JPH07323862A - Operating device for self-propelling type work machine - Google Patents

Abstract

PURPOSE:To improve the operability of levers by providing the maximum speed when a steering lever interlocked with a linkage means is released together with a speed change lever and setting the speed change lever to the neutral position when a deadman lever is interlocked with the linkage means to release the deadman lever. CONSTITUTION:Deadman levers 53L, 53R are provided together with grips 51a, 51a. A brake link 63 and link 64 are connected to a stay 53b of a connecting shaft 53a and the other end of the brake link 63 is connected to a brake device. On the other hand, the other end of the link 64 is connected to interlock plates 67L, 67R. A link 70 is pivotably supported by steering levers 54L, 54R attached together with the grips 51a, 51a and the other end of the link 70 is connected to the interlock plates 67L, 67R. Also, the interlock plates 67L, 67R are energized by a spring 76 to always energize speed change levers 6L, 6R to the maximum speed position of the advance side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a self-propelled working machine in which the left and right axles can be separately driven by a pair of left and right hydraulic continuously variable transmissions.

[0002]

2. Description of the Related Art Conventionally, in a walk-behind type self-propelled working machine, two sets of left and right hydraulic continuously variable transmissions are used to drive the left and right running wheels, and the left and right handles are diagonally rearward from the machine body frame. A work machine is known in which a grip is provided at a rear portion of the handle so as to project, and right and left steering levers are provided near the grip to enable steering and speed shifting. For example, US Pat.
This is the technology of No. 27215.

[0003]

In the above walking type working machine, when the operator releases the left and right steering levers, the left and right speed change levers are automatically set to the neutral position with the intention of preventing runaway of the working machine. It is configured to return.
For this reason, when the work implement is moved straight forward or backward, it is required to push in (or pull in) both steering levers at the same time and with an equal operating force. I could not do it, and it was easy to bend to the left and right, and it was difficult to operate. Also, when turning to correct the traveling direction of the work machine,
Since one steering lever had to be pushed in and the other steering lever had to be pulled in at the same time, if the timing was a little wrong, it would not be possible to turn as desired and it required skill to operate. .

[0004]

The problems to be solved by the present invention are as described above. Next, the means for solving the problems will be described. That is, around the grip of the handle provided in the self-propelled working machine, the left and right steering levers that are located on the left and right of the grip and can be individually gripped, and at least one deadman lever that can be gripped,
The left and right steering levers are provided with a spring bias mechanism in the left and right control linkage means for linking the left and right steering levers and the left and right steering levers of the pair of left and right hydraulic continuously variable transmissions capable of separately driving the left and right axles. When each gear shift lever is set so as to reach the maximum speed on the forward side of the work machine when the gear is released, when the dead man lever is linked to the control linkage means through the interlock mechanism, the dead man lever is opened. It is configured to set each shift lever to a neutral position.

Further, each of the left and right control linkage means is linked to an independent left and right speed control lever capable of changing the operation ratio of the speed controller with respect to the operation ratio of the steering lever by the operator. Is. Further, in the variable displacement type hydraulic device constituting the hydraulic continuously variable transmission, a tilting moment to a non-neutral position is given to a movable swash plate operated by the shift lever. .

[0006]

[Operation] Next, the operation will be described. That is, the operator simply grips the deadman levers provided on the grips on both sides of the steering wheel and opens both steering levers, and the spring bias mechanism simultaneously operates the speed change levers of the left and right hydraulic continuously variable transmissions via the control linkage. It is possible to automatically move the working machine in a straight line by synchronizing the left and right axles and rotating them at the maximum forward speed. If the tuning speed is not reached, it can be corrected by appropriately operating the left and right speed control levers independently to change the link ratio of the control linkage means.

By gripping one of the left and right steering levers provided on the grip, the hydraulic continuously variable transmission can be operated to the deceleration side through the control linkage means on that side and turned. When the steering lever is released, it returns to the original forward maximum travel position. When the deadman lever is released, the gear shift levers are returned to the neutral positions by the interlock mechanism, and the working machine is stopped. Since the tilting moment to the non-neutral position is applied to the movable swash plate of the hydraulic continuously variable transmission, the biasing force of the spring bias mechanism is
It is relatively small, and the operation when gripping the steering lever is light.

[0008]

EXAMPLES Next, examples will be described. 1 is a perspective view of a walk-behind mower as an example of a self-propelled working machine, FIG.
3 is a perspective view of an axle drive device mounted on a self-propelled working machine, FIG.
Is a plan view and a partial cross-sectional view with the upper housing half 1 removed from the axle drive device, FIG. 4 is a cross-sectional view taken along the line AA of FIG. 3, and FIG. 5 is a cross-sectional view taken along the line BB of FIG. 6 is a plan view showing the first embodiment of the pump mounting surface of the center section, FIG. 7 is a plan view showing the second embodiment of the same, FIG. 8 is a side sectional view of the movable swash plate, and FIG. 9 is the present invention. FIG. 10 is a development view of the control device, showing a state when the work machine is stopped, FIG. 10 is a development view of the control device, showing a state of a straight-ahead operation, and FIG. 11 is a view showing a state of a turning operation.

The overall structure of a walk-behind mower shown as an example of a self-propelled working machine in FIG. 1 will be described.
A pair of left and right handles 51, 51 are projected obliquely rearward from the rear part of the machine body frame 50, and an operation box 52 accommodating a control linkage means described later is disposed between the rear upper parts of the handles 51, 51. On the operation box 52, speed control levers 55L and 55R for adjusting the speed of the left and right axles, an accelerator lever 56 for adjusting the rotation speed of the engine E, and a bypass lever 60 for freely rotating the axle are provided. 51 ・
Deadman levers 53L and 53R and steering levers 54L and 54R, which will be described later, are disposed above and below the grip portions 51a and 51a of 51.

Further, a mower deck 58 is mounted on the front end of the machine frame 50, caster wheels 59, 59 are arranged on the front end of the mower deck 58, and a vertical engine E is arranged substantially above the center of the machine frame 50. The crankshaft 22, which is the output shaft of the engine E, is provided so as to project downward. As shown in FIG. 2, a triple pulley 21 is fixedly mounted on the lower end of the crankshaft 22.
An electromagnetic clutch 40 is built in the first pulley 21 a of the first pulley 21 a, and the belt 20 is wound around the first pulley 21 a to move the mower deck 58.
The cutter blade housed inside can be driven. A belt 23R is wound around the second pulley 21b, and a belt 23L is wound around the third pulley 21c. The input pulleys 25L and 25L provided above the housing H of the axle drive device through the belts 23L and 23R, respectively.
Axles 7L and 7R are transmitted through a pair of left and right hydraulic continuously variable transmissions, which will be described later, configured to transmit power to the R and to be configured in the housing H.
Is driven to rotate the traveling wheels 61L and 61R to travel.

The housing H of this axle drive is shown in FIG.
As shown in FIG. 3, a recessed portion Ha is formed in the center of the rear portion, and the crankshaft 22 and the triple pulley 21 are disposed in the recessed portion Ha so as to face the engine E at a low position and
It is configured so that it can approach the axles 7L and 7R. Further, the housing H is mainly constructed by joining the two upper housing half portions 1 and the lower housing half portion 2 to each other at their peripheral flat joining surfaces, and the axle drive device is mounted on the working machine. At this time, the joint surface of the housing H is located on a horizontal plane. The internal structure of the housing H will be described with reference to FIGS. 3, 4, and 5.

Inside the housing H, various transmission parts for driving the axles 7L and 7R are housed substantially symmetrically, and the left and right center sections 5L and 5R are attached to the axle 7L.
7R are arranged substantially parallel to the longitudinal direction, and each is 3
It is stably fixed to the upper housing half portion 1 by a book bolt without being distorted. A protrusion is formed upward at a position near the front of the upper wall of the upper housing half 1 to form an oil tank portion 1b communicating with the inside of the housing, and an operation in the housing H is performed via an air breather 26b attached to the upper end. The oil is allowed to expand and contract.

The center sections 5L and 5R are formed in an L-shape when viewed from the rear, and the pump attachment surface 5a is provided on the horizontal surface thereof.
And a motor mounting surface 5b is formed on the outer vertical surface, and the hydraulic pump PL / PR is formed on the pump mounting surface 5a.
Cylinder blocks 16L and 16R are mounted in a vertical direction, and cylinder blocks 17L and 17R of hydraulic motors ML and MR are mounted in a horizontal direction on the motor attachment surface 5b. In this way, the combination of the hydraulic pump PL and the hydraulic motor ML, and the hydraulic pump PR and the hydraulic motor M are combined.
A pair of combinations of R is arranged in a row in the housing H in the left-right direction.

The left and right hydraulic pumps PL and PR are axial piston type variable displacement hydraulic devices and are composed of the same parts. That is, the cylinder block 16L
A plurality of pistons 13 are reciprocally fitted in a plurality of cylinder holes of 16R via biasing springs, and the head of the piston 13 has a lower surface of the thrust bearing of the movable swash plates 8L and 8R. Is contacted with the cylinder block 16L.
Pump shafts 3L and 3R are inserted and engaged on a vertical rotation axis of 16R to form hydraulic pumps PL and PR. The upper portions of the pump shafts 3L and 3R are supported by bearings held on the upper wall of the upper housing half portion 1, and the upper end portions thereof protrude from the housing H. The input pulleys 25L and 25R are attached to the respective pump shafts 3L and 3R so that the left and right hydraulic pumps PL and PR can be driven simultaneously. Input pulley 25L ・ 2
Since 5R is attached so that the heights thereof are different from each other, the two pump shafts 3L and 3R can be arranged close to each other, and the width of the housing H in the left-right direction is compressed. As shown in FIG. 5, the movable swash plates 8L and 8R each have a shaft portion 8a protruding rearwardly rotatably supported by a leg portion 1a protruding downward from the upper housing half portion 1 and projecting forward. A shaft portion 8b having the same axis as the shaft portion 8a is rotatably supported by support plates 9L and 9R attached to the outer surface of the upper housing half portion 1, and the housing H
Gear levers 6L and 6R are fixedly installed at the outer end of the shaft portion 8b,
The steering levers 54L and 54R are connected to the speed change levers 6L and 6R through a link mechanism described later,
By tilting the movable swash plates 8L and 8R by this lever operation, the discharge amount and the discharge direction of oil from the hydraulic pumps PL and PR can be changed.

The movable swash plates 8L and 8R are hydraulic pumps P.
When the L / PR cylinder blocks 16L and 16R rotate, a tilting moment to a non-neutral position is given. Specifically, for example, as shown in FIG. 6, the pressure center P1 of the pair of kidney ports 5f and 5f provided on the pump attachment surface 5a of the center sections 5L and 5R.
-The virtual line β connecting P2 is the shaft portions 8a and 8b of the movable swash plate 8.
Is provided so as to be rotated from the center line α of the pump shaft 3 by an angle θ, and the reaction force from the piston 13 applied to the movable swash plates 8L and 8R is displaced by θ, and the displacement is movable. A tilting moment to a non-neutral position is given to the swash plates 8L and 8R.

As another embodiment for giving a tilting moment to the non-neutral position to the movable swash plates 8L and 8R, as shown in FIG. 7, the pressure center P1 of the kidney ports 5f and 5f is set.
The movable swash plate 8 can also be designed by making the center line α of the shaft portions 8a and 8b of the movable swash plates 8L and 8R relatively parallel to the virtual line β that connects P2 and offset by the length Δh.
A tilting moment to the non-neutral position can be given to L · 8R.

The left and right hydraulic motors ML and MR are axial piston type fixed displacement hydraulic devices.
It is composed of the same parts. That is, the cylinder block 17
Plural pistons 1 in plural cylinder holes of L / 17R
2 is reciprocally fitted while being biased by a spring. The head of the piston 12 contacts a thrust bearing held by the fixed swash plates 19L and 19R in an inclined state, and the fixed swash plates 19L and 19R are sandwiched between the upper housing half 1 and the lower housing half 2. It is fixed. Further, the motor shafts 4L and 4R are engaged and inserted on the horizontal rotation axes of the cylinder blocks 17L and 17R to form hydraulic motors ML and MR.

In the center sections 5L and 5R, a pair of kidney ports 5f and 5f for connecting the suction portion and the discharge portion of the cylinder blocks 16L and 16R are opened in the pump attachment surface 5a. And the motor mounting surface 5b, respectively,
A pair of kidney ports (not shown) for connecting the suction part and the discharge part of the cylinder blocks 17L and 17R are opened.

Inside the center sections 5L and 5R, a pair of kidney ports of the pump attachment surface 5a,
A pair of oil passages 5d and 5e are provided for mutually connecting the pair of kidney ports of the motor mounting surface 5b,
With this, the hydraulic pump PL / PR and the hydraulic motor ML
-A closed circuit for circulating hydraulic oil between MRs is configured. The hydraulic oil discharged from the left and right hydraulic pumps PL and PR by rotating the cylinder blocks 16L and 16R flows through a closed circuit in the center sections 5L and 5R and the hydraulic motors ML and MR cylinder blocks 17L and 17R. Received by the cylinder block 1
Converted to 7L / 17R rotational torque. Then, the rotational torque generated by the hydraulic motors ML and MR is changed according to the degree of tilt of the movable swash plates 8L and 8R of the hydraulic pumps PL and PR. In this way, the hydraulic continuously variable transmissions are respectively configured on the center sections 5L and 5R arranged side by side.

As shown in FIGS. 4 and 5, the lower portion of the pump shafts 3L and 3R penetrates the pump attachment surface 5a of the center sections 5L and 5R, and the lower end of the pump shafts 3L and 3R causes the back surface of the pump attachment surface 5a. Attached to the charge pump 11
Are driven respectively. A pump case 10 for accommodating the charge pump 11 is provided with an oil passage 10a on the suction side to the charge pump 11 and an oil passage 10b on the discharge side.
The suction-side oil passage 10a communicates with the filter 15 so that the working oil in the housing H can be filtered and sucked, and the discharge-side oil passage 10b is provided with a relief valve (not shown) so that the discharge oil has a predetermined hydraulic pressure. I am adjusting. Reference numeral 15a is a cover for allowing the filter 15 to be pulled out from the inside of the housing H at the time of maintenance and inspection of the filter 15.

The oil flowing from the oil passage 10b is supplied to the closed circuit in the center sections 5L and 5R through the check valves 31 and 32 shown by broken lines in FIG. The check valves 31 and 32 are provided with open push rods 33 and 34 that project outward from the center sections 5L and 5R. Both ends of the open push rods 33 and 34 contact one pressing plate 36, and the pressing plate 36 can be slid outward by the rotation of the bypass shaft 37. The bypass arm 38 is fixedly installed, and the bypass arm 38 is connected to the bypass lever 60 on the operation box 52 via a wire. Therefore, when the bypass lever 60 is operated, the bypass arm 38 is rotated, the bypass shaft 37 is rotated, and the pressing plate 36 is opened.
Push 4 to check the left and right check valves 31.3
2 can be opened at the same time to open the two closed circuits to freely rotate the motor shafts 4L and 4R of the hydraulic motors ML and MR. This allows the walk-behind more to be pushed and moved by hand even if a trouble such as the engine not starting occurs.

Housing H for the motor shafts 4L and 4R
Brake drum 42L / 4
2R is fixed and well-known band type brake device BL
BR is configured. As will be described later, this brake device BL / BR simultaneously brakes the motor shafts 4L / 4R by simultaneously tightening the brake drums 42L / 42R by brake bands (not shown) while the deadman levers 53L / 53R are released. I am able to do it. Further, the gear 41L is provided in the middle of the motor shafts 4L and 4R.
・ 41R is provided, and the gears 41L and 41R are large diameter gears 44L and 44R on the counter shafts 43L and 43R.
Meshes with. The small diameter gears 45L and 45R on the counter shafts 43L and 43R mesh with the final gears 46L and 46R fixedly mounted on the axles 7L and 7R, and the power from the hydraulic motors ML and MR is transmitted to the axles 7L and 7R. It

The rotation axes of the left and right motor shafts 4L and 4R, the left and right counter shafts 43L and 43R, and the left and right axle shafts 7L and 7R are substantially on the same plane as the joint surface of the upper housing half 1 and the lower housing half 2. Located on the left and right sides, the hydraulic pumps PL / PR, hydraulic motors ML / MR, and axles 7L /
The power transmission mechanism to 7R is arrange | positioned substantially left-right symmetrically, and an axle drive device is comprised. 30 is an input pulley 2
A cooling fan mounted on the upper surface of 5 L, which rotates together with the input pulley 25 L and blows cooling air from above the upper housing half portion 1 to suppress an increase in the oil temperature of the working oil in the housing H. ing. Although not shown in the figure, by providing a cooling fan on the pulley 21b on the engine side as well, an increase in the oil temperature of the hydraulic oil can be further suppressed.

Next, the construction of the control device according to the present invention for advancing / stopping / retracting / turning the self-propelled working machine will be described with reference to FIGS. 9, 10 and 11. The deadman levers 53L and 53R are arranged so as to be gripped from the upper side of the grips 51a and 51a, and the one connecting shaft 5 that connects the deadman levers 53L and 53R.
3a is pivotally supported by a stay 62 on the bases of the grips 51a and 51a, and stays 53b are fixed to both ends of the connecting shaft 53a. One ends of a brake link 63 and a link 64 are respectively connected to the stay 53b, and the other ends of the brake links 63 are connected to the brake arms 65, 65 of the left and right brake devices BL, BR. The brake arms 65, 65 are biased by springs 66, 66 in the direction of operating the brake device. On the other hand, the other end of the link 64 is pivotally connected to the first elongated holes 67a and 67a provided in the interlock plates 67L and 67R, respectively.

The left and right steering levers 54L are attached to the support stays 69 at the bottom of the bases of the grips 51a and 51a.
The front end of 54R is pivotally supported, and each of them is attached together with the grips 51a, 51a so that they can be gripped. One end of a link 70 is pivotally supported at the front of each of the steering levers 54L and 54R, and the other end of the link 70 is connected to the interlock plates 67L and 67R.

The interlock plates 67L and 67
The R is pivotally supported by a pivot shaft 72 provided in the operation box 52 so as to be swingable, and its swing range is restricted by position-adjustable stoppers 74, 74 provided on the left and right sides. The first elongated hole portion 67a has an arc shape centered on the pivot shaft 72, and a concave portion 67b is continuously provided in the middle of the arc portion. When the pivot portion 64a of the link 64 is located in this arc portion, the interlock plates 67L and 67R can freely swing, and the pivot portion 64a is located in the concave portion 67b. When doing
The interlock plates 67L and 67R are stopped at their positions and cannot swing. The stopped position of the interlock plates 67L and 67R corresponds to the neutral position of the speed change levers 6L and 6R described later. The interlock mechanism is configured as described above. The interlock plates 67L and 67R are further provided with second elongated holes 67c, and the shift levers 65L and 65R are provided.
The left and right steering levers 54L and 54R and the shift lever 6L are pivotally connected by the rod 75 connected to
-The control linkage means is formed between the 6Rs.

The pair of left and right control levers 55L and 55R provided in the operation box 52 has an arm 55a which is integral with a pivoting support portion thereof. The second
The long hole 67c has the control levers 55L and 55R.
It has an arcuate shape centered on the rotation pivot fulcrum of, and the pivotal connection portion 75a of the link 75 therein is also located in the linear elongated hole 55b provided in the arm 55a. . Therefore, when the control levers 55L and 55R are operated in the (a) direction and the (b) direction to displace the arm 55a, the connection position of the pivotal connecting portion 75a of the link 75 with respect to the interlock plates 67L and 67R is changed. . This means that the operation ratio of the shift levers 6L and 6R, that is, the link ratio is changed with respect to the operation ratio of the steering levers 54L and 54R. For example,
When the pivotal connection 75a of the link 75 is located above the second elongated hole 67c in the plane of the drawing, the link ratio becomes large and the gear shift levers 6L and 6R are large even if the steering levers 54L and 54R are slightly gripped. Operated. on the other hand,
When the pivotal portion 75a is located on the lower side of the second elongated hole 67c in the drawing, the link ratio becomes small, and the speed change levers 6L and 6R are delicately adjusted according to the degree of grip of the steering levers 54L and 54R. Can be operated.

Further, in the operation box 52, a tension type spring 7 which constitutes a spring bias mechanism.
6 is provided, one end of which is locked to the fixed side and the other end of which is locked to the interlock plates 67L and 67R. This spring 76 allows the interlock plate 67L
The 67R is always urged in the direction in which the shift levers 6L and 6R on one side are directed to the forward maximum speed position F. As the spring bias mechanism, as shown in FIG.
It may be provided in the housing H of the axle drive. That is,
Winding spring 7 around shaft 8b of movable swash plates 8L and 8R
6 is provided, and a fixed pin 49a provided on the support plates 9L and 9R and a movable pin 49b provided on the movable swash plates 8L and 8R are sandwiched at both ends thereof. By adopting such a configuration, the spring 76 can maintain its performance for a long period of time without being affected by dust and rust.

Reference numerals 71L and 71R are steering lever lock plates swingably provided on the base side of the grip portions 51a and 51a of the handle 51, and the pins 54a provided on the steering levers 54L and 54R can be fitted therein. The lock groove 71a and the unlock groove 71b which are continuous in a bifurcated shape are provided. When the working machine is not operated by the alternative posture changing operation of the steering lever lock plates 71L and 71R, the pin 54a is positioned in the lock groove 71a as shown in FIG. In this way, the steering lever 54L ・ 54
R cannot be squeezed in while being held in the neutral position. When the work machine is operated, the pin 54a
Is positioned in the unlock groove 71b, and the steering levers 54L and 54R are automatically moved to the forward-side maximum speed position F, which is the lowermost end position of the unlock groove 71b, under the bias of the spring bias mechanism. It is pushed down and can be grasped freely from this position.

In FIG. 9, the operator selects the deadman levers 53L and 53R and the steering lever 54L and 53L.
Neither of the 54R is gripping. Therefore, the deadman lever 53 is raised by the springs 66, 66, and both brakes BL, BR are in an operating state in which the axles 7L, 7R are being braked. In addition, the pivot 64a of the link 64
Is located in the recessed portion 67b of the first elongated hole portion 67a of the interlock plate 67L / 67R, and the shift lever 6L
6R is held in the neutral position N, and the axles 7L and 7R are not driven.

Next, deadman levers 53L and 53R
As shown in FIG. 10, the working machine goes straight. That is, when the deadman levers 53L and 53R are pushed downward, the arm 53b pushes in the link 64, and the pivoting portion 64a is disengaged from the recessed portion 67b and positioned in the arc portion, the interlock plates 67L and 67R are fixed. At the same time as the release, the springs 76 force the interlock plates 67L and 67R to be tilted to one side. As a result, the link 70 is pulled and the steering levers 54L and 54R are automatically pushed down to the lowest position. Then, the link 75 is pushed in and the transmission levers 6L and 6R are automatically operated to the forward maximum speed position F. Further, the arm 53b pushes down the link 63 against the urging force of the spring 66, and the axle braking state of the brake device BL / BR is released. Therefore,
The left and right axles 7L and 7R rotate at the maximum speed toward the side where the work implement is moved forward.

In order to turn the working machine from this straight traveling state, the operator turns the steering lever 54 on the turning side.
All you have to do is grasp the L / 54R. For example, when the left steering lever 54L is gripped, the link 70 is pulled down, and the interlock plate 67L moves to the spring 7.
Moved to the other side against 6. By this movement, the link 75 is pulled in, and the shift lever 6L is operated to the deceleration side. Therefore, the rotation speed of the axle 7L becomes lower than that of the axle 7R, and the working machine turns to the left. When the steering wheel 54L on the left side is further gripped and tightened as much as possible, the gear shift lever 6L is operated to the reverse side maximum speed position R as shown in the figure, and the axle 7L rotates in the opposite direction to the axle 7R for maximum rotation. As a result, the work machine is turned with the minimum turning radius. If the steering levers 54L and 54R are gripped at the same time when moving the vehicle backward, the discharge directions of both hydraulic pumps PL and PR are reversed, and the rotation directions of the hydraulic motors ML and MR are simultaneously reversed. The axles 7L and 7R rotate the traveling wheels 61 and 61 to the reverse side.

The steering levers 54L and 54R
The gripping operation is performed against the spring 76, but as described above, since the movable swash plates 8L and 8R of the hydraulic pumps PL and PR are given a tilting moment to the non-neutral position, It is not necessary to design the biasing force of the spring 76 so strongly. Therefore, the operator can grip the steering levers 54L and 54R with a light operation.

Depending on the condition of the road surface, the left and right running wheels 61
・ If 61 does not rotate evenly and the aircraft is meandering, left and right speed control levers 55L ・ 5
By appropriately operating the 5R in the (a) direction and the (b) direction, the working machine can be corrected to the straight traveling state. Then, when the operator falls down during work and the hand is released from the grip 51a, the brake arm 65 is operated by the urging force of the spring 66 and the brake device BL is operated.
When the BR operates and the axles 7L and 7R are braked, the pivot 64a of the link 64 enters the recess 67b of the interlock plates 67L and 67R and the shift levers 6L and 6R are forced to the neutral position N. It is returned and the work machine stops quickly.

The present invention is not limited to walk-behind mowers but can be widely applied to various walk-behind type working machines such as snow blowers and power carriers.

[0036]

Since the present invention is constructed as described above, it has the following effects. That is, since the construction is as set forth in claim 1, when the operator directly advances the working machine forward, the operator grasps the deadman lever and releases the hands from both steering levers, and the spring bias mechanism automatically operates the left and right axles. Is synchronized and driven to the maximum speed on the forward side. Then, only when the trajectory is corrected, if the steering lever on the bend side is grasped, the rotation of the axle on that side can be decelerated, so that the maneuverability of the working machine can be remarkably improved. Also, when the operator releases his or her hand from the deadman lever, the pair of left and right hydraulic continuously variable transmissions and the left and right brake devices do not double-operate, and the progress of the work implement is stopped instantaneously to prevent runaway. You can In addition, the operator does not have to operate the brake device one by one during parking, which improves safety. The interlock mechanism allows the left and right steering levers to be locked at the neutral position while the left and right brake devices are operating, and the drive when the axle is braking can be reliably cut off.

According to the second aspect of the invention, the left and right axles can be finely adjusted in rotational speed by the independent left and right speed control levers, the straightness can be guaranteed, and the running performance is improved. Also, by changing the link ratio in the control linkage on the corresponding control lever,
It is possible to limit the maximum speed of the axle and yet
Even if the maximum speed is limited, the stroke of the steering lever remains unchanged, and its operability does not change at all.

According to the third aspect of the invention, when the conventional neutral return type variable displacement hydraulic system in which the movable swash plate is provided with the tilting moment to the neutral position, the operator operates the steering lever from the left and right. If the left and right axles are braked to the maximum forward speed when the hands are released, the spring bias mechanism must have a large biasing force to overcome the tilting moment to the neutral position. Therefore, the operation of the steering lever becomes heavy. However, according to this structure, since the tilting moment to the non-neutral position is always applied to the movable swash plate, the biasing force of the spring bias mechanism can be remarkably reduced, and the steering lever at the time of gripping the steering lever can be reduced. The operation force can be very light. Further, when the working machine descends a downhill, the overspeed acts on itself to improve safety.

[Brief description of drawings]

FIG. 1 is a perspective view of a walk-behind mower as an example of a self-propelled working machine.

FIG. 2 is a perspective view of an axle drive device mounted on a self-propelled working machine.

3A and 3B are a plan view and a partial cross-sectional view, respectively, in which an upper housing half portion 1 of an axle drive device is removed.

4 is a cross-sectional view taken along the line AA of FIG.

5 is a sectional view taken along the line BB of FIG.

FIG. 6 is a plan view showing a first embodiment of the pump attachment surface of the center section.

FIG. 7 is a plan view showing a second embodiment of the same.

FIG. 8 is a side sectional view of a movable swash plate.

FIG. 9 is a development view of the control device according to the present invention, showing the state when the work machine is stopped.

FIG. 10 is a development view of the control device showing a state of a straight-ahead operation.

FIG. 11 is a drawing which similarly shows a state of a turning operation.

[Explanation of symbols]

 H Housing PL / PR Hydraulic pump ML / MR Hydraulic motor BL / BR Brake device 1 Upper housing half 2 Lower housing half 7L / 7R Axle 51 Handle 51a / 51a Grip 53 Deadman lever 54L / 54R Steering lever 55L / 55R Speed control Lever 67L / 67R Interlock plate 76 Spring

Claims (3)

[Claims] 1. A self-propelled working machine is provided with a left and right steering levers, which are located on the left and right of the grip and can be individually gripped, and at least one deadman lever, which can be gripped, around a grip of the handle. A left and right steering mechanism is provided with a spring bias mechanism in the left and right control linkage means for connecting the left and right steering levers of the pair of left and right hydraulic continuously variable transmissions capable of separately driving the left and right axles. The gear shift levers are configured to be set to the maximum speed on the forward side of the work machine when the levers are opened, and the deadman lever is linked to the control linkage means through an interlock mechanism to open the deadman lever. Sometimes configured to set each shift lever to the neutral position A control device for a self-propelled working machine characterized by. 2. The left and right control linkage means according to claim 1 are linked to independent left and right speed control levers capable of changing an operation ratio of a speed adjuster with respect to an operation ratio of a steering lever by an operator. A control device for a self-propelled working machine characterized by being provided. 3. A tilting moment to a non-neutral position is given to a movable swash plate operated by the shift lever of the variable displacement hydraulic device constituting the hydraulic continuously variable transmission according to claim 1. A control device for a self-propelled working machine having the above-mentioned configuration.