Walk-behind lawn mower

Abstract

To reduce such an event that mown grass mown with a second mowing blade slides down a slope of a ridge and enters a field in a sulky type mower including a first mowing blade and the second mowing blade.SOLUTION: A second housing 22 is supported by a right part or a left part of a first housing 21 so as to vertically change an attitude around a longitudinal axis P3. Rotation directions B1 and B2 of a first mowing blade 11 and a second mowing blade 12 are set such that the first mowing blade 11 and the second mowing blade 12 move rearward at a position of the longitudinal axis P3. At least one of a part adjacent to the second housing 22, on a rear face 25 of the first housing 21 and a part adjacent to the first housing 21, on a rear face 29b of the second housing 22 includes an opening part 78 provided so as to locate rearward the longitudinal axis P3 and capable of discharging mown grass rearward. Opening area change parts 30, 30c and 34 capable of changing an opening area of the opening part 78 are provided.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a walk-behind grass mower equipped with a first cutting blade and a second cutting blade. [Background technology]

[0002] One example of a walk-behind grass mower is disclosed in Patent Document 1. In Patent Document 1, a first housing that houses a first cutting blade and a second housing that houses a second cutting blade are provided, the second housing is supported on the left part of the first housing so that its position can be changed up and down around a front-to-rear axis along the front-to-rear direction, and front and rear wheels are provided to support the first housing.

[0003] This allows the first housing to run along the top surface of the ridge using the front and rear wheels, and the second housing to run along the slope (inclined surface) of the ridge, making it possible to mow the top surface and slope of the ridge. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-183678 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the walk-behind grass mower of Patent Document 1, grass cut by the first cutting blade is left on the upper surface of the ridge from the rear part of the first housing, and grass cut by the second cutting blade is left on the slope of the ridge from the rear part of the second housing.

[0006] In this case, since the slope of the ridge is an inclined surface, the grass clippings left on the slope of the ridge may slide down the slope and get into the field. When this happens, the worker needs to enter the field to remove the grass clippings, so there is room for improvement.

[0007] The present invention aims to reduce the occurrence of situations in which grass cut by the second blade slides down the slope of a ridge and enters a field in a walk-behind grass cutter equipped with a first cutting blade and a second cutting blade. [Means for solving the problem]

[0008] The walk-behind grass mower of the present invention comprises a first cutting blade that is driven to rotate about a first vertical axis along a vertical direction, a first housing that houses the first cutting blade, a second cutting blade that is driven to rotate about a second vertical axis along a vertical direction, a second housing that houses the second cutting blade, a front wheel provided in front of the first housing and supporting the first housing, and a rear wheel provided at the rear of the first housing and supporting the first housing, the second housing is supported on the right or left part of the first housing so that its position can be changed up and down about the front-to-rear axis along the front-to-rear direction, the rotation directions of the first cutting blade and the second cutting blade are set so that the first cutting blade and the second cutting blade move rearward at the position of the front-to-rear axis, and at least one of a portion of a rear surface of the first housing adjacent to the second housing and a portion of a rear surface of the second housing adjacent to the first housing is provided with an opening that is located rearward of the front-to-rear axis and allows grass clippings to be discharged rearward, While the second housing is maintained in a vertical position relative to the first housing, An opening area changer capable of changing the opening area of ​​the opening is provided.

[0009] According to the present invention, grass clippings cut by the first and second cutting blades come out mainly from the opening in the first housing (second housing) due to the forward movement of the walk-behind mower and the rotation of the first and second cutting blades, and little grass clippings come out from parts of the second housing other than the opening.

[0010] According to the present invention, as the grass clippings come out from the opening of the first housing (second housing), the grass clippings are formed into a single continuous streak-like (mountain-like) mass, and because the streak-like (mountain-like) grass clippings are in the form of a mass, they are less likely to slide down the slope of the ridge. Because the opening of the first housing (second housing) passes near the connection between the top surface of the ridge and the slope, the streaked (mountain-like) mass of grass clippings is formed near the top of the slope of the ridge. As a result, even if the streaked (mountain-like) mass of grass clippings slides down the slope of the ridge, it is likely to stop midway through the slope of the ridge and is unlikely to slide down into the field. As described above, it is possible to reduce the occurrence of grass clippings sliding down the slope of the ridge and entering the field, improving the workability of the grass cutting operation.

[0011] According to the present invention, the opening area of ​​the opening in the first housing (second housing) can be changed by the opening area change section, so that the opening area of ​​the opening in the first housing (second housing) can be increased or decreased depending on the amount of grass on the ridge and the condition of the grass (for example, whether it is wet after rain or dry, etc.). This makes it possible to appropriately form streaky (mountain-shaped) clumps of grass clippings by setting the opening area of ​​the opening in the first housing (second housing) in accordance with the amount of grass on the ridges and the condition of the grass.

[0012] In the present invention, it is preferable that the opening is arranged so as to be located on the side of the second housing relative to the rear wheel when viewed from behind, and the opening area change portion has a vertical side member having the vertical side portions opposite the rear wheel at the right and left vertical side portions of the opening, and a position change portion capable of changing the position of the vertical side members along the left-right direction.

[0013] According to the present invention, when the first housing is supported by the front and rear wheels, the opening of the first housing (second housing) is located on the second housing side relative to the rear wheels, so that the streaky (mountain-shaped) clumps of grass clippings coming out from the opening of the first housing (second housing) will not be crushed by the rear wheels.

[0014] According to the present invention, by changing the position of the vertical side member of the opening area changing portion in the left-right direction, the opening of the first housing (second housing) can be enlarged or reduced in the left-right direction. In this case, since the vertical side member of the opening area changing part is located on the opposite side to the rear wheel, when changing the position of the vertical side member of the opening area changing part, it is less restricted by the rear wheel, and the operability of the opening area changing part is good.

[0015] In the present invention, it is preferable that the vertical side member is removable and replaceable.

[0016] When grass clippings come out from the opening of the first housing (second housing) and form a streaky (mountain-shaped) mass of grass clippings, the grass clippings will concentrate at the opening of the first housing (second housing), which will cause wear to progress easily on the vertical side members of the opening area changing section. According to the present invention, in the opening area changing portion, the vertical side member can be removed and replaced with another vertical side member, thereby reducing problems caused by the progression of wear.

[0017] In the present invention, a fixed vertical side member is provided at the right and left vertical side portions of the opening, having the vertical side portion on the rear wheel side and attached to the first housing, and it is preferable that the fixed vertical side member is removable and replaceable.

[0018] As mentioned above, as grass clippings concentrate at the opening of the first housing (second housing), wear is also likely to progress to the fixed vertical side member on the opposite side of the vertical side member of the opening area changing portion at the opening of the first housing (second housing). According to the present invention, the fixed vertical side member can be removed and replaced with another fixed vertical side member, thereby reducing problems caused by the progression of wear.

[0019] In the present invention, it is preferable that an extension portion is provided on at least one of the right and left vertical sides of the opening, extending obliquely from the vertical side toward the rear and toward the left and right center of the opening.

[0020] According to the present invention, when grass clippings come out from the opening of the first housing (second housing) and a streaky (mountain-like) mass of grass clippings is formed, the side portions of the streaky (mountain-like) mass of grass clippings can be compressed by the extension portion, thereby forming a stable streaky (mountain-like) mass of grass clippings.

[0021] In the present invention, it is preferable that the vertical side portion is arranged at an angle in rear view so that the lower part of the vertical side portion is further outward from the left-right center of the opening than the upper part of the vertical side portion in rear view.

[0022] According to the present invention, when the side portions of the streaked (mountain-shaped) mass of grass clippings are compressed by the extension portion as described above, the side portions of the streaked (mountain-shaped) mass of grass clippings are more likely to be compressed into an inclined surface by the extension portion, and the streaked (mountain-shaped) mass of grass clippings is more likely to be formed into a trapezoidal cross-section, so that a stable streaked (mountain-shaped) mass of grass clippings can be formed.

[0023] In the present invention, it is preferable that a flexible pressing member be provided behind the opening and capable of compacting from above downward the grass clippings that come out rearward from the opening.

[0024] According to the present invention, when grass clippings come out from the opening of the first housing (second housing) and a streaky (mountain-shaped) mass of grass clippings is formed, the upper part of the streaky (mountain-shaped) mass of grass clippings can be compressed by the pressing member, thereby forming a stable streaky (mountain-shaped) mass of grass clippings.

[0025] In the present invention, it is preferable that a connection portion between a side surface portion of the first housing opposite the front-to-rear axis and a rear surface portion of the first housing is formed to follow the rotation locus of the outer periphery of the first cutting blade in a planar view, and a connection portion between a side surface portion of the second housing opposite the front-to-rear axis and a rear surface portion of the second housing is formed to follow the rotation locus of the outer periphery of the second cutting blade in a planar view.

[0026] According to the present invention, the rotation directions of the first and second cutting blades are set so that the first and second cutting blades move rearward at the connection portion (front-rear axis) between the first housing and the second housing.

[0027] When the first cutting blade moves from the connection portion (front-to-back axis) between the first housing and the second housing, along the rear surface of the first housing, and then along the side surface of the first housing on the opposite side of the front-to-back axis, grass clippings tend to become trapped at the connection portion between the side surface and rear surface of the first housing. Similarly, when the second cutting blade moves from the connection portion (front-to-back axis) between the first housing and the second housing, along the rear surface of the second housing, and then along the side surface of the second housing on the opposite side of the front-to-back axis, grass clippings tend to become trapped at the connection portion between the side surface and rear surface of the second housing.

[0028] According to the present invention, the connection portion between the side surface portion and the rear surface portion of the first housing is formed to follow the rotational trajectory of the outer periphery of the first cutting blade in a planar view, and the connection portion between the side surface portion and the rear surface portion of the second housing is formed to follow the rotational trajectory of the outer periphery of the second cutting blade in a planar view. This reduces the amount of grass clippings that accumulates at the connection between the side and rear sections of the first housing and at the connection between the side and rear sections of the second housing, making it easier for the grass clippings to be guided into the opening of the first housing (second housing) by the rotation of the first cutting blade and the second cutting blade, which is advantageous in terms of forming streaky (mountain-shaped) clumps of grass clippings. [Brief description of the drawings]

[0029] [Figure 1] FIG. [Diagram 2] FIG. 2 is a plan view of the walk-behind grass mower. [Diagram 3] 4 is a schematic diagram showing a transmission system to front and rear wheels, a first cutting blade, and a second cutting blade. FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 4 is a rear view of the first housing and the second housing. [Figure 7] FIG. 4 is a vertical sectional rear view of the first housing and the second housing. [Figure 8] FIG. 4 is a bottom view of the first housing and the second housing. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. 2 is an exploded perspective view of a first cutting blade and a second cutting blade. [Figure 12] FIG. 2 is an exploded perspective view of the vicinity of a second housing and an auxiliary wheel. [Figure 13] FIG. 4 is an exploded perspective view of the second housing. [Figure 14] FIG. 4 is a vertical sectional left side view of the second housing. [Figure 15] FIG. 11 is a longitudinal sectional rear view showing a configuration for setting the left and right inclined attitudes of the support base, the support member, and the auxiliary wheels. [Figure 16] 11 is a plan view showing a configuration for setting the left and right inclination attitudes of a support base, a support member, and auxiliary wheels. FIG. [Figure 17] FIG. 2 is a perspective view showing the state of mowing work on a ridge using a walk-behind mower. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] 1 to 17, a walk-behind grass cutter equipped with a first cutting blade 11 and a second cutting blade 12 is shown, where F indicates the forward direction, B indicates the rearward direction, U indicates the upward direction, D indicates the downward direction, R indicates the rightward direction, and L indicates the leftward direction.

[0031] (Overall configuration of the walk-behind lawnmower) As shown in Figures 1 and 2, the walk-behind grass cutter has a first housing 21 that houses a first cutting blade 11, a second housing 22 that houses a second cutting blade 12, a front wheel 1 and a rear wheel 2 attached to the first housing 21, an engine 3, a steering handle 4, an auxiliary wheel 33 attached to the second housing 22, and the like.

[0032] (Configuration of the first housing) As shown in Figures 2, 6, 7, 8 and 12, the first housing 21 has a top plate portion 23, a vertical surface portion 24 located on the right side of the first housing 21, a fixed vertical side member 25 which is the rear surface of the first housing 21, a cover 27, etc.

[0033] The vertical surface portion 24 is connected to the right part of the top plate portion 23 with bolts, and can be replaced with another vertical surface portion 24 by removing the bolts. The fixed vertical side member 25 is connected to the rear part of the top plate portion 23 with bolts, and can be replaced with another fixed vertical side member 25 by removing the bolts. The cover 27 is made of a flexible rubber plate, and is attached to the right and left parts of the front part of the top plate portion 23.

[0034] As shown in FIG. 8, the vertical surface portion 24 has a front portion 24a and a rear portion 24b, and is configured by bending the middle portion of the vertical surface portion 24 so that the orientation of the front portion 24a and the orientation of the rear portion 24b intersect.

[0035] A front portion 24a of the vertical surface portion 24 forms a horizontal surface portion on the opposite side of the axis P3 (see (Configuration of the Second Housing) described below) of the first housing 21, and a rear portion 24b of the vertical surface portion 24 forms a connection portion between the front portion 24a of the vertical surface portion 24 and a fixed vertical side member 25 which is the rear surface portion of the first housing 21. The rear portion 24b of the vertical surface portion 24 is formed so as to follow a rotation trajectory C1 of the outer periphery of the first cutting blade 11 in a plan view (see (State of the First and Second Cutting Blades) described below).

[0036] (Configuration of the second housing) As shown in FIGS. 2, 6, 7, 8, 12 and 13, the second housing 22 has a top plate portion 28, a vertical surface portion 29, a vertical side member 30 which is an opening area changing portion, a cover 31, a guard member 32, auxiliary wheels 33 and the like.

[0037] 6, 8, 12, and 13, the vertical surface portion 29 has a horizontal surface portion 29a located on the left side of the second housing 22, a rear surface portion 29b located on the rear side of the second housing 22, and an intermediate portion 29c. The vertical surface portion 29 is connected to the top plate portion 28 with bolts, and can be replaced with another vertical surface portion 29 by removing the bolts.

[0038] The vertical side member 30 is attached to the rear surface 29b of the vertical surface portion 29 by a bolt 34 which is an opening area changing portion and a position changing portion, and can be replaced with another vertical side member 30 by removing the bolt 34.

[0039] 2, the cover 31 is made of a flexible rubber plate, and is attached to the front of the top plate 28. The guard member 32 is made of a round bar material, and is attached to the front of the top plate 28.

[0040] As shown in Figures 2, 6, 7, and 8, the right portion of the top plate portion 28 is attached to the left portion of the top plate portion 23 so as to be able to swing up and down around axis P3, and the second housing 22 is supported on the left portion of the first housing 21 so as to be able to change its position up and down around axis P3, which is a front-to-rear axis along the front-to-rear direction.

[0041] A wire (not shown) is connected between the angle adjustment lever 13 (see (Configuration of the Steering Handle) described below and FIG. 2) provided on the steering handle 4 and the second housing 22. The angle adjustment lever 13 allows the second housing 22 to be set to a horizontal position parallel to the first housing 21, and a downward position facing diagonally downward from the first housing 21 (see FIGS. 6 and 7).

[0042] A plurality of downward postures with different angles can be set by the angle adjustment lever 13. In this case, in each of the plurality of downward postures, the second housing 22 is prevented from swinging downward from the set angle and is allowed to swing upward from the set angle.

[0043] As shown in Figures 8 and 13, in the vertical surface portion 29, the horizontal surface portion 29a of the vertical surface portion 29 becomes the horizontal surface portion on the opposite side of the axis P3 in the second housing 22, the rear surface portion 29b of the vertical surface portion 29 becomes the rear surface portion of the second housing 22, and the intermediate portion 29c of the vertical surface portion 29 becomes the connection portion between the horizontal surface portion 29a and the rear surface portion 29b of the vertical surface portion 29.

[0044] The intermediate portion 29c of the vertical surface portion 29 is formed in an arc shape when viewed in a plane, and the intermediate portion 29c of the vertical surface portion 29 is formed so as to follow the rotational trajectory C2 of the outer periphery of the second cutting blade 12 when viewed in a plane (see (State of the first cutting blade and the second cutting blade) described below).

[0045] (Engine, steering handle, and rear wheel support configuration) As shown in FIGS. 2, 6 and 8, in the first housing 21, the frame 5 is connected to the rear part of the top plate portion 23 along the left-right direction, and the engine 3 is supported by the frame 5.

[0046] The frame 6 is connected to the right part of the frame 5 in the up-down direction, and the angle-shaped frame 7 is connected to the left part of the frame 5 in the up-down direction. The handle base 8 is connected to the frame 7 in the up-down direction, and the steering handle 4 is attached to the handle base 8. The steering handle 4 is attached to the first housing 21 via the handle base 8 so as to extend rearward from the first housing 21.

[0047] 1 and 2, a rear wheel support case 9 is provided, and a rear wheel 2 is supported on a lower part of the rear wheel support case 9. An upper part of the rear wheel support case 9 is connected to a handle base 8, a front part of the rear wheel support case 9 is connected to an upper part of the frame 6 via a bracket 10, and a lower part of the rear wheel support case 9 is connected to a right part of the frame 5 and a lower part of the frame 6. As described above, the rear wheel 2 supporting the first housing 21 is attached to the first housing 21 so as to be provided behind the first housing 21.

[0048] (Control handle configuration) 1 and 2, the steering handle 4 has a right handle portion 81 and a left handle portion 82 made of round pipes. The right handle portion 81 has a right first portion 81a, a right second portion 81b, and a right grip portion 81c, and the left handle portion 82 has a left first portion 82a, a left second portion 82b, and a left grip portion 82c.

[0049] The right first portion 81a of the right handle portion 81 extends obliquely rearward and rightward from the handle base 8 (first housing 21) in a plan view, and extends obliquely rearward and upward in a side view. A hook portion 81f is connected to a rear surface of the right first portion 81a.

[0050] In a plan view, the right second portion 81b of the right handle portion 81 extends from the rear portion 81d of the right first portion 81a diagonally toward the rear right, slightly toward the center of the steering handle 4 from the extension direction of the right first portion 81a, and in a side view, extends approximately horizontally toward the rear from the rear portion 81d of the right first portion 81a.

[0051] The right grip portion 81c of the right handle portion 81 extends rearward in the fore-and-aft direction from the rear portion 81e of the right second portion 81b in a plan view, and extends rearward approximately horizontally from the rear portion 81e of the right second portion 81b in a side view.

[0052] The left first portion 82a of the left handle portion 82 extends diagonally left rearward from the handle base 8 (first housing 21) in a plan view, and extends diagonally upward rearward in a side view. The hook portion 82f is connected to the rear surface of the left first portion 82a.

[0053] In a plan view, the left second portion 82b of the left handle portion 82 extends from the rear portion 82d of the left first portion 82a diagonally toward the rear left, slightly toward the center of the steering handle 4 from the extension direction of the left first portion 82a, and in a side view, extends approximately horizontally toward the rear from the rear portion 82d of the left first portion 82a.

[0054] The left grip portion 82c of the left handle portion 82 extends rearward in the fore-and-aft direction from the rear portion 82e of the left second portion 82b in a plan view, and extends rearward approximately horizontally from the rear portion 82e of the left second portion 82b in a side view.

[0055] The right handle portion 81 is provided with the angle adjustment lever 13, the speed change lever 55, the mowing clutch lever 72, and an accelerator lever 83 for the engine 3. The left handle portion 82 is provided with the positioning lever 37, the traveling clutch lever 56, and a stop switch 84 for the engine 3.

[0056] (Steering wheel status) 1 and 2, an operator standing behind the walk-behind mower holds the right handle portion 81c of the right handle portion 81 and the left handle portion 82c of the left handle portion 82. In this case, the left-right distance W1 between the right handle portion 81c of the right handle portion 81 and the left handle portion 82c of the left handle portion 82 is determined approximately uniquely based on the general physique of the operator, etc.

[0057] As described above (Configuration of the steering handle), the left-right distance W2 between the rear 81d of the right first portion 81a of the right handle portion 81 and the rear 82d of the left first portion 82a of the left handle portion 82 is large and close to the distance W1.

[0058] As described below in (Operations Relating to Changing the Posture of the Support Members and Auxiliary Wheels), when setting the tilted posture of the support members 46 and the support base 45 (auxiliary wheels 33) or when changing the posture of the support members 46 up or down, an operator standing behind the walk behind mower can easily fit his or her body between the right handle portion 81 and the left handle portion 82 of the steering handle 4.

[0059] This allows the operator to easily perform operations to set the inclined posture of the support member 46 and the support base 45 (auxiliary wheel 33) and to change the posture of the support member 46 up and down by extending his or her hand forward.

[0060] When the walk-behind grass mower is mounted on the bed of a truck (not shown) for transportation, the walk-behind grass mower can be secured to the bed of the truck by hanging a rope between the hook portion of the bed of the truck and the hook portions 81f, 82f of the steering handle 4 (right handle portion 81 and left handle portion 82).

[0061] (Configuration for supporting the front wheels in the left and right direction) 4 and 5, in the first housing 21, a front wheel support member 14 is provided in front of the top plate portion 23. The front wheel support member 14 is formed by bending a plate material, and a right portion of a base plate portion 14a of the front wheel support member 14 is attached to the top plate portion 23 so that the direction can be changed left and right around an axis P4 along the up-down direction.

[0062] A long hole 14b extending in the front-rear direction is opened in the left part of the base plate portion 14a of the front wheel support member 14. A bolt 15 fixed facing upward to the top plate portion 23 is inserted into the long hole 14b of the front wheel support member 14, and a fixed handle 16 having a female thread is attached to the bolt 15.

[0063] Right and left support parts 14c are provided on a base part 14a of the front wheel support member 14, and a front wheel support case 17 is supported so as to be swingable up and down around an axis P5 along the left-right direction. As shown in Fig. 1 and Fig. 2, the front wheel support member 14 passes between a cover 27 (see the above-mentioned (Configuration of the first housing)) and extends forward, and the front wheel 1 is supported at the front part of the front wheel support case 17.

[0064] As shown in Figures 2 and 5, within the range of the long hole 14b of the front wheel support member 14, the posture of the front wheel support case 17 and the front wheel support member 14 can be changed from side to side between a straight-ahead posture A11 in which the front wheel 1 rotates along the fore-and-aft direction in a planar view, and an inclined posture A12 in which the front wheel 1 rotates along an imaginary direction extending diagonally forward on the opposite side of the second housing 22 from the fore-and-aft direction.

[0065] The worker can fix the position of the front wheel support member 14 by turning the fixing handle 16 and tightening the base plate portion 14a of the front wheel support member 14. The operator can change the posture of the front wheel support case 17 and the front wheel support member 14 left and right within the range of the long hole 14b of the front wheel support member 14 by turning the fixed handle 16 to loosen the tightening of the base portion 14a of the front wheel support member 14, and can set the inclined posture of the front wheel support case 17 and the front wheel support member 14 (front wheel 1) to any position between the straight-ahead posture A11 and the inclined posture A12.

[0066] (Configuration for supporting the front wheels in the vertical direction) As shown in Figures 4 and 5, the positioning member 18 is connected to the front wheel support case 17 and extends rearward, the positioning member 19 is connected to the rear of the positioning member 18, and three engagement holes 19a are opened in the positioning member 19 so as to be aligned in the vertical direction.

[0067] The cylindrical member 20 is connected to the front wheel support member 14. A positioning pin 35 is provided on the cylindrical member 20 so as to be slidable along the front-rear direction, and a spring 36 is provided for biasing the positioning pin 35 in the protruding direction. A wire 38 is connected between a positioning lever 37 (see the above-mentioned (Configuration of the steering handle) and FIG. 2) and the positioning pin 35.

[0068] While holding the steering handle 4, the operator operates the positioning lever 37 to remove the positioning pin 35 from the locking hole 19a of the positioning member 19, and moves the front part of the first housing 21 up and down with the rear wheel 2 as a fulcrum. Because the front wheel 1 is in contact with the ground due to the weight of the front wheel 1 and the front wheel support case 17, the attitude of the front wheel support case 17 relative to the first housing 21 is changed up and down.

[0069] When the front of the first housing 21 reaches the desired height, the operator can operate the positioning lever 37 and insert the positioning pin 35 into one of the locking holes 19a of the positioning member 19, thereby setting the posture of the front wheel support case 17 relative to the first housing 21 in three positions up or down, and setting the cutting height of the first cutting blade 11 to the desired height. As described above, the front wheel 1 supporting the first housing 21 is attached to the first housing 21 so as to be provided in front of the first housing 21.

[0070] (Configuration regarding auxiliary wheels) As shown in Figures 2, 12, and 14, in the second housing 22, a support base 45, which is a position-changing part formed by bending a plate material into a channel shape, is provided, and the support base 45 is attached to the top plate portion 28 so that its position can be changed left and right around axis P6, which is an up-down axis along the up-down direction.

[0071] A round pipe-shaped support member 46 is provided, and is attached to a support base 45 so that its position can be changed up and down around an axis P7 along the left-right direction. The support member 46 is attached to the second housing 22 via the support base 45 so as to protrude forward from the second housing 22, and the auxiliary wheel 33 is attached to a front end of the support member 46 so as to be located in front of the second housing 22.

[0072] A lock lever 47 is attached to the rear of the support member 46 so as to be able to swing up and down around an axis P8 along the left-right direction, and the up-down position of the support member 46 can be fixed by engaging a pin 47a of the lock lever 47 with one of a plurality of engaging portions 45a of the support base 45. A spring 48 is connected between the lock lever 47 and the support member 46, and the spring 48 biases the lock lever 47 in the direction in which the pin 47a of the lock lever 47 engages with the engaging portion 45a of the support base 45.

[0073] 2, 12, 15, and 16, the base member 49 is fixed to a portion of the top plate 28 adjacent to the right of the rear part of the support base 45, and a nut 49a is fixed to the upper part of the base member 49. A flat fixing member 50, which is a position changing part and a fixing part, is connected to the right part of the rear part of the support base 45 and extends rightward from the support base 45 so as to be located above the base member 49.

[0074] A long hole 50a is opened in the fixed member 50, and a right end portion 50b of the fixed member 50 is bent downward. A fixed handle 51, which is a position changing part and a fixed part, is provided, and a male screw part is provided at the lower part of the fixed handle 51.

[0075] (Operations for changing the position of the support members and auxiliary wheels) As shown in Figures 2, 12, 15, and 16, the support base 45 can be changed in position left and right around the axis P6 within the range of positions where the rear of the support base 45 abuts the left portion of the base member 49 and where the end 50b of the fixing member 50 abuts the right portion of the base member 49.

[0076] As a result, as shown in FIG. 2, in a plan view, the posture of the support member 46 and the support base 45 can be changed from side to side across a straight-ahead posture A21 (where the rear part of the support base 45 abuts on the left part of the base member 49) in which the auxiliary wheel 33 rotates along the fore-aft direction, and an inclined posture A22 (where the end part 50b of the fixed member 50 abuts on the right part of the base member 49) in which the auxiliary wheel 33 rotates along an imaginary direction extending diagonally forward toward the first housing 21 side relative to the fore-aft direction.

[0077] As shown in Figures 2, 12, 15, and 16, the male threaded portion of the fixed handle 51 can be attached to the nut 49a of the base member 49 through the long hole 50a of the fixing member 50, and the support base 45 can be fixed to the second housing 22 by turning the fixed handle 51 to tighten the fixing member 50.

[0078] The operator can release the fixation of the support base 45 by turning the fixed handle 51 to loosen the fastening of the fixing member 50, and change the posture of the support member 46 and the support base 45 to the left or right. By turning the fixed handle 51 to fasten the fixing member 50, the inclined posture of the support member 46 and the support base 45 (auxiliary wheels 33) can be set to any position between the straight posture A21 and the inclined posture A22.

[0079] The operator can change the position of the support member 46 up or down by gripping the rear part of the support member 46 and the lock lever 47 and pulling the pin 47a of the lock lever 47 out of the engagement portion 45a of the support base 45. By engaging the pin 47a of the lock lever 47 with the desired engagement portion 45a of the support base 45, the cutting height of the second cutting blade 12 can be set to the desired height.

[0080] (Front and rear wheel transmission structure) 1, 2 and 3, the transmission 53 is provided on the upper part of the rear wheel support case 9. A transmission belt 54 is attached between the pulley 3b of the output shaft 3a of the engine 3 and the pulley 53b of the input shaft 53a of the transmission 53.

[0081] The transmission 53 is equipped with a traveling clutch (not shown) and is configured to be able to shift between three forward gears and one reverse gear. A wire (not shown) is connected between the gear shift lever 55 (see the above-mentioned (Configuration of the steering handle) and Figures 1 and 2) and the transmission 53, and the transmission 53 can be operated between three forward gears and one reverse gear by using the gear shift lever 55.

[0082] In the transmission 53, the traveling clutch is biased to a disengaged state, and a wire (not shown) is connected between the traveling clutch lever 56 (see the above-mentioned (Configuration of the steering handle) and FIG. 2) and the traveling clutch. When the operator grips the traveling clutch lever 56 and pulls the wire toward the traveling clutch lever 56, the traveling clutch is operated to a transmission state, and when the operator releases the traveling clutch lever 56, the traveling clutch is operated to a disengaged state.

[0083] A transmission chain 58 is attached inside the rear wheel support case 9 between a sprocket 53d of the output shaft 53c of the transmission 53 and a sprocket 57a of an axle 57 supporting the rear wheel 2. A transmission shaft 59 is provided in the vertical middle part of the rear wheel support case 9, and a sprocket 59a of the transmission shaft 59 meshes with the transmission chain 58.

[0084] As shown in FIGS. 1 to 5, a transmission shaft 63 is supported on the right front portion of the first housing 21, and a transmission chain 64 is attached between a sprocket 59b of the transmission shaft 59 and a sprocket 63a of the transmission shaft 63.

[0085] An input shaft 65 of the front wheel support case 17 is disposed at the position of the axis P5, and the input shaft 65 and the transmission shaft 63 are connected via a universal joint 66. Inside the front wheel support case 17, a transmission chain 68 is attached between a sprocket 65a of the input shaft 65 and a sprocket 67a of an axle 67 that supports the front wheel 1.

[0086] With the above configuration, as shown in Fig. 3, the power of the engine 3 is transmitted to the transmission 53 via the transmission belt 54. The power changed in speed by the transmission 53 is transmitted to the rear wheel 2 via the transmission chain 58, and is then transmitted to the front wheel 1 via the transmission chain 58, the transmission shaft 59, the transmission chain 64, the transmission shaft 63, the input shaft 65, and the transmission chain 68. When the running clutch of the transmission 53 is disengaged, the front wheel 1 and the rear wheel 2 are stopped.

[0087] In this case, the universal joint 66 is positioned so as to be located on an extension line of the axis P4, so that, as described above (Configuration regarding support of the front wheels in the left-right direction), even if the position of the front wheel support case 17 and the front wheel support member 14 is changed left and right around the axis P4, power is transmitted smoothly from the transmission shaft 63 to the input shaft 65.

[0088] (Configuration of the first cutting blade and the second cutting blade) As shown in FIGS. 9, 10 and 11, the first cutting blade 11 and the second cutting blade 12 each have a base 60 having an elongated diamond shape in a plan view, two first cutting blade portions 61, and two second cutting blade portions 62.

[0089] A large opening 60e is formed in the center of the base 60, and openings 60f are formed on both sides of the opening 60e. The base 60 is provided with a first extension 60a extending in one direction from the opening 60e, and a second extension 60b extending in the opposite direction from the opening 60e.

[0090] In this case, the length of the base 60 of the second cutting blade 12 (the length extending between the end of the first extension portion 60a and the end of the second extension portion 60b) is configured to be longer than the length of the base 60 of the first cutting blade 11 (the length extending between the end of the first extension portion 60a and the end of the second extension portion 60b).

[0091] In the base 60, one edge of the first extending portion 60a and the opposite edge of the second extending portion 60b are formed into an inclined surface 60c, and the other edge of the first extending portion 60a and the opposite edge of the second extending portion 60b are formed into an inclined surface 60d. In Fig. 10, the inclined surface 60c of the base 60 faces obliquely downward, and the inclined surface 60d of the base 60 faces obliquely upward.

[0092] In the first cutting blade 11 and the second cutting blade 12, the four first cutting blade portions 61 and the four second cutting blade portions 62 are all configured to the same shape, and blade portions 61a, 61b, 62a, 62b are formed on both one and the other edges of the first cutting blade 11 and the second cutting blade 12.

[0093] In the first cutting blade 11, the first cutting blade portion 61 is attached to both the upper and lower sides of the first extending portion 60a of the base 60 by the support pins 52 so as to be freely swingable around an axis P11, which is a first axis along the up-down direction. As a result, the first cutting blade portion 61 is provided on the first extending portion 60a of the base 60 so as to extend outward from the first extending portion 60a of the base 60.

[0094] In the second cutting blade 12, the second cutting blade portion 62 is attached to both the upper and lower sides of the second extending portion 60b of the base 60 by the support pin 52 so as to be freely swingable around the axis P12, which is a second axis along the up-down direction. As a result, the second cutting blade portion 62 is provided on the second extending portion 60b of the base 60 so as to extend outward from the second extending portion 60b of the base 60.

[0095] (Configuration related to support of first cutting blade and second cutting blade) 2, 6, 7 and 8, in the first housing 21, the blade case 26 is connected to the top plate 23. The drive shaft 41 is supported by the blade case 26 so as to be rotatable about an axis P1 that is a first vertical axis along the vertical direction, and a bracket 41a is connected to a lower part of the drive shaft 41 by a nut 39.

[0096] In the second housing 22, the blade case 43 is connected to the top plate portion 28. The drive shaft 42 is supported by the blade case 43 so as to be rotatable around an axis P2 that is a second vertical axis along the vertical direction, and a bracket 42a is connected to a lower portion of the drive shaft 42 by a nut 39.

[0097] 7 and 8, a cylindrical cover 44 with a bottom is provided. In the first housing 21, while the bottom of the cover 44 is sandwiched between the base 60 of the first cutting blade 11 and the bracket 41a of the drive shaft 41, the nut 39 is inserted into the opening 60e (see FIG. 11) of the base 60 of the first cutting blade 11, and the bolt 40 is connected across the opening 60f (see FIG. 11) of the base 60 of the first cutting blade 11 and the bracket 41a of the drive shaft 41, whereby the first cutting blade 11 and the cover 44 are attached to the lower part of the drive shaft 41.

[0098] In the second housing 22, the bottom of the cover 44 is sandwiched between the base 60 of the second cutting blade 12 and the bracket 42a of the drive shaft 42, while the nut 39 is inserted into the opening 60e (see Figure 11) of the base 60 of the second cutting blade 12, and the bolt 40 is connected through the opening 60f (see Figure 11) of the base 60 of the second cutting blade 12 and the bracket 42a of the drive shaft 42, thereby attaching the second cutting blade 12 and the cover 44 to the lower part of the drive shaft 42.

[0099] With the above-mentioned configuration, in the first cutting blade 11 and the second cutting blade 12, the base 60 is attached to the lower part of the drive shafts 41, 42, and the base 60 has a first extension part 60a extending in one direction from the lower part of the drive shafts 41, 42, and a second extension part 60b extending in the opposite direction from the lower part of the drive shafts 41, 42.

[0100] For the first cutting blade 11 and the second cutting blade 12, the bolt 40 can be removed, the base 60 can be removed from the brackets 41a, 42a of the drive shafts 41, 42, the first cutting blade 11 and the second cutting blade 12 can be turned upside down, and the base 60 can be reattached to the brackets 41a, 42a of the drive shafts 41, 42 using the bolt 40, and the first cutting blade 11 and the second cutting blade 12 can be attached to the lower part of the drive shafts 41, 42.

[0101] As described later (Transmission structure to the first and second cutting blades) and shown in Figures 8, 9 and 10, the first cutting blade 11 is rotationally driven in a rotational direction B1, and the second cutting blade 12 is rotationally driven in a rotational direction B2. The rotational direction B1 is counterclockwise when the first housing 21 is seen in a plan view, and the rotational direction B2 is clockwise when the second housing 22 is seen in a plan view.

[0102] With the above configuration, the first cutting blade 11 is rotatably supported about axis P1, which is a first vertical axis along the vertical direction, and is housed in the first housing 21. The second cutting blade 12 is rotatably supported about axis P2, which is a second vertical axis along the vertical direction, and is housed in the second housing 22.

[0103] (State of the first and second cutting blades) As shown in Figures 9 and 10, the length of the base 60 of the second cutting blade 12 is longer than the length of the base 60 of the first cutting blade 11 (see the previous section (Configuration of the first cutting blade and the second cutting blade)), and therefore the diameter D2 of the rotational locus C2 of the second cutting blade 12 is larger than the diameter D1 of the rotational locus C1 of the first cutting blade 11.

[0104] Below the connection portion (axis center P3) between first housing 21 and second housing 22, rotation locus C1 of first cutting blade 11 and rotation locus C2 of second cutting blade 12 partially overlap in a plan view.

[0105] Since the four first cutting blade portions 61 and the four second cutting blade portions 62 are all configured to have the same shape (see the above-mentioned (Configuration of the first cutting blade and the second cutting blade)), in the first cutting blade 11 and the second cutting blade 12, the length L11 extending from the axis P11 to the outer end of the first cutting blade portion 61 and the length L12 extending from the axis P12 to the outer end of the second cutting blade portion 62 are the same length.

[0106] In the first cutting blade 11, the length L21 spanning between the axis P1 and axis P11 of the drive shaft 41 and the length L22 spanning between the axis P1 and axis P12 of the drive shaft 41 are the same length, and L11, L12 are set to be longer than lengths L21, L22.

[0107] In the second cutting blade 12, the length L31 extending between the axis P2 and the axis P11 of the drive shaft 42 and the length L32 extending between the axis P2 and the axis P12 of the drive shaft 42 are the same length, and L31, L32 are set to be longer than the lengths L11, L12.

[0108] 8 to 11, the first cutting blade 11 and the second cutting blade 12 are rotationally driven in the rotation directions B1 and B2, so that cutting edges 61a, 61b, 62a, and 62b are formed on both the upstream and downstream edges in the rotation directions B1 and B2 of the first cutting blade portion 61 and the second cutting blade portion 62. Both the upstream and downstream edges in the rotation directions B1 and B2 of the first extending portion 60a and the second extending portion 60b of the base 60 are formed into inclined surfaces 60c and 60d.

[0109] The upstream edge of the first extension portion 60a of the base 60 in the rotational directions B1, B2 and the upstream edge of the second extension portion 60b of the base 60 in the rotational directions B1, B2 are formed into an inclined surface 60c that is diagonally downward with respect to the rotational directions B1, B2.

[0110] The edge portion on the downstream side in the rotational directions B1, B2 of the first extension portion 60a of the base 60 and the edge portion on the downstream side in the rotational directions B1, B2 of the second extension portion 60b of the base 60 are formed into an inclined surface 60d that is diagonally upward with respect to the rotational directions B1, B2.

[0111] As described above (Configuration for supporting the first and second cutting blades), when the first cutting blade 11 and the second cutting blade 12 are attached upside down to the bottom of the drive shafts 41, 42, the upstream edge and the downstream edge of the first extension portion 60a of the base 60 in the rotation directions B1, B2 are interchanged, and the upstream edge and the downstream edge of the second extension portion 60b of the base 60 in the rotation directions B1, B2 are interchanged.

[0112] As a result, the upstream edges of the first extending portion 60a and the second extending portion 60b of the base 60 in the rotational directions B1 and B2 become diagonally downward inclined surfaces 60d, and the downstream edges of the first extending portion 60a and the second extending portion 60b of the base 60 in the rotational directions B1 and B2 become diagonally upward inclined surfaces 60c.

[0113] (Transmission structure for first cutting blade and second cutting blade) 1, 2, 3 and 7, in the first housing 21, the transmission shaft 69 is supported by the blade case 26, and a transmission belt 70 is attached between the pulley 3c of the output shaft 3a of the engine 3 and the pulley 69a of the transmission shaft 69. Inside the blade case 26, the bevel gear 41b of the drive shaft 41 and the bevel gear 69b of the transmission shaft 69 are engaged with each other.

[0114] A tension pulley type mowing clutch 71 is provided for the transmission belt 70. A wire (not shown) is connected between a mowing clutch lever 72 (see the above-mentioned (Configuration of the steering handle) and Figures 1 and 2) and the mowing clutch 71, and the mowing clutch lever 72 can be used to operate the mowing clutch 71 between a transmission state and a disconnection state.

[0115] In the second housing 22, a transmission shaft 73 is supported by the blade case 43, and the transmission shaft 69 and the transmission shaft 73 are connected via two universal joints 74 and an extendable transmission shaft 75. Inside the blade case 43, the bevel gear 42b of the drive shaft 42 and the bevel gear 73a of the transmission shaft 73 are engaged with each other.

[0116] As shown in Figures 1, 2 and 3, a metal cover 76 is attached to the first housing 21, and the cover 76 covers the output shaft 3a and pulleys 3b, 3c of the engine 3, the transmission belt 54, the input shaft 53a and pulley 53b of the transmission 53, the transmission shaft 59 (sprocket 59b), the transmission chain 64, the transmission shaft 63 (sprocket 63a), the transmission shaft 69 (pulley 69a), the transmission belt 70, the mowing clutch 71, etc.

[0117] As shown in Figures 2, 6, and 7, an expandable and flexible cylindrical cover 77 is attached across the blade case 26 and the blade case 43, and the universal joint 74 and the transmission shaft 75 are housed inside the cover 77.

[0118] With the above-described configuration, as shown in FIG. 3, the power of the engine 3 is transmitted to the drive shaft 41 via the transmission belt 70 and the transmission shaft 69, and is then transmitted to the drive shaft 42 via the transmission shaft 69, the universal joint 74, the transmission shaft 75, and the transmission shaft 73.

[0119] 8, 9 and 10, the drive shaft 41 and the first cutting blade 11 are rotationally driven in a rotational direction B1, and the drive shaft 42 and the second cutting blade 12 are rotationally driven in a rotational direction B2, and the rotational trajectories C1, C2 and the rotational directions B1, B2 are set so that the first cutting blade 11 and the second cutting blade 12 move rearward at the position of the axis P3. The first cutting blade 11 and the second cutting blade 12 stop when the cutting clutch 71 is operated to the disengaged state.

[0120] In this case, as described above (Configuration of the second housing), even if the position of the second housing 22 is changed up or down, power is transmitted smoothly from the transmission shaft 69 to the transmission shaft 73 by bending the universal joint 74 and expanding and contracting the transmission shaft 75.

[0121] (Configuration of the opening for discharging grass clippings cut by the first and second cutting blades) As shown in FIGS. 6, 8 and 12, in the first housing 21, the left end of the fixed vertical side member 25 is located closer to the left-right center of the first housing 21 than the left end of the top plate portion 23 (closer to the drive shaft 41).

[0122] As a result, an opening 78 capable of discharging grass clippings rearward is formed in a portion of the fixed vertical side member 25 of the first housing 21 adjacent to the second housing 22, so as to be located rearward of the axis P3 (the connection portion between the first housing 21 and the second housing 22). The opening 78 is provided so as to be located on the left side, which is the side of the second housing 22 with respect to the rear wheel 2, in a rear view and a plan view (see FIG. 2).

[0123] In a plan view, the left rear portion of the top plate portion 23 of the first housing 21 and the fixed vertical side member 25 are located forward of the vertical side member 30 of the second housing 22. In a rear view, the left rear portion of the top plate portion 23 of the first housing 21 and the fixed vertical side member 25, and the vertical side member 30 of the second housing 22 form the outer periphery of the opening 78.

[0124] The vertical side portion 25a of the fixed vertical side member 25 becomes the right vertical side portion on the rear wheel 2 side of the right and left vertical side portions of the opening 78. The vertical side portion 25a of the fixed vertical side member 25 is disposed at an incline in rear view so that the lower portion of the vertical side portion 25a of the fixed vertical side member 25 is laterally outwardly spaced from the left-right center of the opening 78 (so as to be located on the rear wheel 2 side) relative to the upper portion of the vertical side portion 25a of the fixed vertical side member 25 in rear view.

[0125] The extension portion 25b of the fixed vertical side member 25 extends diagonally from the vertical side portion 25a of the fixed vertical side member 25 toward the rear and the left-right center of the opening 78, and the extension portion 25b of the fixed vertical side member 25 is an extension portion provided on the right vertical side portion of the opening 78.

[0126] The vertical side portion 30a of the vertical side member 30 is the left vertical side portion opposite the rear wheel 2 at the right and left vertical side portions of the opening 78. The vertical side portion 30a of the vertical side member 30 is disposed at an angle in rear view so that the lower portion of the vertical side portion 30a of the vertical side member 30 is laterally outwardly spaced from the left-right center of the opening 78 (so as to be located on the opposite side of the rear wheel 2) than the upper portion of the vertical side portion 30a of the vertical side member 30 in rear view.

[0127] The extension portion 30b of the vertical side member 30 extends diagonally from the vertical side portion 30a of the vertical side member 30 toward the rear and the left-right center of the opening 78, and the extension portion 30b of the vertical side member 30 is an extension portion provided on the right vertical side portion of the opening 78.

[0128] As described above in (Configuration of the second housing) and shown in Fig. 6, when the second housing 22 is set in a downward position facing diagonally downward from the first housing 21, the vertical side portion 30a and the extending portion 30b of the vertical side member 30 are close to an upright position. When the second housing 22 is set in a horizontal position parallel to the first housing 21, the vertical side portion 30a and the extending portion 30b of the vertical side member 30 are in an inclined position as described above.

[0129] 2 and 6, a bracket 79 is connected to the lower part of the frame 7 so as to face rearward. A pressing member 80 made of a flexible rubber plate is attached to the bracket 79 and extends diagonally rearward and downward. The pressing member 80 is disposed behind the opening 78.

[0130] (Configuration for changing the opening area of ​​the opening through which grass clippings cut by the first cutting blade and the second cutting blade are discharged) 6, 8, 12, and 13, the long hole 30c, which is an opening area changing portion and a position changing portion, is opened along the left-right direction in the vertical side member 30. The bolt 34 is inserted into the long hole 30c of the vertical side member 30 and fastened to the rear surface portion 29b of the vertical surface portion 29, whereby the vertical side member 30 is fixed to the rear surface portion 29b of the vertical surface portion 29.

[0131] By loosening the bolt 34, the vertical side member 30 can be moved left and right relative to the rear surface portion 29b of the vertical surface portion 29. When the vertical side member 30 is moved leftward and away from the fixed vertical side member 25, the opening area of ​​the opening 78 becomes larger, and when the vertical side member 30 is moved rightward and closer to the fixed vertical side member 25, the opening area of ​​the opening 78 becomes smaller.

[0132] (Status of weeding work on the ridges) When mowing a ridge with a walk-behind mower, as shown in Figures 6, 7 and 17, the first housing 21 is moved along the upper surface E1 of the ridge by the front wheels 1 and the rear wheels 2, and the second housing 22 is moved along the sloped surface E2 of the ridge by the auxiliary wheels 33, thereby mowing the upper surface E1 and sloped surface E2 of the ridge.

[0133] As described above (configuration related to vertical support of the front wheels) and shown in Fig. 4, the vertical position of the front wheel support case 17 relative to the first housing 21 is set to set the cutting height of the first cutting blade 11. As described above (operation related to changing the position of the support member and auxiliary wheel) and shown in Fig. 14, the cutting height of the second cutting blade 12 is set by changing the position of the support member 46 up and down.

[0134] The front wheels 1 and rear wheels 2 are rotated and the first housing 21 receives a forward driving force from the front wheels 1 and rear wheels 2, whereas the auxiliary wheels 33 are not rotated and therefore the second housing 22 does not receive a forward driving force from the front wheels 1 and rear wheels 2. As a result, when second housing 22 encounters resistance from grass on slope portion E2 of the ridge as the walk-behind mower moves forward, second housing 22 may try to move downward toward the bottom of slope portion E2 of the ridge, with rear wheel 2 as a fulcrum (see arrow F1).

[0135] When the above-mentioned situation occurs, as described above (operations related to changing the attitude of the support member and auxiliary wheels) and as shown in FIG. 2, the left and right attitudes of the support member 46 and the support base 45 are set to the inclined attitude A22 or any inclined attitude between the straight-ahead attitude A21 and the inclined attitude A22.

[0136] As the walk-behind mower moves forward, the auxiliary wheels 33 rotate while in contact with the slope E2 of the ridge, attempting to climb diagonally upwards up the slope E2 of the ridge (see arrow F2), which generates a force (see arrow F3) that attempts to lift the second housing 22 upward to the upper side of the slope E2 of the ridge.

[0137] This prevents the second housing 22 from descending toward the bottom of the slope portion E2 of the ridge, with the rear wheel 2 as a fulcrum, due to the moment caused by the length (moment arm) of the support member 46 extending forward from the first housing 21 and the aforementioned force (arrow F3).

[0138] If simply setting the left and right attitudes of the support member 46 and the support base 45 to the inclined attitude A22 is not enough to prevent the second housing 22 from descending toward the lower side of the slope portion E2 of the ridge, with the rear wheel 2 as a fulcrum, then, as described above (configuration regarding support of the front wheels in the left and right direction) and as shown in Figure 2, the left and right attitudes of the front wheel support case 17 and the front wheel support member 14 are set to the inclined attitude A12 or any inclined attitude between the straight-ahead attitude A11 and the inclined attitude A12.

[0139] This generates a force (see arrow F4) that tries to move the first housing 21 to the opposite side of the slope portion E2 of the ridge by the front wheel 1, and the second housing 22 tries to be pulled up to the upper surface portion E1 of the ridge via the first housing 21, thereby assisting the function of the auxiliary wheel 33 described above.

[0140] (Mowing state by the first and second blades) As described above (state of mowing grass on ridge) and as shown in Figures 6, 7 and 8, when the first housing 21 travels over the upper surface E1 of the ridge, the first cutting blade 11 is driven to rotate in the rotational direction B1, causing grass to be cut by the first cutting blade 11 near the front of the first housing 21, and the cut grass moves rearward about the position of the axis P3 as the first cutting blade 11 rotates, and mainly exits rearward through the opening 78.

[0141] The grass clippings may move from the fixed vertical side member 25 along the rear portion 24b and front portion 24a of the vertical surface portion 24 together with the first cutting blade 11, without coming out rearward from the opening 78. In this case, as described above (Configuration of the first housing) and shown in Fig. 8, the rear portion 24b of the vertical surface portion 24 is formed so as to follow the rotation trajectory C1 of the outer periphery of the first cutting blade 11 in a plan view, so that the grass clippings rarely stay near the rear portion 24b of the vertical surface portion 24.

[0142] 6, 7 and 8, when the second housing 22 travels along the slope E2 of the ridge, the second cutting blade 12 is rotationally driven in the rotation direction B2, causing grass to be cut by the second cutting blade 12 near the front of the second housing 22, and the cut grass moves rearward along the axis P3 as the second cutting blade 12 rotates, and mainly comes out rearward through the opening 78. Little grass comes out rearward between the rear surface 29b of the second housing 22 (vertical surface 29) and the slope E2 of the ridge, or between the vertical side member 30 and the slope E2 of the ridge.

[0143] The grass clippings may move together with the second cutting blade 12 from the rear surface 29b of the vertical surface portion 29 along the middle portion 29c and the horizontal surface portion 29a of the vertical surface portion 29, without coming out rearward from the opening 78. In this case, as described above (Configuration of the second housing) and shown in Fig. 8, the middle portion 29c of the vertical surface portion 29 is formed in an arc shape so as to follow the rotation trajectory C2 of the outer periphery of the second cutting blade 12 in a plan view, so that the grass clippings rarely stay near the middle portion 29c of the vertical surface portion 29.

[0144] When the first cutting blade 11 and the second cutting blade 12 are rotationally driven, the upstream edges of the first extension portion 60a and the second extension portion 60b of the base 60 splash away pebbles and the like from the upper surface portion E1 and the slope portion E2 of the ridge.

[0145] As shown in Figures 8 and 11, in the first cutting blade 11 and the second cutting blade 12, the upstream edges of the first extension portion 60a and the second extension portion 60b of the base 60 are formed into an inclined surface 60c that is diagonally downward with respect to the rotational directions B1, B2. Therefore, pebbles, etc. are not bounced in a direction along the rotational directions B1, B2 of the base 60, but are bounced diagonally downward with respect to the rotational directions B1, B2 of the base 60 and hit the upper surface portion E1 and slope portion E2 of the ridge.

[0146] This reduces the possibility that pebbles or the like will fly out from the first housing 21 and the second housing 22. Even if pebbles or the like fly out from the first housing 21 and the second housing 22, the force with which the pebbles or the like fly out is significantly reduced.

[0147] As described above (Configuration for supporting the first and second cutting blades), even if the first cutting blade 11 and the second cutting blade 12 are attached upside down to the bottom of the drive shafts 41, 42, the upstream edge and the downstream edge in the rotation directions B1, B2 of the first extension portion 60a of the base 60 will be interchanged, and the upstream edge and the downstream edge in the rotation directions B1, B2 of the second extension portion 60b of the base 60 will be interchanged.

[0148] As a result, the edges on the upstream side in the rotation directions B1, B2 of the first extending portion 60a and the second extending portion 60b of the base portion 60 become the inclined surface 60d facing diagonally downward, so that the same situation as described above is obtained.

[0149] (Discharge state of grass cut by the first cutting blade and the second cutting blade from the opening) 2 and 17, as the grass clippings come out rearward from the opening 78, the grass clippings are formed into a single continuous streak-like (mountain-like) mass. The streak-like (mountain-like) mass of grass clippings is formed near the connection between the top surface E1 of the ridge and the slope E2, and near the top of the slope E2 of the ridge (see state G1).

[0150] As described above (configuration relating to the opening for discharging grass clippings cut by the first and second cutting blades) and as shown in Figures 2 and 6, the vertical side portion 25a of the fixed vertical side member 25 is arranged at an incline when viewed from behind, and the vertical side portion 30a of the vertical side member 30 is arranged at an incline when viewed from behind, which makes it easy for streaky (mountain-like) clumps of grass clippings to be formed into a trapezoidal cross-section.

[0151] Because the extension portion 25b of the fixed vertical side member 25 extends diagonally from the vertical side portion 25a of the fixed vertical side member 25 toward the rear and toward the left-right center of the opening 78, and because the extension portion 30b of the vertical side member 30 extends diagonally from the vertical side portion 30a of the vertical side member 30 toward the rear and toward the left-right center of the opening 78, the lateral portions of the streaky (mountain-like) mass of grass clippings are compressed by the extension portion 25b of the fixed vertical side member 25 and the extension portion 30b of the vertical side member 30.

[0152] The pressing member 80 is disposed behind the opening 78 and extends diagonally rearward and downward, so that the upper portion of the streaky (mountain-shaped) clump of grass clippings is compacted by the pressing member 80.

[0153] The opening area of ​​the opening 78 can be increased or decreased by changing the position of the vertical side member 30 to the left or right depending on the amount of grass on the ridge and the condition of the grass (for example, whether it is wet after rain or dry, etc.). Since the opening 78 is located on the second housing 22 side with respect to the rear wheel 2 , the streaky (mountain-like) mass of grass clippings emerging from the opening 78 will not be crushed by the rear wheel 2 .

[0154] This makes it difficult for the streaked (mountain-shaped) clumps of grass clippings to slide down the slope E2 of the ridge. Even if the streaked (mountain-shaped) clumps of grass clippings do slide down the slope E2 of the ridge, they tend to stop midway up the slope E2 of the ridge and are unlikely to slide down into the field.

[0155] (First Alternative Embodiment of the Invention) 6 and 8, an opening 78 is provided in a portion of the rear surface (fixed vertical side member 25) of the first housing 21 adjacent to the second housing 22. As shown in FIG. In Figures 6 and 8, if the position of the vertical side member 30 is set a little further to the left, openings 78 will be provided in both the portion of the rear surface of the first housing 21 (fixed vertical side member 25) adjacent to the second housing 22 and the portion of the rear surface of the second housing 22 (rear surface portion 29b of the vertical surface portion 29) adjacent to the first housing 21.

[0156] (Second Alternative Embodiment of the Invention) In Figures 6 and 8, if the position of the vertical side member 30 is set a little further to the left and the fixed vertical side member 25 is moved to the position of the axis P3, an opening 78 is provided in the portion of the rear surface portion 29b of the vertical surface portion 29 of the second housing 22 adjacent to the first housing 21.

[0157] (Third Alternative Embodiment of the Invention) The vertical side portion 25a of the fixed vertical side member 25 may be formed in an upright state perpendicular to the top plate portion 23 of the first housing 21 in rear view. The vertical side portion 30a of the vertical side member 30 may be formed in an upright state perpendicular to the top plate portion 28 of the second housing 22 in rear view.

[0158] (Fourth Alternative Embodiment of the Invention) In the configurations shown in Figs. 6 and 8 and in the third alternative embodiment of the invention, the extending portion 25b of the fixed vertical side member 25 may be eliminated. In the configurations shown in Figs. 6 and 8 and in the third alternative embodiment of the invention, the extending portion 30b of the vertical side member 30 may be eliminated.

[0159] (Fifth Alternative Embodiment of the Invention) The second housing 22 may be provided to the right of the first housing 21 . [Industrial Applicability]

[0160] The present invention is applicable to a walk-behind grass cutter equipped with a first cutting blade and a second cutting blade. [Explanation of symbols]

[0161] 1 Front wheel 2 Rear wheels 11 1st cutting blade 12 Second cutting blade 21 1st Housing 22 Second Housing 24a Front part (side part) 24b Rear (connection part) 25 Fixed vertical side member (rear part) 25a Vertical side 25b Extension 29a Side part 29b Rear part 29c Middle section (connection part) 30 Vertical side member (opening area change part) 30a Vertical side 30b Extension 30c Long hole (position change part) (opening area change part) 34 Bolt (position change part) (opening area change part) 78 Opening 80 Holding member B1 Rotation direction B2 Rotation direction C1 Rotation trajectory C2 Rotation trajectory P1 axis (first vertical axis) P2 axis (second vertical axis) P3 axis (front and back axis)

Claims

1. a first cutting blade that is rotatably driven about a first vertical axis along a vertical direction; and a first housing that accommodates the first cutting blade; a second cutting blade that is rotatably driven about a second vertical axis along a vertical direction, and a second housing that accommodates the second cutting blade; a front wheel provided in front of the first housing and supporting the first housing; a rear wheel provided behind the first housing and supporting the first housing; the second housing is supported on the right or left part of the first housing so as to be vertically changeable about a front-rear axis along a front-rear direction, a rotation direction of the first cutting blade and the second cutting blade is set so that the first cutting blade and the second cutting blade move rearward at the position of the front-rear axis; an opening is provided in at least one of a portion of the rear surface portion of the first housing adjacent to the second housing and a portion of the rear surface portion of the second housing adjacent to the first housing, the opening being located rearward of the front-rear axis and allowing grass clippings to be discharged rearward; The walk-behind grass mower is provided with an opening area changer that can change the opening area of ​​the opening while the vertical orientation of the second housing relative to the first housing is maintained.

2. the opening is provided to be located on a side of the second housing with respect to the rear wheel in a rear view, The opening area changing unit is A vertical side member having right and left vertical side portions of the opening on the opposite side of the rear wheel; 2. The walk-behind grass mower according to claim 1, further comprising a position changing portion that changes the position of the vertical side member in the left-right direction.

3. 3. The walk-behind grass mower according to claim 2, wherein the vertical side member is removable and replaceable.

4. a fixed vertical side member having the vertical side portion on the rear wheel side at right and left vertical side portions of the opening and attached to the first housing; 4. The walk-behind grass mower according to claim 1, wherein the fixed vertical side member is removable and replaceable.

5. A walk-behind grass mower as claimed in any one of claims 1 to 4, further comprising an extension portion provided on at least one of the right and left vertical sides of the opening, the extension portion extending obliquely from the vertical side toward the rear and toward the left-right center of the opening.

6. The walk-behind grass mower according to claim 5, wherein the vertical side portion is inclined when viewed from behind so that the lower portion of the vertical side portion is further outward from the left-right center of the opening than the upper portion of the vertical side portion when viewed from behind.

7. The walk-behind grass mower according to any one of claims 1 to 6, further comprising a flexible pressing member disposed behind the opening and capable of compacting the cut grass coming out rearward from the opening from above downward.

8. a connection portion between a lateral surface portion of the first housing on an opposite side to the front-rear axis and a rear surface portion of the first housing is formed to follow a rotation trajectory of an outer periphery of the first cutting blade in a plan view, A walk-behind grass mower according to any one of claims 1 to 7, wherein a connection portion between a lateral surface portion on the opposite side of the front-to-rear axis in the second housing and a rear surface portion of the second housing is formed so as to follow a rotation trajectory of an outer periphery of the second cutting blade in a plan view.

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