US643734A - Brake-shoe. - Google Patents

Description

No. 643,734. Patented Feb. 20, I900. -w. n. SARGENT. A

BRAKE SHOE.

(Application filed Aug.'17, 1899.)

(No Model.)

and sides of the shoe.

UNITED STATES WILLIAM DURHAM SARGENT, or OHKAGQLLLNQQ PATE T OFFICE.

BRAKE-SHOE.

SPECIFICATION forming part of Letters Patent 0. 643,734, dated February 20, 1900.

Application filed August 17,1899. Serial No. 727,501. (No model.)

To ctZZ whom it may concern:

Be it known that I, WILLIAM DURHAM SAR- GENT, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Brake-Shoes, of which the following is a specification.

This invention relates to improvements in brake-shoes, and has for its primary objects to prolong the life of the shoe, to afford a corn stant and practicallyuniform wearingsurface throughout thelife of the shoe, and to provide a soft-cast-iron shoe with chilled portions so disposed that the transition from-the soft to the hardened metal will be gradual and not of a nature to injuriously wear the wheel, as has heretofore uniformly beenthe case. These and such other objects as may hereinafter appear are obtained by the devices illustrated in the accompanying drawings, in whicl1 Figure 1 represents a side elevation, partly lines at the upper end of the shoe,) and D the chill for producing the chilled prolongations.

The dotted line E and E indicates the line of termination of the body of the brake-shoe as ordinarily constructed, so that the portion B projecting beyond this line at each end of the shoe constitutes a prolongation of the shoe beyond What is ordinarily provided and affords a means for chilling the ends of the shoe from the back instead of from the front It will be noted that the chill D does not embrace the sides of the shoe nor extend around the wearing-face thereof,but makes contact only with the brake at the prolongations. While I have shown the prolongation as generally triangular in shape, it may be squ are, rounding, orof any portions in the other desired contour. The chill is set into I the mold and the shoe is cast, that portion opposing'the chill being hardened from the back inwardly toward the bottom of the shoe,

' teeuths of an inch of soft cast-iron-say from the line a a to the wearing-faceof the shoebetween the chilled portion and the Wearingface, so that when the shoe is first put in service there will be no contact with the wheel of the chilled portion of the metal until this soft-iron facing is worn down and the wearing-face of the shoe conforms to the arc of the wheel-tread. As will be seen, however, during the wear of the shoe from the 'point a a to the point I? b the area of chilled metal exposed on the wearing-face of the shoe will be substantially uniform, and this uniformity will continue throughout the life of the shoe, as will be readily seen by an examination of Fig. 1, which shows with approximate correctness the area of the chilled portion at the successive points indicated by the lines o c, d d, and e c.

The chill which is produced by hardening from the back of the end of the shoe is of an entirely-different character from that which is produced by hardening the faceof the shoe at the end or at any point intermediate to the ends". In the case of my shoe the area of chilled metal at each end of-the shoe in contact with the wheel is practically uniform throughout the life of the shoe after the softmetal facing is worn away, and the chill coming from the back of the shoe, causing the greatest density immediately on the back face of the shoe, with grad ually-decreasin g density as the chill penetrates the shoe, is not of a nature to inj uriously wear the wheel, whereas in the case of shoes having chilled parts made from the Wearing-face of the shoe inwardly the area of the chilled section is far greater at the commencement of wear and greatly diminishes as the shoe is worn, While the chill is hardest at the wearing-face of the shoe and of a character calculated to injuriously wear the Wheel.

Practically the entire body portion of my shoe coming in contact with the wheel is an area of soft cast-iron, and the area in contact with the wheel at the commencement of service is the same as the Master Car-Builders standard cast-iron shoe.

My aim is to take a soft-cast-iron brakeshoe and add metal at the ends which may be so hardened from the back as to prolong the life of the shoe without injuriously affecting the wheel or diminishing the frictional power of the shoe. Of course, as before stated, the metal that is added to the end of the shoe may be either shaped as in the drawings or it may be rounded or squared, so long as the essential feature is retained-that of its being chilled or hardened from the back, so that the chill merges into the soft cast-iron before reaching the surface of the shoe exposed to wear against the wheel in commencing service.

lVhile I have shown in the drawings the prolongations as extending tengeutially to the tread of the wheel, it is within the contemplation of my invention to form this extension concentric with the tread of the wheel, if desired, though the form shown in the drawings is preferred, because in the commencement of service the area of contact between the shoe and the wheel is the same as the standard cast-iron shoe.

My invention possesses numerous advantages over any prior form of chilled-cast-iron shoe known to me, especially as regards the strength of construction due to the fact that the entire body of the shoe is composed of soft and strong iron and the chilling of the prolongations at the ends does not in any way diminish the strength of the shoe, but rather byincreasing the density of the metal inside of and contiguous to the chilled portion adds to the strength of the shoe. Thislhavedemonstrated by tests.

Furthermore, I have 'ard area for shoe-surface.

found that it is possible by chilling from the back to obtain greater uniformity, from the fact that all of the surface of the shoe, as stated above, is of soft cast-iron until the shoe has suffered a wear of about three-sixteenths of an inch, while in all other forms of shoes containing chilled sections there is either a portion of the chilled surface in contact with the wheel at the outset-or the area of soft cast-iron in contact with the Wheel constitutes only a part of the Master Oar-Builders stand- With the characteristics of durability obtained from the chilled portion of my shoe I have greater strength, more friction, and greater uniformity of action on the wheel than any other chilled shoe, and all of these results arise from chilling the back of the prolongation on each end of the shoe.

Having described my invention, what I claim, and desire to secure'by Letters Patent, 1s-

1. A cast-iron brake-shoe having triangular prolongations tapering from the back to the wearing-surface of the shoe at the ends thereof and chill-hardened from the back, said chilled port-ions not extending to the wearingsurface of the shoe, substantially as and for the purpose described.

2. A cast-iron brake-shoe having tangential triangular prolongations at the ends thereof chill-hardened from the back, said chilled portions not ex tending to the wearing-face of the shoe, substantially as and for the purpose described.

WILLIAM DURIIAM SARGEX'I..

Witnesses:

C. L. WOOD, J. N. RAYMOND.

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