Wheel substitutes for land vehicles – Endless belt having nonmetallic track or tread – Track formed of endless flexible belt
Reexamination Certificate
2000-01-28
2001-10-02
Stormer, Russell D. (Department: 3617)
Wheel substitutes for land vehicles
Endless belt having nonmetallic track or tread
Track formed of endless flexible belt
C305S178000, C524S492000, C525S098000
Reexamination Certificate
active
06296329
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an endless vehicular rubber track. The invention particularly relates to such track having a ground-contacting tread component of a rubber composition.
Endless rubber tractor tracks are increasingly being used for propelling various vehicles over the ground such as, for example, various tractors and other agricultural vehicles including, for example, combines and spreaders, as well as various earth moving machines.
In particular, such track is conventionally positioned over at least two wheels, normally a drive wheel for engaging an inner surface of the track and driving the track and at least one driven wheel to control the path of the track as it moves to propel the associated vehicle. The outer surface of the peripheral tread configuration of the track typically contains a plurality of raised lugs designed for engaging the ground and assisting the propelling of the associated vehicle such as, for example, a tractor over an agricultural ground, such as lugs, are referred to herein as ground-contacting lugs.
In practice, the ground-contacting tread of such rubber tracks provide a considerably wider footprint than conventional pneumatic tires and are, thereby, more adaptable to agricultural fields in that they offer better flotation and less soil compaction than rubber tires, which may result in better crop yield. In addition, use of rubber tracks instead of pneumatic tires may permit a farmer to get out into a field earlier in the planting season and plant crops sooner in point of time and may permit a harvesting of a crop on a more timely basis as compared to conventional pneumatic rubber tire equipped agricultural vehicles. Such use and advantages of rubber tractor tracks are well known to those having skill in such art.
Such rubber tracks are conventionally in a form of an endless rubber belt reinforced with continuous steel cables molded into the rubber composition itself to add dimensional stability for the track.
As the rubber track is driven around the aforesaid wheels, it is (1) subject to extensive contortional flexing and, thus, may be subject to tread crack initiation and propagation over time and (2) may be subject to various agricultural chemicals and crop stubble as is well known to those having skill in such art.
Accordingly, it is desired that the rubber composition for the ground-contacting tread component of the track have appropriate resistance to flex fatigue, resistance to abrasion and durability.
In the description of this invention, the term “phr” represents parts by weight of a particular material per 100 parts by weight of rubber. As used herein, the terms rubber and elastomer may be used interchangeably, unless otherwise identified.
BRIEF SUMMARY OF THE INVENTION
In accordance with this invention, an endless rubber track designed to encompass at least one drive wheel and at least one driven wheel is comprised of an inner component containing a plurality of guide lugs designed to be engaged and/or guided by said drive and driven wheels and an outer tread component, said tread component being of a configuration comprised of a plurality of co-extensive, raised lugs thereon designed to ground engaging; wherein said tread, designed to be ground contacting, is of a rubber composition comprised of, based upon 100 parts by weight elastomers (phr)
(A) elastomers comprised of:
(1) about 15 to about 40 phr of cis 1,4-polybutadiene elastomer and, correspondingly;
(2) 60 to about 85 phr at least one additional elastomer selected from:
(a) about 60 to about 75, alternatively about 40 to about 55, phr of natural cis 1,4-polyisoprene elastomer and, correspondingly;
(b) zero to about 15, alternatively about 5 to about 10, phr of styrene/butadiene copolymer rubber which contains from about 10 to about 40 weight percent bound styrene; wherein said additional elastomer is preferably only natural rubber,
(B) about 40 to about 80 phr of reinforcing filler comprised of carbon black and a minor amount of precipitated silica; wherein said carbon black is present in an amount of about 35 to about 65 phr and said precipitated silica is present in an amount of from 3 to about 15 phr; wherein said reinforcing filler is exclusive of a coupling agent having a moiety reactive with silanol groups on the surface of said silica and another moiety interactive with said elastomer(s);
(C) sulfur curative in a range of about 0.75 to about 1.5 phr and a sulfenamide sulfur cure accelerator;
(D) about 4.5 to about 10 of antidegradant; and
(E) zero to about 10, preferably about 1 to about 5, phr of rubber processing oil selected from at least one of aromatic rubber processing oil and mixture of aromatic and naphenic rubber processing oil; wherein said carbon black is characterized by having an Iodine Number in a range of about 115 to about 130 g/kg, a DBP value in a range of about 105 to about 125 cm
3
/100 g, and a Tint value in a range of about 120 to about 140.
The invention also contemplates a vehicle containing at least two (2) of said endless tracks.
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European Search Report Apr. 8, 1999.
Gordon Larry Ashley
Krishnan Ram Murthy
Maly Neil Arthur
Rodgers Michael Brendan
Sandstrom Paul Harry
Stormer Russell D.
The Goodyear Tire & Rubber Company
Young, Jr. Henry C.
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