JPH10140519A - Road cutter and hydraulic backhoe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve performance by connecting an output shaft for a motor installed to a lower-opened box-shaped body to a body of revolution having a bit in an outer circumferential surface borne into the box-shaped body. SOLUTION: The road cutter has a box-shaped body 20 whose lower section is opened, and is mounted detachably to an arm for the hydraulic backhoe by a bracket set up to an upper plate 21. One end of a cylindrical body 34 is fixed into a hole 33 formed to the side plate of the main body 20 and projected into the main body 20, and a shaft 35 is borne rotatably through a bearing 36 while a cutter drum 48 is fastened onto a cylindrical body 40 fixed onto the shaft 35. A motor 51 is installed on the outside of the hole 33, and an output shaft 53 for the motor 51 is connected to the shaft 35. First and second flywheels 55, 57 and a bit mounting body 56, in which a plurality of bits 61 are fitted on an outer circumferential surface, are mounted on the outer circumference of the drum 48. Accordingly, when the road cutter is attached to the hydraulic backhoe and a road is cut, the output torque of the motor can be transmitted efficiently to a body of revolution, and the number of parts is decreased and cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load cutter mounted on a working arm of a construction machine such as an arm of a hydraulic shovel for cutting an asphalt roadbed into a groove, and a hydraulic shovel provided with the load cutter.

[0002]

2. Description of the Related Art As a load cutter for cutting an asphalt roadbed into a groove, the one disclosed in Japanese Patent Application Laid-Open No. 7-54309 is known. In this load cutter, a cutter drum is rotatably mounted in a box-shaped main body having an open bottom, and a bit is mounted on the cutter drum. A motor is attached to a chain case attached to the main body, and the output torque of the motor is transmitted to the cutter drum via a chain to rotate the cutter drum.

The main body of this load cutter is detachably attached to the end of the arm of a hydraulic shovel. Then, the arm is swung up and down, and the cutter drum is rotated to cut the asphalt roadbed with the bit.

[0004]

In the above-described load cutter, a sprocket is mounted on a shaft of a cutter drum, a sprocket is mounted on an output shaft of a motor, a chain is wound between the sprockets, and the output torque of the motor is reduced by the cutter drum. To rotate the cutter drum and cut it with a bit.

For this reason, the number of components for rotating and driving the cutter drum is large and the cost is high. In addition, the efficiency of transmitting the output torque of the motor to the cutter drum is poor due to the chain drive, and the output torque of the motor cannot be effectively used as the cutting force of the bit.

Further, since the cutter drum is driven to rotate by the output torque of the motor, the rotational driving force of the cutter drum is constant. On the other hand, since the bit is intermittently cut by the rotation of the cutter drum, the rotation resistance intermittently increases or decreases.

[0007] For this reason, the rotation of the cutter drum becomes slow during cutting, resulting in poor cutting performance.

Further, since the bit protrudes from the opening edge of the main body, if the load cutter is stored alone or the like directly on the ground or the like, the bit is damaged or becomes unstable.
For this purpose, the opening edge of the main body is placed on a table so that the bit does not contact the ground or the like and is stored in a stable state.

Therefore, a table is required to store the load cutter, and the table must be transported to store the load cutter at an arbitrary location.

In the above-described hydraulic shovel equipped with a load cutter, a hydraulic pump is driven by an engine mounted on the hydraulic shovel, and a motor is rotationally driven by discharge pressure oil of the hydraulic pump. In order to obtain the required rotation drive force (bit cutting force) of the cutter drum due to poor transmission efficiency of the output torque of the motor to the cutter drum due to the chain drive and the lack of smooth rotation, as shown in FIG. A hydraulic shovel with an output engine is required.

For this reason, the load cutter cannot be mounted on a small-sized hydraulic excavator on which a small-output engine is mounted. If the load cutter is mounted on the above-mentioned small hydraulic excavator, it is necessary to increase the horsepower of the small output engine to a large output.

However, in order to increase the power of the engine, it is necessary to significantly modify the body of the excavator. Therefore, mounting the load cutter on a small excavator is expensive.

Accordingly, an object of the present invention is to provide a load cutter capable of solving the above-mentioned problem and a hydraulic shovel provided with the load cutter.

[0014]

A first aspect of the present invention is a box-shaped main body 20 having an opening at the bottom and having a connecting bracket 26, and an outer peripheral surface rotatably supported in the main body 20. A rotating body in which a plurality of bits 61 are attached at intervals in the circumferential direction;
Wherein the output shaft 53 of the motor 51 is connected to the rotating body.

According to the first aspect, the output torque of the motor 51 is efficiently transmitted to the rotating body, so that the output torque of the motor 51 can be effectively used as the cutting force of the bit 61.
The number of parts for rotating and driving the rotating body is small and the cost is low.

According to a second aspect of the present invention, there is provided a main body 20 having a box-like shape with
A cutter drum 48 rotatably supported therein, a bit mounting body 56 and a flywheel mounted on the outer peripheral surface of the cutter drum 48, and a plurality of peripheral parts mounted on the outer peripheral surface of the bit mounting body 56 at intervals in the circumferential direction. A load cutter comprising a bit 61 and a motor 51 attached to the main body 20 and driving the cutter drum 48 to rotate.

According to the second aspect of the present invention, a rotary inertia force is applied to the cutter drum 48 by the flywheel, and the rotary inertia force accumulates the rotational inertia force, thereby reducing the speed change of the bit cutting operation.

As a result, the cutting performance is improved because the cutter drum 48 rotates smoothly.

The third aspect of the present invention relates to a main body 20 having a box-like shape with a lower opening and having a connecting bracket 26,
A bit mounting body 56 rotatably supported therein, a plurality of bits 61 mounted on an outer peripheral surface of the bit mounting body 56 at intervals in the circumferential direction, and a bit mounting body 56 mounted on the main body 20 to rotate the bit mounting body 56 A bit 61 attached to the bit attachment body 56 is provided with a
a is a first sine curve trajectory which is sequentially mounted from one end in the width direction of the bit mounting body 56 to the other end in the width direction.
And a second bit 61-2 attached between the adjacent first bit 61-1 and having a bit tip 61a opposite to the first bit 61-1. A load cutter characterized in that:

According to the third aspect, the first bit 61-
1, the bit mounting body 56 is sequentially cut from one end to the other end in the width direction of the bit mounting body 56, and the second bit 61-2 is used to cut the bit mounting body 56 at the time of cutting the first bit 61-1.
The reaction force in the width direction is canceled, and the generation of vibration is suppressed.

Thus, the groove can be efficiently cut on the asphalt roadbed by the bit 61.

According to a fourth aspect of the present invention, there is provided a main body 20 having a box-like shape with an opening
A bit mounting body 56 rotatably supported therein, a plurality of bits 61 mounted on the outer peripheral surface of the bit mounting body 56 at intervals in the circumferential direction, and a bit mounting body 56 mounted on the main body 20 to rotationally drive the bit mounting body 56 A motor 51 is provided, and the bit 61 attached to the bit attaching body 56 is
A plurality of first bit strings a, which are alternately attached so that one bit tip 61a faces one end and the other end in the width direction of the bit attaching body 56, and a bit tip attached between the adjacent bit strings a. A load cutter characterized by comprising a plurality of second bit strings b whose reference numeral 61a faces the middle of the bit mounting body 56 in the width direction.

According to the fourth aspect of the present invention, the bit 61 of the first bit train a alternates between a portion facing the one end in the width direction of the bit attachment body 56 and a portion facing the other end in the width direction on the asphalt roadbed. After cutting, the bit 61 of the second bit string b is used to cut a portion of the asphalt roadbed facing the bit mounting body 56 in the width direction.

Thus, the groove can be efficiently cut on the asphalt roadbed by the bit 61.

According to a fifth aspect of the present invention, there is provided a main body 20 having a box-like shape with
A rotating body which is rotatably supported therein and has a plurality of bits 61 mounted on its outer peripheral surface at intervals in the circumferential direction; a motor 51 which is mounted on the main body 20 to rotate the rotating body; The grounding strip 71 is formed of a support leg 70 that can move up and down over a position above the lower end surface of the main body 20 at a position below the grounding strip 71 protruding below the tip of the bit. It is a road cutter.

According to the fifth aspect of the present invention, since the grounding piece 71 projects below the tip of the bit by setting the support leg 70 to the lower position, the load cutter is grounded by grounding the grounding piece 71. The bit can be placed so that the tip does not touch the ground. Further, by setting the support leg 70 at the upper position, the grounding piece 71 is positioned above the lower end surface of the main body 20, so that the support leg 70 does not hinder the cutting operation of the bit 61.

This makes it possible to easily store the load cutter in a stable state at an arbitrary place.

According to a sixth aspect of the present invention, an upper body 3 is pivotally mounted on a lower body 2 provided with a traveling body 1, and a boom 4 is vertically swingably mounted on the upper body 3, and an arm 6 is attached to the boom 4. A hydraulic excavator mounted vertically swingably and having a load cutter A mounted on its arm 6; a box-shaped main body 20 having an opening at the bottom, and having a connecting bracket 26;
The cutter drum 48 rotatably supported in the main body 20
A bit mounting body 56 and a flywheel mounted on the outer peripheral surface of the cutter drum 48; and a plurality of bits 6 mounted on the outer peripheral surface of the bit mounting body 56 at circumferential intervals.
1 and the motor 51 attached to the main body 20 are used as the load cutter A, and the bit 61 attached to the bit attaching body 56 is sequentially moved from one end in the width direction of the bit attaching body 56 to the other end in the width direction. A first bit 61-1 attached substantially as a sine curve trajectory toward the end, and a bit tip 61a attached between adjacent first bits 61-1 has a bit tip 61a opposite to the first bit 61-1. A hydraulic pump 12 driven by an engine 11 mounted on the upper body 3 by connecting an output shaft 53 of the motor 51 to a cutter drum 48.
The hydraulic excavator is characterized in that the motor 51 is driven to rotate by the discharge pressure oil.

According to the sixth aspect, the output torque of the motor 51 can be used as the cutting force of the bit 61, the cutter drum 48 can be smoothly rotated by using the inertia force of the flywheel, and the efficiency of the bit 61 can be improved. Since cutting can be performed well, the efficiency of the bit 61 can be increased using a motor having a small output torque.

Thus, a small power shovel on which a small output engine is mounted, but a large bit 6
A cutting force of 1 is obtained.

According to a seventh aspect of the present invention, there is provided the main body 2 according to the sixth aspect.
A plurality of support legs 70 provided with a grounding strip 71 at
A hydraulic excavator 1 is vertically movably mounted at a lower position where the lower end protrudes below the bit tip portion and at an upper position above the lower end surface of the main body 20.

According to the seventh aspect, the main body 20 is connected to the arm 6
When the cutting work is performed by attaching the supporting legs 70 to the support legs 70, the supporting legs 70 are set at the upper position, so that the supporting legs 70 do not interfere.

Since the support leg 70 is located at the lower position, the grounding piece 71 is grounded, and the load cutter A can be stably placed on the ground or the like. It can be easily and stably placed anywhere.

[0034] Since the load cutter A and the bucket are alternately mounted on the work site and work is performed, the load cutter A can be placed and stored in the work site. Can be performed efficiently.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an upper vehicle body 3 is pivotally mounted on a lower vehicle body 2 provided with a traveling body 1. A boom 4 is attached to the upper body 3 by a boom cylinder 5 so as to be vertically swingable.
Are mounted on the arm cylinder 7 so as to be swingable up and down. A working machine coupler 8 is attached to the arm 6 so that the working machine cylinder 9 can swing up and down.

A driver's cab 10 is mounted on the upper body 3, and an engine 11, a hydraulic pump 12, and the like are mounted on the upper body 3.
Covered with 3.

The lower vehicle body 2 has a blade arm 14 mounted on a cylinder (not shown) so as to be vertically swingable. A blade 15 is attached to the blade arm 14.
A rod 17 is mounted on an upper portion of the blade 15 via a bracket 16.

A bucket is usually attached to the working machine coupler 8 to form a hydraulic shovel, but a load cutter A is attached to the working machine coupler 8 as shown in FIG.

The load cutter A has a main body 20 as shown in FIGS. The main body 20 is formed in a box shape having an upper plate 21, a front and rear vertical plate 22, a front and rear other vertical plate 23, a left and right one vertical plate 24, and a left and right other vertical plate 25 with an open bottom.
A connecting bracket 26 is fixed to one side of the upper plate 21 in the front-rear direction, and the connecting bracket 26 is detachably attached to the lower portion 8a of the working machine coupler 8 with a pin 27.

A support bracket 28 is fixed to the upper plate 21 near the front and rear sides, and a concave portion 29 of the support bracket 28 is fitted to the rod 17 and the main body 20 is connected to the blade 15.

Accordingly, the cutting reaction force during the cutting operation is supported by the lower vehicle body 2 via the support bracket 28, the rod 17, the blade 15, and the blade arm 14, and the arm 6
Will not work.

A flexible plate 30 such as a rubber plate is attached to an outer surface near an opening edge of the left and right vertical plates 24 and the left and right vertical plates 25 of the main body 20 with a plate 31 and bolts 32, respectively. A flexible plate 30 is attached by bolts 32 to the outer surfaces near the opening edge of the front and rear one-side vertical plate 22 and the front and rear other-side vertical plate 23 of the main body 20.

As shown in FIG. 6, a hole 33 is formed in the left and right side vertical plate 25, and one end of a cylindrical body 34 is fitted and fixed to the hole 33. The cylinder 34 protrudes into the main body 20, and a shaft 35 is rotatably supported on the cylinder 34 by a pair of bearings 36. A spline hole 37 is formed in the shaft center near one end of the shaft 35, and a bolt hole 38 is formed in the shaft center near the other end.

A spline 39 is formed on the outer surface of the shaft 35 near the other end.
A spline 41 formed at an intermediate portion of the inner peripheral surface of the inner peripheral surface is spline-fitted. An inner surface 42 closer to one end than the spline 41 on the inner peripheral surface of the cylindrical body 40 is fitted to an outer peripheral surface closer to the other end of the shaft 35, and is closer to the other end than the spline 41 on the inner peripheral surface of the cylindrical body 40. The inner surface 43 is fitted to the outer peripheral surface of the other end of the shaft 35 via a ring 44.

A holding plate 45 is in contact with the other end surface of the cylindrical body 40, and a bolt 46 is screwed into the bolt hole 38 from the holding plate 45 so that the cylindrical body 40 does not come off the shaft 35.

As described above, the rotation of the shaft 35 is transmitted to the cylindrical body 40 by the splines 39 and 41, and the cylindrical body 40 is supported by the shaft 35 at two positions near both ends with the spline 41 as a boundary. Even if a large force acts on the cylindrical body 40, it does not come off the shaft 35, and the splines 39, 41
The excessive force does not act on.

The flange 47 of the cylindrical body 40 is fixed to a ring 49 fixed to the inner peripheral surface of a cylindrical cutter drum 48 with bolts 50. The ring 49 is fitted on the outer peripheral surface of the cylindrical body 40, and the cutter drum 48 is firmly connected to one end of the shaft 35 via the ring 49 and the cylindrical body 40.

The hole 33 of the vertical plate 25 on the left and right side of the main body 20
, A motor 51 is fitted and fixed. The motor 51 protrudes outward, and the lower portion is protected by an L-shaped cover 52 fixed to the other left and right vertical plate 25. The output shaft 53 of the motor 51 is spline-fitted to the spline hole 37 of the shaft 35 to directly drive the cutter drum 48 to rotate.

A ring member 54 is fixed to one end of the outer peripheral surface of the cutter drum 48 near the cutter drum 48.
A first flywheel 55, a bit mounting body 56, and a second flywheel 57 are sequentially fitted on the outer peripheral surface of 8, and bolts 58 are connected to the second flywheel 57 and the bit mounting body 5.
6. Ring body 54 penetrating first flywheel 55
To the first flywheel 55 and the bit mounting body 5
6. The second flywheel 57 is fixed to the outer peripheral surface of the cutter drum 48.

The outer peripheral surface of the cutter drum 48 is shown in FIG.
As shown in the figure, the protrusion 59 is attached integrally or separately,
Grooves 60 that fit into the protrusions 59 are formed on the inner peripheral surfaces of the first flywheel 55, the bit attachment body 56, and the second flywheel 57.

As described above, by loosening the bolt 58, the first flywheel 55, the bit attaching body 56,
Since the second flywheel 57 can be removed, the flywheel can be easily replaced with a flywheel having a different weight, and the bit can be replaced outside the main body 20 by removing the bit attachment body 56. Can be exchanged.

Therefore, the flywheel and the bit mounting body can be mounted according to the cutting conditions, and the bit replacement work becomes easy.

A plurality of bits 61 are mounted on the outer peripheral surface of the bit mounting body 56 at intervals in the circumferential direction. As shown in FIG. 8, the bit 61 is a first bit 61-1 which is mounted as a substantially sinusoidal locus with the bit tip 61a being sequentially shifted from one end in the width direction to the other end in the width direction of the bit mounting body 56. And the first bit 61a, which is attached between the first bits 61-1 and whose bit tip 61a is adjacent to the first bit 61-1.
And a second bit 61-2 opposite in the width direction of the bit attachment body 56.

As described above, the first bit 61-1 is rotated by the rotation of the bit mounting member 56, thereby causing the first bit 61-1 to rotate.
6, since the cutting operation is sequentially performed from one end in the width direction to the other end in the width direction, a groove having a predetermined width can be efficiently cut, and the first bit 61-1 can cut the bit mounting body 56 in the width direction. Since the reaction force is canceled by the second bit 61-2, no force in the width direction acts on the bit mounting body 56.

As shown in FIG. 9, the bit 61 is arranged at one end in the width direction of the bit attaching body 56 at the bit tip 6.
A plurality of first bit strings a in which a predetermined number of first bits 61-1 facing 1a and a second number of second bits 61-2 facing the bit tip 61a are alternately attached to the other end in the width direction in the circumferential direction.
And a bit leading end 61 between the first bit strings a.
A second bit string b composed of a plurality of third bits 61-3 attached such that a faces toward the middle in the width direction of the bit attachment body 65 may be used.

The motor 51 is a hydraulic motor.
And is rotationally driven by discharge pressure oil of a hydraulic pump 12 driven by an engine 11 shown in FIG.

A support leg 70 is provided between the left and right middle portions of the left and right vertical plates 24 of the main body 20 and the left and right sides of the left and right other vertical plates 25.
Are installed respectively. This support leg 70 is a grounding piece 71
A rod 72 having an upper pin hole 74 and a lower pin hole 7 is attached to the U-shaped bracket 73 so as to be vertically movable.
5 is formed, and a pin 76 is inserted into one of the upper pin hole 74 and the lower pin hole 75 from the bracket 73 and connected so as not to move up and down.

When the pin 76 is inserted into the upper pin hole 74 from the bracket 73, the grounding piece 71 protrudes below the bit tip 61a, and the load piece is stably mounted on the ground or the like by contacting the grounding piece 71. Can be placed.

When the pin 76 is fitted into the lower pin hole 75 from the bracket 73, the grounding piece 71 is located above the lower end surface of the main body 20, so that the support leg 70 does not hinder the cutting operation by the bit 61.

[Brief description of the drawings]

FIG. 1 is an overall front view of a hydraulic shovel showing an embodiment of the present invention.

FIG. 2 is a front view of a load cutter.

FIG. 3 is a rear view of the load cutter.

FIG. 4 is a side view of the load cutter.

FIG. 5 is a plan view of a load cutter.

FIG. 6 is a sectional view of a cutter drum mounting portion.

FIG. 7 is a side view of a cutter drum mounting portion.

FIG. 8 is a developed view showing an arrangement of bits.

FIG. 9 is a developed view showing another arrangement of bits.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Running body 2 ... Lower body 3 ... Upper body 4 ... Boom 6 ... Arm 11 ... Engine 12 ... Hydraulic pump 20 ... Main body 26 ... Connection bracket 35 ... Shaft 40 ... Cylindrical body 48 ... Cutter drum 51 ... Motor 53 ... Output shaft 55 First flywheel 56 Bit mounting body 57 Second flywheel 61 Bit 61-1 First bit 61-2 Second bit 61a Bit tip 70 70 Support leg 71 ... Grounding piece A ... Load cutter a ... First bit string b ... Second bit string

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuji Kitano 19-18 Sakuradacho, Atsuta-ku, Nagoya City, Aichi Prefecture Toho Gas Co., Ltd. (72) Mikio Nojiri 1-6 Minamishinozaki, Kazo City, Saitama Prefecture (72) Inventor Koji Amano 1-6 Minamishinozaki, Kazo City, Saitama Prefecture Komatsu Zenoa Co., Ltd.

Claims (7)

[Claims] 1. A main body 20 having a box-like shape with a lower opening and having a connecting bracket 26, and a plurality of bits 61 rotatably supported in the main body 20 and mounted on an outer peripheral surface of the main body 20 at intervals in a circumferential direction. And a motor 51 mounted on the main body 20. An output shaft 53 of the motor 51 is connected to the rotary body. 2. A main body 20 having a box-like shape with an opening at the bottom and having a connecting bracket 26, a cutter drum 48 rotatably supported in the main body 20, and a cutter drum 48.
A bit mounting body 56 and a flywheel mounted on the outer peripheral surface of the above, a plurality of bits 61 mounted on the outer peripheral surface of the bit mounting body 56 at intervals in the circumferential direction, and a cutter drum 48 mounted on the main body 20. A load cutter comprising a motor 51 that is driven to rotate. 3. A main body 20 having a box-like shape with an opening at the bottom and having a connecting bracket 26, a bit mounting body 56 rotatably supported in the main body 20, and a bit mounting body 56.
A plurality of bits 61 attached to the outer peripheral surface of the body at intervals in the circumferential direction, and a motor 51 attached to the main body 20 to rotationally drive the bit attachment body 56. The bits 61 attached to the bit attachment body 56 are: Between the first bit 61-1 whose bit tip 61a is attached as a substantially sinusoidal locus from one end in the width direction of the bit attachment body 56 to the other end in the width direction, and the adjacent first bit 61-1 And the second bit 6 whose bit tip 61a is opposite to the first bit 61-1.
A load cutter comprising: a load cutter; 4. A main body 20 having a box-like shape having an opening at the bottom and having a connecting bracket 26, a bit mounting body 56 rotatably supported in the main body 20, and a bit mounting body 56.
A plurality of bits 61 attached to the outer peripheral surface of the body at intervals in the circumferential direction, and a motor 51 attached to the main body 20 to rotationally drive the bit attachment body 56. The bits 61 attached to the bit attachment body 56 are: The bit end portion 61a of the adjacent bit 61 is
A plurality of first bit strings a alternately mounted so as to face one end and the other end in the width direction, and a bit tip 61 a is mounted between the adjacent bit rows a so that the bit tip 61 a is located at the middle in the width direction of the bit mounting body 56. A load cutter comprising a plurality of second bit strings b facing each other. 5. A main body 20 having a box-like shape with a lower opening and having a connecting bracket 26, and a plurality of bits 61 rotatably supported in the main body 20 and mounted on an outer peripheral surface of the main body 20 at circumferential intervals. A rotating body, a motor 51 attached to the main body 20 to rotate the rotating body, a lower position where the grounding piece 71 mounted on the main body 20 projects below the tip of the bit, and the grounding piece 71 is A load cutter comprising a support leg 70 that can move up and down over an upper position above a lower end surface of the load cutter. 6. An upper body 3 is pivotally mounted on a lower body 2 provided with a traveling body 1, and a boom 4 is mounted on the upper body 3 so as to be vertically swingable, and an arm 6 is vertically swingably mounted on the boom 4. A hydraulic excavator in which a load cutter A is mounted on the arm 6 of the main body 20 is provided with a box-shaped body 20 having a connection bracket 26 and a cutter drum 48 rotatably supported in the body 20. A bit mounting body 56 and a flywheel mounted on the outer peripheral surface of the cutter drum 48, a plurality of bits 61 mounted on the outer peripheral surface of the bit mounting body 56 at intervals in the circumferential direction, and mounted on the main body 20. The bit 61 attached to the bit attaching body 56 is sequentially attached to the bit attaching body 56 from the one end in the width direction of the bit attaching body 57 to the other end in the width direction. A first bit 61-1 attached as a substantially sinusoidal locus toward the first bit 61-1 and a bit tip 61a attached between the adjacent first bits 61-1 so that the bit tip 61a faces in the opposite direction to the first bit 61-1. The second bit that became 6
1-2, an output shaft 53 of the motor 51 is connected to a cutter drum 48, and the motor 51 is driven to rotate by discharge pressure oil of a hydraulic pump 12 driven by the engine 11 mounted on the upper body 3. A hydraulic excavator characterized in that: 7. A plurality of support legs 70 provided with a grounding piece 71 on the main body 20 at a lower position where the grounding piece 71 protrudes below the tip end of the bit, and when the grounding piece 71 is positioned lower than the lower end surface of the main body 20. 7. The hydraulic excavator according to claim 6, wherein the hydraulic excavator is mounted so as to be vertically movable over an upper position.