective cover closes the elongated hole when the hydraulic cylinder is extended, and the tip of the protective cover projects further forward than the step body side surface of the cylinder cover. The main feature is being made.

Furthermore, the main feature of the present invention is that the protective cover is composed of a wear-resistant plate.
The main feature of the present invention is that the protective cover is made of hard rubber.

  In the present invention, the protective cover that slides along with the expansion and contraction of the hydraulic cylinder is configured to be slidable along the long hole of the cylinder cover formed along the longitudinal direction of the cylinder rod. With this configuration, the long hole can be closed with a protective cover so as to be freely opened and closed.

  With this configuration, even if mud, stones, or the like is splashed up when the construction machine is running, a long hole into which mud, stones, etc. easily enter can be blocked by the protective cover. Further, it is possible to prevent the mud, stones and the like that have been splashed from entering the cylinder cover and to prevent the cylinder rod from being damaged. In addition, sediment and the like can be prevented from accumulating in the cylinder cover.

It is a principal part perspective view which shows the expansion state of a movable ladder. (Example) It is a principal part side view of the construction machine which provided the movable ladder. (Example) It is the principal part perspective view which looked at the drive mechanism from diagonally downward. (Example) It is a perspective view which shows the internal structure of the cylinder cover at the time of reduction of a hydraulic cylinder. (Example) It is a sectional side view which shows the action | operation of a drive mechanism at the time of reduction of a hydraulic cylinder. (Example) It is a perspective view from the vehicle body bottom side at the time of reduction of a hydraulic cylinder. (Example) It is a principal part perspective view which shows the storage state of a movable ladder. (Example) It is a perspective view which shows the internal structure of the cylinder cover at the time of expansion | extension of a hydraulic cylinder. (Example) It is a sectional side view showing operation of a drive mechanism at the time of extension of a hydraulic cylinder. (Example) It is a perspective view from the vehicle body bottom side at the time of reduction of a hydraulic cylinder. (Example) It is sectional drawing which shows the rotation state of the stairs for vehicles. (Conventional example) It is XII-XII sectional drawing of FIG. (Conventional example)

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. As a configuration of a construction machine including a movable ladder according to the present invention, a configuration example applied to a wheel loader will be described below. However, in addition to the shapes and arrangements described below, any shapes and arrangements that can solve the problems of the present invention can be adopted. For this reason, this invention is not limited to the Example demonstrated below, A various change is possible.

  In addition, the construction machine is not limited to a wheel loader as long as it has a movable ladder for access to a driver's cab located at a high position, and is also suitable for a hydraulic excavator or the like. Can be applied to.

As shown in FIG. 1, the movable ladder 3 is arranged as a staircase in which an operator moves up and down between the movement path 2 of the construction machine 20 and the ground. Stairs for further upward climbing are connected to the moving passage 2 and further climbing up the stairs can lead to a driver's cab (not shown). The moving path 2 is not limited to a configuration in which stairs are further connected to the end of the moving path 2, but can also be configured as a landing that is connected to the entrance of the driver's cab or the movable ladder 3.
The movable ladder 3 includes a step body 18 and a handrail 7. A step 18 a and a pair of left and right handrails 19 are fixed to the step body 18.

  The step body 18 is configured to be rotatable in the vertical direction about the first rotation axis A. The first rotation axis A supports the step body 18 so as to be rotatable with respect to the vehicle body 1. The step body 18 is rotated about the first rotation axis A by the hydraulic cylinder 4 of the drive mechanism 15 that drives the step body 18 to be described later in an expanded state and a retracted state. The drive mechanism 15 and the hydraulic cylinder 4 are shown in FIG. In the illustrated example, the step 18a including seven steps is illustrated, but the number of steps is not limited to seven steps, and may be configured as an appropriate number of steps.

  The pair of handrails 19 are configured such that the lower end portions thereof do not protrude from the step body 18 and are fixed to the step body 18. The pair of handrails 7 are supported by the vehicle body 1 via the second rotation shaft B at the lower ends thereof.

The state shown in FIG. 1 shows an expanded state of the step main body 18 and the handrail 7, and FIG. 7 described later shows a retracted state of the step main body 18 and the handrail 7.
As shown in FIG. 2, the hydraulic cylinder 4 (see FIG. 3) of the drive mechanism 15 that rotates the step body 18 is provided on the bottom surface 1 a of the vehicle body 1, and the hydraulic cylinder 4 is stored in the cylinder cover 21. Has been. As shown in FIG. 4, hydraulic hoses 36 a and 36 b for supplying and discharging pressure oil for expanding and contracting the hydraulic cylinder 4 are connected to the oil chambers of the cylinder 4 b in the hydraulic cylinder 4.

  In FIG. 2, the code | symbol 35 is a rear wheel of the construction machine 20, and the code | symbol 11 has shown the 1st link member. Reference numeral 12 denotes a second link member that is rotatably connected to the first link member 11, and converts the operating force from the hydraulic cylinder 4 together with the first link member 11 into rotation of the step body 18. A rotating link mechanism 5 (see FIG. 3) is configured.

  FIG. 3 is a perspective view of the drive mechanism 15 as viewed obliquely from below, and shows a state where the cylinder cover 21 is removed. As shown in FIG. 3, a single hydraulic cylinder 4 is used as an actuator for rotating the step body 18 and the handrail 7. The hydraulic cylinder 4 is disposed on the bottom surface 1 a of the vehicle body 1 on the lower side of the moving passage 2. The cylinder base end portion 4c of the hydraulic cylinder 4 is pivotally supported on the vehicle body 1 via a support shaft 40 (see FIG. 5).

  The axial direction of the support shaft 40 that supports the cylinder base end 4c, the axial direction of the first rotation shaft A that supports the step body 18, and the second that supports the handrail 7 are supported. The rotating shaft B is disposed so as to be parallel to the axial direction of the rotating shaft B.

  The link mechanism 5 for turning the step body includes an L-shaped first link member 11 and a second link member 12 whose other end is divided into two. The drive mechanism 15 for rotating the step body 18 of the present invention is configured to include a hydraulic cylinder 4, a first link member 11, and a second link member 12.

  Further, the link mechanism 6 for rotating the handrail is configured to include a connecting member 13 that rotatably connects the step body 18 and the handrail 7. The connecting member 13 can convert the turning motion of the step body 18 into the turning motion of the handrail 7.

The first end portion 11a which is one end portion of the first link member 11 is pivotally supported to the vehicle body 1 through a shaft C _1, and a second end 11b which is the other end portion of the first link member 11 first the first end portion 12a which is one end portion of the second link member 12 is pivotally supported to each other via a shaft C _2. Each second end 12b which is the other end portion of the second link member 12 bifurcated is pivotally supported at the site of the base end of the step main body 18 via the respective axes C _3. Further, the tip of the cylinder rod 4 a of the hydraulic cylinder 4 is pivotally supported by the support shaft 31 on the bending portion 11 c of the first link member 11.

  The bifurcated portion of the second link member 12 is configured via a linkage 24. That is, the first end 12a side of the second link member 12 is erected from the center of the linkage 24, and the second end 12b side of the second link member 12 is erected from both ends of the linkage 24. It has become. As described above, the second link member 12 can convert the rotation operation of the first link member 11 into the rotation operation of the step body 18.

  As shown in FIGS. 3 and 4, the periphery of the hydraulic cylinder 4 is covered with a cylinder cover 21. The cylinder cover 21 is configured to have a shape having a side surface composed of three surrounding surfaces and a bottom surface 21b with the upper part opened. Of the side surfaces of the cylinder cover 21, the fourth side surface can be closed by a plate-like member (not shown) provided on the vehicle body 1.

  As shown in FIG. 3, in order to allow the cylinder 4b and the cylinder rod 4a to swing around the support shaft 40 when the hydraulic cylinder 4 is operated, the cylinder cover on the step body 18 side within the side surface of the cylinder cover 21 is used. An opening 22a is formed in the front surface 21a of the cylinder 21, and a long hole 22b formed along the longitudinal direction of the hydraulic cylinder 4 is formed in the bottom surface 21b of the cylinder cover 21. The opening 22a and the long hole 22b Is formed in communication.

Further, the cylinder cover 21 can be attached to the bottom surface 1a of the vehicle body 1 by fixing means such as bolts and nuts via an attachment hole 39a formed in the cylinder cover 21 and an attachment hole 39b formed on the vehicle body 1 side.
In FIG. 3, illustration of a protective cover 32 (see FIGS. 4 and 8) for closing and opening the long hole 22 b described below and an interlocking link 30 (see FIGS. 4 and 8) for sliding the protective cover 32 is omitted. doing.

  As shown in FIG. 4, a protective cover 32 that is guided along the longitudinal direction of the long hole 22b by a pair of left and right guide portions 38 and slides along the long hole 22b is provided in the cylinder cover 21. . The protective cover 32 is configured to have a shape wider than the lateral width of the long hole 22b, and the long hole 22b can be closed by sliding toward the front surface 21a of the cylinder cover 21.

  Further, by sliding the protective cover 32 in a direction away from the front surface 21a of the cylinder cover 21, a part of the long hole 22b communicating with the opening 22a formed on the front surface 21a of the cylinder cover 21 is opened. can do.

  The protective cover 32 is composed of a wear-resistant plate, and a preferable material can be composed of hard rubber. By configuring the protective cover 32 with hard rubber, even if a stepping stone that is thrown up while the construction machine is running collides with the protective cover 32, the protective cover 32 is plastically deformed by the collision of the stepping stone. Can be prevented. Then, good sliding of the protective cover 32 is maintained without causing kinking in the protective cover 32. Moreover, noise when a stepping stone collides can be suppressed. The material of the protective cover 32 is not limited to hard rubber, and may be made of a material such as hard vinyl, sheet metal, or resin.

  L-shaped notches 32b are formed at both corners of the tip 32a of the protective cover 32. When the protective cover 32 slides toward the front surface 21a of the cylinder cover 21, the front end portion 32a of the protective cover 32 passes through the opening 22a formed in the front surface 21a of the cylinder cover 21 through the notch 32b, and the cylinder cover 21 It can be made to protrude further forward than the front surface 21a of 21.

  The portion of the notch 32b that cannot pass through the opening 22a comes into contact with the inner surface of the front surface 21a of the cylinder cover 21. With this contact, the front surface 21a of the cylinder cover 21 and the protective cover 32 can be sealed.

The position of the distal end portion 32a of the protective cover 32 which may be further projected on the front side than the front surface 21a of the cylinder cover 21, by the operation of the hydraulic cylinder 4, rotating the first link member 11 around the axis C ₁ In this case, the first link member 11 and the front end portion 32a of the protective cover 32 can be protruded to a limit position where they do not interfere with each other.
By causing the front end portion 32a of the protective cover 32 to protrude further forward than the front surface 21a of the cylinder cover 21, it is possible to prevent dirt and the like from adhering to the cylinder rod 4a.

  A pair of attachment members 33a and 33b (see FIG. 5) for holding the protective cover 32 from both the front and back surfaces are attached to the distal end portion 32a side of the protective cover 32. As shown in FIGS. 4 and 5, a bracket 34 is formed on the attachment member 33a, and an interlocking link 30 is disposed between the bracket 34 and a portion of the first link member 11 near the support shaft 31. Has been. One end side of the interlocking link 30 is supported near the support shaft 31 in the first link member 11 via the support shaft 30a, and the other end side of the interlocking link 30 is supported on the bracket 34 via the support shaft 30b. Yes.

By supporting the one end of the interlocking link 30 in the vicinity of the support shaft 31 in the first link member 11, the stroke amount when the first link member 11 is rotated about the axis C _1, the interlock link 30 is moved Can be made larger. And by making the stroke amount of the interlocking link 30 large, the sliding stroke of the protective cover 32 can be made long, and the entire long hole 22b can be closed by the protective cover 32.

  As shown in FIG. 4, the tip end side of the cylinder rod 4 a is arranged between the pair of first link members 11, and the tip end of the cylinder rod 4 a is between the pair of first link members 11. It is supported by a support shaft 31. Further, the interval between the pair of first link members 11 is formed to be slightly wider than the shaft diameter of the cylinder rod 4a.

4, 5, 8, and 9, when the hydraulic cylinder 4 is extended, the cylinder rod 4 a is moved left and right in the region where the pair of first link members 11 are marked with a star. It can be covered by surrounding it from both sides.
In addition, the area | region of the star mark attached | subjected to a pair of 1st link member 11 does not show only the position to which the star mark is attached, but the cylinder by which the front-end | tip part is pivotally supported by the spindle 31 in FIG. The entire region where the rod 4a is covered by the pair of first link members 11 is shown.

When the hydraulic cylinder 4 is extended, so may be left surrounding the cylinder rod 4a from both right and left sides by a pair of first link member 11, the shape of the first link member 11 in the axial C ₁ side, at least interlocking link 30 It is possible to configure a shape having a region where one end of the shaft can be supported by the support shaft 30a and a region with a star mark.
In the pair of first link members 11, a pair of lid members 41 are provided between portions on the side connected to the second link member 12.

  In addition to the arrangement configuration in which the cylinder rod 4a is covered between the pair of first link members 11, when the hydraulic cylinder 4 is contracted, as shown in FIGS. The portion 32a can be disposed at a position close to the pair of first link members 11. Further, when the hydraulic cylinder 4 is extended, the tip end portion 32a of the protective cover 32 can be made to protrude farther forward than the front surface 21a of the cylinder cover 21, as shown in FIGS. The area of the cylinder rod 4a that can be protected by the protective cover 32 can be configured to be long.

  In particular, when the hydraulic cylinder 4 is extended, the step body 18 is in the retracted state, and the construction machine is in a travelable state, so that the earth and sand jumped up when the construction machine travels adheres to the cylinder rod 4a. This can be prevented by the cylinder cover 21, the pair of first link members 11, and the protective cover 32 in which the tip end portion 32 a protrudes further forward than the front surface 21 a of the cylinder cover 21. In particular, the pair of first link members 11 can efficiently protect stepping stones that are slanted rearward from the rear wheel 35.

As shown in FIGS. 5 and 6, when the hydraulic cylinder 4 is in the contracted state, the hydraulic cylinder 4 is disposed in a downwardly inclined state. Further, when the hydraulic cylinder 4 is extended, the first link member 11 can be rotated counterclockwise in the drawing about the axis C ₁ to open the step body 18 in an expanded state. That is, as shown in FIG. 1, the step body 18 can be expanded, and the operator can go up and down through the stairs of the step body 18.

  When the hydraulic cylinder 4 is in the contracted state, the protective cover 32 is connected to the rear end face side of the cylinder cover 21, that is, the cylinder cover 21 by the interlocking link 30 that rotatably connects the first link member 11 and the protective cover 32. Will move away from the front surface 21a. Then, a part of the long hole 22b communicating with the opening 22a formed in the front surface 21a of the cylinder cover 21 can be opened, and the refracting portion 11c side of the first link member 11 is connected to the cylinder through the opened long hole 22b. It can be inserted into the cover 21.

A rotation mechanism for rotating the step body 18 between the expanded state and the retracted state will be described with reference to FIGS.
As shown in FIG. 3, when the step body 18 is in the expanded state, the position of the shaft C ₃ that pivotally supports the second end portion 12 b of the second link member 12 and the first link member 12. the position of the axis C ₂ of the second end portion 11b of the end portion 12a and the first link member 11 rotatably supports each other, are arranged such that the positional relationship on a substantially straight line in the vertical direction.

By arranging in this way, when the hydraulic cylinder 4 is extended from the state shown in FIG. 3 and the first link member 11 is rotated in the clockwise direction in the drawing, the second end of the first link member 11 is Both the part 11b side and the second link member 12 move in a substantially linear shape with respect to the vertical direction. Then, the upward pushing force by the first link member 11 can be efficiently applied to the second end portion 12b of the second link member 12.
In this way, the driving force of the hydraulic cylinder 4 can be efficiently used for the rotation of the step body 18.

When the step body 18 is rotated from the expanded state to the retracted state, as shown in FIG. 8, the pressure oil is supplied from the hydraulic hose 36a to the cylinder 4b, and the pressure oil from the cylinder 4b is discharged through the hydraulic hose 36b. Will be. Then, as shown in FIGS. 8 to 10, the hydraulic cylinder 4 is extended, the first link member 11 will be rotated in the counterclockwise direction in FIG around the axis C _1. At the same time, as the first link member 11 rotates, the interlocking link 30 is pulled and moved in the rotation direction of the first link member 11, and the protective cover 32 pivotally supported by the interlocking link 30 is provided with a long hole 22b. Sliding in the direction to block.

  At this time, as shown in FIGS. 9 and 10, the tip end portion 32 a of the protective cover 32 can be made to protrude farther forward than the front surface 21 a of the cylinder cover 21. Then, as shown in FIG. 7, when the hydraulic cylinder 4 is extended and the step body 18 is retracted, that is, when the construction machine is ready to run, the shaft is supported between the pair of first link members 11. The cylinder rod 4a can be protected by the cylinder cover 21, the pair of first link members 11 and the protective cover 32.

  Thus, since the cylinder rod 4a can be protected when the construction machine is ready to travel, it is possible to greatly prevent the earth and sand jumped up during traveling of the construction machine from adhering to the cylinder rod 4a.

  The present invention can be suitably applied to a construction machine in which a hydraulic cylinder is disposed at the bottom of a vehicle body.

  DESCRIPTION OF SYMBOLS 1 ... Car body, 3 ... Movable ladder, 4 ... Hydraulic cylinder, 4a ... Cylinder rod, 5 ... Link mechanism for step body rotation, 6 ... Link for handrail rotation Mechanism: 11 ... 1st link member, 12 ... 2nd link member, 13 ... Connection member, 15 ... Drive mechanism, 18 ... Step body, 20 ... Construction machine, 21. ..Cylinder cover, 21a ... front surface, 21b ... bottom surface, 22a ... opening, 22b ... long hole, 30 ... interlocking link, 32 ... protective cover, 34 ... bracket, 50: Elevating ladder, 52: Ladder support frame, 53: Hydraulic cylinder, 53a: Cylinder rod.

Claims (5)

A step body provided rotatably on the vehicle body;
A drive mechanism for driving the step body into an expanded state and a retracted state,
The drive mechanism includes a hydraulic cylinder having a base end pivotally supported on the vehicle body,
The vehicle body and the step body are connected to each other and pivotally supported by the vehicle body and the step body, respectively, and a cylinder rod tip of the hydraulic cylinder is pivotally supported. A link mechanism for rotating the step body;
A cylinder cover that covers and accommodates the hydraulic cylinder, and that has an opening that allows the cylinder rod to rotate around the base end portion associated with expansion and contraction of the hydraulic cylinder;
The opening includes an opening formed on the surface of the cylinder cover on the side of the step body, and a long hole that communicates with the opening and is formed along the longitudinal direction of the cylinder rod.
A construction machine, wherein a protective cover for closing and opening the long hole is slidably disposed along the long hole in conjunction with expansion and contraction of the hydraulic cylinder. In the link mechanism, an interlocking link is disposed between a link member pivotally supported by the vehicle body and the protective cover,
One end side of the interlocking link is pivotally supported in the vicinity of the portion of the link member that pivotally supports the tip of the cylinder rod, and the other end side of the interlocking link is pivotally supported by a bracket provided on the protective cover. The construction machine according to claim 1.   The protective cover is configured such that the elongated hole is closed when the hydraulic cylinder is extended, and a front end portion of the protective cover is further protruded forward than a surface of the cylinder cover on the step body side. The construction machine according to claim 1 or 2.   The construction machine according to any one of claims 1 to 3, wherein the protective cover is formed of a wear-resistant plate-like body.   The construction machine according to claim 4, wherein the protective cover is made of hard rubber.

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