Harvesters – Motorized harvester – Having motor on ground-supported carrier
Reexamination Certificate
2003-03-28
2004-05-04
Pezzuto, Robert E. (Department: 3671)
Harvesters
Motorized harvester
Having motor on ground-supported carrier
C280S043130
Reexamination Certificate
active
06729116
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to height adjustment for wheel assemblies, and more particularly to height adjustment in relation to structures utilizing caster wheels. The invention is particularly advantageous as applied to mobile equipment employing caster wheels such as lawnmowers.
BACKGROUND ART
Power equipment such as lawnmowers typically include a set of three or four wheels to support the equipment or a main structure thereof on the ground and to enable the equipment to be rolled along the ground. In the case of lawnmowers, and particularly walk-behind lawnmowers of either the self-propelled or manually pushed type, the main structure for which wheels are provided includes a mower deck to which a motor and cutting blades are mounted. The wheel set often includes one or two front wheels located at the front of the main structure and one or two rear wheels located at the rear of the main structure. Typically, the front and rear wheels are directly coupled to the mower deck, and often are rendered adjustable relative to the mower deck to provide a means by which the height of the mower deck relative to the ground can be adjusted. This height adjustment enables an operator of the lawnmower to cut grass or other vegetation to a desired height.
The means for height adjustment typically constitutes a lever and bracket mounted between each wheel and the mower deck. Adjustment of the lever to a selected position on the bracket, usually by rotating or pivoting the lever to engage a selected notch or aperture of the bracket, changes the angle of the lever relative to the mower deck. The lever is typically interfaced with the mower deck such that changing the angle of the lever changes the angle and spacing of the wheel relative to the mower deck. A lever and bracket can be provided for each wheel, necessitating the individual adjustment of each wheel to attain a desired, level height of the entire mower deck relative to the ground. In the case of a pair of front or rear wheels interconnected by a common axle, a similar means for adjusting the axle position relative to the mower deck can be implemented to adjust both front or rear wheels simultaneously.
In some lawnmowers, the front or rear wheels are provided in the form of caster wheels to improve maneuverability of the lawnmower. For three-wheel lawnmowers, one end (i.e., front or back) of the mower deck includes a pair of fixed-position wheels while the opposite end includes a single caster wheel. For four-wheel lawnmowers, a pair of caster wheels is usually mounted at the front of the mower deck and a pair of fixed-position wheels is mounted at the rear. For instance, a lawnmower equipped with one or two front-mounted caster wheels can be easily steered or turned left or right without having to first lift the front of the mower deck and front wheels off the ground, and without having to drag fixed-position wheels along the ground. As is appreciated by persons skilled in that art, a caster wheels, the caster wheel rotates about the horizontal axis that is generally axis of rotation and a horizontal rolling axis of rotation. Like fixed-position wheels, the caster wheel rotates about the horizontal axis that is generally parallel with the ground, enabling the lawnmower to be rolled forwardly or backwardly along the ground. Unlike fixed-position wheels, however, the caster wheel additionally rotates about the vertical axis, i.e., an axis perpendicular or substantially perpendicular to the ground that allows the caster wheel to be steered or swiveled, thereby enabling the rolling direction of the lawnmower to be changed to the left or to the right.
As is appreciated by persons skilled in the art, in order for a caster wheel-equipped lawnmower to be steered or turned properly, the verticality of the swivel axis of each caster wheel must be maintained. This limitation poses challenges to successfully rendering a caster wheel adjustable relative to mower deck height or, equivalently, rendering a mower deck adjustable relative to caster wheel height. For instance, a conventional lever that changes the angle between a wheel and a deck is unsuitable for use with a caster wheel, since such a lever would cause the swivel axis to deviate from the vertical and impair or even defeat the ability of the caster wheel or wheels to render the lawnmower steerable.
Accordingly, the adjustment means for a caster wheel is preferably designed to adjust the height of the horizontal rolling axis of the caster wheel, without altering the vertical orientation of its swivel axis. In the past, height adjustment for caster wheels has been addressed in a number of ways that have required undue complexity in terms of mechanical design, the use of tools, and/or an excessive expenditure of time. The difficulty presented in providing height-adjustable caster wheels is demonstrated by systems disclosed in the prior art. For example, in one known height-adjustment system, each caster wheel must be locked to prevent rotation and then adjusted individually through a traditional lever and bracket arrangement. In another known system, each wheel must be unbolted from the mower deck and then rebolted into new holes of the mower deck.
In another example, U.S. Pat. No. 4,942,726 to Bowditch discloses a lawnmower with two front-mounted, height-adjustable caster wheels. A pivotable lever is mounted on one side of the adjacent to the lever is a vertical plate that is provided with a series of notches. A pin extending transversely from the lever engages one of the notches to fix the lever in position and thus fix the height of the caster wheels relative to the mower deck. To adjust the height of the caster wheels relative to the mower deck, the lever is pivoted so as to move its pin into engagement with one of the notches of the vertical plate. The arrangement of the lever interfaced with the notched vertical plate is similar to conventional means for adjusting the height of fixed-position wheels, and is characterized by similar disadvantages. For lawnmowers of typical size and weight, the operator must use one hand to lift the mower deck to support its weight while using the other hand to operate the lever. Because the lever and associated vertical bracket are located at one side of the mower deck and operate to adjust both caster wheels simultaneously, the weight of the mower deck must be balanced while forcefully moving the lever from one notch of the bracket to another notch. Moreover, the protruding, exposed structure of the lever renders the lever susceptible to being jarred or knocked out of engagement with the desired notch and into re-engagement with a new notch, with the result that the mower deck is unintentionally adjusted to an undesired height during operation and out of agreement with the height relative to the other wheels. This problem has conventionally been addressed by constructing the lever from a stiff spring material that requires additional effort to be adjusted from one notch to another notch, further necessitating the use of both hands or otherwise increasing the effort required for effecting height adjustment of the caster wheels.
In U.S. Pat. No. 5,065,568 to Braun et al., a lawnmower with two front-mounted, height-adjustable caster wheels is disclosed in which a single crank handle mechanism mounted centrally at the front of the mower deck operates to adjust the height of the entire mower deck relative to both the caster wheels and the rear fixed-position wheels. The interface between the caster wheels, the crank handle mechanism, and the mower deck consists of an elaborate assembly including a transverse bar, hook brackets, push arms, a vertical rear plate, a tie rod, a central arm, a central linkage assembly, and a bell crank. To adjust the height of the caster wheels relative to the mower deck, the crank handle mechanism is turned by the operator, causing a number of interactions among the various afore-mentioned components and resulting in the raising or lowering of the mower deck. It can thus be seen that this height
Graus George B.
Hojo Hiroshi
Keane James C.
Honda Giken Kogyo Kabushiki Kaisha
Jenkins & Wilson & Taylor, P.A.
Pezzuto Robert E.
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