Metal working – Method of mechanical manufacture – Repairing
Reexamination Certificate
1999-07-15
2001-08-21
Echols, P. W. (Department: 3726)
Metal working
Method of mechanical manufacture
Repairing
C029S402030, C029S402040, C029S402060, C056S229000, C056S289000
Reexamination Certificate
active
06276039
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to lawn mowers of the type having a housing with a cutting blade mounted on a shaft journalled for rotation in the housing and, more particularly, to a clamp assembly which can be used to limit rotation of the cutting blade, as to facilitate safe handling of the blade during assembly, disassembly and reconditioning thereof. The invention is also directed to a method of using the clamp assembly.
2. Background Art
Elongate cutting blades are used on a wide range of lawn mowing equipment. One typical lawn mower construction utilizing an elongate blade has a fixed housing mounted on wheels and manipulated through a push-type handle. The housing defines a cutting chamber within which a cutting blade is mounted. The cutting blade is mounted on a shaft which is journalled for rotation in the housing.
In another construction, decks, with one or more cutting blades, are mounted on a vehicle, such as a tractor. The deck has a housing with at least one chamber for a cutting blade. On decks having multiple blades, typically each cutting blade is mounted upon a shaft on the housing that projects upwardly therethrough to allow a pulley to be mounted on the shaft. One or more belts can be used to engage the pulleys and simultaneously drive the shafts and the cutting blades thereon.
Periodically, cutting blades need to be accessed to effect removal and/or reconditioning thereof. In a typical blade mount, the shaft has an enlarged fitting on the end which accommodates one or multiple bolts. A blind bore on the fitting has an axis that is coincident with the rotary axis for the shaft. Two diametrically opposite through bores are provided to accept a like number of bolts to prevent rotation of the blade relative to the fitting around the shaft axis.
There are a number of dangers associated with cutting blade maintenance. The cutting blade is free to rotate about the shaft axis during this maintenance. By attempting to tighten or loosen the mounting bolts, an individual may inadvertently rotate the cutting blade around the axis of the shaft. This could cause inadvertent and harmful contact between the cutting blade and the individual.
Often, individuals securing or removing a cutting blade may directly grasp the cutting blade with one hand while manipulating a wrench with the other hand. A torque exerted, principally upon the center bolt which coincides with the shaft axis, tends to rotate the shaft and the cutting blade. If the user exerts a substantial torque on the wrench, the hand holding the blade may be cut thereby.
Aside from the physical dangers, the individual holding the blade may not be able to hold the blade with sufficient force to allow the bolts to be properly tightened or loosened.
A more serious problem is that a torque applied to the cutting blade may cause inadvertent ignition of the engine driving the cutting blade, with potentially severe consequences.
To address these problems, various mechanisms have been devised for limiting rotation of a cutting blade relative to a deck/housing. Examples of these structures are shown in each of U.S. Pat. Nos. 4,564,991 (Taylor); 4,208,859 (Brockway); 5,865,018 (Wanie); 3,173,234 (Vodinelich); and 4,882,960 (Kugler).
In U.S. Pat. No. 4,956,905 (Davidson) a structure is shown for allowing a user to exert a force to limit rotation of the cutting blade without directly contacting the cutting blade.
SUMMARY OF THE INVENTION
In one form, the invention is directed to the combination of a lawn mower assembly and a clamp assembly. The lawn mower assembly has a housing defining a cutting chamber, a shaft journalled for rotation in the housing around an axis, and a cutting blade that is selectively a) releasably attached to the shaft to rotate with the shaft in a predetermined path around the shaft axis and b) separable from the shaft as to facilitate reconditioning or replacement of the cutting blade. The clamp assembly includes a first jaw having a first surface and a second jaw having a second surface. The second jaw is movable relative to the first jaw between i) a first relative position wherein the first and second surfaces are spaced from each other a first distance and ii) a second relative position wherein the first and second surfaces are spaced from each other a second distance that is less than the first distance. The second jaw is movable relative to the first jaw between the first and second relative positions by guided movement of the second jaw relative to the first jaw. One of the first and second jaws has a blocking surface thereon. The clamp assembly can be situated in an operative position on the lawn mower assembly wherein, with the second jaw in the second relative position, the first and second jaws captively, grippingly engage the housing and the blocking surface resides in the predetermined path of the cutting blade to thereby prevent free rotation of the cutting blade relative to the housing.
The clamp assembly may further have first and second grip elements that are graspable by a hand of a user and movable relative to each other to move the second jaw from the first relative position into the second relative position.
In one form, the grip elements are repositionable relative to each other between a gripping state and a release state. The first and second grip elements are graspable by a hand of a user and movable towards each other to change the grip elements from the release state into the gripping state. The second jaw moves from the first relative position into the second relative position as an incident of the grip elements repositioning from the release state into the gripping state.
The blocking surface may be defined by wood, rubber, plastic, or other like material.
The clamp assembly may further include a locking linkage which releasably maintains the second jaw in the second position without the user's having to grasp the grip elements.
The locking linkage may be engaged to maintain the second jaw in the second position as an incident of the grip elements being repositioned from the release state into the gripping state.
The locking linkage may have a plurality of links which, with the locking linkage engaged, assume an over center position to thereby maintain the second jaw in the second relative position.
The blocking surface may be defined by a squared piece of material having a length and a cross-sectional area taken transversely to the length.
In one form, the cross-sectional area of the squared piece of material is at least four inches.
The length of the squared piece of material may be at least four inches.
The first and second jaws may each have a “C” shape.
One of the first and second jaws may have an elongate strap, with there being a piece of material attached to the strap to define the blocking surface.
The invention is also directed to a method of working on a lawn mower blade that is mounted on a housing for rotation in a predetermined path. The method includes the steps of providing a clamp assembly having a first jaw with a first surface and a second jaw with a second surface, with the second jaw being movable by guided movement relative to the first jaw between a) a first relative position wherein the first and second surfaces are spaced from each other a first distance and b) a second relative position wherein the first and second surfaces are spaced from each other a second distance that is less than the first distance. The method may further include the step of placing a part of the housing between the first and second jaws with the second jaw in the first relative position and thereafter placing the second jaw in the second relative position so that the first and second jaws captively, grippingly engage the part of the housing to maintain the clamp assembly in an operative position on the housing, wherein the clamp assembly resides in the predetermined path of the cutting blade. The method may further include the step of performing an operation on the cutting blade with the clamp assembly in the operative posi
Echols P. W.
Hong John C.
Wood Phillips VanSanten Clark & Mortimer
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