Improvements in Brake Shoes for Railway and Tramway Vehicles.
Year: 1896

page_text: Date of Application, 10th Mar., 1896-Accepted, 16th May, 1896
COMPLETE SPECIFICATION.
Improvements in Brake Shoes for Railway and Tramway Vehicles.
I, WILLIAM DURHAM SARGENT, of 82 to 86 Van Buren Street (Old Colony
Building) Chicago, Illinois, United States of America, Manufacturer, do hereby
declare the nature of this invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
"
This invention relates to the class of brake shoes known in the art as "dressing
brake shoes, because in addition to their function of brakes, they serve the purpose
of dressing the entire tread and flange of car-wheels in proportion to the wear on
said wheels resulting from contact with the rails. This class of brake shoes is
exemplified in British Letters Patent No. 13763 dated July 17th, 1894, upon
which my present invention is more especially designed as an improvement.
The primary object of this invention is a brake shoe which will not only dress
car-wheels proportionately to the wear thereof, due to contact with the rails, so as
to maintain the tread and flange of the wheels in uniform and proper condition at
all times during their lives, but will also possess the maximum degree of longevity
in service, without detriment to the strength or braking quality of the shoe.
A further object is to provide a brake shoe with a wearing surface that shall be
practically continuous over the tread and flange of a car-wheel, which will dress
with maximum effect those portions of the wheel which do not contact with the
rail, and which will dress those portions of the wheel that are worn by contact with
the rail with proportionate effect, and which will yet have a composite metallic
wearing surface, a portion of which is directed to affording braking effect, while
the other portion serves to retard the wear of the shoe.
Another object of the invention is a brake shoe having integral hard and soft or
composite metallic wearing surfaces, which shall possess in the maximum and an
exceptional degree strength, durability and effectiveness.
These, and such other objects as may hereinafter appear, are attained by the
device illustrated in the accompanying drawing, in which
Figure 1 is a perspective view of a brake shoe provided with alternate chilled
parts and openings.
Figure 2 is a cross-sectional view of the brake shoe shown in Figure 1, taken
through an opening.
Figure 3 is, a perspective view showing a brake shoe provided with chilled
surfaces and without openings.
Figure 4 is a transverse sectional view of the shoe shown in Figure 3.
Figure 5 is a perspective view of an ordinary flat brake shoe.
Figure 6 is a cross-sectional view of a flat brake shoe showing a flange on the
back thereof; and
Figure 7 is a diagrammatic view illustrating the wear upon a wheel and the
position of the chilled parts in the brake shoe with relation to the wear on the
wheel.
In all of the drawings, A designates the body-portion of the brake-shoe, and B
the chilled parts thereof.
These chilled parts may be variously disposed and, in Figure 1, I have shown

page_text: them arranged alternately with openings C, one or more of which may be provided
as desired. In this case the chilled parts extend through all that portion of the
shoe between the openings, as clearly shown in Figure 1.
In Figure 3, I have shown a number of chilled parts with narrow webs D
separating said parts; and, in Figure 5, the webs separating the chilled parts are
wider than those shown in Figure 3.
These chilled parts may be made in many ways, but a common way is to subject
parts of the shoe to the action of a cold piece of metal in the process of casting.
The chilled parts may be of any desired configuration and size, and it will be
understood by those skilled in the art, as well as by others, that the number and
size, as well as the location and arrangement of the chilled parts with relation to
the other parts of the brake shoe, will vary under different conditions, but the
chilled parts are arranged in such a position with relation to the other parts of the
brake shoe that they will be located opposite to that portion of the wheel which is
worn by contact with the rail; and those portions of the wheel which do not
contact with the rail, and therefore are not worn, will be dressed by the soft parts
of the brake shoe around the chilled parts thereof, with maximum effect.
In Figure 7, I have shown the preferred location of the chilled parts with
relation to the wear on the wheel. In actual use, it will be found that the chilled
parts of the brake shoe wear more or less, but they do not have the dressing effect
upon the wheel that is afforded by the other parts of the brake shoe. While the
soft parts of the brake shoe wear the wheel by reason of the grinding action
afforded by the particles rubbed off of the shoe, the chilled parts form polished
surfaces and do not, to any material extent, dress the portion of the wheel with
which they come in contact. The chilled parts merge into the soft parts of the
shoe gradually and the corners thereof are rounded, as at d, whereby the dressing
face of the shoe is gradually enlarged on either side of the line where the wheel is
worn the most by the rail.
The foregoing will be clearly understood by referring to the diagrammatic view
(Figure 7) in which G represents the car-wheel, H the rail, I a portion of the
brake shoe, J the original outline of the ear wheel, and K the outline showing the
ordinary wear upon a car wheel by the rail to which a dressing brake shoe has not
been applied in service.
That portion of the wheel tread between the lines a, a' represents the area of
maximum and practically uniform wear of the rail upon the wheel-tread. That
portion of the wheel-trend between the lines a and b and a' and represents the
area of proportional wear of the rail upon the tread, the minimum wear being at about
the lines &,. That portion of the tread and flange between the lines, and, e
represents the area of no wear upon the wheel by the rail, because these portions
of the wheel never come in contact with the rail.
It is therefore desirable to dress with maximum wearing effect substantially that
portion of the wheel-tread and flange included between the lines b, c and 6, e; to
dress with minimum wearing effect that portion of the wheel-tread between the
lines a and a; and to dress with a proportionate effect, from the maximum to the
minimum, that portion of the wheel-tread and flange between the lines a, b and a', '.
That portion of the shoe indicated by the letters d is intended to illustrate the
merging of the chilled portion of the brake shoe into the soft or unchilled portion
thereof; and, while I have shown in this view and in the other views a comparatively
sharp line of demarcation between the chilled and unchilled or soft portions of the
shoe, in practice no such line does or can exist as the effect of the chill will extend,
in a rapidly lessening degree, from the desired outlines of the chilled portion into
the soft portion, so that the wearing surface of my brake shoe, in point of fact, is
of composite metal of three degrees of hardness, the hardest being over the area
of maximum wear, the softest being over the area of minimum wear and the
intermediate being over the area of proportionate wear of the rail upon the wheel.
I am aware that there are many different constructions in the art which propose"
or attempt to provide for the uniform dressing of wheels, aside from my patented

page_text: invention herein before referred to, but, so far as I am aware, it is broadly new to-
provide chilled parts in a brake shoe which are disposed so that they will contact.
with or be located opposite to that portion of the wheel which receives the greatest
wear by contact with the rail. The use of chilled parts in the manner I have
described will provide a brake shoe of great strength and durability.
In Figures 4 and 6 of the drawings, I have shown the rib E, which is provided
on the back of the brake shoe, for attachment to the brake-head. I have also
shown two different forms of brake shoes in these drawings which appear to be.
sufficient for the purpose of fully disclosing the invention, but it will be understood,
of course, that the improvements may be embodied in brake shoes of any kind not
inconsistent for the purposes of the invention.
It will be noted, in Figures 2 and 6, more especially, that the contour of the
wearing surface of my shoe does not coincide exactly with that of the wheel-tread
and flange or, in other words, that the chilled portion practically spans between
the tread and flange of the brake shoe over the areas of maximum and proportionate.
wear and does not make contact therewith. This condition, however, to the fullest
extent exists only when the shoe is first applied to the wheel, the length of span.
gradually lessening as the shoe wears until finally the contour of the shoe and.
wheel will actually correspond.
This feature is important in order to afford detriment to the full effectiveness of
the brake shoes when first applied, which might result from carelessness or the
exigencies of chilling, when the chilled portion might otherwise serve for some
time to prevent the application of the full wearing surface of the shoes to the-
wheels when first applied, and consequently prevent the maximum braking effect
of the shoe being brought into play.
I am aware that changes and variations. in the form and proportion of the
different parts of my improved brake shoe may be made without departing from
the spirit or sacrificing the advantages of the invention and I would, therefore, have
it distinctly understood that I reserve to myself the right to make all such changes.
as fall within the spirit and scope of the invention.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performned, I declare that what I
claim is :-
1. A brake shoe composed of cast metal having chilled parts in its wearing
surface so disposed as to contact only with that portion of the wheel which contacts.
with the rail, substantially as described.
2. A cast metal brake shoe having a composite integral wearing face composed.
of unchilled cast metal, chilled cast metal and partially chilled cast metal, the
chilled portion being located opposite the area of maximum wear of a rail upon a
car-wheel, substantially as described.
3. A cast metal brake shoe having continuous wearing surfaces to bear upon
those portions of the wheel which do not make contact with the rail, that portion.
of the shoe between such continuous wearing surfaces being chilled so as to leave
a substantially uniform wearing surface of chilled metal over the area of maximum.
wear of the rail upon the wheel, approximately from a to a', and gradually
decreasing wearing surfaces of chilled metal between said uniform chilled portion
and the said continuous wearing surfaces, approximately from a to b and a¹ to b¹.
substantially as described.
4. A brake shoe composed of soft metal having chilled parts located in the
wearing surface of said shoe opposite that portion of the wheel which contacts with
the rail, said chilled parts being substantially uniform opposite the area of maximum
wear of the wheel and gradually reduced from said uniform portion at each side to
approximately a point where the wear of the rail upon the wheel ceases,.
substantially as described.
5. As a new article of manufacture, a brake shoe having parts of its wearing.
surface chilled opposite that portion of the wheel which contacts with the rail, said.

page_text: chilled portion being adapted and arranged to span the area of the wheel worn by
contact with the rail when first applied to the wheel, substantially as described.
Dated this 10th day of March 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.