Woodworking – Special-work machine – Stump removing
Reexamination Certificate
2000-08-15
2001-10-23
Bray, W. Donald (Department: 3725)
Woodworking
Special-work machine
Stump removing
C037S302000, C144S334000, C241S101720, C414S694000
Reexamination Certificate
active
06305445
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to stump grinding machines of the type having a grinding wheel located at the distal end of a movable boom. More particularly, the invention relates to a stump grinding machine incorporating a novel support structure for pivotally mounting the boom to the machine's frame.
Stump grinding machines are widely used to remove tree stumps. These machines are constructed having a grinding wheel located at the distal end of a movable boom. Typically, the grinding wheel is swept back and forth in a generally horizontal plane across the tree stump. With each sweep, the grinding wheel is lowered slightly to remove more of the stump. The final sweeps of the grinding wheel may be below ground level to ensure elimination of the entire stump.
Often, stump grinding machines have a wheeled frame structure to facilitate movement of the machine from place to place. The frame may be self-propelled or configured for towing behind a separate vehicle. An engine, typically a gasoline or diesel engine, located on the wheeled frame generates power to drive the grinding wheel.
The grinding wheel generally receives power from the engine through a series of belts. In one known arrangement, a first belt connects the engine output to a rotatable idler shaft. A second belt is connected between the idler shaft and the grinding wheel. The idler shaft thus rotates at very high speeds to transmit power to the grinding wheel.
In addition to facilitating the transmittal of power from the engine to the grinding wheel, the idler shaft serves to pivotally support the machine's boom. To allow the idler shaft to rotate, the boom is mounted about the rotating idler shaft by bearings. Such an arrangement is disclosed in U.S. Pat. No. 6,003,570 entitled “Stump Grinder Machine Having Turntable Mounted Engine Arrangement,” incorporated herein by reference.
Arrangements utilizing an idler shaft to transmit power to the cutting wheel have worked generally well for their intended purpose. It has been found, however, that vibrations generated at the stump grinding wheel may be transmitted to the bearings used to support the boom on the idler shaft. The combination of vibration and the rotational speed of the bearings' inner race gives rise to various maintenance considerations.
SUMMARY OF THE INVENTION
The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods. Accordingly, it is an object of the present invention to provide a novel stump grinding machine.
It is a further object of the present invention to provide a stump grinding machine having a novel support structure for pivotally mounting the boom to the machine's frame.
It is a more particular object of the present invention to provide a novel support structure for pivotally mounting the boom to the machine's frame which isolates rotation of the idler shaft from the pivoting motion of the boom.
Some of these objects are achieved by a stump cutting apparatus including a frame structure supported by at least one wheel to facilitate movement of the stump cutting apparatus from place to place. An engine is supported by the frame structure. A boom having a proximal end and a distal end is pivotally mounted to the frame structure at its proximal end. A grinding wheel is rotatably mounted to the distal end of the boom.
The stump cutting apparatus further includes a power train arrangement for transmitting power from the engine to the grinding wheel. The power train arrangement includes an idler shaft mounted on the frame structure for rotation so as to be coaxial with the pivot axis of the boom. The boom is pivotally mounted to the frame structure independently of the idler shaft.
In some exemplary embodiments, a boom tube fixed to the proximal end of the boom surrounds the idler shaft. Additionally, the boom tube may be supported by at least one bearing. For example, the boom tube may be supported by two bearings. In some exemplary embodiments, the idler shaft may be rotatably supported by two bearings coaxial with a pivot axis of the boom. Additionally, the boom bearings may be located between the idler shaft bearings.
Preferably, the power train arrangement includes a first belt stage transmitting power between the engine and the idler shaft and a second belt stage transmitting power between the idler shaft and the grinding wheel. The first belt stage may include an engine pulley wheel, a first idler shaft pulley wheel fixed to the idler shaft and coaxial with the pivot axis of the boom, and a first belt transmitting power between the engine pulley wheel and the first idler shaft pulley wheel. The second belt stage may include a second idler shaft pulley wheel coaxial with the pivot axis of the boom fixed to the idler shaft, a grinding wheel pulley wheel, and a second belt transmitting power between the second idler shaft pulley wheel and the grinding wheel pulley wheel. In addition, the bearings supporting the idler shaft and the boom may be located between the first and second belt stages.
In some exemplary embodiments, the frame structure includes a turntable assembly mounted for rotational movement in a first plane. The boom may be pivotally mounted on the turntable assembly for movement in a second plane generally perpendicular to the first plane.
In some preferred embodiments, the engine is gasoline powered and the bearings for mounting the boom and idler shaft to the frame structure are tapered roller bearings. Additionally, the first belt stage may include a multiple v-belt and the second belt stage may include a poly-chain.
Other objects of the invention are achieved by stump cutting apparatus including a frame structure supporting an engine. The engine includes an engine pulley wheel rotationally driven by the engine. A boom having a proximal end and a distal end includes a boom tube pivotally mounted to the frame structure by at least one first bearing. A grinding wheel is mounted for rotation to a grinding wheel shaft at the distal end of the boom. An idler shaft, extending through the boom tube, is rotatably mounted to the frame by a plurality of second bearings.
The apparatus further includes a power train arrangement for transmitting power from the engine to the idler shaft and from the idler shaft to the grinding shaft pulley wheel to rotationally drive the grinding wheel. In some exemplary embodiments, the idler shaft is mounted to the frame by two outer bearings that are coaxial with a pivot axis of the boom.
Other objects of the invention are achieved by a mounting arrangement having a frame. A pivoting boom structure having a proximal end and a distal end is pivotally mounted to the frame by at least one first bearing at its proximal end. A first shaft is rotatably mounted to the frame and is coaxial with a pivot axis of the boom structure. The first shaft is mounted to the frame by a plurality of second bearings. A tool is rotatably mounted about a drive shaft at the distal end of the boom structure. A power train arrangement transmits power from the first shaft to the tool, with the boom structure being pivotally mounted to the frame independently of the first shaft.
In some exemplary embodiments, a boom tube is fixed to the proximal end of the boom structure and is pivotally mounted to the frame by at least one first bearing so that it surrounds the first shaft. In another preferred embodiment, the at least one first bearing includes two bearings.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention.
REFERENCES:
patent: Re. 28651 (1975-12-01), Welborn
patent: 1397324 (1921-11-01), Moore
patent: 3198224 (1965-08-01), Hiley
patent: 3308860 (1967-03-01), De Shano
patent: 3664645 (1972-05-01), Cobey
patent: 3818957 (1974-06-01), Schoonover
patent: 4268214 (1981-05-01), Zeldman
patent: 4438575 (1984-03-01), Roe
patent:
BB&F Enterprises, LLC
Bray W. Donald
Nelson Mullins Riley & Scarborough
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