Wheel substitutes for land vehicles – Endless belt having nonmetallic track or tread – Track formed of endless flexible belt
Reexamination Certificate
2001-07-27
2003-03-25
Morano, S. Joseph (Department: 3617)
Wheel substitutes for land vehicles
Endless belt having nonmetallic track or tread
Track formed of endless flexible belt
C305S178000, C305S179000
Reexamination Certificate
active
06536852
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resilient crawler.
2. Description of the Related Art
An endless crawler vehicle to be used for civil engineering machines, construction machines, farm machines, snow mobiles and snow cars comprises a resilient crawler wrapped around a driving wheel, a following wheel, and a rolling wheel on a track frame.
The resilient crawler comprises a crawler body formed of a resilient material such as rubber in the shape of an endless belt, and the crawler body is constructed to be turned by an engaging transmitting system using a sprocket as a driving wheel, or by a friction transmitting system using a drum wheel.
The crawler body includes a lug for traction projecting from the outer peripheral surface at intervals along the longitudinal direction of the belt.
In a conventional resilient crawler of this type, core metals having laterally extending wings are buried at intervals longitudinally along the crawler in order to assure traction or to prevent coming-off of the rolling wheel from the crawler by enhancing rigidity in the widthwise direction of the crawler, i.e., lateral rigidity. However, such core metals increase weight and manufacturing cost of the resilient crawler.
Therefore, a technology in which cords such as wire extending in the direction of the width of the crawler body is buried in the lug instead of, or in addition to the core metal, whereby increasing lateral rigidity and avoiding or minimizing the use of core metals is disclosed in Japanese Examined Patent Publication No. HEI 8-11549 (hereinafter referred to as Related Art 1), Japanese Unexamined Patent Publication No. HEI 4-189688 (hereinafter referred to as Related Art 2).
In the resilient crawler of Related Art 1, a number of cords are buried only in the portions where the lugs are formed (within the lug), and they are not buried in the portions between the lugs.
Therefore, advantageously, lateral rigidity of the lug is enhanced and thus traction is ensured, and the portions between lugs can be bent smoothly when they comes around the driving wheel or the following wheel and thus possibility of occurrence of drive transmission loss can be reduced.
However, since the difference in rigidity between the portion where the lug is formed and the portion between the lugs is significant, the rolling wheel considerably sinks into the crawler body, thereby impairing riding comfort.
On the other hand, in Related Art 2, a resilient crawler having cords buried not only in the portion where the lug is formed, but also in the portion between the lugs is shown.
In this case, a multiplicity of cords are provided at regular intervals along the circumference of the crawler body both in the portion where the lug is formed and the portion between the lugs, and a multiplicity of these materials are provided also within the lug.
Therefore, since the number of the cords in the portion where the lug is formed is increased, the lateral rigidity of the lug is enhanced and the difference in rigidity between the portion where a lug is formed and the portion between the lugs is reduced in comparison with Related Art 1, whereby improvement in riding comfort can be realized.
However, since the cords are arranged at regular intervals both in the portions where a lug is formed and the portions between the lugs, when the intervals between the cords are decreased to increase the number of the cords so that rigidity of the lug is enhanced, the intervals of the cords in the portion between the lugs are also reduced and thus the number of the cords are increased. As a consequence, the flexibility of the crawler around the wheel is impaired, and the quantity of rubber between the lugs decreases, thereby increasing the possibility of occurrence of separation or cracking.
The lateral bending occurring on the resilient crawler is mainly caused by the load of the rolling wheel passing along and thus sinking the lateral center of the crawler body when the vehicle travels on a soft ground or on the snow. However, in Related Art 1 and 2, the cords are buried in almost uniform numbers along the width of the crawler body, and thus rigidity is also uniform along the width. Therefore, when rigidity of the lateral center of the crawler body, which contributes highly to the prevention of bending, is increased, rigidity of both side portions of the width of the crawler body, which contributes less to the prevention of bending, is also increased more than necessary, and thus the weight of the crawler is unnecessarily increased.
On the other hand, in Related Art 1, the cords having almost the same length as the lug are buried in the lug so as to be distributed throughout the lug from the foot portion, or the root of the lug projecting form the crawler body, and the volume proportion of the cords with respect to the lug is in the range between 20% to 70%. In other words, most part of the lug is filled with the cords.
In this state, a resilient material, which is a material forming the crawler body, cannot be sufficiently spread among the cords, and thus the thickness of the resilient material of the surface layer, or at the portion surrounding the cords, of the lug is decreased. As a consequent, separation or cracking may disadvantageously occur relatively easily between the cords or between the layers of the cords and the resilient material.
Even when they are the same in proportion of volume, lateral rigidity of the crawler varies depending on the position where the cords are buried, and thus variation in the position where the cords are buried may disadvantageously cause variation in tractive force, which may result in impairment of its original capability.
OBJECT AND SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to assure flexibility between the lugs and prevent separation of rubber while assuring lateral rigidity of the lug by properly disposing lateral reinforcing members in the crawler body without deteriorating riding comfort.
It is another object of the present invention to prevent increase in weight while effectively preventing lateral bending of the crawler body.
It is still another object of the present invention to increase durability by preventing occurrence of separation or cracking of the lug and to obtain a uniform tractive force by the lug.
The first specific means for solving the problems according to the present invention is a resilient crawler comprising: a crawler body formed of a resilient material in the shape of an endless belt and having a multiplicity of lugs projecting from its outer peripheral surface at intervals longitudinally along the crawler; and a multiplicity of lateral reinforcing members in the shape of cords extending laterally (in the widthwise direction) of the crawler body and arranged longitudinally along the crawler body; wherein the lateral reinforcing members are arranged at close intervals with respect to each other in each portion of the crawler body where the lug is formed, and at larger intervals with respect to each other in each portion between the lugs.
In this arrangement, since the difference in rigidity between the portion where the lug is formed and the portion between the lugs is reduced, riding comfort is expected to be improved, and the flexibility between the lugs can be assured and separation of rubber can be prevented while improving lateral rigidity of the lug and obtaining preferable traction.
The second specific means for solving the problems according to the present invention is a resilient crawler comprising: a crawler body formed of a resilient material in the shape of an endless belt and having a multiplicity of lugs projecting from its outer peripheral surface at intervals longitudinally along the crawler body; and a multiplicity of linear lateral reinforcing members extending laterally of the crawler body and arranged longitudinally along the crawler body; wherein the volume proportion of the lateral reinforcing members is high at the lateral center of the crawler body and low at
Fukushima Yasuharu
Katayama Teruyuki
Sakai Ken'ichi
Jules Frantz F.
Morano S. Joseph
Nixon & Peabody LLP
Ohtsu Tire & Rubber Co., Ltd.
Safran David S.
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