IMPROVEMENTS IN RAILWAY BRAKES
Year: 1875

page_text: LETTERS PATENT to Edwin Powley Alexander, of 14, Southampton
Buildings, in the County of Middlesex, Consulting Engineer and
Patent Agent, for the Invention of " IMPROVEMENTS IN RAILWAY
BRAKES." A communication from abroad by Abel Barker, of
Wyoming, State of Pennsylvania, United States of America,
Gentleman.
Scaled the 29th June 1875, and dated the 3rd May 1875.
COMPLETE SPECIFICATION filed by the said Edwin Powley Alexander
at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 3rd May 1875, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWIN
POWLEY ALEXANDER, of 14, Southampton Buildings, in the County.
of Middlesex, Consulting Engineer and Patent Agent, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
RAILWAY BRAKES," and have petitioned Her Majesty to grant unto me,

page_text: my executors, administrators, and assigns, Her Royal Letters Patent
for the same, and have made solemn Declaration that the said Inven-
tion was communicated to me by Abel Barker, of Wyoming, State of
Pennsylvania, United States of America, Gentleman.
NOW KNOW YE, that I, the said Edwin Powley Alexander, do
hereby declare that the following Complete Specification, under my
hand and seal, fully describes and ascertains the nature of the said
Invention, and in what manner the same is to be performed, in and
by the following statement, reference being had to the accompanying
Drawings, and to the letters and figures marked thereon, that is to
say :-
In the use of railway brakes, more especially those operated by steam,
compressed air, or by a vacuum, it is well known that the pressure of
each brake upon the wheels is the same whatever the weight of the load
within the vehicle, so that if such brake is adjusted to produce the
necessary friction, when the vehicle is loaded, and retard the motion of
the wheels as much as is possible without causing them to slide upon the
rail, such friction will arrest the movement of the said wheels whenever
the weight supported by them is lessened by the removal of a portion of
the load from the vehicle. If the pressure of the break be adjusted to the
weight of the unloaded vehicle its efficiency will not equal the require-
ments as load is added to said vehicle, so that it has heretofore been
necessary to adjust the pressure of said brake to the mean weight of the
vehicle and load, at which point only could the full efficiency of the
former be relied upon. The result of such want of adaptability of
the brake pressure to the load is that large numbers of railway carriage
wheels become flattened at points upon their peripheries by being dragged
along instead of rolling upon the rails whenever the breaks are applied;
such flattening rendering said wheels unfit for use and increasing
materially the expense of railroad traffic. To remedy these objections
and render the pressure of a brake upon its wheels automatically and
correspondingly variable, as the weight of the car is increased or
diminished is the design of this Invention, which consists in railway
carriage or waggon brake in which the weight of the vehicle limits the
maximum pressure upon the brake shoes, and causes a correspondence
to be maintained between such pressure and weight as the latter is

page_text: specined.
And in order that the said Invention may be fully understood I shall
now proceed more particularly to describe the same, and for that purpose
shall refer to the several Figures on the explanatory Sheet of Drawings
hereunto annexed, the same letters of reference indicating corresponding
parts in all the Figures.
Figure 1 of the Drawings is a side elevation of a car truck with brake
constructed in accordance with this Invention; Figure 2 is a vertical
transverse section of the same, showing the arrangement of parts before
the brake is applied; and Figure 3 is a like view of the same showing
the position of the said parts when said brake is on.
In the annexed Drawings A, A, represent the side rails; B, B, the end
rails; and C, O, two cross centre rails which extend between and con-
nect together said side rails, the whole forming the under or main frame
of a railway carriage, which frame rests upon and is supported by means
of two axles D, D, and four wheels d, d, that are secured upon the
latter. Between the centre beams C, C, which are parallel with each
other is placed a swing beam E, that is suspended from the upper
side of the former by means of two links F, F, that pass around said
parts and are pivoted to or upon the lower side of said swing beam and
the upper
side of said cross beams. The usual bolster G is pivotted
upon the upper side of said swing beam and receives and sustains the
weight of the carriage.
Upon each side of the frame directly above the wheels d, d, is placed
a horizontal brake bar H, which is capable of vertical motion only, is
provided upon its lower side with shoes h, h, that correspond to and
may be caused to bear upon the peripheries of said wheels and rests
upon suitable springs I, I, which hold said bar in an elevated position
and prevent accidental contact between said shoes and wheels, as shown
in Figure 1.
Pivotted upon each side and at the upper end of each link F is a
lever K which has the form shown in Figures 2 and 3, and has its hori-
zontal arm k loosely connected with the lower side of the adjacent
brake bar H so that by moving the lower end of said lever toward or

page_text: depressed or elevated.
The lower ends of the levers K, K, of each brake bar are connected
together and move simultaneously, and have attached thereto a rod L
which through suitable mechanism is connected with the motive power,
so that when desired said levers may be caused to apply to or release
from the wheels the brake shoes.
It will be seen that as the brake levers are operated the swing beam
and of course the carriage is raised, the resistance offered by the weight
of said carriage increasing regularly until said levers have reached a
vertical position, at which point the further upward motion of said swing
beam is arrested by a stop M, that is attached to and extends upward
'from each end of the same, and bears against the lower side of the
brake bar immediately above.
When the stops M, M, are in contact with the brake bars H, H, the
levers K, K, cannot increase the pressure of the brake shoes upon
the wheels, which pressure is varied only by changes in the load of the
carriage, and as the power necessary to arrest the motion of said wheels
increases in proportion to the weight to be carried, it is found that by so
adjusting the mechanism as to cause it to exert the maximum of
efficient friction upon said wheels when the carriage is unloaded such
relation between the weight and friction will be maintained as a
load is added, the wheels being just permitted to revolve in either
case.
While the peculiar construction and arrangement of parts shown is a
preferably employed I do not confine myself to the same, as the principle
involved will admit of numerous modifications and is applicable to any
form of brake.
Having now described and particularly ascertained the nature of the
said Invention and the manner in which the same is or may be used or a
carried into effect I would observe in conclusion that what I consider to
be novel and original and therefore claim as the said Invention is, the
construction and use of railway brakes wherein by mechanism, sub-
stantially such as is herein-before described, the weight of the vehicle
limits the maximum pressure upon the brake shoes or blocks, and causes 3

page_text: a correspondence to be maintained between such pressure and weight as
the latter is increased or diminished, substantially as and for the purpose
herein set forth.
In witness whereof, I, the said Edwin Powley Alexander, have
hereunto set my hand and seal, this Thirtieth day of April,
in the year of our Lord One thousand eight hundred and seventy-
five.
EDWIN P. ALEXANDER. (L.S.)