U.S. patent application number 09/789488 was filed with the patent office on 2002-04-04 for lawn mower.
This patent application is currently assigned to KUBOTA CORPORATION. Invention is credited to Esaki, Yoshiyuki, Minoura, Akira, Samejima, Kazuo, Togoshi, Yoshikazu, Umemoto, Hideya, Yamada, Masahiro.
Application Number | 20020038537 09/789488 |
Document ID | / |
Family ID | 26601210 |
Filed Date | 2002-04-04 |
United States Patent
Application |
20020038537 |
Kind Code |
A1 |
Umemoto, Hideya ; et
al. |
April 4, 2002 |
LAWN MOWER
Abstract
A lawn mower with a vehicle body; an engine mounted on the
vehicle body; caster-type front wheels; a rear wheel unit having a
left rear drive wheel and a right rear drive wheel; a mower unit
disposed between the front wheels and rear wheel unit; a left
stepless transmission for transmitting drive, switched between
forward drive and backward drive, to the left rear wheel; and a
right stepless transmission for transmitting drive, switched
between forward drive and backward drive, to the right rear wheel;
wherein the right and left stepless transmissions are operable
independently of each other. A caster-type auxiliary ground wheel
unit (9) is disposed rearwardly of the rear wheel unit and
supported by a support member (24) to be vertically movable
relative to the vehicle body, A braking mechanism (30) is provided
for braking an upward movement of the support member.
Inventors: |
Umemoto, Hideya; (Osaka,
JP) ; Togoshi, Yoshikazu; (Osaka, JP) ;
Yamada, Masahiro; (Osaka, JP) ; Esaki, Yoshiyuki;
(Osaka, JP) ; Minoura, Akira; (Osaka, JP) ;
Samejima, Kazuo; (Osaka, JP) |
Correspondence
Address: |
Russell D. Orkin
WEBB ZIESENHEIM LOGSDON ORKIN & HANSON, P.C.
700 Koppers Building
436 Seventh Avenue
Pittsburgh
PA
15219-1818
US
|
Assignee: |
KUBOTA CORPORATION
Osaka
JP
|
Family ID: |
26601210 |
Appl. No.: |
09/789488 |
Filed: |
February 20, 2001 |
Current U.S.
Class: |
56/13.3 |
Current CPC
Class: |
A01D 2101/00 20130101;
A01D 34/6806 20130101; A01D 43/0635 20130101; A01D 43/077
20130101 |
Class at
Publication: |
56/13.3 |
International
Class: |
A01D 087/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2000 |
JP |
2000-300128 |
Sep 29, 2000 |
JP |
2000-300132 |
Claims
What is claimed is:
1. A lawn mower comprising: a vehicle body; an engine mounted on
said vehicle body; caster-type front wheels; a rear wheel unit
having a left rear drive wheel and a right rear drive wheel; a left
stepless transmission for transmitting drive, switched between
forward drive and backward drive, to said left rear wheel; a right
stepless transmission for transmitting drive, switched between
forward drive and backward drive, to said right rear wheel; said
right and left stepless transmissions being operable independently
of each other; a mower unit disposed between said front wheels and
said rear wheel unit; a caster-type auxiliary ground wheel unit
disposed rearwardly of said rear wheel unit; a support member for
supporting said auxiliary ground wheel unit to be vertically
movable relative to said vehicle body; and a braking mechanism for
braking an upward movement of said support member.
2. A lawn mower as defined in claim 1, wherein said braking
mechanism is constructed as a biasing mechanism for biasing said
auxiliary ground wheel unit downward.
3. A lawn mower as defined in claim 2, wherein said biasing
mechanism comprises a suspension spring for biasing said auxiliary
ground wheel unit downward.
4. A lawn mower as defined in claim 1, wherein said auxiliary
ground wheel unit comprises a single ground wheel.
5. A lawn mower as defined in claim 1, wherein said auxiliary
ground wheel unit comprises a plurality of ground wheels arranged
transversely of the vehicle body.
6. A lawn mower as defined in claim 1, wherein said support member
includes a proximal arm portion extending longitudinally of said
vehicle body and laterally outwardly of said engine and having a
front end thereof connected to a body frame to be pivotable about
an axis extending transversely of the vehicle body, and a distal
arm portion extending transversely of the vehicle body from a rear
end of said proximal arm portion, with an extended end having said
auxiliary ground wheel unit attached thereto.
7. A lawn mower as defined in claim 6, wherein said proximal arm
portion is disposed laterally of the vehicle body opposite from a
side where a blower is disposed for transmitting grass clippings
into a grass catcher.
8. A lawn mower as defined in claim 6, wherein said proximal arm
portion is disposed laterally of the vehicle body opposite from a
side where a grass outlet of said mower unit is disposed.
9. A lawn mower as defined in claim 1, wherein said support member
comprises a U-shaped arm having said auxiliary ground wheel unit
attached to an arm portion remote from an open end of the U-shaped
arm.
10. A lawn mower as defined in claim 1, wherein said auxiliary
ground wheel unit is disposed such that said auxiliary ground wheel
unit describes a turning track within a maximum turning track of
the lawn mower when said right and left rear wheels are driven at
an equal speed in opposite directions to steer the vehicle
body.
11. A lawn mower as defined in claim 10, wherein said auxiliary
ground wheel unit is disposed such that said auxiliary ground wheel
unit describes a turning track not exceeding a turning radius of
said right and left rear wheels when said right and left rear
wheels are driven at an equal speed in opposite directions to steer
the vehicle body.
12. A lawn mower as defined in claim 10, wherein said auxiliary
ground wheel unit is disposed such that said auxiliary ground wheel
unit describes a turning track not exceeding a turning radius of
said front wheels when said right and left rear wheels are driven
at an equal speed in opposite directions to steer the vehicle body.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a lawn mower with a vehicle body;
an engine mounted on the vehicle body; caster-type front wheels; a
rear wheel unit having a left rear drive wheel and a right rear
drive wheel; a mower unit disposed between the front wheels and
rear wheel unit; a left stepless transmission for transmitting
drive, switched between forward drive and backward drive, to the
left rear wheel; and a right stepless transmission for transmitting
drive, switched between forward drive and backward drive, to the
right rear wheel; wherein the right and left stepless transmissions
are operable independently of each other.
[0003] 2. Description of the Related Art
[0004] A lawn mower of this type has an advantage that the vehicle
body turns with a small radius about a middle position between the
right and left rear wheels when the rear wheels are driven to
rotate at the same speed in opposite directions. However, as the
center of gravity of the vehicle body is located relatively
rearwardly, a lawn mower has been developed which has an auxiliary
ground wheel fixed to the rear of the vehicle body for contacting
the ground rearwardly of the rear wheels. This construction
prevents lifting of the front of the vehicle body to avoid poor
grass cutting results.
[0005] Such an auxiliary ground wheel fixed to the vehicle body
could adversely affect the running performance of the lawn mower,
depending on the position or support structure of the auxiliary
ground wheel. For example, the auxiliary ground wheel impairs the
turning performance of the vehicle and tends to produce body
vibration during a run.
SUMMARY OF THE INVENTION
[0006] The object of this invention is to provide a lawn mower with
an auxiliary ground wheel mounted in a manner not adversely
affecting its running performance.
[0007] In order to achieve the above object, with a lawn mower set
forth at the outset hereof, this invention provides a caster-type
auxiliary ground wheel unit disposed rearwardly of the rear wheel
unit and supported by a support member to be vertically movable
relative to the vehicle body, and a braking mechanism for braking
an upward movement of the support member.
[0008] With a rigidly fixed auxiliary ground wheel not vertically
movable relative to the vehicle body, a strong reaction force acts
on the auxiliary ground wheel when the vehicle goes up a sloping
terrain. This reaction force from the ground constitutes a
resistance to vehicle movement. In the worst case, the vehicle is
unable to advance to the sloping terrain. According to this
invention, the auxiliary ground wheel is movable up and down
through the support member so that an upward movement of the
auxiliary ground wheel prevents excessive reaction forces from
generating when the vehicle travels on a sloping terrain. With a
structure for allowing free vertical movements of the auxiliary
ground wheel, the auxiliary ground wheel does not support the rear
portion of the vehicle body for stable running, as a matter of
course. The braking mechanism acts to produce a predetermined
supporting force.
[0009] Preferably, this braking mechanism is provided in the form
of a biasing mechanism, and more preferably in the form of a
suspension spring, to bias the auxiliary ground wheel downward.
When the vehicle travels on an uneven terrain, the auxiliary ground
wheel is raised relative to the vehicle body by a reaction force
from the ground, and at the same time lowered relative to the
vehicle body by the suspension spring. Thus, the auxiliary ground
wheel keeps contact with the ground while the vehicle travels over
an uneven terrain. When the vehicle advances to an uphill terrain,
the auxiliary ground wheel is raised relative to the vehicle body
by a reaction force from the ground. As a result, the vehicle body
is kept in contact with the ground by the auxiliary ground wheel,
while preventing the generation of body vibration and changes in
the body orientation caused by ups and downs of the auxiliary
ground wheel. When the mower travels over an uneven terrain, and
the auxiliary ground wheel is prevented from acting as a traveling
resistance which would not allow the vehicle to advance to an
uphill ground.
[0010] In a preferred embodiment of the invention, the auxiliary
ground wheel unit includes a plurality of auxiliary ground wheels
arranged transversely of the vehicle body. The plurality of
auxiliary ground wheels arranged in the right and left direction
increase the width of contact with the ground. This contributes to
stable traveling of the vehicle by contacting the ground in a
plurality of locations, and by preventing the auxiliary ground
wheel unit from falling into hollows of the ground. As a result,
with the auxiliary ground wheel unit having a stable contact with
the ground, the orientation of the vehicle body is stabilized to
improve grass cutting quality.
[0011] In another preferred embodiment of the invention, the
support member includes a proximal arm portion extending
longitudinally of the vehicle body and laterally outwardly of the
engine and having a front end thereof connected to a body frame to
be pivotable about an axis extending transversely of the vehicle
body, and a distal arm portion extending transversely of the
vehicle body from a rear end of the proximal arm portion, with an
extended end having the auxiliary ground wheel unit attached
thereto. With this construction, even when the mower draws too
close to a tree or the like, the proximal arm portion extending
laterally of the engine protects the engine from directly striking
the tree or the like. In other words, the support member acts as a
protector for the engine.
[0012] The proximal arm portion of the support member may be
disposed laterally of the vehicle body opposite from a side where a
blower is disposed for transmitting grass clippings into a grass
catcher. Then, the proximal arm portion of the support member is
allowed to move up and down through an increased range without
interfering with the blower.
[0013] When the lawn mower engages in an operation, turning around
a tree or the like, the side having a grass outlet of the mower
unit lies outwardly of the turning circle. Where the proximal arm
portion of the support member is disposed laterally of the vehicle
body opposite from the side where the grass outlet of the mower
unit is disposed, the support member lies inwardly of the turning
circle. Thus, the support member acts as a protector to keep the
engine out of direct contact with the tree or the like when the
mower draws too close to the tree or the like.
[0014] In yet another preferred embodiment of the invention, the
auxiliary ground wheel unit is disposed such that the auxiliary
ground wheel unit describes a turning track within a maximum
turning track of the lawn mower when the right and left rear wheels
are driven at an equal speed in opposite directions to steer the
vehicle body. If the auxiliary ground wheel described a maximum
turning track of the mower when the vehicle body is steered by
driving the right and left rear wheels at the same speed in
opposite directions, the auxiliary ground wheel would be liable to
strike an obstacle such as a tree or a wall as an operator operates
and turns the mower around the obstacle while looking ahead.
However, the aforesaid structure eliminates the possibility that
the carelessness of the operator causes the auxiliary ground wheel
to strike an obstacle. The operator has only to pay attention to
the most forwardly projecting part of the mower.
[0015] Furthermore, from the viewpoint of the operator' skill in
driving the lawn mower, it will be convenient if the auxiliary
ground wheel unit is disposed such that the auxiliary ground wheel
unit describes a turning track not exceeding a turning radius of
the right and left rear wheels when the right and left rear wheels
are driven at an equal speed in opposite directions to steer the
vehicle body. With this structure in which the auxiliary ground
wheel unit turns with a radius not exceeding that of the right and
left rear wheels, the auxiliary ground wheel will have no
possibility of colliding with an obstacle as long as the operator
turns the lawn mower near the obstacle with care so that the rear
wheels move clear of the obstacle.
[0016] It will also be convenient if the auxiliary ground wheel
unit is disposed such that the auxiliary ground wheel unit
describes a turning track not exceeding a turning radius of the
front wheels when the right and left rear wheels are driven at an
equal speed in opposite directions to steer the vehicle body. With
this structure in which the auxiliary ground wheel unit turns with
a radius not exceeding that of the right and left front wheels, the
auxiliary ground wheel will have no possibility of colliding with
an obstacle as long as the operator turns the lawn mower near the
obstacle with care so that the front wheels move clear of the
obstacle.
[0017] Other features and advantages of this invention will be
apparent from the following description of the embodiment to be
taken with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a side elevation of a lawn mower in one embodiment
of this invention;
[0019] FIG. 2 is a plan view of the lawn mower;
[0020] FIG. 3 is a plan view showing a body frame;
[0021] FIG. 4 is a rear view of the lawn mower;
[0022] FIG. 5 is a sectional view of a suspension spring;
[0023] FIG. 6 is a side view showing an auxiliary ground wheel in a
raised position;
[0024] FIG. 7 is a side view of a grass catcher support
structure;
[0025] FIG. 8 is a side view showing the grass catcher in a raised
position;
[0026] FIGS. 9A and 9B are front views showing a mounting structure
of a front axle member, and a jack mechanism;
[0027] FIG. 10 is a plan view showing a support member of the
auxiliary ground wheel in another embodiment;
[0028] FIG. 11 is a plan view showing a support member of the
auxiliary ground wheel in yet another embodiment;
[0029] FIG. 12 is a schematic plan view of a lawn mower in another
embodiment;
[0030] FIG. 13 is a schematic plan view of a lawn mower in a
further embodiment; and
[0031] FIG. 14 is a schematic plan view of a lawn mower in a still
further embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0032] As shown in FIGS. 1 through 4, a lawn mower has a pair of
freely rotatable caster-type right and left front wheels 1 and a
pair of right and left rear drive wheels 2 supporting a body frame
3. An engine 4 is mounted on a rear portion of the body frame 3 so
that the engine 4 is positioned rearwardly of the axis of rear
wheels 2. A motor section including an engine hood 5 covering the
engine 4 is mounted on the rear portion of the body. A driving
platform is disposed forwardly of the motor section. The driving
platform includes a driver's seat 6 placed slightly forwardly of
and above a position between the right and left rear wheels 2
forming a rear wheel unit, a driving platform frame 7 covering a
driver accommodating space, and a sun shade 8 supported by the
platform frame 7. A caster-type auxiliary ground wheel 9 is
disposed rearwardly of the vehicle body, to act as an auxiliary
wheel unit for contacting the ground in a location rearwardly of
the rear wheels 2.
[0033] A mower unit 11 is suspended between the front and rear
wheels from a pair of pivot links 10 vertically pivotably supported
by the body frame 3. The torque from the engine 4 is transmitted
through a rotary shaft 12 to an input case 11b disposed on a top
panel of a mower deck ha to drive rotary cutting blades arranged in
the mower deck 11a transversely of the vehicle body.
[0034] A grass catcher 13 is carried above the motor section, and a
grass receiving part 13a disposed laterally of the grass catcher 13
as shown in FIG. 4 is connected through a transport duct 15 to a
grass outlet 11c disposed at a lateral end of the mower deck 11a of
mower unit 11. The transport duct 15 has a blower 14 disposed in an
intermediate position thereof and laterally outward from the engine
4.
[0035] This mower is intended mainly for use in a grass cutting
operation. The mower travels with the mower unit 11 lowered to a
working level at which gauge wheels lid attached outside the mower
deck 11a contact the ground. Lawn or grass is cut by the rotary
blades rotating in the mower unit 11, and grass clippings are
discharged into the transport duct 15 by carrier air currents
generated by the rotation of the blades. As the blower 14 is driven
by torque transmitted from an output unit at the rear of engine 4
through a belt transmission mechanism 16, the grass clippings are
transported from the mower unit 11 into a portion of transport duct
15 between the mower unit 11 and the blower 14 and to the sucking
end of the blower 14. Further, the grass clippings are transported
into the grass catcher 13 through a duct portion 15a extending
vertically between the blower 14 and the grass catcher 13.
[0036] As shown in FIG. 3 and so on, torque from a front output
part of the engine 4 is transmitted to an input of a transmission
17 mounted to bridge a pair of right and left rearward portions 3a
of the body frame 3. Torque from an output of the transmission 17
is transmitted to hydraulic pumps of hydrostatic stepless
propelling transmissions 18 attached to opposite sides of the
transmission 17, respectively. Torque output of a hydraulic motor
of the left one of the two stepless propelling transmissions 18 is
transmitted to the left rear wheel 2 through a left reduction case
19. Torque output of a hydraulic motor of the right stepless
propelling transmission 18 is transmitted to the right rear wheel 2
through a right reduction case 19. A pair of right and left control
levers 20 are arranged at opposite sides of the driver's seat 6 on
the driving platform. These control levers 20 are operatively
connected to control portions of the stepless propelling
transmission 18 for the left rear wheel and the stepless propelling
transmission 18 for the right rear wheel, respectively. The lawn
mower is driven and steered by rocking these control levers 20 in
longitudinal directions of the vehicle body and independently of
each other.
[0037] Specifically, by rocking the left control lever 20
longitudinally of the vehicle body, the stepless transmission 18
for the left rear wheel is shifted to a forward drive position, a
neutral position and a backward drive position to drive the left
rear wheel forward, backward and to stop the left rear wheel. By
rocking the right control lever 20 longitudinally of the vehicle
body, the stepless transmission 18 for the right rear wheel is
shifted to a forward drive position, a neutral position and a
backward drive position to drive the right rear wheel forward and
backward and to stop the right rear wheel. Each of the right and
left control levers 20 is rockable the further forward from the
neutral position to shift the stepless transmission 18 to the
faster forward drive position. Each lever 20 is rockable the
further rearward from the neutral position to shift the stepless
transmission 18 to the faster backward drive position.
[0038] That is, the right and left control levers 20 are operable
to control the stepless transmissions 18, respectively, to drive
the right and left rear wheels 2 forward or backward or to stop the
rear wheels 2. Thus, the vehicle may be driven forward or backward
at varied speeds. Furthermore, by changing the driving speed and
driving direction of the right and left rear wheels 2, the vehicle
may be controlled to run straight or to turn right and left.
[0039] As shown in FIG. 1, 3 and so on, the right and left front
wheels 1 are rotatably supported by caster-type front wheel support
members 21. The front wheel support members 21 have a front axle
member 22 extending therebetween transversely of the vehicle body.
Each front wheel support member 21 is supported by a front end
portion of the body frame 3 through the front axle member 22 to be
pivotable about a steering axis 21a. As a result, the right and
left front wheels 1 pivot about the steering axes 21a, together
with the front wheel support members 21, when the self-propelled
vehicle is steered.
[0040] As shown in FIG. 3, 4 and so on, the auxiliary ground wheel
9 is rotatably supported by a gate-shaped wheel support member 23.
The wheel support member 23 is connected to be pivotable about a
steering axis 23a to one end of an auxiliary ground wheel support
arm 24 acting as an auxiliary ground wheel support member. The
other end of the auxiliary ground wheel support arm 24 is pivotally
attached to one of the rear portions 3a of the body frame 3. In
this embodiment, the auxiliary ground wheel support arm 24 extends
longitudinally of the vehicle body and outside along the side of
the vehicle body opposite from the side where the grass outlet 11c
of mower unit 11 and the blower 14 of transport duct 15 are
located. The auxiliary ground wheel support arm 24 includes a
proximal arm portion 24b and a distal arm portion 24c. The proximal
arm portion 24b has a proximal end thereof connected to an outward
surface of the rear frame portion 3a to be pivotable about a
transverse axis 24a. The distal arm portion 24c extends from the
rear end of the proximal arm portion 24b transversely of the
vehicle body toward the engine 4 and to a position rearwardly of
the engine 4, with an extended portion thereof supporting the
auxiliary ground wheel 9 through the wheel support member 23.
[0041] As a result, with a vertical pivotal movement of the
auxiliary ground wheel support arm 24, the auxiliary ground wheel 9
is pivotable vertically relative to the vehicle body to be movable
upward by a departure angle:or more of the self-propelled vehicle
as shown in FIG. 6. When the vehicle is steered, the auxiliary
ground wheel 9 is pivotable with the wheel support member 23 about
the steering axis 23a to change directions.
[0042] As shown in FIGS. 1, 3, 5 and so on, a suspension spring 30
is mounted between a spring bearing 26 on the auxiliary ground
wheel side and a spring bearing 29 on the vehicle body side. The
spring bearing 26 is pivotably connected by a connecting pin 25 to
an intermediate position of the proximal arm portion 24b of the
auxiliary ground wheel support arm 24. The spring bearing 29 is
pivotably connected by a connecting pin 28 to a pole 27 supported
by the rear portion 3a of the body frame 3. The suspension spring
30 consists of two coil springs 30a and 30b of different outside
diameters disposed coaxially, one within the other. The suspension
spring 30, the spring bearing 26 on the auxiliary ground wheel side
and the spring bearing 29 on the body side are held by a spring
holder 31 extending through the suspension spring 30. One end of
the spring holder 31 is fixed to the spring bearing 26 on the
auxiliary ground wheel side, while the other end slidably extends
through a support portion 29a of the spring bearing 29 on the body
side.
[0043] The suspension spring 30 biases the auxiliary ground wheel
support arm 24 downward through the spring bearing 26 on the
auxiliary ground wheel side, while being reinforced by the spring
holder 31 against yielding, and utilizing the spring bearing 29 on
the body side as an reaction member. Consequently, the auxiliary
ground wheel 9 is biased downward. At the same time, the suspension
spring 30 is resiliently compressed by a ground reaction force
acting on the auxiliary ground wheel 9 and transmitted to the
spring bearing 26 on the auxiliary ground wheel side through the
auxiliary ground wheel support arm 24. Thus, the suspension spring
30 allows the auxiliary ground wheel support arm 24 to pivot
upward, while applying a predetermined braking force thereto, to
raise the auxiliary ground wheel 9.
[0044] When the terrain is uneven or the vehicle body inclines
forward or rearward, a reaction force from the ground raises the
auxiliary ground wheel 9 relative to the vehicle body against the
force of suspension spring 30, or the suspension spring 30 lowers
the auxiliary ground wheel 9 relative to the vehicle body. Thus,
the auxiliary ground wheel 9 follows and keeps contact with the
ground, while protecting the vehicle from vibration or changes in
orientation, which contributes to the traveling stability of the
vehicle.
[0045] The auxiliary ground wheel 9 is disposed such that the front
wheels 1, rear wheels 2 and the auxiliary ground wheel 9 have
turning radii in a relationship as shown in FIG. 2. When the right
and left rear wheels 2 are driven at the same speed in opposite
directions to steer the vehicle body so as to turn about the center
P which is a middle position between the right and left rear wheels
on the rear wheel axes in plan view, the right and left front
wheels 1 turn with a radius R1 which is a linear distance between
the turn center P and the steering axes 21a. The right and left
rear wheels 2 turn with a radius R2, and the auxiliary ground wheel
9 turns with a radius R3 which is a linear distance between the
turn center P and the steering axis 23a. The turning radius R3 of
the auxiliary ground wheel 9 is larger than the turning radius R2
of the right and left rear wheels and smaller than the turning
radius R1 of the right and left front wheels 1. Naturally, the
auxiliary ground wheel 9 is disposed such that the turning track
thereof is within a maximum turning track of the lawn mower when
the vehicle body is steered by driving the right and left rear
wheels at the same speed in opposite directions.
[0046] As shown in FIG. 7, 8 and so on, the grass catcher 13 is
connected to posts of the driving platform frame 7 through a
support frame 34 pivotally supporting the grass catcher 13 to be
pivotable about an axis 34a, and a link mechanism 38 having a pair
of pivot links 38a connected at distal ends thereof to the support
frame 34.
[0047] The grass catcher 13 is swung about the axis 34a, by a
driving force of a dump cylinder 40 attached to the support frame
34, between a collecting position with a discharge opening directed
rearward and a discharging position with the discharge opening
directed downward. The grass catcher 13 has a lid 41 pivotally
attached thereto for closing the discharge opening. By the action
of a link mechanism 42 extending between the lid 41 and the support
frame 34, the lid 41 is automatically opened when the grass catcher
13 pivots to the discharging position, and automatically closed
when the grass catcher 13 pivots to the collecting position.
[0048] When a lift cylinder (not shown) included in the link
mechanism 38 is not operated, i.e., when the link mechanism 38
maintains its vertical orientation, the grass catcher 13 has a
discharging position nearly at the level of the collecting
position, which is called a low dump system (See FIG. 7). When the
lift cylinder (not shown) is operated, i.e., the link mechanism 38
turns to a slanting position, the grass catcher 13 has a
discharging position far higher than the collecting position, which
is called a high dump system (See FIG. 8).
[0049] As shown in FIG. 9A, the front axle member 22 is pivotally
attached in the middle position thereof, by a connecting rod 32, to
a front wheel support member 3b formed by placing a bracket on the
front end portion of the body frame 3. Thus, the front axle member
22 is capable of rolling relative to the self-propelled vehicle
body about the axis of connecting rod 32 extending longitudinally
of the vehicle body.
[0050] A jack-up device includes a control member 33 extending from
the middle position of the front axle member 22 to swing the front
axle member 22, and a screw-type jack mechanism 34. One end of the
jack mechanism 34 is connected to the control member 33 by a
connecting pin 34a slidably inserted into a rolling slot of the
control member 33, while the other end is connected to the front
end of the body frame 3.
[0051] When the vehicle travels on a terrain sloping transversely
of the vehicle body, or one front wheel 1 rides on a mound or falls
into a hollow, the front axle member 22 rolls relative to the body
frame 3, within a range that the control member 34 is allowed to
move relative to the jack mechanism 34 by the rolling slot 34a.
Thus, the right and left front wheels 1 are variable in the height
of attachment to the body frame 3 to maintain the vehicle body
horizontal or nearly horizontal in the transverse direction during
a grass cutting operation.
[0052] When inspecting the inside of mower deck 11a of the mower
unit 11, for example, the operator removes a cover 35 (FIG. 1)
covering upper and forward portions the front wheel support member
3b, to open up an area above the front wheel support member 3b for
allowing one end of the front axle member 22 to be raised. As shown
in FIG. 9B, a control handle 34b is taken off a holder 36 disposed
on the body frame 3 and turned to extend the jack mechanism 34.
Then, the extending force of the jack mechanism 34 swings the front
axle member 22 relative to the body frame 3, lifting the front of
the vehicle body by using the front wheel in a downward position as
a grounding member. As a result, the front end of mower unit 11 is
lifted to open the inside of the mower deck 11a forwardly.
[0053] [Other Embodiments]
[0054] (1) FIG. 10 shows another embodiment of the support member
for supporting the auxiliary ground wheel 9. While the auxiliary
ground wheel 9 consists of a single wheel, a support member 124 for
supporting the auxiliary ground wheel 9 is formed as a U-shaped
arm, and the auxiliary ground wheel 9 is attached to the middle
portion thereof. A pair of the suspension springs 30 are disposed
as a biasing mechanism (braking mechanism), one each on the right
and left sides of the U-shaped arm.
[0055] (2) FIG. 11 shows yet another embodiment of a support member
for supporting the auxiliary ground wheel 9. A pair of right and
left auxiliary ground wheels 9 are disposed, and each auxiliary
ground wheel 9 has substantially the same support member 24 and
suspension spring 30, the latter acting as a biasing mechanism, as
in the first embodiment. As the biasing mechanism (braking
mechanism), coil springs mounted on pivot shafts, or dampers or gas
springs may be employed in place of the suspension springs.
[0056] (3) FIG. 12 shows another embodiment relating to the layout
of the auxiliary ground wheel 9. In this mower, when the right and
left rear wheels 2 are driven at the same speed in opposite
directions to steer the self-propelled vehicle to turn about the
center P in the middle position on the rear wheel axis between the
right and left rear wheels 2 in plan view, the auxiliary ground
wheel 9 turns with a radius R3 which is smaller than the turning
radius R1 of the right and left front wheels 1 and does not exceed
the turning radius R2 of the right and left rear wheels 2.
[0057] (4) FIGS. 13 and 14 show further embodiments relating to the
layout of auxiliary ground wheels 9. Each of these mowers has a
pair of right and left auxiliary ground wheels 9. When the right
and left rear wheels 2 are driven at the same speed in opposite
directions to steer the vehicle to turn about the center P in the
middle position on the rear wheel axis between the right and left
rear wheels 2 in plan view, the auxiliary ground wheels 9 turn with
a radius R3 which is smaller than the turning radius R1 of the
right and left front wheels 1 and does not exceed the turning
radius R2 of the right and left rear wheels 2.
[0058] In the mower shown in FIG. 13, the right and left auxiliary
ground wheels 9 are supported to be pivotable about one steering
axis 23a relative to an auxiliary ground wheel support arm 24.
[0059] In the mower shown in FIG. 14, the right and left auxiliary
ground wheels 9 are supported to be pivotable about individual
steering axes 23a relative to an auxiliary ground wheel support arm
24. Even with the pair of right and left auxiliary ground wheels 9
installed, the turning radius R3 of the two auxiliary ground wheels
9 is smaller than the turning radius R1 of the right and left front
wheels 1 and does not exceed the turning radius R2 of the right and
left rear wheels 2.
* * * * *