Harvesters – Motorized harvester – Having motor on ground-supported carrier
Reexamination Certificate
2000-03-17
2001-09-11
Pezzuto, Robert E. (Department: 3671)
Harvesters
Motorized harvester
Having motor on ground-supported carrier
C056S255000, C056S295000
Reexamination Certificate
active
06286293
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to lawn mowers and, more particularly, to a lawn mower cutting blade spindle assembly which includes a cutting blade that can withstand impact loading and that can easily be detached from the mower without disturbing the pre-set compression applied to the other components of the spindle assembly.
Conventional lawn mowers utilize a rotatable cutting blade mounted underneath the mower's cutting deck to cut grass, vegetation and the like. Typically in commercial lawn mowers, the cutting blade is attached to the lower end of an elongate spindle shaft that is vertically supported by various bearings and bearing spacers within a spindle housing carried by the mower frame. The upper end of the spindle shaft projects above the spindle housing and has a pulley attached thereto that is configured to receive a drive belt connected to the mower's engine. In operation, the engine activates the drive belt to generate rotation of the pulley, which in turn causes rotation of the spindle shaft, which in turn causes rotation of the cutting blade to thereby cut the grass.
Periodically, the user of such a lawn mower will find it necessary to detach the cutting blade from the mower for the purpose of sharpening the blade, adjusting the height of the cut, or for general maintenance purposes. Therefore, most commercial lawn mowers are designed such that the user can easily detach the cutting blade from the spindle shaft to perform the required maintenance, and then reattach the cutting blade to the spindle shaft after such maintenance has been performed. Preferably, this detachment/reattachment process can be done in the field using ordinary tools.
Some lawn mowers are designed such that the cutting blade is attached to the mower with a short bolt that passes through the cutting blade and into a tapped end of the spindle shaft. The user of the mower can easily detach the cutting blade from the mower by simply unscrewing the short bolt out of the spindle shaft, and can reattach the cutting blade to the mower by screwing the short bolt back into the spindle shaft. One problem with this design, however, is that the short bolt is prone to breakage when the cutting blade encounters thick vegetation, tree branches, stones, or other large objects that can retard or prevent rotation of the cutting blade. Even if the short bolt does not break, the threading in the tapped end of the spindle shaft may become stripped due to the relative movement between the spindle shaft and cutting blade upon impact loading. In either case, damage to the spindle assembly will necessarily result in failure of the lawn mower.
In an attempt to overcome these problems, some lawn mowers have been designed which utilize a longer bolt to attach the cutting blade to the mower. For example, in U.S. Pat. No. 5,782,073 to Sheldon, an elongate bolt passes through the cutting blade and extends upwardly through a longitudinal bore formed on the inside of the spindle shaft. A nut tightened onto the bolt at its upper end is used to attach the cutting blade to the spindle shaft. This longer bolt is not likely to break when the cutting blade strikes a large object. In addition, the nut can be sufficiently tightened onto the threaded upper end of the bolt to prevent relative movement between the cutting blade and spindle shaft upon impact loading.
While use of a longer bolt as disclosed in the Sheldon patent overcomes the problems associated with “short bolt” mowers, it has other shortcomings which can lead to failure of the mower. In particular, the nut that is used to attach the cutting blade to the spindle shaft is also used to compress the pulley and bearing assembly against the spindle shoulder. As such, the compression applied to the pulley and bearing assembly is lost whenever the nut is unscrewed to detach the cutting blade from the spindle shaft. Experience has shown that if the nut is not sufficiently tightened onto the bolt when the cutting blade is reattached to the spindle shaft, the pulley and bearing assembly will become loose and fail due to premature wear. Thus, this mower design is also vulnerable to failure.
SUMMARY OF THE INVENTION
Therefore, in view of the problems associated with the above types of lawn mowers, it is an object of the present invention to provide a lawn mower cutting blade spindle assembly which includes a cutting blade that 1) can easily be detached from and reattached to the mower in the field with the use of ordinary tools, 2) can withstand impact loading, and 3) can be detached from and reattached to the mower without disturbing the compression applied to the other components of the spindle assembly.
These and other objectives are met by the lawn mower cutting blade spindle assembly of the present invention. The spindle assembly comprises a spindle housing configured to mount to the frame of a lawn mower. Mounted within the housing is a spindle including an elongate spindle shaft and a spindle shoulder projecting radially outward from the lower end thereof Also mounted within the housing is a bearing assembly which provides rotational support for the spindle.
Mounted on the upper end of the spindle shaft is at least one pulley which is configured to receive a drive belt connected to the mower's engine. The pulley has a mounting hub extending therebelow that is insertable over the upper end of the spindle shaft. In a preferred embodiment, the mounting hub has a splined opening that is designed to mate with a splined neck portion on the upper end of the spindle shaft. As such, the spindle shaft is fixed for rotation with the pulley.
The spindle assembly also includes a compression nut that can be screwed onto the upper end of the spindle shaft and tightened down against the bottom wall of the pulley mounting hub. As the compression nut is tightened, the bottom wall of the pulley mounting hub pushes down against the bearing assembly, which pushes down against and abuts the top face of the spindle shoulder. The torque applied to the compression nut should be sufficient to maintain the pulley and bearing assembly in compression between the compression nut and spindle shoulder so as to prevent these components from becoming loose and failing due to premature wear. Preferably, this process takes place during the initial factory assembly (or perhaps thereafter during service work performed in a maintenance shop) to ensure that the proper torque is applied thereto.
The spindle assembly has a cutting blade attached thereto, and to the mower, with an elongate through-bolt that passes through the cutting blade and extends upwardly through a longitudinal bore formed on the inside of the spindle shaft. A cutting blade attachment nut can be screwed onto the threaded upper end of the through-bolt to attach the cutting blade to the bottom face of the spindle shoulder. The torque applied to the cutting blade attachment nut can be any reasonable torque that fixes the cutting blade to the spindle for rotation therewith. As such, the process of detaching and reattaching the cutting blade from and to the mower can be performed in the field using ordinary tools. Significantly, the cutting blade can be detached from the bottom face of the spindle shaft without disturbing the pre-set compression applied to the pulley and bearing assembly during the initial factory assembly.
The present invention will be better understood from the following detailed description of the invention, read in connection with the drawings as hereinafter described.
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patent: 55075
Bland Mark C.
Scag Dane T.
Godfrey & Kahn S.C.
Great Dane Power Equipment, Inc.
Kovacs Arpad F
Pezzuto Robert E.
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