Harvesters – Cutting – Housing or guard
Reexamination Certificate
1999-03-10
2001-02-27
Will, Thomas B. (Department: 3671)
Harvesters
Cutting
Housing or guard
C056S016900, C056S013600, C056S017500
Reexamination Certificate
active
06192666
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to lawn mowers, and more particularly, a lawn mower cutter assembly.
Self propelled riding lawn mowers are well known in the art. Such mowers generally include a cutter assembly, an engine for driving the cutter assembly and the mower's drive wheels. Such riding mowers are also often provided with a conduit and blower assembly for conveying the clippings from the cutter assembly to a hopper. In some localities, the collection of grass clippings is prohibited because of limitations on dumping sites. As a result, grass clippings are not collected but are either mulched or discharged from a discharge opening which forms a part of the cutter deck.
In order to provide adequate cutting widths, commercial type lawn mowers are commonly provided with a plurality of cutter blades. One type of mower includes two cutter blades that rotate in opposite directions and discharge grass clippings through the center rear of the cutter deck. In order for the mower to execute a complete cut for each pass, it is necessary for the blades to be long enough to overlap in the center. This, in turn, requires that the blades be mechanically timed to prevent them from engaging. The usual method is to use a gear box for supporting rotating the individual blades. Gears control the timing of the blade rotation to prevent impact. Another method of controlling the blade rotation employs a cog belt and pulleys. In order to uncouple the cutter blade from the gear box or timing belt should the blade strike a heavy or immovable object such as a tree root, rock, pipe or the like, such mowers are commonly provided with shear bolts, which are intended to allow the blades to decouple from the gear box or drive system. In practice, shear bolts do not always work as intended. In such cases, the shock load is severe enough to damage the gear box resulting in an expensive repair. Even when the shear bolts do protect the gear box from damage, the shear bolts themselves must be replaced causing down time and inconvenience to the user.
One system which eliminates the requirement for overlapping blades is to use three cutters which are staggered as disclosed in U.S. Pat. No. 4,226,074. This permits the swath cut by the center blade to overlap those of the outer blades without the blades themselves overlapping. Such three-blade systems, however, are not wholly satisfactory because it is difficult to achieve both a center rear discharge for collecting clippings in a hopper and an optional side discharge when the clippings are not mulched or collected. The use of a center rear collection system insures that both sides of the cutter deck are clear to trim against walls, trees, fences and the like without requiring that the deck be wider than required. Prior art three-blade cutter systems generally employ a side discharge chute or a collection boot for delivering clippings to a catcher system. The side with the chute or boot typically extends ten to twelve inches from the end of the nearest cutter blade. This prevents grass from being cut in that area.
SUMMARY OF THE INVENTION
In general terms, the invention comprises a lawnmower including a cutter assembly having a cutter deck which defines at least three cutting zones and a cutter blade mounted in each cutting zone and rotatable about generally parallel axes. A power transmission assembly is coupled to a power source and the cutter blades for rotating the cutter blades. A first opening is formed in the cutter deck adjacent to the second cutting zone and a closure member is removably mounted over the first opening and configured to close the first opening. Baffles define portions of the first, second and third cutting zones, and additional baffles extend between the first and third cutting zones for directing clippings from the first cutting zone to the third cutting zone and between the third cutting zone and the second cutting zone for directing clippings from the third cutting zone to the second cutting zone. A second opening is formed in the cutter deck defining the second cutting zone and a conduit is coupled at one end to the second opening and its other to a Hopper for conducting grass clippings from the cutter deck to the Hopper. One of the baffles is positioned over the second opening and is removable to communicate the conduit with the second cutting zone.
According to another aspect, the invention comprises a lawnmower including a cutter assembly having a cutter deck defining at least three cutting zones and a cutter blade mounted in each cutting zone for rotation about generally parallel rotation axes. A power transmission assembly is coupled to a power source and the cutter blades for rotating the cutter blades about the rotation axes. A first opening is formed in the cutter deck adjacent the second cutting zone and a first removable member is mounted on the cutter deck for closing the first opening. A plurality of baffles define portions of the first, second and third cutting zones. The baffles are configured to direct clippings from the first cutting zone to the third cutting zone and from the third cutting zone to the second cutting zone. A second opening is formed in the cutter deck portion defining the second cutting zone and spaced from the first opening and a conduit is coupled at one end to the second opening and at its other end to a hopper for conducting grass clippings from the cutter deck to the hopper. A second removable member is constructed and arranged to be mounted over the second opening and is removable to communicate the conduit with the second cutting zone.
The invention provides a lawnmower in which the cutter blades define overlapping cutting swaths without requiring that the rotation of the blades be timed to prevent engagement of their tips. As a result, should the blades engage heavy or immoveable objects they are free to slip relative to a power transmission assembly without engaging or damaging adjacent blades. Moreover, the lawnmower according to the invention may be converted between mulching, side discharge or collection relatively rapidly.
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Boeck Kevin
Hall James W.
Sugden David
Wanie Todd R.
Michael & Best & Friedrich LLP
Petravick Meredith C.
Scag Power Equipment, Inc.
Will Thomas B.
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