Woodworking – Special-work machine – Stump removing
Reexamination Certificate
2000-04-11
2001-07-24
Bray, W. Donald (Department: 3725)
Woodworking
Special-work machine
Stump removing
C144S334000
Reexamination Certificate
active
06263930
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mechanical device used to grind down tree stumps.
2. Description of the Related Art
In land clearing operations, there is frequently a need to remove stumps after trees have been cut. Many methods and devices have been proposed for removing stumps from the earth's surface in order to allow soil tillage, building construction, etc. The related art is represented by the following patents of interest.
U.S. Pat. No. 3,044,509, issued on Jul. 17, 1962 to Jacob Keller, describes a horizontally rotating stump cutting cylinder universally mounted upon the rear end of a tractor. Keller does not suggest a stump grinder according to the claimed invention.
U.S. Pat. No. 3,732,905, issued on May 15, 1973 to James M. Pickel, describes a tree stump removing apparatus for mounting on a prime mover and operative to move a vertical cutting blade laterally during the cutting action thereof. Pickel does not suggest a stump grinder according to the claimed invention.
U.S. Pat. No. 4,530,385, issued on Jul. 23, 1985 to Norman N. York, describes a tree stump removal apparatus which is supported by the standard three point hitch of a tractor and is driven by the power take-off and hydraulic supply systems of the tractor. York '385 does not suggest a stump grinder according to the claimed invention.
U.S. Pat. No. 4,621,668, issued on Nov. 11, 1998 to Norman N. York, describes a tree stump removal apparatus which is supported by the standard three point hitch of a tractor and is driven by the power take-off and hydraulic supply systems of the tractor. York '668 does not suggest a stump grinder according to the claimed invention.
U.S. Pat. No. 4,681,145, issued on Jul. 21, 1987 to Norman N. York, describes a tree stump removal apparatus which is supported by the standard three point hitch of a tractor and is driven by the tractor power take-off, but incorporates a hydraulic supply system which is independent of the tractor hydraulic system. York '145 does not suggest a stump grinder according to the claimed invention.
U.S. Pat. No. 5,435,359, issued on Jul. 25, 1995 to Robert J. Craft, describes a stump grinder having a cutting wheel with peripherally mounted cutter teeth. Craft '359 does not suggest a stump grinder according to the claimed invention.
U.S. Pat. No. 5,655,581, issued on Aug. 12, 1997 to Robert J. Craft, describes a stump grinder attachment capable of being mounted on a three-point hitch of a tractor. Craft '581 does not suggest a stump grinder according to the claimed invention.
U.S. Pat. No. 5,829,497, issued on Nov. 3, 1998 to Freeman D. Muroney, describes a stump grinder designed for attachment to the three point hitch of an agricultural tractor with a stump grinding wheel driven by the tractor power takeoff. Muroney does not suggest a stump grinder according to the claimed invention.
Soviet Union Pat. document 1,240,388, published on Jun. 30, 1986, shows a tree-stump cutting machine. Soviet Union '388 does not suggest a stump grinder according to the claimed invention.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed.
SUMMARY OF THE INVENTION
The present invention is a stump grinder. The stump grinder is configured in the form of a demountable attachment for a conventional tractor. Such a conventional tractor typically includes a power take off shaft extending rearwardly from a vertical wall of the tractor. The power take off shaft provides power to the drive shaft of a trailing implement which is coupled to the power take off shaft by a universal joint. A conventional tractor may also be equipped with a three point hitch positioned above the power take off shaft for connection to a linkage of the trailing implement. The hitch is typically secured for vertical pivotable adjustment to accommodate the height of the particular trailing implement.
The stump grinder includes a frame, a drive shaft, a gearbox, a rotatable shaft, and a grinding drum. The stump grinder preferably also includes a shroud cover. The frame extends longitudinally and supports at its free end a transversely mounted rotatable shaft upon which is mounted a grinding drum. One end of the rotatable shaft is rotatably mounted in the frame, and the other end of the rotatable shaft is rotatably connected to a gearbox. The gearbox is driven by the drive shaft which is configured for coupling to the power take off shaft of a tractor. The opposite end of the frame includes a plurality of fastening means for securely fastening the frame to a tractor. The grinding drum is designed so that its upper circumference rotates away from the tractor and thus away from the operator so that any loose debris is thrust outwardly from the operator. Grinding drum power is achieved through the tractor itself. The shroud covering covers the upper portion of the grinding drum in the interests of operator safety. A deflection plate is attached to the shroud covering for further operator protection. The stump grinder has a three point lift hook-up that allows it to be changed out in less than five minutes.
The power take off shaft of the tractor is coupled to the drive shaft of the stump grinder. The drive shaft is rotatably coupled via a slip-clutch to the gearbox of the stump grinder. The gearbox drives the grinding drum directly. This enables the stump grinder to work even when it rains. The stump grinder is preferably configured for 90 horse power. The stump grinder works by using torque-thrust thus using less fuel.
The grinding drum has a stump abrading surface which contains numerous teeth in a staggered pattern covering the operating width of the grinding drum. The grinding drum comprises a one inch thick hollow steel drum having a cylindrical outer surface studded with removable stump abrading teeth. The teeth, approximately 1.5″ tall, are bolted onto the grinding drum in holes in the outer surface. A number of depth gauges, preferably four, are mounted on the grinding drum and function to prevent the teeth from biting too aggressively into a tree stump to result in ¼″ slivers. The depth gauges on the grinder drum are easy to replace when worn, because of a special cutter layout on the grinder drum.
The outer surface of the grinding drum includes means for releasably mounting the removable teeth. Such means comprise weld on bases that are welded onto the outer surface of the grinding drum. The removable tooth are each bolted and secured to a weld on base with lock bolts. Such weld on bases and removable teeth are commonly used in mining and tunneling equipment to bore through rock surfaces. An advantage of using weld on bases and removable teeth results not only from the ability to quickly repair broken teeth but in the ability to change the teeth depending on the preference of the user. For example, wood shredding teeth, wood chipping teeth, scrapping teeth or other configurations may be used individually or in combination depending on the preferences of the user. Since roots often grow around rocks, use of rock boring teeth, such as used in mining applications may be used as well. Such teeth are typically made of hard, wear-resistant material, usually a refractory material such as cemented carbides. The stump grinder is configured for grinding up to 40″ tall and 26″ deep on almost any terrain. It takes a matter of minutes to grind a 32″ diameter wood stump 12″ deep.
In order to utilize the stump grinder, an operator attaches the stump grinder to the power take off shaft of a tractor. The operator then positions himself in the seat of the tractor and drives the stump grinder to a subject stump. Thereafter, the operator lowers the grinding drum until the shroud covering is positioned just above the stump. The operator then lowers the grinding drum onto the stump until the grinding drum engages the stump. The operator continues grinding until the stump is eradicated.
Accordingly, it is
Bray W. Donald
Litman Richard C.
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