U.S. patent application number 13/622650 was filed with the patent office on 2013-03-28 for integrated transaxles for standing lawn mower.
This patent application is currently assigned to ARIENS COMPANY. The applicant listed for this patent is Ariens Company. Invention is credited to Paul Ferrier, Daniel J. Gindt, Kariann Kalista, Brian Zwieg.
Application Number | 20130074464 13/622650 |
Document ID | / |
Family ID | 47909706 |
Filed Date | 2013-03-28 |
United States Patent
Application |
20130074464 |
Kind Code |
A1 |
Gindt; Daniel J. ; et
al. |
March 28, 2013 |
INTEGRATED TRANSAXLES FOR STANDING LAWN MOWER
Abstract
A standing lawn mower includes right and left side integrated
transaxles for operating the right and left drive wheels
independently. The integrated transaxles may include independent
hydraulic systems and hydraulic fluid for modularity and reduced
risk of cross contamination. The operator support platform is at
least partially behind the right and left integrated
transaxles.
Inventors: |
Gindt; Daniel J.; (Brillion,
WI) ; Zwieg; Brian; (Brillion, WI) ; Ferrier;
Paul; (Brillion, WI) ; Kalista; Kariann;
(Brillion, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ariens Company; |
Brillion |
WI |
US |
|
|
Assignee: |
ARIENS COMPANY
Brillion
WI
|
Family ID: |
47909706 |
Appl. No.: |
13/622650 |
Filed: |
September 19, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61537960 |
Sep 22, 2011 |
|
|
|
Current U.S.
Class: |
56/11.4 |
Current CPC
Class: |
A01D 69/03 20130101;
A01D 34/74 20130101; A01D 34/64 20130101; A01D 34/82 20130101 |
Class at
Publication: |
56/11.4 |
International
Class: |
A01D 69/06 20060101
A01D069/06 |
Claims
1. A standing lawn mower comprising: a frame; a right drive wheel
supporting the frame; a left drive wheel supporting the frame; a
prime mover supported by the frame; a cutting deck assembly
supported by the frame for movement between a cutting position in
which the cutting deck assembly is lowered with respect to the
frame and a travel position in which the cutting deck assembly is
raised with respect to the frame, the cutting deck assembly
including a cutting deck and at least one cutting blade mounted
under the cutting deck and rotating under the influence of the
prime mover to cut vegetation when the cutting deck assembly is in
the cutting position; a right side integrated transaxle operating
under the influence of the prime mover to drive rotation of the
right drive wheel independent of the rotation of the left drive
wheel, the right side integrated transaxle including a right side
housing, a right hydraulic pump within the housing, and a right
hydraulic motor within the housing; a left side integrated
transaxle operating under the influence of the prime mover to drive
rotation of the left drive wheel independent of the rotation of the
right drive wheel, the left side integrated transaxle including a
left side housing, a left hydraulic pump within the housing, and a
left hydraulic motor within the housing; and an operator platform
for supporting a standing operator of the lawn mower, the operator
platform being positioned at least partially behind the right and
left integrated transaxles.
2. The standing lawn mower of claim 1, wherein the right transaxle
includes a right hydraulic system using right hydraulic fluid; and
wherein the left transaxle includes a left hydraulic system
independent of the right hydraulic system and using left hydraulic
fluid that is separate and unmixed with the right hydraulic
fluid.
3. The standing lawn mower of claim 1, wherein the operator
platform is at least partially between the right and left drive
wheels.
4. The standing lawn mower of claim 1, wherein the prime mover
includes a horizontal PTO shaft; the standing lawn mower further
comprising a gear box taking as an input torque from the horizontal
PTO shaft and delivering as an output a vertical rotating
shaft.
5. The standing lawn mower of claim 1, wherein the prime mover
includes a vertical, downwardly extending PTO shaft that defines a
vertical PTO axis, the PTO shaft rotating about the PTO axis during
operation of the prime mover.
6. The standing lawn mower of claim 5, wherein the prime mover
includes a PTO bearing supporting the PTO shaft in cantilevered
fashion for rotation about the PTO axis; and wherein all portions
of both the right side transaxle and the left side transaxle are
below a horizontal plane that is below the PTO bearing.
7. The standing lawn mower of claim 5, further comprising a power
transmission assembly including: a PTO sheave mounted to the PTO
shaft for rotation with the PTO shaft about the PTO axis; a right
transaxle sheave interconnected with the right hydraulic pump and
rotatable to drive operation of the right hydraulic pump; a left
transaxle sheave interconnected with the left hydraulic pump and
rotatable to drive operation of the left hydraulic pump; an idler;
a tensioner; and a belt interconnecting the PTO sheave to the right
transaxle sheave, left transaxle sheave, idler, and tensioner to
transmit rotation of the PTO sheave under the influence of the PTO
shaft into rotation of the right transaxle sheave, left transaxle
sheave, idler, and tensioner; wherein each of the right transaxle
sheave, left transaxle sheave, idler, and tensioner rotate about an
axis of rotation that is parallel to the PTO axis.
8. The standing lawn mower of claim 1, wherein the operator
platform is positioned at least partially behind the right and left
drive wheels.
9. The standing lawn mower of claim 1, further comprising a
hydraulic fluid expansion tank; and wherein the right side
integrated transaxle, the left side integrated transaxle, and the
hydraulic fluid expansion tank are in fluid communication with each
other.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C. 119(e)
of the filing date of U.S. Provisional Application No. 61/537960,
filed Sep. 22, 2011, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to lawn mowers and more
particularly to standing ride-on lawn mowers, and more specifically
to a standing ride-on lawn mower having integrated transaxles.
SUMMARY
[0003] The invention provides a standing lawn mower comprising: a
frame; a right drive wheel supporting the frame; a left drive wheel
supporting the frame; a prime mover supported by the frame; a
cutting deck assembly supported by the frame for movement between a
cutting position in which the cutting deck assembly is lowered with
respect to the frame and a travel position in which the cutting
deck assembly is raised with respect to the frame, the cutting deck
assembly including a cutting deck and at least one cutting blade
mounted under the cutting deck and rotating under the influence of
the prime mover to cut vegetation when the cutting deck assembly is
in the cutting position; a right side integrated transaxle
operating under the influence of the prime mover to drive rotation
of the right drive wheel independent of the rotation of the left
drive wheel, the right side integrated transaxle including a right
side housing, a right hydraulic pump within the housing, and a
right hydraulic motor within the housing; a left side integrated
transaxle operating under the influence of the prime mover to drive
rotation of the left drive wheel independent of the rotation of the
right drive wheel, the left side integrated transaxle including a
left side housing, a left hydraulic pump within the housing, and a
left hydraulic motor within the housing; and an operator platform
for supporting a standing operator of the lawn mower, the operator
platform being positioned at least partially behind the right and
left integrated transaxles.
[0004] In some embodiments, the right transaxle includes a right
hydraulic system using right hydraulic fluid; and wherein the left
transaxle includes a left hydraulic system independent of the right
hydraulic system and using left hydraulic fluid that is separate
and unmixed with the right hydraulic fluid. In some embodiments,
the operator platform is at least partially between the right and
left drive wheels. In some embodiments, the prime mover includes a
horizontal PTO shaft; the standing lawn mower further comprising a
gear box taking as an input torque from the horizontal PTO shaft
and delivering as an output a vertical rotating shaft.
[0005] In some embodiments, the prime mover includes a vertical,
downwardly extending PTO shaft that defines a vertical PTO axis,
the PTO shaft rotating about the PTO axis during operation of the
prime mover. In some embodiments, the prime mover includes a PTO
bearing supporting the PTO shaft in cantilevered fashion for
rotation about the PTO axis; and wherein all portions of both the
right side transaxle and the left side transaxle are below a
horizontal plane that is below the PTO bearing. In some
embodiments, the lawn mower further comprises a power transmission
assembly including: a PTO sheave mounted to the PTO shaft for
rotation with the PTO shaft about the PTO axis; a right transaxle
sheave interconnected with the right hydraulic pump and rotatable
to drive operation of the right hydraulic pump; a left transaxle
sheave interconnected with the left hydraulic pump and rotatable to
drive operation of the left hydraulic pump; an idler; a tensioner;
and a belt interconnecting the PTO sheave to the right transaxle
sheave, left transaxle sheave, idler, and tensioner to transmit
rotation of the PTO sheave under the influence of the PTO shaft
into rotation of the right transaxle sheave, left transaxle sheave,
idler, and tensioner; wherein each of the right transaxle sheave,
left transaxle sheave, idler, and tensioner rotate about an axis of
rotation that is parallel to the PTO axis.
[0006] In some embodiments, the operator platform is positioned at
least partially behind the right and left drive wheels. In some
embodiments, the lawn mower further comprises a hydraulic fluid
expansion tank; and wherein the right side integrated transaxle,
the left side integrated transaxle, and the hydraulic fluid
expansion tank are in fluid communication with each other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a front perspective view of a lawn mower.
[0008] FIG. 2 is a rear perspective view of the lawn mower.
[0009] FIG. 3 is a perspective view of an operator platform
assembly of the lawn mower of FIG. 1.
[0010] FIG. 4 is an exploded perspective view of the operator
platform assembly.
[0011] FIG. 5 is a section view of the operator platform assembly
in an operating position.
[0012] FIG. 6 is a section view of the operator platform assembly
in a stored position.
[0013] FIG. 7 is a top view of a portion of the lawn mower.
[0014] FIG. 8 is an exploded rear perspective view of the lawn
mower.
[0015] FIG. 9 is an exploded perspective view of a mower drive
assembly and drive transmission assembly of the lawn mower.
[0016] FIG. 10 is a schematic view of an integrated transaxle of
the mower drive assembly.
[0017] FIG. 11 is a bottom view of the drive transmission
assembly.
[0018] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting.
DETAILED DESCRIPTION
[0019] FIGS. 1 and 2 illustrate a lawn mower 100 embodying the
present invention. The lawn mower 100 includes a right front wheel
102, a left front wheel 104, a right rear drive wheel 106, a left
rear drive wheel 108, a frame 110, an operator platform assembly
112, a control tower 114, a mower drive assembly 116, a cutting
deck assembly 118, a cutting deck transmission assembly 120, a
cutting deck lift assembly 122, and a height of cut assembly 124.
The figures illustrate a standing ride-on lawn mower 100, which is
a lawn mower on which the operator stands rather than sits. Various
features of this mower 100, including the mower drive assembly 116,
the cutting deck lift assembly 122, and the height of cut assembly
124 are applicable to other types of lawn mowers, including walk
behind lawn mowers and sitting ride-on lawn mowers.
[0020] For the purposes of the present specification, all spatial
and directional terms shall, unless specifically stated otherwise,
refer to space and direction as perceived by an operator of the
lawn mower 100 in the lawn mower's intended operational
orientation, moving over flat, horizontal ground. In ordinary
operation, the lawn mower 100 is intended to be oriented with the
front and rear wheels 102, 104, 106, 108 in contact with the ground
and an operator standing on the operator platform assembly 112
facing toward the front wheels 102, 104. Consequently, the term
"forward" and variations thereon shall mean in a direction parallel
to the direction from the rear wheels 106, 108 toward the front
wheels 102, 104. The term "front" and variations thereon shall mean
positioned further in the forward direction than an element being
compared. The term "reverse" and variations thereon shall mean in a
direction parallel to the direction from the front wheels 102, 104
toward the rear wheels 106, 108. The term "rear" and variations
thereon shall mean positioned further in the reverse direction than
an element being compared. The terms "right," "left," and
variations thereon shall be in reference to the respective right
and left as viewed by a forward-looking operator. The terms "up,"
"down" and variations thereon shall be used as from the perspective
of an operator standing on the operator platform assembly 112. The
terms "above" and "over" shall mean intersecting a comparatively
higher horizontal plane, and the terms "directly above" and
"directly over" shall mean intersecting a comparatively higher
horizontal plane and intersecting a common vertical line. The terms
"below" and "under" shall mean intersecting a comparatively lower
horizontal plane, and the terms "directly below" and "directly
under" shall mean intersecting a comparatively lower horizontal
plane and intersecting a common vertical line. Elements that are
"directly above" or "directly below" other elements are also
"above" or "below" the other elements, but the opposite is not
necessarily true.
[0021] The right and left front wheels 102, 104 in the illustrated
embodiment are of a variety commonly called "caster wheels." The
right and left front wheels 102, 104 are passive, meaning that they
are not driven under power. The right and left front wheels 102,
104 rotate about horizontal axes of rotation. The right and left
front wheels 102, 104 are mounted to the frame 110 with an
arrangement that permits the right and left front wheels 102, 104
to swivel with respect to the frame 110 about vertical axes to
accommodate turning and rotating of the lawn mower 100. In some
embodiments, the right and left front wheels 102. 104 are not
passive, but instead can be actively steered by the operator.
[0022] The right and left rear drive wheels 106, 108 in the
illustrated embodiments are driven under the influence of the mower
drive assembly 116, as will be discussed in more detail below. As
will be discussed, the right and left rear drive wheels 106, 108 in
the illustrated embodiment are capable of rotating independent of
one another in forward and reverse directions to cause forward,
reverse, and turning movement of the lawn mower 100. The right and
left drive wheels 106, 108 rotate about a common horizontal axis of
rotation 126.
[0023] When the right and left drive wheels 106, 108 rotate in
opposite directions (i.e., one forward and one reverse) at the same
speed, the lawn mower 100 rotates about a zero-radius turning axis
128, which may also be referred to as a zero-turn axis or ZT axis.
The ZT axis 128 is a vertical axis that intersects the horizontal
axis of rotation 126 midway between the right and left rear drive
wheels 106, 108. The intersection of the vertical ZT axis 128 and
the horizontal axis of rotation 126 may be referred to as the
"midpoint" between the right and left rear drive wheels 106, 108.
The vertical plane that includes the horizontal axis of rotation
126 and the ZT axis 128 may be referred to as the "reference plane
126, 128."
[0024] The frame 110 is supported by the right and left front
wheels 102, 104 and the right and left rear drive wheels 106, 108.
The other systems of the lawn mower 100 (i.e., the operator
platform assembly 112, the control tower 114, the mower drive
assembly 116, the cutting deck assembly 118, the cutting deck
transmission assembly 120, the cutting deck lift assembly 122, and
the height of cut assembly 124) are supported by the frame 110.
[0025] With reference to FIGS. 3 and 4, the operator platform
assembly 112 includes an operator platform 130, a right pivot
assembly 132, a left pivot assembly 134, a pivot limiting assembly
136, and a latch assembly 138. The operator platform assembly 112
is pivotable between an operating position in which it may be said
to be "pivoted down" as illustrated in FIG. 5, and a stored
position in which it may be said to be "pivoted up" as illustrated
in FIG. 6. Except as specifically noted, the operator platform
assembly 112 will be discussed below with reference to its
operating position.
[0026] The operator platform 130 includes a plate 140 that has a
central flat surface 142 and angled side sections 144. The operator
stands on the operator platform 130 during operation of the lawn
mower 100. For the purposes of the present specification, the term
"operator zone" will be used to mean all areas of the lawn mower
100 that are accessible by an operator of the lawn mower 100
standing on the operator platform 130 during ordinary operation of
the lawn mower 100.
[0027] The central flat surface 142 includes slip-resistant
features 146, such as bumps or a rough surface treatment to resist
slipping of the operator's feet. The angled side sections 144 are
positioned on the right and left sides of the central flat surface
and 142 extend up at angle of between about 10.degree. and
80.degree. with respect to the central flat surface 142. The angled
side sections 144 give the operator tactile feedback as to the
operator's foot position on the operator platform 130. The operator
platform 130 (or, more specifically, the central flat surface 142)
is pivotable between being generally horizontal when in the
operating position (FIG. 5) and generally vertical when in the
stored position (FIG. 6).
[0028] The right and left pivot assemblies 132 and 134 are mirror
images of each other. Each pivot assembly 132, 134 includes an
outer bracket 148, an inner bracket 150, a pivot sleeve 152, and a
pivot pin 154. The terms "outer" and "inner" refer to the brackets'
positions along the horizontal axis of rotation 126 of the rear
drive wheels 106 and 108 with respect to the midpoint between the
drive wheels 106 and 108. The outer bracket 148 is axially further
from the midpoint than the inner bracket 150 is. The outer and
inner brackets 148, 150 include vertical planar sections that are
parallel to each other, and in this regard may be characterized as
a yoke for the pivot pin 154.
[0029] The outer bracket 148 is mounted to the side of the frame
110 and extends down between the drive wheel 106, 108 and the
operator platform 130. The outer bracket 148 reduces access of the
operator's foot, pants, or other body part or clothing to the
rotating drive wheel 106, 108 to reduce the likelihood of the
operator or the operator's clothing from coming into contact with
the drive wheel 106, 108 while the operator is standing on the
operator platform 130. In this regard, the outer bracket 148 may be
termed a wheel blocking bracket. The outer bracket 148 includes a
pivot pin mounting hole 160. The inner bracket 150 is also mounted
to the frame 110 and extends down. The inner bracket 150 includes a
pivot pin mounting hole 162 that aligns with the pivot pin mounting
hole 160 in the outer bracket 148.
[0030] The pivot sleeve 152 includes a through bore 164 and is a
cylindrical member rigidly mounted to the operator platform 130.
The pivot sleeve 152 could be made integrally with the operator
platform 130 or could be provided separately and rigidly joined or
affixed to the operator platform 130. In the illustrated
embodiment, the pivot sleeves 152 are positioned between ears 165
that extend up from the forward ends of the angled side sections
144 of the operator platform 130. The ears 165 are spaced such that
each pair of ears 165 fits between the outer and inner brackets
148, 150. The ears 165 include centering holes 167 that align with
the through bore 164.
[0031] Bushings 169 that have a small diameter portion and a wide
flange secure the pivot sleeves 152 to the ears 165. The small
diameter portions of the bushings 169 extend through the centering
holes 167 and are press fit into the through bore 164. The flanges
of the bushings 169 sit against the away-facing surfaces of the
ears 165. The flange diameter is larger than the diameter of the
centering holes 167. The bushings 169 include a through bore.
[0032] The pivot pin 154 extends through the pivot pin mounting
holes 160, 162, the bushings 167, and the through bore 164 to
pivotally interconnect the operator platform 130 to the outer and
inner brackets 148, 150 (and thereby to the frame 110). A retaining
bracket 166, snap ring, or other means for preventing the pivot pin
154 from axial movement is attached to the pivot pin on the
away-facing surface of the inner bracket 150. The outer end of the
pivot pin 154 is secured from axial movement with a nut or other
fastener. The pivot sleeves 152 and bushings 169 are free to rotate
on the pivot pins 154, such that the operator platform 130 is
pivotable between the operating position and the stored position
about the pivot pins 154.
[0033] The pivot limiting assembly 136 includes a stop plate 168, a
rear cross bar 170, and a plurality of dampening members 172. The
stop plate 168 is mounted to the front edge of the operator
platform 130, between the inner brackets 150 of the pivot
assemblies 132, 134. The stop plate 168 extends at a right angle to
the operator platform 130, and is therefore vertical when the
operator platform assembly 112 is in the operating position and
horizontal when the operator platform assembly 112 is in the stored
position.
[0034] The plurality of dampening members 172 are mounted to the
rear facing surface of the stop plate 168. The dampening members
172 are made of a resilient material such as rubber, to absorb
vibrations and shock.
[0035] The rear cross bar 170 is mounted to the rear end of the
frame 110. The dampening members 172 come into contact with the
forward-facing side of the rear cross bar 170 when the operator
platform assembly 112 is in the operating position. In operation,
the weight of the operator is downwardly directed on the operator
platform 130, which causes the operator platform 130 to pivot down
on the pivot pins 154. Downward pivoting of the operator platform
130 is resisted by the dampening members 172 of the stop plate 168
bearing against the rear cross bar 170. As the lawn mower 100 moves
over bumpy terrain, some of the dynamic stresses and vibrations
that are transferred to the lawn mower 100 are absorbed by the
dampening member 172 to improve the comfort of the operator. Stated
another, way, the dampening members 172 provide suspension for the
operator standing on the operator platform 130, which reduces the
amplitude of vibration and impact loading that is transmitted to
the operator as a result of operating the lawn mower 100.
[0036] The latching assembly 138 includes a latch pin 174, a latch
arm 176, and a biasing member 178. The latch pin 174 is rigidly
affixed to the operator platform 130 and extends to one side (the
right side in the illustrated embodiment). The latch arm 176
includes a cam surface 180 and a latch slot 182, and is pivotably
mounted to the outer bracket 148 or to another bracket above the
outer bracket 148 that is mounted to the frame 110. The illustrated
biasing member 178 is a linearly acting spring, but in other
embodiments it may be a torsion spring. The biasing member 178
biases the latch arm 176 toward an engaged position ("down" in the
illustrated embodiment).
[0037] Upon pivoting the operator platform 130 into the stored
position, the latch pin 174 engages the cam surface 180 of the
latch arm 176 and pivots the latch arm 176 against the biasing
force of the biasing member 178 (i.e., pivots the latch arm "up" in
the illustrated embodiment). Continued movement of the operator
platform 130 toward the stored position moves the latch pin 174
into alignment with the latch slot 182. Upon alignment of the latch
pin 174 with the latch slot 182, the biasing force of the biasing
member 178 pivots the latch arm 176 down, such that the latch pin
174 is captured within the latch slot 182.
[0038] The engagement of the latch pin 174 by the latch arm 176
resists pivotal movement of the operator platform 130 from the
stored position toward the operating position. This is often
desirable during transportation or storage of the lawn mower 100
because it reduces the overall length of the lawn mower to save
space. The operator platform 130 is released from the stored
position by lifting the latch arm 176 (e.g., by engagement of one's
finger against the cam surface 180 on the latch arm 176) such that
the latch pin 174 is free from the latch slot 182 so the operator
platform 130 can pivot down toward the operating position.
[0039] The outer bracket 148 of the left pivot assembly 134
includes an arc-shaped slot 183 to accommodate a fastener 447 that
pivotably interconnects a slotted arm 424 and a deck lift foot
lever 426, which will be described in greater detail below.
[0040] As illustrated, the operator platform 130 is positioned at
least partially behind the right and left rear drive wheels 106 and
108. The pivot pin 154 is positioned behind and below the common
horizontal axis of rotation 126 of the drive wheels 106 and 108.
The entirety of the operator platform 130 is behind the common
horizontal axis of rotation 126 of the drive wheels 106 and 108. In
the operating position, the operator platform 130 is below a plane
containing the engine deck 210.
[0041] Referring to FIG. 7, the control tower 114 extends
vertically from the frame 110 in front of the operator platform
130. Mounted to a rear-facing side of the control tower 114 is a
cushion 184 against which a forward-leaning operator rests during
operation of the lawn mower 100. The control tower 114 includes the
following controls, all of which are in the operator zone: an
ignition switch 186, a blade engagement control 188, a choke 190,
an engine speed control 192, a right control arm 194, a left
control arm 196, a reverse hard stop 198, a forward hard stop 200,
a forward hard stop lock 202, an interlock 204, a deck lift hand
lever 206, a height of cut selector 208, and a height of cut
indicator 209. In the illustrated embodiment, at least some of the
controls are located or locatable forward of the reference plane
126, 128 (i.e., a plane perpendicular to FIG. 7 and including the
axis of rotation 126), but in an alternative preferred embodiment,
at least the reverse hard stop 198, the right control arm 194, the
left control arm 196, and the forward hard stop 200 are all moved
rearward of the reference plane 126, 128.
[0042] FIG. 8 illustrates the mower drive assembly 116, which
includes an engine deck 210, a fuel source 212, an engine 214, a
right integrated transaxle 216, a left integrated transaxle 218,
and a drive transmission assembly 220. The engine deck 210 is above
the operator platform 130 when the operator platform 130 is in the
operating position. The engine 214, acting through the drive
transmission assembly 220, drives a pump in each of the right and
left integrated transaxles 216, 218. The engine 214 also drives
operation of the cutting deck transmission assembly 120 to cause
cutting blades in the cutting deck assembly 118 to rotate and cut
grass or other vegetation.
[0043] The right and left control arms 194, 196 are interconnect to
the right and left integrated transaxles 216, 218 to control the
speed and direction of rotation of the respective right and left
rear drive wheels 106, 108. The right and left control arms 194,
196 have a neutral position in which they do not cause any rotation
of the right and left rear drive wheels 106, 108. When the right
and left control arms 194, 196 are pushed forward from the neutral
position by the operator, the respective right and left rear drive
wheels 106, 108 rotate in a forward direction at a speed
proportional to the degree of forward movement of the control arms
194, 196. When the right and left control arms 194, 196 are pulled
rearward from the neutral position by the operator, the respective
right and left rear drive wheels 106, 108 rotate in a reverse
direction (opposite the forward direction) at a speed proportional
to the degree of rearward movement of the control arms 194, 196.
When one of the control arms is pushed forward and the other is
pulled rearward, one of the drive wheels rotates in the forward
direction and the other rotates in the reverse direction, giving
rise to rotation of the lawn mower 100 about the ZT axis 128.
[0044] The stop plate 168 of the operator platform assembly 112
moves or passes between the right and left integrated transaxles
216, 218 as the foot platform is pivoted between the operating
position (FIG. 5) and the stored position (FIG. 6).
[0045] Referring now to FIG. 7, the reverse hard stop 198 provides
a fixed frame of reference for the operator when manipulating the
control levers 194, 196. The operator's hands and thumbs may rest
on the reverse hard stop 198 while the operator's fingers pull one
or both of the control arms 194, 196 rearward (i.e., in the reverse
direction). Squeezing the control arms 194, 196 against the reverse
hard stop 198 results in maximum reverse speed for the lawn mower
100. The operator's hands are less prone to bouncing or moving
unintentionally due to the terrain when the operator's hands and
fingers rest on the reverse hard stop 198.
[0046] The forward hard stop 200 is adjustable and locked in place
by the forward hard stop lock 202. The forward hard stop 200 may be
pivoted forward or rearward into a desired position by disengaging
or unlocking the forward hard stop lock 202, pivoting the forward
hard stop 200 to a desired position, and engaging or locking the
forward hard stop lock 202. Once the forward hard stop 200 is set,
a desired maximum forward speed has been established for the lawn
mower 100. By squeezing the control arms 194, 196 against the
forward hard stop 200, the operator achieves the desired maximum
forward speed. When locked in place, the forward hard stop 200 is
fixed with respect to the control tower 114 to provide a stable and
fixed resting place for the operator's hands. The operator's hands
and fingers rest on the forward hard stop 200, while the operator's
thumbs manipulate the control arms 194, 196 in the forward
direction. The forward hard stop 200 provides a frame of reference
for the relative speed being requested of each drive wheel 106,
108. The operator's hands are less prone to bouncing or moving
unintentionally due to the terrain when the operator's hands and
fingers rest on the forward hard stop 200.
[0047] Referring again to FIG. 8, in the illustrated embodiment,
the fuel source 212 is a gas tank that contains gasoline for use by
the engine 214. The gas tank can include a primary tank and a
back-up tank. The fuel source 212 is mounted to the engine deck
210. In the illustrated embodiment, the engine 214 is supported by
the engine deck 210 and includes a power take off ("PTO") shaft 238
extending vertically down through the engine deck 210. The engine
214 also includes a PTO bearing that supports the PTO shaft 238 for
rotation about a vertical axis of rotation. Although the
illustrated embodiment includes an internal combustion engine 214
and a gasoline tank 212 as the prime mover and fuel source,
respectively, other embodiments may include alternative prime
movers and suitable fuel sources for such alternative prime movers.
Examples of alternative prime movers and fuel sources include a
hybrid engine and a source of natural gas or gasoline, an electric
motor and batteries, and a fuel cell and hydrogen tank.
[0048] FIGS. 9-11 illustrate the mower drive assembly 116 and drive
transmission assembly 220 in more detail. The PTO bearing noted
above is visible in FIG. 9, and identified with reference number
240. The PTO bearing 240 supports the PTO shaft 238 for rotation
about a vertical PTO axis 242. The right and left integrated
transaxles 216, 218 are identical units in the illustrated
embodiment. One example of a commercially available and suitable
integrated transaxle is manufactured by Hydro-Gear of Sullivan,
Ill.
[0049] As schematically illustrated in FIG. 10, the integrated
transaxles 216, 218 include a housing 244 which contains a
hydraulic pump 246, a hydraulic motor 248, and a dedicated
hydraulic loop 250 that includes a reservoir 252. The hydraulic
pump 246 includes an input shaft 254 and the hydraulic motor 248
includes an output shaft 256. The hydraulic pump 246 also includes
a swash plate 258 that can be manipulated to cause hydraulic fluid
to flow in forward and reverse directions through the motor
248.
[0050] In the illustrated embodiment, the right and left integrated
transaxles 216, 218 are self-contained and do not commingle
hydraulic fluid or share a reservoir. The right integrated
transaxle 216 includes a right hydraulic system using a right
hydraulic fluid, and the left integrated transaxle 218 includes a
left hydraulic system using a left hydraulic fluid. The right and
left hydraulic fluids are separate and unmixed with each other.
This is advantageous over known systems that share hydraulic fluid
or components, because the integrated transaxles 216, 218 can be
separately serviced or replaced and foreign objects or debris in
the hydraulic fluid of one of the transaxles will not be shared
with the other transaxle. In some embodiments, the integrated
transaxles 216, 218 can be placed in hydraulic fluid communication
to share hydraulic fluid, and in other embodiments, the integrated
transaxles 216, 218 can share a common reservoir 252.
[0051] In view of the foregoing, the term "integrated transaxle"
may be used to describe a pump, a motor, and a hydraulic system
contained within a single housing having a pump input shaft and a
motor output shaft extending through the housing such that the
integrated transaxle is a modular, self-contained, independent
unit. A hydraulic drive system can be constructed by connecting a
prime mover capable of delivering an input torque to the pump input
shaft of the integrated transaxle and connecting an object to be
rotated to the motor output shaft of the integrated transaxle. No
additional plumbing, hydraulic components, or other components are
required to construct the hydraulic drive system.
[0052] In operation, a linkage connects the right and left control
arms 194, 196 to the swash plate 258 of the associated integrated
transaxle 216, 218. Movement of the control arms 194, 196
manipulates the swash plates 258. The swash plates 258 can be set
to a neutral setting (corresponding to the control arm 194, 196
being in the neutral position) in which there is substantially no
hydraulic fluid flow despite the input shaft 254 rotating. The
swash plates 258 can be tilted in forward and reverse directions
(corresponding to the control arm 194, 196 being moved from neutral
in the forward and reverse direction, respectively) in an
infinitely adjustable manner to dictate the volumetric flow rate of
hydraulic fluid in the selected direction. The motor output shafts
256 rotate in a forward or reverse direction, depending on the
direction of flow of the hydraulic fluid from the associated pump
246. The speed of rotation of the motor output shafts 256 is
dictated by the volumetric flow rate of the hydraulic fluid. The
output shafts 256 are connected to the associated drive wheels 106,
108 to cause rotation of the drive wheels in a forward or reverse
direction at a desired speed.
[0053] As illustrated in FIG. 11, the drive transmission assembly
220 is mounted directly under the engine deck 210 and includes a
drive sheave 262, a right transaxle sheave 264, a left transaxle
sheave 266, an idler 268, a drive tension assembly 270, and a drive
belt 272. The drive sheave 262 is mounted to the PTO shaft 238 of
the engine 214 for rotation with the PTO shaft 238 under the engine
deck 210. The right and left transaxle sheaves 264 and 266 are
mounted to the respective right and left transaxle input shafts 254
for rotation with those shafts. The stationary idler 268 is
supported for rotation on a shaft that is mounted to the bottom
surface of the engine deck 210.
[0054] The drive tension assembly 270 includes a tension arm 274, a
tensioner 276, and a spring 278. The tension arm 274 includes first
and second opposite ends. The tension arm 274 is mounted to the
engine deck 210 at a pivot point 279 between the first and second
opposite ends of the tension arm 274. One end of the spring 278 is
connected to the first end of the tension arm 274, and the opposite
end of the spring 278 is interconnected to the engine deck 210. The
spring 278 is a linear-acting spring, and consequently applies a
linear biasing force on the tension arm 274 which biases the
tension arm 274 to pivot about the pivot point 279 in a
counter-clockwise direction when viewed from below as illustrated
by FIG. 11. In this regard, the spring 278 can be said to apply a
torque biasing force on the tension arm 274 about the pivot point
279. The tensioner 276 is mounted to the second end of the tension
arm 274 and is free to rotate with respect to the tension arm
274.
[0055] The drive belt 272 interconnects the drive sheave 262, right
transaxle sheave 264, left transaxle sheave 266, idler 268, and
tensioner 276. The drive belt 272 transmits torque from the PTO
shaft 238 and drive sheave 262 to the right and left transaxle
input shafts 254 to drive operation of the pumps 246 in the
transaxles 216 and 218. The idler 268 and the tensioner 276 ensure
that the drive belt 272 contacts each of the sheaves 262, 264, and
266 along an appropriate wrap angle a and that the drive belt 272
is sufficiently tight against the sheaves 262, 264, and 266 to
reduce or eliminate slipping of the drive belt 272 with respect to
the sheaves 262, 264, and 266.
[0056] The wrap angle .alpha. of the drive belt on the sheaves 262,
264, and 266 is at least 90.degree.. The ratio between the diameter
of the drive sheave 262 to the diameter of the right transaxle
sheave 264 is preferably 1:1 or close to 1:1. The ratio between the
diameter of the drive sheave 262 to the diameter of the left
transaxle 266 sheave is preferably 1:1 or close to 1:1. The drive
sheave 262, the right transaxle sheave 264, the left transaxle
sheave 264, the idler 268, and the tensioner 276 fit within a
rectangular footprint that is less than 4.5 drive sheave diameters
by 3.25 drive sheave diameters. The operator platform 130 is at
least partially behind the right transaxle 216 and the left
transaxle 218.
[0057] The entire drive transmission assembly 220 is directly under
the engine deck 210. The entire drive transmission assembly 220 is
below a horizontal plane that is below the PTO bearing 240.
Examples of such horizontal planes are the planes defined by the
top and bottom surfaces of the engine deck 210. The sheaves 262,
264, and 266, idler 268, and tensioner 276 are substantially
vertically aligned (i.e., at the same height) so the drive belt 272
is substantially horizontal and is not angled to any significant
degree up or down between any of the sheaves 262, 264, and 266,
idler 268, and tensioner 276. The input shafts 254 of the right and
left transaxles 216 and 218 are vertical and define axes of
rotation that are parallel to the PTO axis 242 of the PTO shaft
238, as are all of the axes of rotation and pivot axes of the
sheaves 262, 264, and 266, idler 268, tensioner 276, tension arm
274, and spring 278. The output shafts 256 of the right and left
transaxles 216 and 218 are horizontal and therefore define axes of
rotation that are perpendicular to the PTO axis 242 and the axes of
rotation and pivot axes of the other elements of the drive
transmission assembly 220.
[0058] In some embodiments, the prime mover may include a
horizontal PTO shaft. In such a configuration, the standing lawn
mower may include a gear box taking as an input torque from the
horizontal PTO shaft and delivering as an output a vertical
rotating shaft that would engage the drive transmission assembly
220 as noted above.
[0059] In operation, the engine 214 drives rotation of the PTO
shaft 238 about the PTO axis 242. The drive sheave 262 is fixed for
rotation with the PTO shaft 238. Rotation of the drive sheave 262
causes linear movement of the drive belt 272, which causes the
right and left transaxle sheaves 266 and 268 to rotate. Tension is
maintained in the drive belt 272 with the drive tension assembly
270 and proper wrap angles a are maintained by the positioning of
the tensioner 276 and idler 268. Rotation of the right and left
transaxle sheaves 266 and 268 causes rotation of the input shafts
254 of the right and left transaxles 216 and 218. This drives
operation of the hydraulic pump 246 in each of the transaxles 216
and 218. As the swash plate 258 in the right and left transaxles
216, 218 are manipulated (by manipulation of the right and left
control arms 194, 196), hydraulic fluid flows through the motors
248 in the right and left transaxles 218 to drive rotation of the
output shaft 256 in a desired direction and at a desired speed,
which results in rotation of the right and left drive wheels 106,
108 in the desired direction and at the desired speed.
[0060] The right and left drive wheels 106, 108 rotate about the
horizontal axis 126, which is collinear with the axes of rotation
of the transaxle output shafts 256. In the event the right and left
drive wheels 106, 108 are driven in opposite directions of rotation
at the same speeds, the lawn mower 100 will rotate about the ZT
axis 128.
[0061] The cutting deck assembly 118 is supported by the frame 110
for movement between a cutting position in which the cutting deck
assembly 118 is lowered with respect to the frame 110 and a travel
position in which the cutting deck assembly is raised with respect
to the frame 110. The cutting deck assembly 118 includes a cutting
deck and at least one cutting blade mounted under the cutting deck
and rotating under the influence of the engine 214 to cut
vegetation when the cutting deck assembly 118 is in the cutting
position.
[0062] The cutting deck lift assembly 122 includes actuators for
raising and lowering the cutting deck assembly 118, and the
height-of-cut assembly 124 includes an adjustable mechanism for
holding the deck assembly 118 at a desired height during
cutting.
[0063] Various features of the invention are set forth in the
following claims.
* * * * *