JP7387555B2 - work equipment - Google Patents

Description

The present invention relates to working machines such as skid steer loaders, compact track loaders, and backhoes.

BACKGROUND ART Conventionally, there is a technique disclosed in Patent Document 1 as a technique for decelerating and increasing speed in a working machine. The hydraulic system of the work machine disclosed in Patent Document 1 includes a hydraulic pump that discharges hydraulic oil, a hydraulic switching valve that can be switched to a plurality of switching positions according to the pressure of the hydraulic oil, and a hydraulic switching valve that can change the speed according to the switching position of the hydraulic switching valve. is equipped with a changeable travel hydraulic system.

Japanese Patent Application Publication No. 2017-179922

In the working machine of Patent Document 1, since the bleed oil passage is provided in the pressure receiving part of the hydraulic pressure switching valve, it is possible to reduce shift shock when speeding up or decelerating the working machine. However, in Patent Document 1, a bleed oil passage must be provided in order to reduce shift shock, which increases the number of parts.
The present invention was made to solve the problems of the prior art as described above, and an object of the present invention is to provide a working machine that can easily reduce shift shock.

The technical means taken by the present invention to solve the technical problems are as follows.
The working machine of the present invention includes a prime mover, a traveling pump that is operated by the power of the prime mover and discharges hydraulic oil, and is rotatable by the hydraulic oil discharged by the traveling pump, and has a rotational speed of a first speed and a first speed. a travel motor capable of switching to a second speed higher than the first speed; a body provided with the prime mover, the travel pump, and the travel motor; a travel selector valve capable of switching the rotation speed of the travel motor to a second state in which the rotational speed of the travel motor is set to the second speed; a changeover switch that issues a speed change command for either speed increase or deceleration; and a travel pump. an operating valve capable of controlling hydraulic oil; an automatic deceleration for switching from the second state to the first state; and a manual deceleration for switching from the second state to the first state when the changeover switch issues the shift command. and a control device that is capable of executing a first shock reduction control that reduces the opening degree of the operating valve and a second shock reduction control that reduces the rotational speed of the prime mover. .

In one aspect of the present invention, the control device performs the first shock reduction control when performing the automatic deceleration, and performs the second shock reduction control when performing the manual deceleration.
Further, in one aspect of the present invention, when performing the manual deceleration, the control device performs the first shock reduction control in addition to the second shock reduction control.
Further, in one aspect of the present invention, the control device adjusts the opening degree of the operating valve in the first shock reduction control when performing the manual deceleration to the opening degree of the operating valve in the first shock reduction control when performing the automatic deceleration. The opening degree is set smaller than the opening degree of the operating valve.

Further, in one aspect of the present invention, the opening degree of the operating valve can be changed according to a control signal output from the control device , and the control device is configured to control the operation valve according to the control signal in the first shock reduction control. is reduced to a predetermined first reduction value, and in the second shock reduction control, the rotation speed of the prime mover is reduced to a second reduction value that is lower than the target rotation speed.
Further, in one aspect of the present invention, in the first shock reduction control, the control device may control the first reduction period in a first reduction period until the control signal output to the operating valve reaches a first reduction value. A first rate of decrease of the control signal from a starting point to the middle of the first reduction section is made larger than a second rate of decrease of the control signal from the middle of the first reduction section to the end point.

Further, in one aspect of the present invention, in the second shock reduction control, the control device may control the control device in the second reduction section until the actual rotation speed of the prime mover reaches a second reduction value lower than the target rotation speed . The third rate of decrease in the actual rotational speed of the prime mover is kept constant.
Furthermore, in one aspect of the present invention, the work machine includes a first traveling device provided on the left side of the machine body, and a second traveling device provided on the right side of the machine body, and the traveling motor includes: A first traveling motor transmits driving power to the first traveling device and a second traveling motor transmits driving power to the second traveling device, and the traveling pump is connected to the first traveling motor and the second traveling device. The travel motor can be operated, and the travel switching valve can switch the first travel motor and the second travel motor between the first speed and the second speed.

According to the present invention, shift shock can be easily reduced.

It is a diagram showing a hydraulic system (hydraulic circuit) of a work machine. FIG. 3 is a diagram showing the relationship between the control value of the control signal output to the operating valve and the switching of the travel motor in the first shock reduction control using automatic deceleration. FIG. 6 is a diagram showing the relationship between the actual rotational speed of the prime mover and the switching of the travel motor in the second shock reduction control using manual deceleration. FIG. 6 is a diagram showing the relationship between the control value of the control signal output to the operating valve and the switching of the travel motor in the second shock reduction control using manual deceleration. FIG. 7 is a diagram showing a modification in which the operating device is changed to an electrically operated operating device such as a joystick. It is a side view showing a track loader which is an example of a work machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a hydraulic system for a working machine according to the present invention and a working machine equipped with this hydraulic system will be described with reference to the drawings as appropriate.
FIG. 4 shows a side view of the working machine according to the invention. FIG. 4 shows a compact track loader as an example of a work machine. However, the working machine according to the present invention is not limited to a compact track loader, but may be another type of loader working machine, such as a skid steer loader. Moreover, a work machine other than a loader work machine may be used.

As shown in FIG. 4, the work machine 1 includes a body 2, a cabin 3, a work device 4, and a traveling device 5. In the embodiment of the present invention, the front side of the driver seated in the driver's seat 8 of the work equipment 1 (left side in FIG. 4) is the front side, the rear side of the driver (the right side in FIG. 4) is the rear side, and the left side of the driver (the left side in FIG. 4) is the left side, and the driver's right side (the back side of FIG. 4) is the right side. In addition, the horizontal direction, which is a direction perpendicular to the front-rear direction, will be described as the fuselage width direction. The direction from the center of the fuselage 2 toward the right or left side will be described as the outward direction of the fuselage. In other words, the outside of the fuselage is the width direction of the fuselage, and is the direction away from the fuselage 2. The direction opposite to the outside of the fuselage will be described as inside the fuselage. In other words, the inside of the fuselage is the width direction of the fuselage, and the direction approaching the fuselage 2.

Cabin 3 is mounted on fuselage 2. This cabin 3 is provided with a driver's seat 8. The working device 4 is attached to the machine body 2. The traveling device 5 is provided outside the fuselage 2. A prime mover 32 is mounted at the rear inside the aircraft body 2.
The work device 4 includes a boom 10, a work implement 11, a lift link 12, a control link 13, a boom cylinder 14, and a bucket cylinder 15.

The boom 10 is provided on the right and left sides of the cabin 3 so as to be vertically swingable. The work tool 11 is, for example, a bucket, and the bucket 11 is provided at the tip (front end) of the boom 10 so as to be vertically swingable. The lift link 12 and the control link 13 support the base (rear part) of the boom 10 so that the boom 10 can swing vertically. The boom cylinder 14 moves the boom 10 up and down by expanding and contracting. The bucket cylinder 15 swings the bucket 11 by expanding and contracting.

The front parts of the left and right booms 10 are connected to each other by an irregularly shaped connecting pipe. The bases (rear parts) of each boom 10 are connected to each other by a circular connecting pipe.
The lift link 12, the control link 13, and the boom cylinder 14 are provided on the left and right sides of the fuselage 2, corresponding to the left and right booms 10, respectively.
The lift link 12 is provided vertically at the rear of the base of each boom 10. The upper part (one end side) of this lift link 12 is rotatably supported around a horizontal axis via a pivot shaft 16 (first pivot shaft) near the rear of the base of each boom 10. Further, the lower part (the other end side) of the lift link 12 is rotatably supported near the rear of the body 2 via a pivot shaft 17 (second pivot shaft) around a horizontal axis. The second pivot shaft 17 is provided below the first pivot shaft 16.

The upper part of the boom cylinder 14 is rotatably supported around a horizontal axis via a pivot shaft 18 (third pivot shaft). The third pivot shaft 18 is provided at the base of each boom 10 and at the front of the base. The lower part of the boom cylinder 14 is rotatably supported around a horizontal axis via a pivot shaft 19 (fourth pivot shaft). The fourth pivot shaft 19 is provided near the bottom of the rear portion of the body 2 and below the third pivot shaft 18 .

The control link 13 is provided in front of the lift link 12. One end of this control link 13 is rotatably supported around a horizontal axis via a pivot shaft 20 (fifth pivot shaft). The fifth pivot shaft 20 is provided in the body 2 at a position corresponding to the front of the lift link 12. The other end of the control link 13 is rotatably supported around a horizontal axis via a pivot shaft 21 (sixth pivot shaft). The sixth pivot shaft 21 is provided in the boom 10 in front of and above the second pivot shaft 17 .

By expanding and contracting the boom cylinder 14, each boom 10 swings up and down around the first pivot shaft 16 while the base of each boom 10 is supported by the lift link 12 and control link 13, and the tip of each boom 10 goes up and down. The control link 13 swings up and down about the fifth pivot shaft 20 as each boom 10 swings up and down. The lift link 12 swings back and forth around the second pivot shaft 17 as the control link 13 swings up and down.

Another work tool can be attached to the front of the boom 10 instead of the bucket 11. Examples of other working tools include attachments (preliminary attachments) such as hydraulic crushers, hydraulic breakers, angle brooms, earth augers, pallet forks, sweepers, mowers, and snow blowers.
A connecting member 50 is provided at the front of the boom 10 on the left side. The connecting member 50 is a device that connects the hydraulic equipment installed on the preliminary attachment and a first pipe material such as a pipe provided on the boom 10. Specifically, a first pipe member can be connected to one end of the connecting member 50, and a second pipe member connected to a hydraulic device as a preliminary attachment can be connected to the other end. Thereby, the hydraulic oil flowing through the first pipe material passes through the second pipe material and is supplied to the hydraulic equipment.

The bucket cylinders 15 are arranged near the front of each boom 10, respectively. By expanding and contracting the bucket cylinder 15, the bucket 11 is swung.
In this embodiment, each of the left and right traveling devices (first traveling device, second traveling device) 5 is a crawler type traveling device (including a semi-crawler type). Note that a wheel-type traveling device having front wheels and rear wheels may be employed.

The prime mover 32 is an internal combustion engine such as a diesel engine or a gasoline engine, an electric motor, or the like. In this embodiment, prime mover 32 is, but is not limited to, a diesel engine.
Next, the hydraulic system of the work machine will be explained.
As shown in FIG. 1, the hydraulic system of the working machine is capable of driving the traveling device 5. The hydraulic system of the work machine includes a first travel pump 53L, a second travel pump 53R, a first travel motor 36L, and a second travel motor 36R.

The first traveling pump 53L and the second traveling pump 53R are pumps driven by the power of the prime mover 32. Specifically, the first traveling pump 53L and the second traveling pump 53R are swash plate type variable displacement axial pumps driven by the power of the prime mover 32. The first running pump 53L and the second running pump 53R have a pressure receiving part 53a and a pressure receiving part 53b on which pilot pressure acts.The angle of the swash plate is adjusted by the pilot pressure acting on the pressure receiving parts 53a and 53b. Be changed. By changing the angle of the slant plate, the output (discharge amount of hydraulic oil) of the first traveling pump 53L and the second traveling pump 53R and the discharge direction of the hydraulic oil can be changed.

The first travel pump 53L and the first travel motor 36L are connected by a circulation oil path 57h, and the hydraulic oil discharged by the first travel pump 53L is supplied to the first travel motor 36L. The second travel pump 53R and the second travel motor 36R are connected by a circulation oil path 57i, and the hydraulic oil discharged by the second travel pump 53R is supplied to the second travel motor 36R.
The first traveling motor 36L is a motor that transmits power to the drive shaft of the traveling device 5 provided on the left side of the aircraft body 2. The first travel motor 36L can be rotated by hydraulic oil discharged from the first travel pump 53L, and the rotation speed (number of revolutions) can be changed depending on the flow rate of the hydraulic oil. A swash plate switching cylinder 37L is connected to the first travel motor 36L, and the rotational speed (number of rotations) of the first travel motor 36L is also changed by extending and contracting the swash plate switching cylinder 37L to one side or the other side. be able to. That is, when the swash plate switching cylinder 37L is retracted, the rotation speed of the first travel motor 36L is set to a low speed (first speed), and when the swash plate switching cylinder 37L is extended, the rotation speed of the first travel motor 36L is set to a low speed (first speed). The rotation speed is set to high speed (second speed). In other words, the rotation speed of the first travel motor 36L can be changed between a first speed, which is a low speed, and a second speed, which is a high speed.

The second traveling motor 36R is a motor that transmits power to the drive shaft of the traveling device 5 provided on the right side of the aircraft body 2. The second travel motor 36R can be rotated by hydraulic oil discharged from the second travel pump 53R, and the rotation speed (number of revolutions) can be changed depending on the flow rate of the hydraulic oil. A swash plate switching cylinder 37R is connected to the second travel motor 36R, and the rotational speed (rotation number) of the second travel motor 36R is also changed by extending and contracting the swash plate switching cylinder 37R to one side or the other side. be able to. That is, when the swash plate switching cylinder 37R is retracted, the rotation speed of the second travel motor 36R is set to a low speed (first speed), and when the swash plate switching cylinder 37R is extended, the rotation speed of the second travel motor 36R is set to a low speed (first speed). The rotation speed is set to high speed (second speed). In other words, the rotation speed of the second travel motor 36R can be changed between a first speed, which is a low speed, and a second speed, which is a high speed.

As shown in FIG. 1, the hydraulic system of the working machine includes a travel switching valve 34. The travel switching valve 34 switches the rotational speed (rotational speed) of the travel motors (first travel motor 36L, second travel motor 36R) between a first state in which the rotational speed is a first speed and a second state in which the rotation speed is a second speed. It is possible. The travel switching valve 34 includes first switching valves 71L, 71R and a second switching valve 72.
The first switching valve 71L is a two-position switching valve that is connected to the swash plate switching cylinder 37L of the first travel motor 36L via an oil passage and switches to a first position 71L1 and a second position 71L2. The first switching valve 71L contracts the swash plate switching cylinder 37L when it is in the first position 71L1, and extends the swash plate switching cylinder 37L when it is in the second position 71L2.

The first switching valve 71R is a two-position switching valve that is connected to the swash plate switching cylinder 37R of the second travel motor 36R via an oil passage and switches to a first position 71R1 and a second position 71R2. The first switching valve 71R contracts the swash plate switching cylinder 37R when in the first position 71R1, and extends the swash plate switching cylinder 37R when in the second position 71R2.
The second switching valve 72 is a solenoid valve that switches between the first switching valve 71L and the first switching valve 71R, and is a two-position switching valve that can be switched between a first position 72a and a second position 72b by excitation. The second switching valve 72, the first switching valve 71L, and the first switching valve 71R are connected by an oil passage 41. The second switching valve 72 switches the first switching valve 71L and the first switching valve 71R to the first positions 71L1 and 71R1 when the second switching valve 72 is in the first position 72a, and switches the first switching valve 71L and the first switching valve 71R to the first position 71L1 and 71R1 when the second switching valve 72 is in the second position 72b. The first switching valve 71R is switched to the second position 71L2, 71R2.

That is, when the second switching valve 72 is in the first position 72a, the first switching valve 71L is in the first position 71L1, and the first switching valve 71R is in the first position 71R1, the travel switching valve 34 is in the first state, The rotation speed of the travel motors (first travel motor 36L, second travel motor 36R) is set to the first speed. When the second switching valve 72 is in the second position 72b, the first switching valve 71L is in the second position 71L2, and the first switching valve 71R is in the second position 71R2, the travel switching valve 34 is in the second state, and the travel motor The rotational speeds of (the first travel motor 36L and the second travel motor 36R) are set to the second speed.

Therefore, the travel switching valve 34 can switch the travel motors (first travel motor 36L, second travel motor 36R) between a first speed, which is a low speed, and a second speed, which is a high speed.
Switching between the first speed and the second speed in the travel motor can be performed by a switching section. The switching unit is, for example, a changeover switch 61 connected to the control device 60, and can be operated by an operator or the like. The switching unit (switch 61) is configured to increase the speed by switching from the first speed (first state) to the second speed (second state), and from the second speed (second state) to the first speed (first state). Can be switched to either deceleration or toggle.

The control device 60 is comprised of semiconductors such as a CPU and MPU, electrical and electronic circuits, and the like. The control device 60 switches the travel switching valve 34 based on the switching operation of the changeover switch 61. The changeover switch 61 is a push switch. For example, when the changeover switch 61 is pressed while the travel motor is at the first speed, a 2nd speed command to set the travel motor to the second speed (a command to set the travel selector valve 34 to the second state) is sent to the control device 60. is output to. Further, when the changeover switch 61 is pressed while the travel motor is at the second speed, a first speed command to set the travel motor to the first speed (command to set the travel selector valve 34 to the first state) is output to the control device 60. be done. Note that the changeover switch 61 may be a push switch that can be held ON/OFF, and when it is OFF, a command to maintain the travel motor at the first speed is output to the control device 60, and the switch 61 is turned ON. In this case, a command is output to the control device 60 to maintain the travel motor at the second speed.

When the control device 60 obtains a command (first speed command) to set the travel switching valve 34 in the first state, the control device 60 demagnetizes the solenoid of the second switching valve 72 to bring the travel switching valve 34 into the first state. do. Further, when the control device 60 obtains a command (second speed command) to set the travel switching valve 34 to the second state, the control device 60 energizes the solenoid of the second switching valve 72 to switch the travel switching valve 34 to the second state. state.

Now, the hydraulic system of the working machine includes a first hydraulic pump P1, a second hydraulic pump P2, and an operating device (traveling operating device) 54. The first hydraulic pump P1 is a pump driven by the power of the prime mover 32, and is a constant displacement gear pump. The first hydraulic pump P1 can discharge hydraulic oil stored in the tank 22. In particular, the first hydraulic pump P1 discharges hydraulic oil mainly used for control. For convenience of explanation, the tank 22 that stores hydraulic oil may be referred to as a hydraulic oil tank. Further, among the hydraulic oil discharged from the first hydraulic pump P1, the hydraulic oil used for control may be referred to as pilot oil, and the pressure of the pilot oil may be referred to as pilot pressure.

The second hydraulic pump P2 is a pump driven by the power of the prime mover 32, and is a constant displacement gear pump. The second hydraulic pump P2 is capable of discharging hydraulic oil stored in the tank 22, and supplies the hydraulic oil to, for example, an oil path of a working system. For example, the second hydraulic pump P2 supplies hydraulic oil to the boom cylinder 14 that operates the boom 10, the bucket cylinder 15 that operates the bucket, and the control valve (flow control valve) that controls the preliminary hydraulic actuator that operates the preliminary hydraulic actuator. do.

The operating device 54 is a device that operates the traveling pumps (first traveling pump 53L, second traveling pump 53R), and can change the angle of the swash plate (swash plate angle) of the traveling pump. The operating device 54 includes an operating member 59 such as an operating lever, and a plurality of operating valves 55.
The operating member 59 is supported by the operating valve 55 and swings in the left-right direction (body width direction) or the front-rear direction. That is, the operating member 59 can be operated rightward and leftward from the neutral position N, as well as forward and backward from the neutral position N. In other words, the operating member 59 can swing in at least four directions based on the neutral position N. For convenience of explanation, the forward and backward directions, that is, the front-rear direction will be referred to as the first direction. In addition, the right and left directions, that is, the left-right direction (body width direction) may be referred to as a second direction.

Further, the plurality of operating valves 55 are operated in common, that is, by one operating member 59. The plurality of operation valves 55 are operated based on the swinging of the operation member 59. A discharge oil passage 40 is connected to the plurality of operation valves 55, and hydraulic oil (pilot oil) from the first hydraulic pump P1 can be supplied through the discharge oil passage 40. The plurality of operating valves 55 are an operating valve 55A, an operating valve 55B, an operating valve 55C, and an operating valve 55D.

The operation valve 55A is operated to output an output according to the operation amount (operation) of the previous operation when the operation member 59 is swung forward (on one side) in the front-rear direction (first direction) (when the operation member 59 is pre-operated). Oil pressure changes. The operation valve 55B is operated to output an output according to the amount of operation (operation) of the rear operation when the operation member 59 is swung backward (on the other side) in the front-rear direction (first direction) (when the rear operation is performed). Oil pressure changes. In the left-right direction (second direction), when the operation member 59 is swung to the right (one side) (when the operation member 59 is operated to the right), the operation valve 55C outputs an output according to the operation amount (operation) of the right operation. Hydraulic oil pressure changes. When the operation member 59 is swung to the left (the other side) in the left-right direction (second direction) (when the operation member 59 is operated to the left), the operation valve 55D outputs an output according to the operation amount (operation) of the left operation. The pressure of the hydraulic fluid changes.

The plurality of operation valves 55 and the running pumps (first running pump 53L, second running pump 53R) are connected by running oil passage 45. In other words, the traveling pumps (the first traveling pump 53L, the second traveling pump 53R) can be operated by the hydraulic oil output from the operating valves 55 (the operating valves 55A, 55B, 55C, and 55D). It is a device.
The oil passage 45 includes a first oil passage 45a, a second oil passage 45b, a third oil passage 45c, a fourth oil passage 45d, and a fifth oil passage 45e. The first traveling oil passage 45a is an oil passage connected to the pressure receiving part 53a of the traveling pump 53L. The second traveling oil passage 45b is an oil passage connected to the pressure receiving portion 53b of the traveling pump 53L. The third traveling oil passage 45c is an oil passage connected to the pressure receiving part 53a of the traveling pump 53R. The fourth traveling oil passage 45d is an oil passage connected to the pressure receiving portion 53b of the traveling pump 53R. The fifth oil passage 45e is an oil passage that connects the operation valve 55, the first oil passage 45a, the second oil passage 45b, the third oil passage 45c, and the fourth oil passage 45d.

When the operating member 59 is swung forward (in the direction of arrow A1 in FIG. 1), the operating valve 55A is operated and pilot pressure is output from the operating valve 55A. This pilot pressure acts on the pressure receiving part 53a of the first running pump 53L via the first running oil passage 45a, and acts on the pressure receiving part 53a of the second running pump 53R via the third running oil passage 45c. As a result, the swash plate angles of the first travel pump 53L and the second travel pump 53R are changed, the first travel motor 36L and the second travel motor 36R rotate normally (forward rotation), and the work implement 1 moves straight forward. .

Further, when the operating member 59 is swung rearward (in the direction of arrow A2 in FIG. 1), the operating valve 55B is operated and pilot pressure is output from the operating valve 55B. This pilot pressure acts on the pressure receiving part 53b of the first running pump 53L via the second running oil passage 45b, and acts on the pressure receiving part 53b of the second running pump 53R via the fourth running oil passage 45d. As a result, the swash plate angles of the first travel pump 53L and the second travel pump 53R are changed, the first travel motor 36L and the second travel motor 36R are reversed (backward rotation), and the work implement 1 moves straight backward.

Furthermore, when the operating member 59 is swung to the right (in the direction of arrow A3 in FIG. 1), the operating valve 55C is operated and pilot pressure is output from the operating valve 55C. This pilot pressure acts on the pressure receiving part 53a of the first running pump 53L via the first running oil passage 45a, and acts on the pressure receiving part 53b of the second running pump 53R via the fourth running oil passage 45d. As a result, the swash plate angles of the first travel pump 53L and the second travel pump 53R are changed, the first travel motor 36L rotates in the normal direction, the second travel motor 36R rotates in the reverse direction, and the work machine 1 turns to the right.

Furthermore, when the operating member 59 is swung to the left (in the direction of arrow A4 in FIG. 1), the operating valve 55D is operated and pilot pressure is output from the operating valve 55D. This pilot pressure acts on the pressure receiving part 53a of the second running pump 53R via the third running oil passage 45c, and also acts on the pressure receiving part 53b of the first running pump 53L via the second running oil passage 45b. As a result, the swash plate angles of the first travel pump 53L and the second travel pump 53R are changed, the first travel motor 36L rotates in reverse, and the second travel motor 36R rotates in the forward direction, causing the work implement 1 to turn to the left.

Furthermore, when the operating member 59 is swung in a diagonal direction, the rotational direction and rotational speed of the first travel motor 36L and the second travel motor 36R are changed due to the differential pressure between the pilot pressures acting on the pressure receiving portion 53a and the pressure receiving portion 53b. The working machine 1 turns to the right or to the left while moving forward or backward.
That is, when the operating member 59 is swung diagonally forward to the left, the work implement 1 moves forward and rotates to the left at a speed corresponding to the oscillating angle of the operating member 59. When the work implement 1 rotates to the right while moving forward at a speed corresponding to the swing angle of the operating member 59, and when the operating member 59 is operated to swing diagonally backward to the left, the work implement 1 moves at a speed corresponding to the swing angle of the operating member 59. When the working machine 1 turns to the left while moving backward and operates the operating member 59 to swing diagonally backward to the right, the working machine 1 turns to the right while moving backward at a speed corresponding to the swing angle of the operating member 59.

Now, an accelerator 65 for setting a target rotation speed of the prime mover 32 is connected to the control device 60 . The accelerator 65 is provided near the driver's seat 8. The accelerator 65 includes a swingably supported accelerator lever, a swingably supported accelerator pedal, a rotatably supported accelerator volume, a slidably supported accelerator slider, and the like. Note that the accelerator 65 is not limited to the example described above. Further, a rotation detection device 67 that detects the actual rotation speed of the prime mover 32 is connected to the control device 60 . The rotation detection device 67 allows the control device 60 to grasp the actual rotation speed of the prime mover 32 . The control device 60 sets a target rotation speed based on the amount of operation of the accelerator 65, and controls the actual rotation speed to reach the set target rotation speed.
Now, as described above, when the driver (operator) operates the changeover switch 61 to issue a first speed command, the control device 60 changes from the second state (second speed) to the first state (first speed). However, if the changeover switch 61 is not operated and the deceleration conditions (automatic deceleration) are met, the second state (second speed) will be automatically changed from the second state (second speed) to the first state (first speed). to slow down.

Hereinafter, for convenience of explanation, switching from the second state to the first state and decelerating when the changeover switch 61 issues a 1st speed command (shifting command) will be referred to as "manual shifting" and when the deceleration conditions (automatic deceleration) are in place. Automatic deceleration is called "automatic deceleration."
The control device 60 performs automatic deceleration based on the pressure in the circulation oil passages 57h and 57i. A plurality of pressure detection devices 80 are connected to the circulation oil passages 57h and 57i. The plurality of pressure detection devices 80 include a first pressure detection device 80a, a second pressure detection device 80b, a third pressure detection device 80c, and a fourth pressure detection device 80d. The first pressure detection device 80a is provided on the first port P11 side of the first travel motor 36L in the circulation oil passage 57h, and detects the pressure on the first port P11 side as the first travel pressure V1. The second pressure detection device 80b is provided in the circulation oil passage 57h on the second port P12 side of the first travel motor 36L, and detects the pressure on the second port P12 side as the second travel pressure V2. The third pressure detection device 80c is provided in the circulation oil passage 57i on the third port P13 side of the second travel motor 36R, and detects the pressure on the third port P13 side as the third travel pressure V3. The fourth pressure detection device 80d is provided in the circulation oil passage 57i on the fourth port P14 side of the second travel motor 36R, and detects the pressure on the fourth port P14 side as the fourth travel pressure V4.

A mode switch 66 is connected to the control device 60 to enable or disable automatic deceleration. For example, the mode switch 66 is a switch that can be switched ON/OFF, and when it is ON, it enables automatic deceleration, and when it is OFF, it disables automatic deceleration.
When automatic deceleration is enabled, the control device 60 controls the first running pressure V1, the second running pressure V2, the third running pressure V3, and the fourth running pressure V4 to be at or above a predetermined deceleration threshold. Automatic deceleration is performed from the 2nd speed to the 1st speed, and when the 1st running pressure V1, the 2nd running pressure V2, the 3rd running pressure V3, and the 4th running pressure V4 are equal to or higher than the return threshold, the speed is changed from the 1st speed to the 2nd speed. Return to speed. Note that the control device 60 performs manual deceleration when automatic deceleration is disabled.

In the embodiment described above, automatic deceleration is performed when the running pressure (first running pressure V1, second running pressure V2, third running pressure V3, fourth running pressure V4) is equal to or higher than the deceleration threshold. The method of performing automatic deceleration is not limited.
For example, the control device 60 controls a first differential pressure ΔV1 obtained by subtracting the second running pressure V2 from the first running pressure V1, a second differential pressure ΔV2 obtained by subtracting the first running pressure V1 from the second running pressure V2, and a second differential pressure ΔV2 obtained by subtracting the first running pressure V1 from the second running pressure V2. Automatic deceleration is performed when either the third differential pressure ΔV3 obtained by subtracting the fourth running pressure V4 from the pressure V3 or the fourth differential pressure ΔV4 obtained by subtracting the third running pressure V3 from the fourth running pressure V4 is greater than or equal to the deceleration threshold. You may go.

The control device 60 performs shock reduction control to reduce the shock of shifting when performing either manual deceleration or automatic deceleration. The shock reduction control includes a first shock reduction control and a second shock reduction control.
In the first shock reduction control, the control device 60 reduces the shock of shifting by controlling the opening degree of the operating valve 69 shown in FIG. The operating valve 69 is controlled by the control device 60 to reduce the shock of shifting by controlling the hydraulic fluid flowing to the travel pumps 53L and 53R. In other words, in the first shock reduction control, the opening of the operating valve 69 is controlled to be narrowed (reduced).

Furthermore, in the second shock reduction control, the control device 60 controls the prime mover to reduce the actual rotational speed of the prime mover.
As shown in FIG. 1, the operating valve 69 is connected to a section 40a of the branched discharge oil passage 40 that reaches the travel operating device 54, that is, to the upstream side of the operating valve 55. Note that the operating valve 69 may be connected to the travel oil passage 45 on the downstream side of the operating valve 55.

The operating valve 69 is an electromagnetic proportional valve (proportional valve), and its opening degree can be changed by a control signal output from the control device 60. The control signal is, for example, voltage, current, etc. The operating valve 69 is a valve whose opening degree increases as the control signal (voltage, current) output from the control device 60 increases, and decreases as the control signal (voltage, current) decreases. That is, the control device 60 reduces the opening degree of the operating valve 69 by changing the control signal output to the operating valve 69 in the first shock reduction control.

Furthermore, in the second shock reduction control, the control device 60 controls the prime mover to reduce the actual rotational speed of the prime mover.
More specifically, the control device 60 performs first shock reduction control when performing automatic deceleration, and performs second shock reduction control when performing manual deceleration.
FIG. 2A is a diagram showing the relationship between the control value of the control signal output to the operating valve 69 and the switching of the travel motor in the first shock reduction control using automatic deceleration.

As shown in FIG. 2A, at time Q11, when the automatic deceleration command, that is, the automatic deceleration conditions are satisfied, the control device 60 sets the amount of decrease ΔF51 of the control value of the control signal. The control device 60 sets the reduction amount ΔF51 based on the running state of the working machine 1. For example, the control device 60 sets the decrease amount ΔF51 to be large when the work implement 1 is moving straight, and sets the decrease amount ΔF51 to be small when the work implement 1 is making a pivot turn. Note that the method for setting the amount of decrease ΔF51 is not limited to the embodiment described above, and may be set according to the load of the prime mover, that is, the amount of drop that is the difference between the actual rotation speed and the target rotation speed of the prime mover. . In this case, the control device 60 makes the decrease amount ΔF51 smaller when the drop amount is large and the load on the prime mover is large, and increases the decrease amount ΔF51 when the drop amount is small and the load on the prime mover is small.

When setting the reduction amount ΔF51, the control device 60 sets the value obtained by subtracting the reduction amount ΔF51 from the control value (current control value) W51 of the control signal immediately before reduction as the first reduction value W52 in shock reduction control. do.
After setting the first reduction value W52, the control device 60 decreases the control value of the control signal output to the operating valve 69 from time point Q11 toward the first reduction value W52. As shown by a line W55 indicating the control value, when the first reduction value W52 is reached at time Q12, the control device 60 outputs a signal to energize the solenoid of the travel switching valve 34, and the travel switching valve (switching valve ) 34 from the second state (first speed) to the first state (second speed) to perform automatic deceleration. Further, after time Q12, as shown by line W55, the control value is returned to the pre-reduction control value W51.

More specifically, the first reduction interval Ta (until the control value reaches the first reduction value W52) from time point Q11, which is the starting point of reducing the control value of the control signal, to time point Q12, which is the end point of reducing the control value of the control signal. Focusing on the first reduction section Ta), the control device 60 divides the first reduction section Ta into an section (first section) Ta1 from the start point to the middle, and an section (second section) Ta2 from the middle to the end point. , the rate at which the control value of the control signal decreases is changed.

In the line W55 indicating the control value in the first reduction section Ta, the control device 60 sets the first reduction speed in the first section Ta1 by the slope of the line W55a, and sets the second reduction speed in the second section Ta2 by the slope of the line W55b. The first decreasing speed (the slope of line W55a) is set to be larger than the second decreasing speed (the slope of line W55b). In other words, the control device 60 sets the rate of decrease of the control signal (control value) in at least two stages in the first reduction section Ta.

FIG. 2B is a diagram showing the relationship between the actual rotational speed of the prime mover and the switching of the travel motor in the second shock reduction control using manual deceleration.
As shown in FIG. 2B, when the control device 60 obtains a manual deceleration command, that is, a first speed command from the changeover switch 61 at time Q21, it sets a reduction amount ΔF61 in the actual rotational speed of the prime mover. The control device 60 sets the reduction amount ΔF61 based on the rotation speed of the prime mover 32 of the working machine 1. For example, the control device 60 sets the drop amount according to the load of the prime mover, that is, the drop amount that is the difference between the actual rotation speed and the target rotation speed of the prime mover. The control device 60 reduces the amount of decrease ΔF61 when the amount of drop is large and the load on the prime mover is large, and increases the amount of decrease ΔF61 when the amount of drop is small and the load on the prime mover is small. Note that the method for setting the amount of decrease ΔF61 is not limited to the embodiment described above; for example, when the work implement 1 is moving straight, the control device 60 sets the amount of decrease ΔF61 to be large so that the work implement 1 is reliable. When the vehicle is turning on the ground, the amount of decrease ΔF61 may be set to be small.

After setting the reduction amount ΔF61, the control device 60 sets a value obtained by subtracting the reduction amount ΔF61 from the target rotation speed W61 of the prime mover as the second reduction value W62 in the shock reduction control.
After setting the second reduction value W62, the control device 60 decreases the actual rotation speed of the prime mover from time point Q21 toward the second reduction value W62. When the second reduction value W62 is reached at time Q22, as shown by a line W65 indicating the actual rotational speed, the control device 60 outputs a signal to energize the solenoid of the travel switching valve 34, and activates the travel switching valve (switching Manual deceleration is performed by switching the valve 34 from the second state (first speed) to the first state (second speed). Further, after the time point Q22, as shown by line W65, the rotational speed is returned to the target rotational speed W61 before the reduction.

More specifically, the second reduction section Tb (when the actual rotation speed is the second reduction value W62 Focusing on the second reduction section Tb) up to which Tb), the control device 60 fixes the third reduction speed of the actual rotational speed constant.
The control device 60 sets the third reduction speed of the actual rotation speed in the second reduction section Tb by the slope of a line W65 indicating the third reduction speed, and the third reduction speed is constant (per unit time) from the start point to the end point of the second reduction section Tb. (the rate of decline is constant). That is, the control device 60 fixes the third reduction speed of the actual rotational speed in the second reduction section Tb.

As shown in FIGS. 2A and 2B, in the first shock reduction control by automatic deceleration, the travel switching valve (switching valve) 34 is switched to the first state (second speed) from the automatic deceleration command (time point Q11). During the elapsed time T10 up to (time point Q12) and the second shock reduction control by automatic deceleration, from the manual deceleration command (time point Q21), the traveling switching valve (switching valve) 34 is set to the first state (second speed). The control device 60 switches the traveling switching valve (switching valve) 34 in a manner different from the elapsed time T11 until switching (time point Q22). The elapsed times T10 and T11 can be changed.

When performing manual deceleration, the control device 60 may perform first shock reduction control in addition to the second shock reduction control shown in FIG. 2B.
FIG. 2C is a diagram showing the relationship between the control value of the control signal output to the operating valve 69 and the switching of the travel motor in the first shock reduction control using manual deceleration. In the following description, it is assumed that the first shock reduction control shown in FIG. 2B is also performed during manual deceleration.

In the first shock reduction control shown in FIG. 2C, time point Q21, which is the start point of the second reduction section Tb, and time point Q22, which is the end point of the second reduction section Tb, are the same as in FIG. 2B, and shock reduction is started. The explanation will be given assuming that the timing is the same. When performing both the second shock reduction control and the first shock reduction control during manual deceleration, the travel switching valve (switching valve) 34 is switched from the second state (first speed) to the first state (second speed). As long as the timing is the same, the timing for reducing the actual rotational speed of the prime mover, the timing for reducing the control value of the control signal, etc. are not limited to those shown in FIG. 2C.

As shown in FIG. 2C, when the control device 60 sets the reduction amount ΔF71 in the first shock reduction control, the control device 60 subtracts the reduction amount ΔF71 from the control value (current control value) W71 of the control signal immediately before reduction. The value is set as the first reduction value W72 in shock reduction control. Here, the control device 60 sets the reduction amount ΔF71 in the first shock reduction control using manual deceleration to be larger than the reduction amount ΔF51 during the first shock reduction control using automatic deceleration. That is, in the first shock reduction control using manual deceleration, the control device 60 sets the first reduction value W72 to be smaller than the first reduction value W52. In other words, by setting the first reduction value W72 smaller than the first reduction value W52, the control device 60 changes the opening degree of the operating valve 69 set in the first shot reduction control during manual deceleration to the opening degree of the operating valve 69 during automatic deceleration. The opening degree of the operating valve 69 is set smaller than that set in the first shock reduction control.

After setting the first reduction value W72, the control device 60 decreases the control value of the control signal output to the operating valve 69 from time point Q21 toward the first reduction value W72. As shown by a line W75 indicating the control value, when the first reduction value W72 is reached at time Q22, the control device 60 outputs a signal to energize the solenoid of the travel switching valve 34, so that the travel switching valve (switching valve ) 34 from the second state (first speed) to the first state (second speed) to perform manual deceleration. Moreover, after time Q22, as shown by line W75, the control value is returned to the pre-reduction control value W71.

More specifically, focusing on the second reduction section Tb, the control device 60 controls the section (first section) Ta1 from the start point to the middle of the second reduction section Tb, and the section (second section) Ta2 from the middle to the end point. This changes the speed at which the control value of the control signal decreases.
In the line W75 indicating the control value in the second reduction interval Tb, the control device 60 sets the first decreasing rate in the first interval Ta1 by the slope of the line W75a, and sets the second decreasing rate in the second interval Ta2 by the slope of the line W75b. The first decreasing speed (the slope of line W75a) is set to be larger than the second decreasing speed (the slope of line W75b). That is, the control device 60 sets the decreasing speed of the control signal (control value) to at least two stages in the second reduction section Tb.

In the embodiment described above, the traveling operation device 54 is a hydraulic type that changes the pilot pressure acting on the traveling pumps (first traveling pump 53L, second traveling pump 53R) using the operating valve 55, but as shown in FIG. As such, the driving operation device 54 may be an electrically operated device.
As shown in FIG. 3, the travel operation device 54 includes an operation member 59 that swings in the left-right direction (body width direction) or the front-rear direction, and operation valves 55 (operation valves 55A, 55B, 55C) that are composed of electromagnetic proportional valves. , 55D). An operation detection sensor that detects the amount and direction of operation of the operation member 59 is connected to the control device 60 . The control device 60 controls the operation valves 55 (operation valves 55A, 55B, 55C, and 55D) based on the operation amount and operation direction detected by the operation detection sensor.

When the operating member 59 is operated forward (A1 direction, see FIG. 1), the control device 60 outputs a control signal to the operating valve 55A and the operating valve 55C, and controls the first traveling pump 53L and the second traveling pump 53R. Swing the swash plate in the normal (forward) direction.
When the operating member 59 is operated backward (A2 direction, see FIG. 1), the control device 60 outputs a control signal to the operating valve 55B and the operating valve 55D, and controls the first traveling pump 53L and the second traveling pump 53R. Swing the swash plate in the reverse (reverse) direction.

When the operating member 59 is operated to the right (A3 direction, see FIG. 1), the control device 60 outputs a control signal to the operating valve 55A and the operating valve 55D, and causes the swash plate of the first traveling pump 53L to rotate in the normal direction. The swash plate of the second traveling pump 53R is swung in the reverse direction.
When the operating member 59 is operated to the left (direction A4, see FIG. 1), the control device 60 outputs a control signal to the operating valve 55B and the operating valve 55C, and rotates the swash plate of the first traveling pump 53L in the reverse direction. The swash plate of the second traveling pump 53R is swung in the direction of normal rotation.

The work equipment 1 is rotatable by a prime mover 32, traveling pumps 53L, 53R that are operated by the power of the prime mover 32 and discharges hydraulic oil, and hydraulic oil discharged by the traveling pumps 53L, 53R, and has a rotational speed of A machine body 2 provided with traveling motors 36L, 36R that can be switched between a first speed and a second speed higher than the first speed, a prime mover 32, traveling pumps 53L, 53R, and traveling motors 36L, 36R, and a traveling motor 36L, A travel switching valve 34 capable of switching between a first state in which the rotation speed of the travel motor 36R is set to a first speed and a second state in which the rotation speed of the travel motors 36L and 36R is set to a second speed, and either speed increase or deceleration. a changeover switch 61 that issues a speed change command, an operating valve 69 that can control the hydraulic oil flowing to the travel pumps 53L and 53R, an automatic deceleration that switches from the second state to the first state, and a changeover switch 61 that gives a speed change command. a control device 60 that performs manual deceleration to switch from the second state to the first state when A second shock reduction control that reduces the number of shocks can be executed. According to this, manual deceleration and automatic deceleration can be performed by the switching command of the changeover switch 61, and when performing either manual deceleration or automatic deceleration, the opening degree of the operating valve 69 is reduced to cause a shift shock. The shift shock can be reduced by reducing the number of rotations of the prime mover 32 or by lowering the rotational speed of the prime mover 32. That is, in both manual deceleration and automatic deceleration, shift shock can be easily reduced by reducing the opening degree of the operating valve 69 or the rotational speed of the prime mover 32.

The control device 60 performs first shock reduction control when performing automatic deceleration, and performs second shock reduction control when performing manual deceleration. According to this, in automatic deceleration, the opening of the operating valve 69 is reduced, and in manual deceleration, the rotational speed of the prime mover 32 is reduced, thereby reducing shift shock without reducing work efficiency. can. In particular, during manual deceleration, the rotation speed of the prime mover 32 decreases, so the driver (operator) can recognize that the rotation speed of the prime mover 32 has decreased due to manual deceleration, and the driver's intention is to The work machine 1 can be operated as required.

When performing manual deceleration, the control device 60 performs first shock reduction control in addition to second shock reduction control. According to this, when manual deceleration is performed, the opening degree of the operating valve 69 can also be reduced, so that it is possible to further reduce the shift shock.
The control device 60 sets the opening degree of the operating valve 69 in the first shock reduction control when performing manual deceleration to be smaller than the opening degree of the operating valve 69 in the first shock reduction control when performing automatic deceleration. According to this, when manual deceleration is performed, the opening degree of the operating valve 69 can also be reduced, so that it is possible to further reduce the shift shock. In other words, when reducing shock through automatic deceleration, the opening degree of the operating valve 69 can be made larger than when reducing shock through manual deceleration. can also be reduced.

The operating valve 69 can change the opening degree according to the control signal output from the control signal, and the control device 60 lowers the control signal to a predetermined first reduction value in the first shock reduction control, and lowers the control signal to a predetermined first reduction value in the second shock reduction control. In the shock reduction control, the rotation speed of the prime mover 32 is reduced to a second reduction value that is lower than the target rotation speed. According to this, it is easy to set the first reduction value and the second reduction value for reducing the shift shock, and it is possible to easily control the operating valve 69 and the prime mover 32.

In the first shock reduction control, the control device 60 controls, in the first reduction period until the control signal output to the operating valve 69 reaches the first reduction value, the control device 60 controls the control device from the start point of the first reduction period to the middle of the first reduction period. The first rate of decrease of the control signal is made larger than the second rate of decrease of the control signal from the middle of the first reduction section to the end point. According to this, the responsiveness of the operating valve 69 can be improved.

In the second shock reduction control, the control device 60 keeps the third reduction rate of the actual rotational speed of the prime mover 32 constant in the second reduction section until the actual rotational speed of the prime mover 32 reaches the second reduction value. According to this, when reducing the shift shock, the actual rotational speed of the prime mover 32 is reduced while stabilizing the power output from the prime mover 32, so the shift shock is reduced while maintaining workability as much as possible. It can be performed.

The work machine 1 includes a first traveling device 5 provided on the left side of the machine body 2 and a second traveling device 5 provided on the right side of the machine body 2, and the traveling motors 36L and 36R are connected to the first traveling device 5. A first travel motor transmits power for travel to the second travel device, and a second travel motor transmits power for travel to the second travel device, and the travel pumps 53L and 53R are capable of operating the first travel motor and the second travel motor. The travel switching valve 34 can switch the first travel motor and the second travel motor between a first speed and a second speed. According to this, in the working machine 1 equipped with the first traveling device 5 provided on the left side of the machine body 2 and the second traveling device 5 provided on the right side of the machine body 2, shift shock can be reduced more smoothly. It can be carried out.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.
The travel switching valve 34 may be a valve that can switch the travel motors (first travel motor 36L, second travel motor 36R) between a first state in which the travel motors are at the first speed and a second state in which the travel motors are in the second speed. It may also be a proportional valve that is different from the directional control valve.

In the embodiment described above, the pressure of the hydraulic fluid introduced into the operating valves 55 (operating valves 55A, 55B, 55C, and 55D) was changed by the operating valve 69. Any valve that can set the pressure of the hydraulic oil, that is, the pressure of the hydraulic oil acting on the pressure receiving parts 53a, 53b of the traveling pumps 53L, 53R, may be used. By connecting the operating valve 69 to the operating member 59, the hydraulic oil pressure (pilot pressure) acting on the traveling pumps 53L, 53R may be adjusted according to the operation of the operating member 59, and during automatic deceleration, Shock reduction control may also be performed. In this case, the operating valve 69 also serves as the operating valve 55.

The travel motor may be a motor having a neutral state between the first speed and the second speed.
The travel motors (first travel motor 36L, second travel motor 36R) may be an axial piston motor or a radial piston motor. When the travel motor is a radial piston motor, the motor capacity becomes large, allowing switching to the first speed, and the motor capacity becomes small, allowing switching to the second speed.

1: Work equipment 2: Machine body 5: Travel device 32: Prime mover 34: Travel switching valve 36L: First travel motor 36R: Second travel motor 53L: First travel pump 53R: Second travel pump 60: Control device 61: Switching Switch 69: Operating valve Ta: First reduction section Tb: Second reduction section W52: First reduction value W62: Second reduction value

Claims (8)

prime mover and
a traveling pump that is operated by the power of the prime mover and discharges hydraulic oil;
a travel motor that is rotatable by hydraulic oil discharged by the travel pump and whose rotational speed is switchable between a first speed and a second speed higher than the first speed;
an aircraft body provided with the prime mover, the traveling pump, and the traveling motor;
a travel switching valve capable of switching between a first state in which the rotational speed of the travel motor is set at the first speed and a second state in which the rotational speed of the travel motor is set at the second speed;
a changeover switch that issues a speed change command for either speed increase or deceleration;
an operating valve capable of controlling hydraulic oil flowing to the traveling pump;
a control device that performs automatic deceleration for switching from the second state to the first state and manual deceleration for switching from the second state to the first state when the changeover switch issues the shift command;
Equipped with
The control device is a working machine capable of executing a first shock reduction control that reduces the opening degree of the operating valve and a second shock reduction control that reduces the rotational speed of the prime mover. The working machine according to claim 1, wherein the control device performs the first shock reduction control when performing the automatic deceleration, and performs the second shock reduction control when performing the manual deceleration. The working machine according to claim 2, wherein the control device performs the first shock reduction control in addition to the second shock reduction control when performing the manual deceleration. The control device makes the opening degree of the operating valve in the first shock reduction control when performing the manual deceleration larger than the opening degree of the operating valve in the first shock reduction control when performing the automatic deceleration. The working machine according to claim 3, wherein the working machine is set. The operating valve can change the opening degree according to a control signal output from the control device , and the control device reduces the control signal to a predetermined first reduction value in the first shock reduction control. The working machine according to any one of claims 1 to 3, wherein the second shock reduction control reduces the rotation speed of the prime mover to a second reduction value lower than the target rotation speed. In the first shock reduction control, the control device is configured to control the speed of the first reduction period from the starting point of the first reduction period in a first reduction period until the control signal output to the operating valve reaches a first reduction value. The working machine according to claim 4, wherein the first rate of decrease of the control signal halfway through the first reduction section is greater than the second rate of decrease of the control signal from the halfway point to the end point of the first reduction section. In the second shock reduction control, the control device is configured to reduce the actual rotational speed of the prime mover by a third reduction in a second reduction period until the actual rotational speed of the prime mover reaches a second reduction value lower than the target rotational speed. The work machine according to claim 5 or 6, wherein the speed is constant. a first traveling device provided on the left side of the aircraft;
a second traveling device provided on the right side of the aircraft;
Equipped with
The travel motor is a first travel motor that transmits power for travel to the first travel device and a second travel motor that transmits power for travel to the second travel device,
The travel pump is capable of operating the first travel motor and the second travel motor,
7. The working machine according to claim 1, wherein the travel switching valve is capable of switching the first travel motor and the second travel motor between the first speed and the second speed.

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