Railway rolling stock – Trucks – Axle bearing mounting
Reexamination Certificate
1998-10-06
2001-02-20
Morano, S. Joseph (Department: 3617)
Railway rolling stock
Trucks
Axle bearing mounting
C105S182100, C295S036100, C384S459000
Reexamination Certificate
active
06189456
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to railway car axles and more particularly to a high capacity axle capable of withstanding greater loading capacities while maintaining a longer life span.
BACKGROUND OF THE INVENTION
Most modern railway cars include a pair of railway trucks with each railway truck having a pair of axles. Typically, a pair of wheels are secured to each axle with the wheels spaced from each other at a distance corresponding with the gauge of the railway trucks. A pair of roller bearing assemblies are generally mounted on the axle to reduce friction and to allow the axle and associated wheels to rotate with a minimum amount of applied force. A railway axle typically includes a shaft with a wheel seat and journal formed adjacent to opposite ends of the shaft. A wheel is secured to each wheel seat. An associated journal extends from each wheel seat for mounting a respective bearing assembly adjacent to each end of the railway axle. Each bearing assembly is preferably tightly fitted on its respective journal. Each bearing assembly includes a housing that receives a portion of a frame for an associated railway truck. The journals often have the smallest diameter of the railway axle and the wheel seats often have the largest diameter. Therefore, a railway car axle will often flex between the journals and respective wheel seats when the associated railway car is loaded. Movement or flexing of the axle between the bearing assembly and the associated wheel will ultimately result in fretting and failure of the axle.
In order to make the railroad industry more competitive with other modes of transportation various methods have been undertaken to reduce fretting and increase the fatigue life of axles for railway cars. Efforts include hardcoating the journal with a wear resistant metal or alloy, and modifying the bearing assembly connection and accompanying seals. Prior modifications have substantially increased the cost of the axle and bearing assembly or the installation of both.
Other efforts have included railway car axle modifications such as varying the size of the journals and wheel seats. Allowable modifications are limited due to standard American Association of Railroads (AAR) classifications which require interchangeability of component parts.
SUMMARY OF THE INVENTION
Accordingly, a need has arisen in the art for an improved axle for railway cars. The present invention provides an axle for use with a pair of railway car wheels and a pair of roller bearing assemblies that substantially eliminates or reduces problems associated with the prior railway car axles when subjected to heavy loads.
In accordance with teachings of the present invention, an axle for a railway car may comprise a shaft body with a wheel seat and associated journal disposed adjacent to opposite ends of the axle. A dust guard seat may be formed on the axle between each wheel seat and the associated journal. Each journal will preferably be generally cylindrical and may have a diameter of approximately six and one half inches (6.5″) and an approximate length of eight and three fourths inches (8.75″). Each dust guard seat, disposed between each journal from the respective wheel seat, may have a length of approximately three and one half inches (3.50″) and a diameter of approximately seven and one half inches (7.5″). Finally, each wheel seat may preferably have a diameter of approximately nine and one fourth inches (9.25″).
More specifically, in accordance with one embodiment of the present invention, a railway car axle may have fillets formed between each journal and the associated dust guard seat. Also, the railway car axle may have fillets formed between each dust guard seat and the associated wheel seat. In one embodiment, both of these fillets preferably have a radius equal to approximately one and one-half inches (1.5″).
Technical advantages of the present invention include providing a railway car axle which can support heavier loads than current railway car axles with approximately the same dimensions while maintaining an extended fatigue life. In particular, a journal is provided at each end of a railway car axle with an increased outside diameter and a reduced length which cooperate with each other to reduce deflection of the railway car axle and minimize fretting between the axle and components carried on the axle. At an applied vertical load of approximately 315,000 pounds per railway car, a railway car axle incorporating teachings of the present invention may demonstrate a fatigue life approximately equal to an AAR standard “Class F” axle under a vertical load of approximately 286,000 pounds per railway car with a only a slight increase in axle weight as compared to the “Class F” axle. Furthermore, the railway car axle may include wheel seats having a length typical of the AAR standard “Class F” axle, and be suitable for the installation of a thirty-six inch (36″) diameter wheel while maintaining the capability of supporting a load of 315,000 pounds per railway car. A wheel seat incorporating teachings of the present invention preferably has an enlarged outside diameter of approximately nine and one fourth inches (9.25″) to prevent installation of wheels that are not designed for supporting heavy loads.
Still another technical advantage of the present invention includes decreased maintenance costs associated with replacement of failed railway car axles.
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Coulborn John W.
Smith Stephen W.
Baker & Botts L.L.P.
Morano S. Joseph
Olson Lars A.
TRN Business Trust
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