Improvements in Brake Shoes.
Year: 1899

page_text: Date of Application, 5th Aug., 1899
Complete Specification Left, 3rd May, 1900-Accepted, 9th June, 1900
PROVISIONAL SPECIFICATION.
Improvements in Brake Shoes.
I, JOSEPHUS BODINE TERBELL, of the City of Corning, in the County of Steuben,
State of New York, U.S.A., Manufacturer, do hereby declare the nature of this
invention to be as follows:-
The attention which has been given to brake-shoes in recent years has resulted
in a better understanding of their functions, and in consequence more rigid have
become the demands on the maker. Brake shoes were once selected wholly on the
basis of first cost, but now it is generally conceded that this is a poor guide and
that there are several other more important factors entering, each of which
must be given its due weight. A general consideration of the subject makes it
apparent that there are six desirable qualities for a brake shoe from the stand-
point of efficiency and economy.
First. The shoe should not injuriously affect the surface of the wheel with
which it comes in contact.
Second. It should have a proper coefficient of friction.
Third. It should have a long life in service.
Fourth. The cost when considered in connection with the service given should
he low.
Fifth. Shoes of the same kind should be uniform in action.
Sixth. The strength of the shoe should be ample to prevent breakage in service.
The effect of the brake shoe on the wheel is of great importance, and should
stand first among the desirable qualities, as the expenditure for wheels is greatly
in excess of that for brake shoes, being about as ten to one on roads using cast
wheels, and it follows that this ratio would be correspondingly greater where steel
tired wheels are employed.
As the present practice of railroads is to design the brake gear of cars with
reference to the coefficient of friction of ordinary hard cast iron, the use of any
brake shoe which has a friction widely different from that of hard cast iron is
undesirable until a radical change is made in this accepted practice. A high
coefficient of friction will surely result in skidded wheels, while a too low
coefficient of friction makes a long stop. Of the two evils the skidding of wheels is
probably the greater.
The life of the shoe and its first cost determine the economy of its use, and
neither factor can properly be considered apart from the other.
The present invention is designed to obviate the difficulties and meet the
requirements above described and the invention consists essentially of what may
be termed a composite shoe it being in fact an intermixture in an integral
structure of hard and soft portions.
This structure is formed of the combination of a central part or core more or
less irregular in shape and exposed on the working face of the shoe. Around this
core is poured or cast the casing or envelope to complete the shoe. The core
being cold when the casing is cast around it the parts of the casing contiguous to
the core are chilled.

page_text: Improvements in Brake Shoes.
I, JOSEPHUS BODINE TERBELL, Manufacturer, Citizen of the United States,
residing at Corning, in the County of Steuben and State of New York, U.S.A.,
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: -
1...
The attention which has been given to brake shoes in recent years has resulted
in a better understanding of their functions, and in consequence the demands
upon the maker have become more rigid. Brake shoes were formerly selected
wholly on the basis of first cost, but now it is generally conceded that this is a
poor guide, and that there are several other more important factors entering,
each of which must be given its due weight. A general consideration of the
subject makes it apparent that there are six desirable qualities for a brake shoe
from the standpoint of efficiency and economy.
First. The shoe should not injuriously affect the surface of the wheel with
which it comes in contact.
Second. It should have a proper co-efficient of friction.
Third. It should have a long life in service.
Fourth. The cost when considered in connection with the service given should
be low.
Fifth Shoes of the same kind should be uniform in action.
Sixth. The strength of the shoe should be ample to prevent breakage in service.
The effect of the brake shoe on the wheel is of great importance, and should
stand first among the desirable qualities, as the expenditure for wheels is greatly
in excess of that for brake shoes, being about as ten to one on roads using cast
wheels, and it follows that this ratio would be correspondingly greater where
steel tired wheels are employed.
As the present practice of railroads is to design the brake gear of cars with
reference to the co-efficient of friction of ordinary hard cast iron, the use of any
brake shoe which has a friction widely different from that of hard cast iron is
undesirable until a radical change is made in this accepted practice. A high
co-efficient of friction will surely result in skidded wheels, while a too low co-
efficient of friction makes a long stop. Of the two evils the skidding of wheels is
probably the greater.
The life of the shoe and its first cost determine the economy of its use, and
neither factor can properly be considered apart from the other.
The present invention is designed to obviate the difficulties and meet the
requirements above described and the invention consists essentially of what may
be termed a composite shoe, it being in fact an intermixture in an integral
structure of hard and soft portions.
This structure is formed of the combination of a central part or core more or
less irregular in shape and exposed on the working face of the shoe. Around this
core is poured, or cast, the casing or envelope to complete the shoe. The core
being cold when the casing is cast around it, the parts of the casing contiguous
to the core are chilled.
The construction may be more definitely ascertained by reference to the accom-
panying drawing, in which Figure 1 represents a perspective view of a brake
shoe made in accordance with my improvements.
Figure 2 is a longitudinal section thereof.
Figure 3 represents a plan or face view of a modified form.
In this drawing A represents a soft iron core irregular in shape or contour, as
shown.

page_text: The soft iron core A is formed with enlarged portions connected by narrower
or contracted portions B, the latter providing insets 1), which afford pockets for
the reception of the enveloping metal C. These insets or pockets are arranged
successively on alternate sides of the core.
The core being formed the shoe completing metal is poured around it while the
core is cold, the result being that these parts of the envelope in immediate or
proximate contact to it become chilled and consequently hardened and which
parts, when the shoe is in actual use, operate as a wheel trimmer. keeping the
tread true and constant: at the same time, as experiment has shown, the com-
bination and association of the hard and soft metal in the manner described
constitutes an effective and satisfactory braking surface.
I have shown, and preferably employ in actual use, four insets or pockets D.
They are arranged successively on alternate sides. When the enveloping casing C
has been cast around the soft iron core A the pockets or recesses 1) will of course
fill, with the result that such portions of the casing which enter the said pockets
will become chilled and hardened as will also those parts of the casing which
elsewhere are in contact with the said core. The extensions of the casing which
enter the pockets 1) form grinding and trimming surfaces which, in connection
with the other chilled or hardened edges, serve to true the wheel tread.
It is desirable in the construction of a shoe of this nature where it is to conform
to the conditions herein before rehearsed to mass the chilled portions more towards
the ends or terminals of the shoe than at the center. By this means the possibility
of breakage is eliminated while at the same time the co-efficient is maintained. To
these ends I increase the depth of the soft iron core as at a, a thus enlarging
the bulk of the chills at the ends of the shoe while at b, b, b, the soft iron core
decreases in depth, thus reducing the volume of the chill at the center of the shoe.
By this construction the shoe is strongest at the centre and hardest at the ends.
In Figure 3 I show a modification where the core is made in two parts A, A¹.
Here as in the other form the chills are massed towards the end.
It will be seen that I produce a composite brake shoe having the hard and soft
parts so distributed that it will always tend to produce an even wearing effect
on the wheel tread and that by reason of the preponderance of the soft over the
hard parts on the surface of the shoe that sufficient friction between the shoe
and wheel is always assured; also that a shoe of great strength, durability and
uniformity of action is secured at a minimum cost of manufacture.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:―
First A composite brake shoe having a soft iron core with insets or pockets
arranged successively on alternate sides of the core, combined with a completing
casing formed substantially as shown and described and for the purposes set forth.
Second: A composite brake shoe having a soft iron core A of irregular shape,
provided with contracted portions B, pockets D, and an enclosing and shoe
completing envelope or casing C, all arranged and constructed substantially as
and for the purposes set forth.
JOHNSONS,
Applicant's Agents, 115, St. Vincent Street, Glasgow.