Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-06-08
2001-10-09
Mulcahy, Peter D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C525S240000, C305S033000
Reexamination Certificate
active
06300396
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rubber track, and, particularly, to a rubber composition for a guide lug material projecting from the inner surface of a rubber track.
2. Description of the Related Art
A rubber track is generally provided with a plurality of guide lugs formed at spaced intervals in the longitudinal direction of the inner surface thereof. In this positive drive type of rubber track, the guide lugs have functions of transferring the driving force from a sprocket and/or preventing the rubber track from slipping off a wheel, which is called “detracking”.
It is considered that detracking occurs as follows: The rubber track is hit by a lateral force which produces a relative shift between the rubber track and the wheel. In this case, the guide lug repeatedly contacts and collides with the wheel, while the shifted guide lug is forced to return to its previous, regular position, resulting in abrasion of or damage to the guide lug. There is also a possibility of the detracking.
FIG. 1
shows a rubber track
1
, from the inner surface of which a row of guide lugs
3
project. A wheel
5
normally rotates so that it strides over the guide lug
3
. When a relative shift between the rubber track
1
and the wheel
5
is produced, the wheel
5
, as shown by the dotted line in the figure (only one of the wheels
5
is shown), repeatedly contacts and collides with the guide lug
3
whereby the shift between both is limited and the shifted rubber track
1
is forced to return to its previous, regular rolling contact surface. The abrasion of or damage to both sides of the guide lug
3
is therefore significant.
Furthermore, when the guide lug is engaged with a sprocket, not shown, to convey driving force, a guide lug is always rubbed against a sprocket pin. The guide lug is deformed by the force applied especially to the root, which creates abrasion or damage easily. In addition, the contact and collision between the wheel
5
and the guide lug cause a large running resistance resulting in large energy losses.
In order to solve the aforementioned problem, for instance, Japanese Patent Application Laid-Open (JP-A) No. 6-72362 discloses a structure in which a guide lug projecting from the inner surface of a rubber track is formed with a low friction material exposed to the contact face with the other material.
FIG. 3
shows a plate-like low friction material (Ultra High Molecular weight Polyethylene: UHMW-PE)
6
embedded inwardly into the guide lug
3
projecting from the inner surface of the rubber track. As shown in
FIG. 3
, the low friction material
6
is exposed from both sides
3
3
and the top
3
2
of the guide lug
3
so that it contacts and collides with the wheel
5
and with an idler and a sprocket which are not shown. The friction between the low friction material
6
and these materials is low due to the low friction characteristics of the low friction material
6
. This reduces the occurrence of the detracking and the abrasion or damege of guide lugs. And the low running resistance and low energy losses can be obtained due to the good self-lublicating characteristics of this material.
Such a structure using the low friction material
6
poses the following problem: When a relative shift between the guide lug
3
and the wheel
5
is produced, excess force is applied to the guide lug
3
. Consequently, the side
3
3
of the guide lug
3
contacts and collides with the wheel
5
. At this time, a concentrated stress which is imposed on the boundary between a rubber member of the guide lug
3
and the low friction material
6
, though it depends upon the difference in hardness between them, causes breakdown of the boundary. This structure also requires stable adhesion of the low friction material
6
to the rubber member of the guide lug
3
.
SUMMARY OF THE INVENTION
Objects of the present invention are to reduce abrasion of or damage to a guide lug which projects from the inner surface of a rubber track, to improve the characteristics in preventing the rubber track from detracking, to reduce the friction loss which occurs when the guide lug contacts and collides with the wheel thereby reducing energy loss, vibration and noise. The object of the present invention can be attained by the provision of a rubber track using a specific composition for the guide lug which projects from the inner surface of the rubber track.
According to a first aspect of the present invention, there is provided a guide lug composition for a rubber track comprising 5 to 40 parts by weight preferably 5 to 20 parts by weight, more preferably 5 to 10 parts by weight of a fatty acid amide based on 100 parts by weight of a raw rubber material. According to a further aspect of the present invention, there is provided a guide lug composition for rubber track comprising 5 to 40 parts by weight preferably 5 to 30 parts by weight, more preferably 5 to 20 parts by weight of UHMW-PE powder based on 100 parts by weight of a raw rubber material. According to another aspect of the present invention, there is provided a guide lug composition for a rubber track comprising 5 to 40 parts by weight preferably 5 to 20 parts by weight, more preferably 5 to 10 parts by weight of a fatty acid amide and 5 to 40 parts by weight preferably 5 to 30 parts by weight, more preferably 5 to 20 parts by weight of a UHMW-PE powder based on 100 parts by weight of a raw rubber material.
REFERENCES:
patent: 4500666 (1985-02-01), Wada
patent: 4775711 (1988-10-01), Kawamura et al.
patent: 5246994 (1993-09-01), Shibahara et al.
patent: 5314752 (1994-05-01), Bova et al.
patent: 5314912 (1994-05-01), Yoshitani et al.
patent: 5447365 (1995-09-01), Muramatsu et al.
patent: A-6-72362 (1994-03-01), None
Kato Shingo
Nishimura Naoki
Tsunoda Katsuhiko
Bridgestone Corporation
Mulcahy Peter D.
Oliff & Berridg,e PLC
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