Lawn mower having improved deck height adjustment mechanism

A lawn mower having a deck height adjustment mechanism for simultaneously adjusting a height of a deck of a lawn mower at all four wheels of the lawn mower by the use of a single hand of the operator. The mechanism includes an index plate having a plurality of teeth thereon defining a plurality of deck height positions, and therefore a plurality of height positions of a cutting blade supported by the deck. The index plate is fixedly secured to an offset rear axle. An engaging plate having a pawl is coupled to an actuating member which is slidably, vertically moveable relative to the deck when the operator grips the actuating member and pulls upwardly away from the deck, while resting a palm of the same hand on a palm rest portion of the mechanism. A linkage member couples the index plate to a bracket of an offset front axle positioned at a front end of the deck. The operator adjusts the height of the deck relative to a ground surface by pulling upwardly with the fingers of one hand on the actuating member, while resting the palm of the same hand on the palm rest. This causes the engaging plate, and thus the pawl thereon, to be drawn out of engagement with the teeth of the index plate. The operator, while holding the actuating member engaged, may either pull upwardly with the same hand, thus raising the entire deck of the mower, or may urge the deck into a lower position. Movement of the index plate causes a simultaneous rotational movement of the offset front axle. Thus, all four corners of the deck are caused to be raised or lowered simultaneously as the operator either lifts or lowers the deck while engaging the actuation member.

CROSS-REFERENCE TO RELATED APPLICATIONS 
The subject matter of the present application is related to U.S. patent 
application Ser. No. 29/027,102, filed Aug. 12, 1994, and entitled 
"Design: Lawn Mower", assigned to the assignee of the present application; 
and 
U.S. patent application Ser. No. 08/289,453, filed Aug. 12, 1994, and 
entitled "Lawn Mower Having Improved Handle To Deck Coupling Arrangement", 
assigned to the assignee of the present application. 
U.S. patent application Ser. No. 08/383,755, filed Feb. 2, 1995, and 
entitled "Mulching Lawnmower Having Volute Deck", assigned to the assignee 
of the present application. 
BACKGROUND OF THE INVENTION 
1. Technical Field 
This invention relates to lawn mowers, and more particularly to a lawn 
mower having a height adjustment mechanism for enabling an operator to 
adjust the height of a deck of a lawn mower relative to a ground surface 
at all the wheels of the lawn mower simultaneously by temporarily, 
manually engaging a single actuating member. 
2. Discussion 
Some form of deck height adjustment is common with virtually all lawn 
mowers. Typically, such deck height adjustment mechanisms incorporate an 
independent adjusting plate at each one of the four wheels of the mower. 
Some manually engageable release member is typically associated 
independently with each one of the adjusting plates and releasably 
engageable with its associated adjusting plate. Each adjustment plate, in 
turn, is usually fixedly secured to a portion of an offset axle supporting 
the wheel associated with the particular adjusting plate. When the release 
member is engaged, the offset portion of the axle is allowed to rotate 
which allows the vertical height of the wheel to be adjusted relative to 
the deck. Releasing the release member causes it to engage the adjusting 
plate, thus maintaining the adjusting plate stationary, and thereby 
maintaining the wheel at the desired position relative to the deck. By 
thus controlling the relative position of the wheel of the deck, the 
cutting height of the lawn mower blade can be adjusted relative to the 
ground. 
While the above arrangement has proved to be satisfactory for allowing the 
deck height of the mower to be adjusted relative to the ground surface at 
all four corners (i.e., wheels) of the lawn mower deck, this arrangement 
does provide for some inconvenience to the operator. To adjust the deck 
height, the operator must manually adjust the position of each adjustment 
plate, and thus each wheel, relative to the deck. Since four wheels are 
typically employed with most lawn mowers, the operator must typically make 
four independent deck height adjustments, one at each wheel of the mower, 
when the deck height is to be raised or lowered. 
More recently, improvements have been made to simplify the matter in which 
the deck of a lawn mower is adjusted to provide a greater degree of 
convenience to the operator. The assignee of the present application has 
utilized a form of deck height adjustment mechanism in which the operator 
is able to adjust the deck height of a mower relative to a ground surface 
by engaging a single deck height adjustment control. This system is 
embodied in a lawn mower manufactured by the assignee of the present 
application, and is disclosed in U.S. Pat. No. 5,230,208. The disclosure 
of this patent is hereby incorporated by reference into the present 
application. While the deck height adjustment mechanism disclosed in this 
patent has proved effective for increasing the ease with which the 
operator may adjust the deck height, it would be desirable to provide a 
mechanism which is even simpler and even less costly to manufacture, and 
which requires a fewer number of independent component parts to accomplish 
simultaneous adjustment of the deck height at all four wheels of the 
mower. 
Accordingly, it is an object of the present invention to provide a deck 
height adjustment mechanism for a lawn mower which allows an operator of 
the lawn mower to easily and conveniently adjust the height of the deck at 
all four wheels of the lawn mower simultaneously. More specifically, it is 
an object of the present invention to provide a deck height adjustment 
mechanism by which all four wheels of a lawn mower may be simultaneously 
adjusted for height relative to the deck of the mower by simply, 
temporarily engaging a single actuating member and subsequentially using 
the actuating member to lift or lower the deck to a desired position 
before releasing the actuating member, whereafter the height of the deck 
is maintained at the desired position relative to the ground. Such an 
arrangement would obviate the need to independently adjust the deck height 
at each one of the four wheels of the mower one at a time. 
It is yet another object of the present invention to provide a deck height 
adjustment mechanism for a lawn mower which allows the deck height to be 
adjusted at all four wheels of the lawn mower simultaneously with a single 
hand, and which is even simpler in construction and lower in cost to 
manufacture than previously existing deck height adjustment mechanisms. 
It is yet another object of the present invention to provide a deck height 
adjustment mechanism for a lawn mower having a manually, grippable 
actuating member which allows the height of the deck to be adjusted 
simultaneously at all four wheels of the lawn mower when the operator 
grippingly engages the actuating member while simultaneously lifting up on 
or lowering the deck to the desired height with the same hand. When the 
deck is positioned at the desired height, releasing the actuating member 
locks the position of the deck, and thus the height of the cutting blade, 
at the desired position simultaneously at all four wheels of the mower. 
SUMMARY OF THE INVENTION 
The above and other objects are accomplished by a lawn mower having an 
improved deck height adjustment mechanism in accordance with a preferred 
embodiment of the present invention. In the preferred embodiment, the 
present invention includes an index plate which is fixedly secured to one 
of an offset rear axle or an offset front axle. Merely as an example, in 
the preferred embodiment the index plate is fixedly secured to the rear 
axle. An actuating assembly having means for engaging the index plate and 
holding it stationary relative to the deck of the lawn mower is provided 
and positioned above the deck to even further increase the convenience of 
access to the user. The operator can quickly and easily uncouple (i.e., 
release) the actuating assembly from engagement with the index plate by 
gripping the actuating assembly and easily and quickly re-engage the index 
plate by releasing the actuating assembly. 
The index plate is mechanically coupled with the other one of the front or 
rear offset axles by a linkage member such that rotational movement of the 
index plate causes a corresponding rotational movement at the other one of 
the front or rear axles. In the preferred embodiment, the linkage member 
is coupled intermediate the index plate and the offset front axle of the 
lawn mower. Each of the front and rear offset axles further extend 
width-wise across the deck to support a pair of the wheels of the mower. 
In the preferred embodiment, the rear offset axle supports the rear wheels 
of the lawn mower for rotational movement relative to the deck, while the 
front offset axle supports the front wheels of the lawn mower for 
rotational movement relative to the deck. 
When the operator grippingly engages the actuating assembly, the actuating 
assembly is drawn out of engagement with the index plate, thus allowing it 
to rotate in accordance with the offset rear axle, and thus allowing the 
vertical position of the two rear wheels to be adjusted relative to the 
deck. Simultaneously, the linkage member couples the rotational movement 
of the index plate to the offset front axle, thus causing a corresponding 
rotational movement of the offset front axle. The simultaneous rotational 
movement of the front and rear offset axles thus adjusts the height of the 
entire deck at all four wheels relative to a ground surface supporting the 
four wheels. 
When the operator achieves the desired deck height, the operator releases 
the actuating assembly which causes it to reengage with the index plate. 
This maintains the index plate stationary relative to the deck and 
prevents further vertical movement of the four wheels. In this manner, the 
height of the deck, and thus the height of the cutting blade relative to 
the ground surface, can be quickly, easily and conveniently controlled by 
the use of a single hand which simultaneously engages the actuating 
assembly and either lifts or lowers the deck while the actuating assembly 
is held in its engaged position. 
In a preferred embodiment, the index plate further includes a pair of 
shoulder portions spaced vertically apart from one another to define first 
and second mounting positions for the offset rear axle. In the first 
mounting position, the offset rear axle is positioned to accept a first 
diameter wheel, for example, a wheel having a diameter of 7 inches. When 
the offset rear axle is fixedly secured to the second shoulder portion, 
and therefore in the second position, the offset rear axle is held in a 
position closer to a bottom-most edge of the deck to provide for a greater 
minimum ground clearance when a smaller diameter wheel is used, such as a 
six inch diameter wheel. Thus, the first and second shoulder portions 
enable the offset rear axle to be secured in two positions without any 
additional component parts being secured to the index plate. Thus, a 
single index plate can be used for mowers having different rear wheel 
diameters. It will be appreciated that this represents an important 
manufacturing advantage in that multiple index plates need not be 
manufactured to accommodate wheels of differing diameters. 
In a preferred embodiment, the linkage member further includes an indicator 
which moves in accordance with the movement of the linkage member to 
provide a visual indication to the operator as to the current deck height 
position. A preferred embodiment of the lawn mower includes a shroud 
having a portion adjacent the indicator which includes suitable indicia 
for enabling the current deck height setting of the lawn mower to be read. 
It is a principle advantage of the deck height adjustment mechanism of the 
present invention that an even simpler, less costly height adjustment 
mechanism having fewer component parts over prior developed mechanisms is 
provided. The deck height adjustment mechanism of the present invention 
provides a further advantage of not adding appreciably to the overall 
cost, size or weight of the lawn mower while significantly increasing the 
ease and convenience with which the deck height may be adjusted by an 
operator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, a vegetation cutter in the form of a lawn mower 10 is 
shown which incorporates a deck height adjustment mechanism 12 in 
accordance with a preferred embodiment of the present invention. The lawn 
mower generally includes a removable shroud 14 secured to a deck 16. The 
deck is supported above a ground surface 18 by a pair of rear wheels 20a 
and 20b and a pair of front wheels 22a and 22b. The lawn mower 10 is 
traversed over the ground surface 18 by the operator gripping a handle 
member 24 near a top portion thereof (not shown) and pushing the lawn 
mower, if the lawn mower is not of the self-propelled variety, or simply 
steering the lawn mower as needed if the lawn mower is of the 
self-propelled variety. It will be appreciated that while the mechanism of 
the present invention has been described in connection with a lawn mower, 
that the mechanism 12 could easily be adapted with little or no 
modification for use with a wide variety of vegetation cutters having at 
least two wheels. The mechanism 12 can provide quick and easy height 
adjustment on virtually any form of vegetation cutter where it is 
important to have corresponding height adjustments made at the front and 
rear wheels of the cutter. Still further, the adjustment mechanism 12 of 
the present invention can be used with little or no modification with 
cordless (i.e., battery powered) mowers, "corded" mowers driven by an AC 
power source, bagging mowers, discharge mowers, mulching mowers and 
self-propelled mowers, or a combination thereof. 
With further reference to FIGS. 1 and 2, the shroud 14 includes an opening 
26 through which an actuating member 28 of the deck height adjustment 
mechanism 12 protrudes. As will be described more fully in connection with 
FIGS. 2-9, the deck height adjustment mechanism 12 allows the operator to 
adjust the height of the deck 16 relative to the ground surface 18 by 
merely grippingly urging a gripping portion 28a of the actuating member 28 
upwardly in a generally linear path of movement, relative to the ground 
surface 18, and holding the member 28 engaged while lifting or lowering 
the deck 16 with the same hand. Thus, there is no need to make separate 
deck height adjustments at all four wheels of the mower 10 as would be 
required with most prior deck height adjustment systems. By using a single 
hand, the operator is able to simultaneously adjust the deck height at all 
four wheels 20a, 20b and 22a, 22b of the lawn mower 10. The actuating 
member 28 is further positioned well above the rear wheel 20a so that the 
operator is not required to bend over to a significant degree to make a 
deck height adjustment. The positioning of the actuating member 28 
therefore adds significantly to the comfort and convenience of making 
height adjustments of the deck 16. 
Referring now to FIGS. 2-4, the component parts of the deck height 
adjustment mechanism. 12 can be seen even more clearly. The mechanism 12 
generally includes an index plate 30, a linkage member 32 pivotally 
secured to a pivotal mounting portion 31 of the index plate 30 at an 
aperture 32d of a first end 32a of the linkage member 32, an actuating 
assembly comprising an engaging member 34 and the actuating member 28, and 
a palm rest 36. The index plate 30 is physically coupled to an offset 
portion 38 of an offset rear axle 40 of the lawn mower 10, as shown in 
FIG. 3. The index plate 30 is preferably fixedly secured, such as by 
welding, to the offset portion 38 and includes a notched portion 42 for 
receiving a portion of the offset rear axle 40. By this arrangement, 
rotational movement of the offset portion 38 of the rear axle 40 causes a 
corresponding rotational movement of the index plate 30. With further 
reference to FIG. 2, a second end 32b of the linkage member 32 extends 
through an opening 14a in the shroud 14 and through an opening 16c in the 
deck 16, as shown in FIG. 3. The linkage member 32 has fixedly secured 
thereto a height indicator 33. The height indicator is shown disposed 
closely adjacent where the front wheel 22a would be mounted, but it will 
be appreciated that its placement could just as well be at almost any 
point along the length of the linkage member 32. It will also be 
appreciated that the height indicator 33 could just as well be placed on 
any other moving component part of the adjustment mechanism 12, such as 
the index plate 30 or a bracket 48 (to be discussed) associated with a 
front axle 44 (also to be discussed). In these instances, any indicia also 
used to help visually indicate the present deck 16 height will preferably 
be located closely adjacent the height indicator 33 on a stationary 
component of the lawn mower 10. 
With further reference to FIG. 2, the shroud 14 also preferably includes 
some form of indicia 35, such as a label, disposed on a portion thereof 
for cooperating with the indicator 33 to provide an immediate visual 
indication as to the height that a cutting blade (not shown) housed 
underneath the deck 16 is presently set at for any given deck height. As 
will be appreciated, the indicia 35 could be in the form of inches, 
millimeters, etc. 
With specific reference to FIG. 3, the entire construction of the rear axle 
40 can be seen. Since the rear axle 40 is a single-piece component which 
extends across the entire width of the deck 16 and supports both of the 
rear wheels 20a and 20b, rotational movement of the offset portion 38 
allows the vertical height of both rear wheels 20a and 20b to be 
simultaneously varied relative to the deck 16, in addition to varying the 
position of the index plate 30 relative to the deck 16. 
With further brief reference to FIG. 2, it will be appreciated that an 
offset front axle 44 is provided for supporting the two front wheels 22a 
and 22b. Fixedly secured (as by welding) to an offset portion 46 of the 
front axle 44 is a bracket 48 similar in shape to the index plate 30. The 
second end 32b of the linkage member 32 is pivotally coupled via an 
aperture 32e to a pivotal mounting portion 48a of the bracket 48 such that 
rotational movement of the index plate 30 causes a corresponding 
rotational movement of the offset portion 46 of the offset front axle 44. 
This, in turn, causes the vertical position of both front wheels 22a and 
22b, relative to the deck 16, to be changed in accordance with the degree 
of vertical adjustment provided at the rear wheels 20a and 20b. As shown 
in FIG. 3, it will be appreciated that the construction of the offset 
front axle 44 is similar to the offset rear axle 38 in order to provide 
relatively consistent height adjustment from front to back of the mower 10 
throughout the adjustment range. 
With brief reference to FIGS. 8 and 9, to aid in lifting the deck 16 during 
an adjustment, an elongated coil spring 49 is preferably included. The 
spring 49 is secured to the linkage member 32 through an aperture 32c, 
and, via an aperture 24b, to a tab portion 24a (FIG. 3) of one handle bar 
of the handle member 24. The biasing force of the spring 49, which is 
under constant tension, assists in urging the linkage member 32 to the 
left in the drawings of FIGS. 3, 8 and 9, and therefore rotating the index 
plate 30 counter-clockwise to thus help lift the deck 16 when the 
actuating member 28 is lifted to its disengaged position. This operation 
will be described in greater detail in connection with FIG. 8 and the 
operation of the mechanism 12. 
With continued reference to FIGS. 3, 4, 5 and 7, the engaging member 34 is 
disposed for sliding movement within a channel 50 (FIG. 3), integrally 
formed in a sidewall portion 52 of the deck 16. The engaging member 34 
includes a "pawl" 54 formed from a punched out section 56 thereof. The 
pawl 54 further includes a tooth 54a protruding laterally therefrom, as 
best seen in FIG. 4. The pawl 54 is positioned such that it is disposed 
closely adjacent a plurality of teeth 30a of the index plate 30 so that 
when the engaging member 34 is urged slidably into its lowermost position, 
the tooth 54a is in interlocking engagement between an adjacent pair of 
teeth 30a to thus maintain the index plate 30 stationary. The teeth 30a 
define a plurality of predetermined cutting blade height positions. A slot 
54b is also provided to allow a lower end portion 54c to fit over a 
portion of the offset rear axle 40, to thus provide horizontal stability 
of the engaging member 34, while allowing vertical sliding movement. 
With specific reference to FIG. 5, the coupling of the engaging member 34 
and the actuating member 28 can be seen, together with the construction of 
the palm rest 36 relative to the deck 16. The palm rest 36 includes an 
upper surface portion 36a against which a palm of a hand is placed when 
the actuating member 28 is to be engaged. The palm rest 36 includes a 
generally hollow bottom portion 58 from which a pair of integrally formed 
outward locating posts 60 and a centrally disposed boss portion 62 
project. A mounting portion 64 projects generally laterally of the 
locating posts 60 and includes a semicircular cut-out 66 and a pair of 
somewhat flexible arm members 67. The palm rest 36 is integrally formed as 
a single-piece component, and preferably from a high-strength plastic. 
With continued reference to FIG. 5, the actuating member 28 includes a pair 
of tubular locating posts 68 positioned to slidably accept the locating 
posts 60, and a central mounting post 70 positioned between the tubular 
locating posts 68. A biasing member in the form of a coil spring 72 is 
positioned between the palm rest 36 and the actuating member 28 such that 
an upper end 72a is held within the central boss portion 62, and a lower 
end portion 72b fits over an upper portion 70a of the central mounting 
post 70. In this manner, the spring 72 is held captively under compression 
between the palm rest 36 and the actuating member 28 when the height 
adjustment mechanism 12 is assembled, and provides a biasing force against 
the actuating member 28 to hold the pawl 54 in a normally downwardly 
biased position in engagement with the index plate 30. 
With further reference to FIGS. 4, 5 and 7, the engaging member 34 includes 
a cut-out portion 74 at an upper end portion 76 thereof. When assembling 
the actuating member 28 and the engaging member 34, the upper end portion 
76 is slidably inserted into a main body portion 78 of the actuating 
member 28. With specific reference to FIG. 7, the actuating member 28 
includes a tapered rib portion 80 projecting from a locking arm member 82 
which is integrally formed with the main body portion 78 of the actuating 
member 28. The tapered rib portion 80 is shaped so as to lockably engage 
the cut-out portion 74 as the upper end portion 76 of the engaging member 
34 is slidably inserted into the main body portion 78 of the actuating 
member 28. 
With specific reference to FIG. 5, to further help maintain the coupling of 
the engaging member 34 with the actuating member 28, a pair of lip members 
84 are also preferably integrally formed with the main body portion 78 so 
as to form a channel 86 into which the upper end portion 76 of the 
engaging member 34 is inserted. Optionally, an aperture 88 is provided in 
the upper portion 76 of the engaging member 34 together with a slot 90 
(FIG. 4) in the main body portion 78 of the actuating member 28. A 
threaded fastener may be inserted through the slot 90 and the aperture 88 
to even more securely hold these two component parts together. 
With specific reference to FIG. 6, the mounting portion 64 of the palm rest 
36 is coupled to a portion 92 of the tubular handle member 24 via a 
conventional threaded fastener 94 (or other form of fastener), shown in 
phantom, which extends through apertures (not shown) in the tubular handle 
member, through an aperture 96 in the mounting portion 64, and through an 
aperture 97 in a handle support portion 99 of the deck 16. A conventional 
threaded nut 98 or other fastener may be used together with the threaded 
fastener 94 to securely hold the palm rest 36 to the portion 92 of the 
handle member 24. The arm portions 67 may be used to help engage one or 
more electrical cables running parallel to the length of the tubular 
handle member 24. 
Referring now to FIGS. 2, 3 and 8, to adjust the deck height of the lawn 
mower 10 to a higher position of height relative to the ground surface 18, 
the operator places his/her palm on the palm rest 36, places the fingers 
of the same hand over the gripping portion 28a of the actuating member 28 
and lifts up on the actuating member 28 against the biasing force of the 
spring 72, thus causing the pawl 54 to be slidably released from 
engagement with the teeth 30a of the index plate 30. While the engaging 
member 34 and the pawl 54 are held in an upper, released position by the 
operator, the operator may lift upwardly on the deck 16 via the actuating 
member 28 with the same hand. The biasing force provided by the spring 49 
provides an assist to the operator in lifting the weight of the deck 16. 
As the operator lifts upwardly, the index plate 30 is urged rotatably in a 
counter-clockwise direction, as viewed in FIG. 8, by the rotation of the 
offset portion 38 of the offset rear axle 40. Simultaneously, the linkage 
member 32 urges the bracket 48 counter-clockwise a corresponding degree 
which, in turn, causes the offset portion 46 of the offset front axle 44 
to be rotated by a corresponding degree. In this manner, the axis of 
rotation of the rear wheels 20a and 20b and the axis of rotation of the 
front wheels 22a and 22b are lowered relative to a lower edge surface 16b 
of the deck 16. Put differently, the lower edge surface 16b of the deck 
16, and thus a cutting blade 17 housed within the deck 16, are raised 
relative to the axis of rotation of all four wheels 20a, 20b and 22a, 22b 
of the lawn mower 10. The orientation of the wheels 20a, 20b and 22a, 22b, 
the index plate 30, the engaging member 34, the actuating member 28 and 
the linkage member 32 are shown in FIG. 8 when the deck 16 is in its 
maximum height position relative to the ground surface 18. 
To maintain the deck 16 at the position shown in FIG. 8, the operator 
merely releases the actuating member 28 once the deck is positioned at the 
desired height relative to the ground surface 18. Releasing the actuating 
member 28 causes the actuating member 28, and thus the pawl 54, to be 
urged downwardly by the spring 72 to engage between the right-most pair of 
teeth 30a of the index plate 30, as viewed in FIG. 8. The index plate 30, 
and thus the axis of rotation of all four wheels 20a, 20b and 22a, 22b 
will be maintained at this desired position until the operator readjusts 
the height of the deck 16. 
With brief reference to FIG. 9, the orientation of the above mentioned 
components and the position of the deck 16 relative to the ground surface 
18 is shown with the deck 16 height adjusted to its lower most position 
relative to the ground surface 18. This is achieved by gently urging the 
palm of the hand positioned on palm rest 36 downwardly, while holding the 
actuating member 28 engaged with the fingers of the same hand. In the 
lower most position, the index plate 30 is held in its clockwise-most 
position by engagement of the pawl 54 between the left-most pair of teeth 
30a of the index plate 30, after the operator releases the actuating 
member 28. 
With brief reference again to FIGS. 3, 4 and 8, the index plate 30, in the 
preferred embodiment, includes an upper shoulder portion 100 defining a 
first axle position and a lower shoulder portion 102 defining a second 
axle position. In the figures, the offset portion 38 of the offset rear 
axle 40 is shown fixedly secured to the lower shoulder portion 102, which 
places the rear wheels 20a, 20b in the second position relative to the 
deck 16, and thus positions the deck 16 in a second position relative to 
the ground surface 18. When the offset portion 38 is secured fixedly to 
the first shoulder portion 100, the rear wheels 20a,20b are supported in 
the first position relative to the deck 16 which positions the deck 16 in 
a first position relative to the ground surface 18 which is closer to the 
ground surface for any given position of the index plate 30 than it would 
be when the offset portion 38 is secured to the second shoulder portion 
102. Accordingly, a single index plate 30 may be used with wheels of 
differing diameters provided it is known in advance of assembly of the 
lawn mower 10 the diameter of the rear wheels 20a, 20b to be employed. As 
an example, when seven inch diameter rear wheels 20a, 20b are used, the 
offset rear axle 38 may be fixedly secured to the upper shoulder portion 
100. When a six inch diameter wheel is to be used, the offset rear axle 38 
may be fixedly secured to the lower shoulder portion 102, thus allowing a 
similar degree of minimum ground clearance to be provided as when the 
larger diameter rear wheels 20a, 20b are used. It will be appreciated by 
those of ordinary skill in the art that this feature represents a 
significant manufacturing advantage in that only a single index plate 30 
need be used for the lawn mower 10, regardless if the lawn mower 10 is to 
be assembled with rear wheels 20a, 20b having diameters which may vary 
from between two predetermined, desirable wheel diameters. This further 
obviates the need to modify the linkage member 32 and the deck height 
indicator 33 to ensure consistent deck height indications when rear wheels 
20a, 20b having differing diameters are employed. 
From the above, it will be appreciated that the height adjustment mechanism 
12 of the lawn mower 10 represents a significant improvement over prior 
designs by requiring fewer component parts, generally less complicated 
construction and generally greater ease of operation. The deck height 
adjustment mechanism 12 of the present invention further does not add 
appreciably to the overall cost of the lawn mower 10, nor does it tangibly 
increase the overall outer dimensions of the lawn mower 10 or its overall 
weight. Because of the simplified construction of the mechanism 12, 
reliability of operation is also improved. 
Those skilled in the art can now appreciate from the foregoing description 
that the broad teachings of the present invention can be implemented in a 
variety of forms. Therefore, while this invention has been described in 
connection with particular examples thereof, the true scope of the 
invention should not be so limited since other modifications will become 
apparent to the skilled practitioner upon a study of the drawings, 
specification and following claims.