Harvesters – Cutting – Oscillating cutter
Reexamination Certificate
2000-01-06
2001-11-13
Pezzuto, Robert E. (Department: 3671)
Harvesters
Cutting
Oscillating cutter
C056S013600, C056S017600
Reexamination Certificate
active
06314707
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to an anti-vibration, brush cutting attachment. More specifically, the attachment is a reciprocating cutter for mounting on the front of a vehicle, such as a tractor or riding lawn mower. The reciprocating cutter removes high grass and brush prior to mowing or traversing the area in front of the vehicle, without causing excessive vibrations to the vehicle or the attachment.
2. Description of the Prior Art
One common type of cutting attachment for lawn tractors, riding lawn mowers, and other vehicles is a sickle bar. Sickle bars can also be formed as stand-alone devices (such as electric hedge trimmers or sickle type lawn mowers) and include two sets of cutting teeth disposed adjacent and abutting one another. As one or both sets of teeth are moved relative to one another in a reciprocating motion, brush, grass and debris located between adjacent teeth are severed. Several types of sickle bars are disclosed in the following U.S. Patents. What is lacking in these references and the prior art as a whole, is a reciprocating sickle bar having two sets of oppositely and continuously driven cutting teeth. This feature of the present invention reduces vibration by balancing oppositely driven masses.
A reciprocating tedder attachment for power mower sickle bars is taught in U.S. Pat. No. 2,448,078, issued on Aug. 31, 1948 to Brown. While the sickle bars shown in this reference are similar in basic operation to the reciprocating cutter of the present invention, the main thrust of this invention involves removal of the cut brush, and the issue of anti-vibration is not discussed. Furthermore, the sickle bars of Brown are not an attachment, but a permanent part of a power mower.
In U.S. Pat. No. 2,680,340, issued on Jun. 8, 1954 to Pazandak, a sickle head mechanism with support mounting is disclosed. This sickle head also operates in a similar fashion to the present invention and is designed to reduce vibrations by yieldably mounting non-reciprocating parts of the sickle head. In this manner, the vibrations of the sickle knife are offset, by the opposite vibrations of the cutter bar and other non-reciprocating parts. While this construction may reduce the overall vibrations transmitted from the sickle head to the handles of the mower, there is no discussion of oppositely driving mower components to thereby cancel the vibration, as in the present invention.
U.S. Pat. No. 5,157,906, issued to Abrahamson on Oct. 27, 1992 shows a divided sickle bar arrangement wherein separate half-sickle portions are individually driven in opposition by belts. This arrangement differs significantly from the positive central crankshaft drive of the instant invention.
An impact actuated mowing machine is described in is U.S. Pat. Nos. 3,657,868, and which issued on Apr. 25, 1972 to Cousino. Two cutting plates are driven in opposite directions against the force of a resilient element. The front edge of each of the cutting plates includes a plurality of cutting teeth that are superimposed over one another in the rest position. Two impact rollers simultaneously drive the cutting plates in opposite directions, thereby reducing vibrations using a cancellation effect. This design uses oppositely moving masses to cancel vibrations, however, it requires two driving sources (the impact rollers), and due to the non-continuous nature of the motion, inherently produces greater vibration than the present invention, wherein only a single driving source (crankshaft) is used, and the oppositely moving parts are continuously driven in opposite directions.
In U.S. Pat. No. 4,107,906, issued on Aug. 22, 1978 to Cousino, another type of impact actuated lawn mower is disclosed. In this impact mower, however, the cutting teeth are not driven simultaneously in opposite directions. The subject of vibration reduction is not discussed or taught in this patent.
None of the above references and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
SUMMARY OF THE INVENTION
The present invention is a reciprocating sickle bar head for cutting brush, grass, small trees and other types of vegetation. This sickle bar head is intended to be mounted on the front of a riding lawn mower, lawn tractor or other type of vehicle, but may be used in other applications as well. A number of teeth are formed on a front blade edge of a bottom solid plate. The bottom plate acts as a support for the other components of the sickle head. Two top blades are supported on top of the bottom plate, one on the right side of the sickle head and one on the left. The top blades include teeth along their front blade edge, such that the teeth align with those on the front blade edge of the bottom plate. A central, vertical drive shaft is supported in a bearing that is mounted in a hole in the bottom plate. The drive shaft extends below the bottom plate and includes a drive pulley mounted on its bottom portion. The drive pulley is operatively connected to a blade driving system or a power take-off (PTO) by a drive belt. The upper portion of the drive shaft includes two cranks extending 180° relative to each other, with the distal ends of the cranks being operatively connected to a respective top blade by a connecting rod. As the driveshaft rotates, the relative positions of the cranks result in the top blades being driven continuously in opposite directions. The top blades (along with their driving components) are formed substantially identical, so that the combined mass of moving parts on one side of the sickle head is the same as the combined mass of moving parts on the opposite side.
The above described sickle head construction, results in a substantial reduction of vibrations being transmitted to the vehicle to which the sickle head is mounted. The method of reducing vibrations by driving equal masses in opposite directions and at opposite positions is the main thrust of the present invention. Other vibration reducing advantages include the two top blades being mounted on top of the bottom plate in a co-linear arrangement. This decreases the vibrations as small offsets between the driven blades cause a rotational vibration to be introduced about the center of mass of the system. The continuous driving motion imparted by the drive shaft, cranks and connecting rods also reduces vibrations by moving the top blades with a smooth, reciprocating action. Instead of cutting using an intermittent impact manner, the present invention uses a less violent shearing action.
In addition to the anti-vibration features of the present invention, other advantages are presented by the sickle head construction. The lower pulley allows the sickle head to be easily retrofitted on existing vehicles having belt driven blade systems. Once the lower plate is mounted to the front of the vehicle, a drive belt can be routed about the drive pulley and the installation is complete. The attachment of the sickle head and drive belt is similar to that used in the inventor's previous U. S. Pat. No. 5,600,943 which issued on Feb. 11, 1997 and is hereby incorporated by reference. In addition, the sickle head of the present invention has a relatively simple construction, allowing for lighter weight and easier maintenance.
Accordingly, it is a first object of the invention to provide a sickle head that reduces vibrations by moving equal masses in opposite directions.
It is another object of the invention to reduce vibrations in a sickle head by oppositely driving cutting blades in a co-linear arrangement.
It is a further object of the invention to provide an anti-vibration sickle head that can be easily retrofit to the front of a vehicle.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.
REFERENCES:
patent: 2448078 (1948-08-01), Brown
patent: 2680340 (1954-06-01), Pazandak
patent: 3657868 (1972-04-01), Cousino
patent: 3763638 (1973-10-01), Vogelenzang
patent: 3973378 (1976-08
Kováacs ÁArpáad Fáabiáan
Pezzuto Robert E.
Siemens Patent Services LC
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