JP2009178148A - Self-propelled two-face cutting mower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-propelled two-face cutting mower capable of smoothly and safely cutting two faces of a levee site and the like with various field conditions changing depending on time and districts. <P>SOLUTION: The self-propelled two-face cutting mower is designed so that, when the axial speeds n<SB>A</SB>and n<SB>B</SB>of a front wheel 11A and a rear wheel 11B are equal, the radius r<SB>B1</SB>of the rag tip end of the rear wheel 11B is designed larger than the radius r<SB>A1</SB>of the spike tip end of the front wheel 11A, the front wheel 11A has a rugged running resisting part on the inside diameter side of the spikes and is equipped with a wide bearing wheel 11A<SB>1</SB>having a widened grounding width, the radius r<SB>B2</SB>of the rag base end and of the rear wheel 11B is set lager than the effective radius r<SB>A2</SB>of the wide bearing wheel 11A<SB>1</SB>, and an one-way clutch 55 allowing the front wheel 11A to idly turn in the forward direction is installed at the hub part of the front wheel 11A. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a self-propelled two-sided mower that has a drive wheel and can simultaneously mow both a flat surface and a sloping ground on a fence or the like while traveling.

  The prior art described in the following Patent Document 1 includes a traveling unit having drive wheels, a main cutter housing having a main cutter that rotates horizontally, and a sub-cutter that can rotate on a plane that intersects the plane of the main cutter in the rotational direction. The side part of the sub cutter housing is pivotally supported by the side part of the main cutter housing, and the sub cutter housing can swing up and down with respect to the main cutter housing. According to this, by placing the main cutter housing along the flat ground and the sub cutter housing along the inclined ground, the place where the flat land and the inclined land extend in one direction, At the same time mowing work can be performed.

  Such a self-propelled two-sided mower is provided with a handle for walking work behind the main cutter housing, and is equipped with a prime mover for driving the wheels of the running section, the main cutter and the sub cutter, and the prime mover A power transmission unit for transmitting power to the wheel, main cutter, and sub cutter is provided.

In this prior art, in order to obtain reliable traveling performance even on rough terrain, the traveling portion is driven by front and rear wheels. That is, a front wheel that is a driven wheel is provided on the front side of the fuselage frame, and a rear wheel that is a driving wheel is provided on the rear side, and the rotation of the rear axle is transmitted to the front axle by the power transmission unit. ing. The power transmission unit includes a gear device attached to the axle of the rear wheel, which is a driving wheel, a gear device attached to the axle of the front wheel, which is a driven wheel, and a drive shaft that links and interlocks these gear devices.
JP 2006-7990 A

  In such a walking type self-propelled two-sided mower, when the sub cutter housing is operated along an inclined ground, a lateral load due to the weight of the sub cutter housing or traveling resistance is applied to the traveling portion. . Therefore, in a self-propelled two-sided mower that is supposed to work in a slippery place such as a paddle in a field or a field, in order to prevent a side slip in the traveling part in order to perform a safe mowing work Need to be creative. For this, the front wheel is a disc-shaped wheel and a spike is provided on the outer periphery thereof. According to this, the front wheel sinks into the ground during running and becomes resistance to lateral load and also serves as a guide for straight running, so safe work can be done while maintaining straight running without frequent correction by steering wheel operation It becomes possible.

  On the other hand, rubber tires with lugs with a wide contact width are often used for the rear wheels to ensure running performance on rough terrain. It is a different type of wheel. In this case, if the front and rear wheel drive by the power transmission unit as described above is adopted, there is a problem that the axle is stressed and the durability of the traveling portion is deteriorated for the following reason.

  That is, in order to drive the front and rear wheels so that the axle is not stressed, it is necessary that the front and rear wheels move at the same ground speed at the ground contact points of the front and rear wheels. When the axial speed of the front and rear wheels is constant, the radii to the ground contact points of the front and rear wheels must be equal. Even if the front-rear wheel speed ratio and front-rear wheel radius are properly designed to obtain this condition, if the front and rear wheels are of different types, as described above, the amount of sinking on the ground Will be different for each front and rear wheel, and the amount of sinking will change depending on the ground conditions, so the movement speed of the front and rear wheels relative to the ground will not match during actual driving. Thus, a load exceeding the running resistance is applied to one or both axles.

  It is also possible to set the effective diameter of the front wheel after predicting the sinking amount of the disk-shaped front wheel with respect to the ground, and to set the effective diameter of the rear wheel by the radius to the lug base end of the rubber tire with the lug of the rear wheel Although it is possible, road conditions in remote areas vary from time to time or from region to region, and even in a single work site, road surface conditions vary from place to place. In a self-propelled two-sided mower based on work, the effective diameter changes according to the ground condition, and the moving speeds of the front and rear wheels with respect to the ground do not always match according to the set effective diameter. As a result, there is a problem that a situation where the traveling part is stressed and the traveling becomes unstable is irregularly visited.

  Furthermore, the self-propelled two-sided mower does not only travel on the work site, but also travels on the paved road surface when moving to the work site. Since the amount of subsidence with respect to is zero, when the above-described design based on the prediction of the effective diameter is performed, a large stress is applied to the traveling portion when traveling on a paved road surface.

  In order to avoid such stress on the running part, it is also possible to drive only the rear wheel, but driving only the rear wheel may make it impossible to run if the rear wheel slips in a soft field, In order to smoothly perform the mowing work at a time when the dredging tends to be soft, it is essential to drive the front wheel side in addition to the rear wheel drive.

  In addition, it is possible to absorb the speed difference between the front and rear wheels by interposing a torque limiter or differential mechanism in the drive system of the front and rear wheels, but the torque limiter basically allows the drive system to slip. Yes, if the set allowable torque is excessive, there is no point in using it.For example, when traveling with a load exceeding the allowable value, such as when driving while climbing up and down one wheel, it is possible to transmit power. There is a problem that it becomes impossible to run due to loss, and if a differential mechanism is installed in the front and rear wheel drive system, it will not be possible to run one wheel with one wheel lifted, so it will be possible to climb over a drainage ditch or over a saddle Traveling unique to remote work such as traveling cannot be performed by one-wheel traveling, and the workability is extremely deteriorated. Furthermore, if a torque limiter or a differential mechanism is provided, there is a problem that the cost of the apparatus increases.

  An object of the present invention is to deal with such a problem. That is, without using an expensive torque limiter or differential mechanism, it is possible to smoothly and safely perform two-sided mowing work on dredged land that changes to various ground conditions depending on the time and region, It is an object of the present invention to be able to travel without stressing the traveling section in all ground conditions including paved road surfaces while preventing side slip and ensuring reliable traveling workability on soft ground. .

In order to achieve such an object, a self-propelled two-sided mower according to the present invention has at least the following characteristics.
A main cutter having a traveling unit having a front wheel and a rear wheel and having a handle for walking operation at the rear, and a main cutter that is mounted on the aircraft and is driven to rotate horizontally between the front wheel and the rear wheel. A sub-cutter unit provided with a sub-cutter that is pivotally supported on a side of the machine body or the main cutter unit and that can be driven to rotate in a plane inclined with respect to a rotation surface of the main cutter, the traveling unit, A plurality or a single prime mover for driving the cutter part and the sub-cutter part, and a power transmission mechanism part for transmitting power from one of the prime movers to a front wheel and a rear wheel of the traveling part at a constant axial speed ratio. The front wheel is a disc-shaped wheel provided with a spike on the outer periphery, and the moving speed with respect to the ground at the grounding point of the rear wheel is driven in a state where the rear wheel is not slipped. Always faster than the peripheral speed Thus, the axial speed ratio and the effective diameter of the front and rear wheels are set, and the front wheel side drive system absorbs the speed difference between the two only when the moving speed is faster than the peripheral speed, and the front wheel is not driven. A self-propelled double-sided mower characterized by providing speed difference absorbing means.

  According to such a feature, since the front wheel is a disc wheel with a spike, it sinks into the ground and becomes a resistance against a lateral load and serves as a guide for straight traveling. In addition, even when the amount of subsidence of the front wheels changes depending on the situation and the effective diameter to the grounding point changes, in the situation where the rear wheels do not slip, the speed difference absorbing means always works and the front wheels are not driven. Therefore, in a situation where there is no slip on the rear wheels including the traveling on the paved road surface, the driving of the rear wheels without applying stress to the traveling portion is performed. When the rear wheel slips during running on soft ground, the function of the speed difference absorbing means is released and the driving force is transmitted to the front wheel, so that reliable running performance can be obtained by front and rear wheel driving.

  According to the self-propelled two-sided mower having such a feature, the two-sided mowing operation can be performed smoothly and safely on a remote place or the like that changes to various ground conditions depending on the time and region. In addition, it is possible to travel without stressing the traveling part in all ground conditions including the paved road surface while preventing side slipping during work and ensuring reliable traveling workability on soft ground.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a self-propelled two-sided mower according to an embodiment of the present invention, FIG. 2 is a bottom view thereof, and FIG. 3 is a front view showing a use state.

  A self-propelled two-sided grass mower 1 according to an embodiment of the present invention includes a traveling unit 11 having a front wheel 11A and a rear wheel 11B, and includes a body 10 having a handle 12 for walking operation at the rear, and the body 10 is equipped. The main cutter unit 20 is provided with a main cutter 21 that is horizontally rotated between the front wheel 11A and the rear wheel 11B, and is pivotally supported to the side of the machine body 10 or the main cutter unit 20. And a sub-cutter unit 30 having a sub-cutter 31 that can be driven to rotate in an inclined plane, and a plurality or a single prime mover 40 (41, 42) for driving the traveling unit 11, the main cutter unit 20, and the sub-cutter unit 30. And a power transmission mechanism 13 that transmits power from one of the prime movers 40 to the front wheels 11A and the rear wheels 11B of the traveling unit 11 at a constant axial speed ratio.

  In the illustrated example, the prime mover 40 includes an electric motor 41 and an engine 42, one (for example, the electric motor 41) drives the traveling unit 11, and the other (for example, the engine 42) is the main cutter unit 20 and the sub cutter. The unit 30 is driven. In order to drive the main cutter unit 20 and the sub cutter unit 30 by the engine 42, the power transmission mechanism unit 14 is provided.

  The steering wheel 12 is provided with various operation units. When the traveling unit 11 is driven by the electric motor 41, a forward / reverse / stop switching switch and a speed adjustment lever are provided. When driving 20, 30, a clutch lever and a throttle adjusting lever are provided. The handle 12 is also provided with a lever for adjusting the tilt angle of the sub cutter unit 30.

  As shown in FIG. 3, such a self-propelled two-sided mower 1 can simultaneously perform mowing work on two surfaces of a flat land and an inclined land. For example, when performing mowing work in a remote area, the upper flat ground is cut by the main cutter unit 20, and the side inclined land is cut by the auxiliary cutter unit 30. The sub cutter unit 30 is pivotally supported on the main cutter unit 20 by a hinge 22, for example, and can be operated at a predetermined angle along an inclined ground by a ground ring 32. Of course, the sub cutter part 30 can be used not only for working on an inclined land but also for leveling the mowing work width on a flat ground in the same manner as the main cutter part 20.

FIG. 4 is a plan view (FIG. 4A) and a front view (FIG. 4B) of the front wheel 11A in the embodiment of the present invention. Wheel 11A is adapted spike s discoid wheel 11A ₀ provided on the outer periphery. The disc-shaped wheel 11A ₀ can be formed of a steel plate having a thickness of about several millimeters. In the illustrated example, a plurality of hollow holes p are formed for weight reduction, and the axle mounting portion a is formed at the center. Is formed.

Front wheels 11A are optionally comprises a wide support wheel 11A ₁ which expand the contact width and has a running resistance portion b on the inner diameter side of the irregularities of the spike s. Wide support wheel 11A ₁ may be formed by resin molding, are arranged as running resistance portion b which irregularities are formed on the outer peripheral portion is on the inner diameter side of the outer periphery of the disk-shaped wheel 11A _0, shown in this example, it is attached by bolts and nuts so as to sandwich the disc-shaped wheel 11A ₀ from both sides.

According to such a front wheel 11A, with discoid wheel 11A ₀ with spike s is the resistance to lateral load sinks into the ground vertically, the guide of straight running. Also, those having a wide support wheel 11A _1, will be broad wide support wheels 11A ₁ a sunken ground contact width of the disc-shaped wheel 11A ₀ to regulate the effective diameter (the recess of the wide support wheels 11A ₁ when sunk to the diameter of a circle connecting) would traction body by running resistance portion b of the wide support wheels 11A ₁ by driving the front wheels 11A occurs.

  In the self-propelled two-sided mower 1 according to the embodiment of the present invention, the moving speed of the rear wheel 11B with respect to the ground at the contact point of the rear wheel 11B is such that the rear wheel 11B does not slip. The axial speed ratio and effective diameter of the front and rear wheels are set so as to always be faster than the peripheral speed at the point, and the speed difference between the two is absorbed only in the drive system on the front wheel 11A side when the moving speed is faster than the peripheral speed. Thus, speed difference absorbing means for non-driving the front wheels 11A is provided.

  According to this, when there is no slip on the rear wheel 11B, such as when traveling on a paved road surface or hard ground, the speed difference absorbing means acts and the front wheel 11A becomes non-driven, and at the grounding point of the rear wheel 11B. The front wheel 11 </ b> A rotates at a moving speed at the same ground point as the moving speed with respect to the ground. At this time, the front wheel 11A rotates faster than the rotational speed of the drive shaft. However, since the rotational speed difference between the drive shaft and the front wheel 11A is absorbed by the speed difference absorbing means, stress is applied to the drive shaft of the front wheel 11A. There is no such thing. At this time, although the rear wheel drive is substantially performed, good running performance can be obtained without any problem under the situation where the rear wheel 11B does not slip.

  When the rear wheel 11B slips, the movement speed of the rear wheel 11B with respect to the ground at the ground contact point becomes slow. Accordingly, the movement speed of the front wheel 11A with respect to the ground at the ground contact point also slows down, and the front wheel 11A. When the actual rotational speed coincides with the rotational speed at the time of driving the front wheel 11A, the speed difference absorbing means stops operating and the front wheel 11A is driven. In this way, under the condition of the soft ground where the rear wheel 11B slides, front and rear wheel driving is realized, thereby covering the sliding of the rear wheel 11B with the traction force by driving the front wheel 11A and obtaining reliable traveling performance. be able to.

  By setting the slip rate of the rear wheel 11B to 90 to 95% and the moving speed of the rear wheel 11B with respect to the ground at the ground contact point coincide with the peripheral speed at the ground contact point of the front wheel 11A to be driven, Immediately after 11B starts to slide, front and rear wheel driving is realized, and mowing work can be performed simultaneously on two surfaces while ensuring good running performance even on soft ground.

Hereinafter, in case where the shaft speed n _A and the rear wheel shaft speed n _B and the constant velocity of the front wheels 11A and (n A _{= n B),} the rear wheel 11B on rubber tires with lugs, as a speed difference absorbing means, front wheel An example of setting the effective diameters of the front wheels 11A and the rear wheels 11B will be described by taking as an example a case in which a one-way clutch that allows free rotation of the 11A in the forward direction is provided in the hub portion of the front wheels 11A.

  FIG. 5 is an explanatory diagram for describing the front and rear wheel drive systems and the front and rear wheel effective diameters in the embodiment of the present invention. The front wheels 11A and the rear wheels 11B are driven by the electric motor 41 via the power transmission mechanisms 13A and 13B. That is, a wrapping type (chain or belt) power transmission mechanism 13A is wound around a pulley 50 attached to the output shaft 41A of the electric motor 41 and a pulley 53 attached to the axle 51 of the front wheel 11A. A similar power transmission mechanism 13B is wound around 50 and a pulley 54 attached to the axle 52 of the rear wheel 11B. A one-way clutch 55 is built in the hub portion of the front wheel 11A. The one-way clutch 55 allows the front wheels 11 </ b> A to rotate in the forward direction while the axle 51 is stopped.

Front wheels 11A, when traveling on a pavement, because there is no sinking of the front wheels 11A, the ground point becomes shown R1, the radius r _A1 from the center O _A of the front wheel 11A to the tip of the spike s the effective diameter. Also, when driving the soft ground of the ridge areas, etc., wide support since wheels 11A ₁ in sinking of the front wheels 11A is limited, becomes shown ground point R2, wide support wheels 11A ₁ from the center O _A of the front wheel 11A radius _{r A2} to recess the outer circumference of the (effective diameter of the wide support wheel 11A ₁₎ is considered effective diameter of the front wheel 11A.

Rear wheel 11B, when traveling on a pavement, because there is no sinking of the rear wheel 11B, grounding points becomes shown R3, the radius r _B1 from the center O _B of the rear wheel 11B until the lug tip becomes effective diameter . Further, when driving a normal ground, the radius r _B2 of the proximal end of the lug is ground point (shown R4), and the from the center O _B of the rear wheel 11B until the lug base is the effective diameter of the rear wheel 11B.

First, considering the case where the self-propelled double mower 1 travels on a paved road surface, it is considered that the rear wheel 11B does not slip, but the effective diameter of the front wheel 11A is the radius to the spike tip as described above. r _A1 , and the effective diameter of the rear wheel 11B is the radius r _B1 to the lug tip as described above, but r _B1 −r _A1 = t> 0 (that is, up to the lug tip of the rear wheel 11B) By setting the radius r _B1 to be larger than the radius r _A1 to the tip of the spike of the front wheel 11A), the moving speed (2πr _B1 · n _B ) with respect to the ground at the ground contact point of the rear wheel 11B can be reduced. The front wheel 11A, which is faster than the peripheral speed (2πr _A1 · n _A ) at the point, is pushed by the rear wheel 11B, rotates faster than the rotational speed of the axle 51 of the front wheel 11A. Worked Travel stress-free by the rear-wheel drive is carried out.

Also, considering the case where self-propelled dihedral mower 1 travels on the ground non-slip of the rear wheel 11B, the effective diameter of the front wheel 11A is enabled diameter r _A2 of the wide support wheels 11A _1, effective for the rear wheels 11B The diameter is the radius r _B2 to the base end of the lug, but by setting so that r _A2 <r _B2 , the traveling speed (2πr _B2 · n _B ) becomes faster than the peripheral speed (2πr _A2 · n _A ) at the ground contact point of the front wheel 11A to be driven, and the front wheel 11A pushed by the rear wheel 11B rotates faster than the rotational speed of the axle 51 of the front wheel 11A. As a result, the idle function of the one-way clutch 55 works, and the vehicle runs without stress due to the rear wheel drive.

For example, in order to set the slip ratio of the rear wheel 11B to be 95% and to drive the front and rear wheels, 2πr _B2 · n _B × 0.95 = 2πr _A2 · n _A is required, so that n _A = In n _B , r _B2 × 0.95 = r _A2 may be set. According to this, as soon as the rear wheel 11B starts to slide, the rotational speed of the axle 51 of the front wheel 11A catches up with the actual rotational speed of the front wheel 11A, and the driving force of the axle 51 is transmitted to the front wheel 11A to drive the front and rear wheels. Will be realized.

In the above-described embodiment, although the description of the case where the shaft speed _{n B} and the constant velocity of the shaft speed _{n A} and the rear wheels 11B of the front wheels 11A and _(n A = _{n B),} not limited to this, _{n A} ≠ in the case of n _B can perform setting similar to that described above by the following formula (1) to (3).

According to embodiments of the present invention, first, by a disk-shaped wheel 11A ₀ having a spike s on the outer periphery of the front wheels 11A, it is possible to perform a secure operation while suppressing the side slip of the aircraft tip can, by the straight guide function of the disk-shaped wheel 11A _0, it is possible to perform a stable straight working against soft ground.

By providing a wide support wheel 11A ₁ to the front wheels 11A, it is possible to a certain degree of particularity the effective diameter of the front wheel 11A in soft ground, it is possible to obtain sufficient traction force during a front-wheel drive. By combining with the rear wheel 11B of the rubber tire with lugs, the weight of the airframe can be stably supported, and stable running performance can be obtained.

  Since the rear wheels 11B are always driven directly, the front wheels 11A are not affected by the driving conditions of the front wheels, and even if the front wheels 11A are lifted when climbing or stepping over, the rear wheels 11B can travel on one wheel without any problems. On the other hand, the front wheel 11A is driven only when the ground driving force of the rear wheel 11B decreases and the function of the one-way clutch 55 is released, and does not depend on the load amount as in the torque limiter type. When the rear wheel 11B is lifted when climbing or over a step, the rear wheel 11B starts to idle and loses the driving force. At the same time, the driving force is transmitted to the front wheel 11A, which is equivalent to the directly connected state. Wheel drive is possible. As a result, even if there are grooves, steps, etc. on the runway, it is possible to pass self-propelled while sequentially floating one wheel. This can be carried out stably with only one wheel running of the rear wheel 11B.

When traveling on a paved road surface on which the rear wheels 11B do not slip, since (n _A / n _B ) · r _A1 <r _B1 is set, the free rotation function of the one-way clutch 55 works on the front wheels 11A. Thus, the rear wheel drive is performed, and the traveling unit 11 is not subjected to excessive stress, and stable traveling can be performed. Further, when the vehicle travels on the ground where the rear wheel 11B does not slip, (n _A / n _B ) · r _A2 <r _B2 is set, and in this case as well, the free function of the one-way clutch 55 is applied to the front wheel 11A. Will work, and it will be substantially rear-wheel drive, and the traveling part 11 will not be excessively stressed. Under such circumstances, sufficient driving performance can be ensured by the rear wheel drive, so that stable driving workability can be realized. In particular, since a rubber tire with a lug having a low contact pressure is used for the rear wheel 11B, high running performance can be obtained.

  Moreover, even if the amount of subsidence of the front wheel 11A increases and the effective diameter of the front wheel 11A changes under the above-described situation, the front wheel 11A is pushed by the rear wheel 11B and rotates faster than the front shaft 11A rotates. As a result, the idle function of the one-way clutch 55 works in the same manner, so that no extra stress is applied to the traveling unit 11.

  When the rear wheel 11B slips during running on soft ground and the rotational speed of the front wheel 11A decreases due to the pushing of the rear wheel 11B, the front wheel 11A and the driving speed of the axle 51 of the front wheel 11A coincide with each other. The driving force is transmitted to 11A, and traveling on soft ground can be reliably performed by front and rear wheel driving.

  As described above, according to the embodiment of the present invention, two-sided mowing can be performed smoothly and safely against remote areas that change to various ground conditions depending on the time and region without using an expensive torque limiter or differential mechanism. Work can be done. Further, it is possible to travel without stressing the traveling unit 11 in all ground conditions including the paved road surface while preventing side slipping during work and ensuring reliable traveling workability on soft ground.

1 is a plan view of a self-propelled two-sided mower according to an embodiment of the present invention. It is a bottom view of the self-propelled two-sided mower according to one embodiment of the present invention. It is the front view which showed the use condition of the self-propelled two-sided mower which concerns on one Embodiment of this invention. It is the top view (the figure (a)) and front view (the figure (b)) of the front wheel in the embodiment of the present invention. In embodiment of this invention, it is explanatory drawing for demonstrating the effective diameter of the drive system of a front-rear wheel and a front-rear wheel.

Explanation of symbols

1: Self-propelled double mower,
10: Airframe, 11: Traveling part, 11A: Front wheel, 11B: Rear wheel,
11A ₀ : disc-shaped wheel, 11A ₁ : wide support wheel,
12: Handle, 13, 13A, 13B, 14: Power transmission mechanism,
20: Main cutter part, 21: Main cutter,
30: Sub cutter part, 31: Sub cutter
40: prime mover (41: electric motor, 42: engine)
50, 53, 54: pulley,
51, 51: Axle,
55: One-way clutch

Claims (5)

A vehicle body (10) having a traveling part (11) having a front wheel (11A) and a rear wheel (11B) and having a handle (12) for walking operation at the rear, and the vehicle body (10) are equipped with the front wheel. (11A) and a main cutter part (20) provided with a main cutter (21) driven horizontally and rotated between the rear wheel (11B) and to the side of the machine body (10) or the main cutter part (20). A sub-cutter part (31) provided with a sub-cutter (31) that is pivotally supported and can be rotationally driven in a plane inclined with respect to the rotation surface of the main cutter (21), the traveling part (11), and the main cutter part (20) and a plurality or a single prime mover (40) for driving the auxiliary cutter part (30), and the front wheel (11A) and the rear wheel (11B) of the traveling part (11) from one of the prime movers (40). ) To transmit power at a constant shaft speed ratio A reach mechanism portion (13),
The front wheel (11A) consists of a disk-shaped wheel (11A ₀ ) provided with a spike (s) on the outer periphery,
In a state where the rear wheel (11B) is not slipped, the moving speed of the rear wheel (11B) with respect to the ground at the contact point is always higher than the peripheral speed at the contact point of the driven front wheel (11A). Set the axial speed ratio and effective diameter of the front and rear wheels,
A self-propelled two-wheeler characterized in that the front wheel side drive system is provided with speed difference absorbing means for absorbing the speed difference between the two only when the moving speed is faster than the peripheral speed and not driving the front wheel. Face mower.   The self-propelled two-sided mower according to claim 1, wherein the rear wheel (11B) has a slip rate of 90 to 95% and the moving speed and the peripheral speed coincide with each other.   3. The vehicle according to claim 1, wherein a one-way clutch (55) that allows the front wheel (11 </ b> A) to idle in the forward direction is provided in the hub portion of the front wheel as the speed difference absorbing means. A traveling double mower.   The self-propelled two-sided mower according to any one of claims 1 to 3, wherein the rear wheel (11B) is a rubber tire with a lug. When the axial speeds of the front wheel (11A) and the rear wheel (11B) are constant,
A radius (r _B1 ) to the lug tip of the rear wheel (11B) is set larger than a radius (r _A1 ) to the spike tip of the front wheel (11A);
The front wheel (11A) includes a wide support wheel (11A ₁ ) having an uneven running resistance portion on the inner diameter side of the spike and an increased ground contact width.
The self-propelled according to claim 4, wherein a radius (r _B2 ) to the lug base end of the rear wheel (11B) is set larger than an effective diameter (r _A2 ) of the wide support wheel (11A ₁ ). Formula double mower.

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