Brakes – Elements – Shoes
Reexamination Certificate
1999-08-06
2001-06-05
Butler, Douglas C. (Department: 3613)
Brakes
Elements
Shoes
C188S25100R, C188S25100R
Reexamination Certificate
active
06241058
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates, in general, to railway vehicle type braking equipment and, more particularly, this invention relates to a composition type brake shoe for use in a railway type vehicle brake system and, even still more specifically, the invention relates to an improved brake shoe member with an insert of aggressive high friction material for removing defects of the tread surface of a wheel.
BACKGROUND OF THE INVENTION
Prior to the conception and subsequent development of this invention, it is generally well known in the art to use various type brake shoes having different compositions to achieve quite specific braking requirements. For example, these compositions may include cast iron and various other type friction materials that are specifically formulated for a number of predetermined applications.
It is further well recognized, in the brake shoe art, that these various types of friction material will normally exhibit a number of uniquely different friction characteristics. Such friction characteristics, for example, include both high friction material and low friction material which are usually selected on the basis of braking performance requirements.
Since braking performance is the prime function of brake shoes, use of such lower type friction material may be adequate for braking purposes. However, there is normally no consideration of providing a secondary beneficial function toward the reconditioning of a wheel tread surface that may have surface defects, such as shells or spalls. Removal of these surface defects will normally extend the useful life of a wheel that is in service.
A brake shoe surface could be used which would be aggressive as far as reconditioning the wheel surface; however, this design may not provide appropriate friction levels for braking and may also have a disadvantage of creating significant sparking during brake applications which could result in a hazardous condition.
Applicant is aware of another design which is a shoe material made entirely from the aggressive grinding type material, however, this shoe must be applied and then immediately removed after a very low speed brake application. Thus, there is a need for a reconditioning brake shoe that will not present a safety problem because of inappropriate friction performance or because of a sparking condition while the brake shoe is reconditioning the defective surface of a wheel tread and still further a brake shoe that can continue to be used for normal braking operations after the wheel tread has been reconditioned.
SUMMARY OF THE INVENTION
The present invention provides a composition brake shoe for use on a railway vehicle for reconditioning a wheel tread surface during a normal braking application on such railway vehicle. The composition brake shoe includes a backing plate having a stirrup and a brake surface having a predetermined configuration and a predetermined surface area. It further includes a first friction type composition material extending over the surface area of such brake surface of such composition brake shoe. The composition brake shoe further contains a second friction type material, formed as at least one discrete insert, having a predetermined shape and molded into such first friction type composition material. Such second friction type material initially being completely embedded within such first friction type composition material. One surface of such at least one discrete insert being disposed facing such predetermined surface area of such brake surface of such composition brake shoe, such one surface-of such discrete insert being incrementally exposed as such first friction type composition material is eroded away due to frictional engagement with such wheel tread surface during normal braking operations, such second friction type material exhibiting greater abrasive properties than such first friction type composition material. Such at least one discrete insert of such second friction type material is bonded to such backing plate.
OBJECTS OF THE INVENTION
It is, therefore, one of the primary objects of the present invention to provide a brake shoe with an aggressive grinding material in a composition brake shoe matrix which will remove defects from the tread surface of a wheel during normal braking applications.
It is also an object of the present invention to provide a brake shoe which will at least substantially minimize production of a sparking condition while removing defects from the tread surface.
It is still another object of the present invention to provide a brake shoe which will extend the useful life of a wheel in service by reducing the need to remachine or reprofile wheels to remove defects from the tread surface.
Yet, it is still another object of the present invention to provide a brake shoe which will provide the correct friction for braking while at the same time removing wheel tread surface defects.
Still, it is another object of the present invention to provide a brake shoe which will strengthen such backing plate at stress points where potential failures may occur.
Additionally, it is a further object of the present invention to provide a brake shoe which can be used to recondition a wheel tread and still remain in service on the railway vehicle until the shoe is fully worn.
In addition to the various objects and advantages of the present invention which have been described in some specific detail above, various additional objects and advantages of the invention will become much more readily apparent to those persons who are particularly skilled in the relevant brake shoe friction art from the following more detailed description of such invention, particularly, when such detailed description is taken in conjunction with the attached drawing Figures and with the appended claims.
REFERENCES:
patent: 412572 (1889-10-01), Whalen
patent: 514655 (1894-02-01), Kerwin
patent: 655381 (1900-08-01), Stromeyer
patent: 678139 (1901-07-01), Spear
patent: 995067 (1911-06-01), Jones
patent: 1136936 (1915-04-01), Chipley
patent: 3738463 (1973-06-01), Kunst et al.
patent: 4781275 (1988-11-01), Olsen
patent: 5341904 (1994-08-01), Christie
patent: 5407031 (1995-04-01), Christie
patent: 5585166 (1996-12-01), Kearsey
patent: 5788027 (1998-08-01), Shute et al.
Nov. 1997 article in The Magazine and Journal of TWI
Kahr Joseph C.
Shute Bruce W.
Burch Melody
Butler Douglas C.
James Ray & Associates
Westinghouse Air Brake Company
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