Patent Application
20140026528
This invention pertains to tractor-mounted brush-cutting sickle bars, and more particularly, it pertains to resilient mounting joints for sickle bars that are operable in horizontal and vertical positions for cutting vegetation along forest roads.
Conventional sickle bars remain the implements of choice for cutting grass, hay, weeds, bushes and for trimming small branches along forest roads. Although conventional sickle bars are sturdy and efficient, their mounting joints are sometimes mechanically complex. These joints include power transmission linkages for operating the cutting bar. These complicated moving parts are easily damaged by the shocks and wear associated with the nature of this work.
Only one example of a sickle bar for cutting vegetation along forest roads has been found in the prior art.
Canadian Patent 510,271 issued to Earl W. Holmes on Feb. 22, 1955. This document describes a truck-mounted turret and telescoping boom. A sickle bar is mounted to the end of the telescoping boom. The sickle bar is operable at all angles starting below a horizontal position to a vertical position. Abnormal shocks on the sickle bar when the sickle bar is in a horizontal position are absorbed by an hydraulic cylinder and a pressure relief valve on the rotating base of the turret. The same mechanism is used to indirectly absorb stresses when the sickle bar is operated in the vertical position.
Although the machine of the prior art deserves undeniable merits, it is believed that there is a market need for a better mounting joint for a brush-cutting sickle bar. There is a market need for a mounting joint that can effectively absorb shocks whether the sickle bar is in a horizontal alignment or in a vertical orientation. It is believe that there is a need in this field for a mounting joint that is simple to build; that is sturdy and which can improve the cutting efficiency of the sickle bar.
In the present invention, there is provided a new and improved mounting joint for a brush-cutting sickle bar. The mounting joint is relatively inexpensive to build. It is compact in size and easy to install. Its operation is advantageous for absorbing shocks on the sickle bar and for converting these shocks into torsion stresses on the branches being cut to facilitate the cutting of branches.
In one aspect of the present invention, there is provided a joint for installation between a tractor-mounted frame and a sickle bar. This mounting joint has a first and second axes extending at right angle from each other. A shaft and bearing assembly extends along the first axis. The shaft has mobility relative to the bearing housing and comprises a crank arm mounted on the end thereof for controllably turning the shaft about the first axis.
The mounting joint also has a resilient wrist pin assembly mounted along the second axis. The resilient wrist pin assembly has torsional resilience about the second axis. The shaft and bearing assembly has a first connection for connecting to the tractor-mounted frame and a second connection for connecting to the resilient wrist pin assembly. The resilient wrist pin assembly has a third connection for connecting to the sickle bar such that the sickle bar is controllably rotatable about the first axis and resiliently rotatable about the second axis.
The first axis always extends horizontally and the second axis always lies in a vertical plane, such that the sickle bar is selectively movable for operation in a horizontal position or in a vertical position. Shocks on the sickle bar from cutting branches cause the sickle bar to resiliently tilt about the second axis thereby applying torsion stresses on the branches being cut to facilitate the cutting of these branches. This phenomenon occurs whether the sickle bar is operated horizontally or vertically.
The mounting joint according to the present invention is susceptible of a low cost of manufacture with regard to both materials and labour and which accordingly is then susceptible of low prices of sale to the consumer, thereby making such mounting joint economically available to the public.
This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings.
A preferred embodiment of the present invention is illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which:
Referring firstly to
The sickle bar 22 is preferably mounted to the quick attachment frame, or quick coupler 24 on the front-loader arms of a farm tractor 26. A hollow beam 28 is attached to the quick coupler 24. An extension beam 30 is telescopically mounted in the hollow beam 28. The extension beam 30 is adjustable inside the hollow beam 28 and it is locked in position inside the hollow beam 28 by means of a pin 32 for example. The preferred mounting joint 20 is affixed to the end on the extension beam 30.
As can be seen on
Referring now specifically to
The shaft and bearing assembly 52 is well known in forest machinery industry. The shaft 54 (partly shown in
Still referring to
The wrist pin 70, the rubber jacket 74, the square tube 76, and the mounting plate 78 and bracket 80 jointly constitute a resilient linkage in the preferred mounting joint. This resilient linkage is also referred to herein as the resilient wrist pin assembly.
Referring now to
As can be seen in
This mounting also reduces excessive strain on the preferred mounting joint 20 from an overhung sickle bar 22. While it is possible to install the preferred mounting joint 20 at the centre of the main frame plate 92, it has been found that a mounting offset from the bar's centre is advantageous and more efficient in most situations. Still a preferred placement of the mounting joint 20 along the sickle bar 22 is about one third to one fifth of the sickle bar's length, from the near end of the sickle bar 22.
It will also be appreciated that the actuation of the hydraulic cylinder 60 causes the sickle bar 22 to move from a horizontal to a vertical orientation as illustrated in
Referring now to
In order to understand this phenomenon, the reader is invited to consider cutting a branch or a raw carrot with a pocket knife. A movement of the wrist to move the knife blade about the branch's axis will produce better result than trying to cut the branch straight across by shear pressure. It has been found that wood fibres under stress, even slight, are easier to cut.
If a number of branches are being cut at the same time, the sickle bar 22 also tilts backward to twist all these branches to facilitate cutting of these branches. The torsion stresses applied to branches being cut has been found to enhance the efficiency of the sickle bar 22.
The same phenomenon exists when cutting branches in the lower portion of the sickle bar 22 below the preferred mounting joint 20. The torsion stresses applied to branches are simply in the opposite direction.
As soon as a branch is cut, the sickle bar 22 returns to its vertical alignment due to the resiliency of the rubber-mounted wrist pin 70. A same advantage has been found when the sickle bar 22 is operated horizontally. This is partly due to the axis 72 of the wrist pin 70 being always oriented in a vertical plane and at a right angle with the direction of travel of the tractor.
In view of the above, it will be appreciated that the oscillatory movement of the sickle bar 22 under load about axis 72 has advantageous effects on the cutting of branches along a forest road.
