BRIDGES FOR ELEVATED RAILROADS AND OTHER PURPOSES
Year: 1887

page_text: Date of Application, 18th Mar., 1887.
Specification Accepted, 29th Apr., 1887.
I, GEORGE HERNDON PEGRAM of the City of Wilmington in the County of
Newcastle, State of Delaware, United States of America, Civil Engineer do hereby
declare the nature of this invention for BRIDGES FOR ELEVATED RAILROADS AND
OTHER PURPOSES 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 a bridge for elevated railroads the object of which is to
construct a suitable and proper bridge in such a manner that the rails are carried
directly by the longitudinal trusses, the usual cross ties, and the longitudinal beams
above said cross ties, as heretofore employed, being dispensed with.
And the invention consists in a truss for an elevated railroad or other bridge, the
top chord of which is substantially in the form of a longitudinal trough, which
longitudinal trough, is adapted to serve, in addition to the functions of the top chord
of the truss, also as a stringer for the support of the car-wheel-rail, and as a guard for
the car-wheel.
In the accompanying sheet of Drawings is shown a form of structure which
embodies the present invention in which
Figure 1 is a side elevation of one span or bridge of an elevated railroad constructed
according to the present invention.
Figure 2 is a plan view of figure 1.
Figure 3 is a partial cross section of figure 1, on a somewhat enlarged scale.
Figure 4 is a cross section of the top chord of the truss on an enlarged scale taken
on the line - figures 1 and 2.
Figure 5 is a similar cross section of the same taken on line 5-5.
Figures 6 and 7 are cross sections of top chords of somewhat different construction
from that shown in the preceding figures.
In the Drawings A represents a truss for an elevated railroad bridge, of which
truss, B is the top chord, C, the bottom chord, D the ties, and E, the braces. Fis
the cross bracing between two parallel trusses, and G, the lateral braces between such
trusses.
The top chord B of each truss is made substantially in the form of a trough, a, and,
as shown, consists of two parallel longitudinal pieces, H, each extending the entire
length of the truss, and which constitute the sides of said trough, and said pieces El
are placed a suitable distance apart from each other, and kept separate and parallel
and firm by the interposition of horizontal plates, J, having angular projections, b,
placed between the pair of parallel pieces H, and firmly secured in such position by
bolts or rivets, d, passing through their said angular projections, b, and the thickness
of the pieces H. These horizontal plates, J, are preferably placed between the

page_text: parallel pieces, II, at intervals in the length thereof, although, in some instances, they
might be replaced by one continuous piece; and these said plates, J, constitute in
substance the bottom of the trough, the said pieces H constituting the sides thereof,
and the whole combines to form the top chord of the truss.
Upon each of the horizontal plates J, or upon such of them as is desired, or
necessary, are placed blocks, K, of suitable height which blocks are suitably secured
in position in any suitable manner, such as by the employment of bolts,, passing
through the thickness of the horizontal plates J, and of said blocks, K.
The car-wheel-rail, L, is placed upon and properly secured to the said blocks, K,
midway between, and parallel with, the side pieces H of the trough.
A simple and effective means of securing the car-wheel-rail, L, in its position,
consists in the employment of narrow metal plates, M, on each side of the rail each of
which by one edge lies upon the bottom lateral flange m, of the rail L, and by its
other edge upon the upper end 62, of the flanged projection b, of the plate J, which
end 62, is in or about the same horizontal plane with the top of the said lower lateral
flange m, and bolting said plates to the blocks K, and plate M, and this is practically
and economically secured by passing the bolt or rivet f, (used for the confinement of
the blocks K with the plate J) also through the thickness of said plate M, where it is
headed or provided with a nut.
In the truss shown the ties D are connected to the top chord B by pins, p, passing
through them and through the pieces, H, and the braces E are connected with the
top chord B, of the truss by the employment of projections, 1, formed upon or secured
to the inner faces of the pieces H, below the points of support for the car-wheel-rail,
through which projections 7, and the braces, E, pass the pins, p, as shown.
Thus it will be seen that the plates II, II, together with the horizontal plates, J,
either placed at intervals or made continuous, constitute in substance a trough, and
this trough shaped structure, as a whole, is and serves the purpose of, the top chord of
the truss, the bottom thereof the support for the car-wheel-rail, and the sides thereof
the guards for the car-wheel.
And while a particular construction of several parts joined together has been
particularly shown and described as forming the trough shaped top chord of the truss
other parts and forms may be employed to form such trough shaped chord of the iruss,
for the purposes designated; and in figures 6 and 7 obvious modified constructions
are shown in the formation of the trough shape of the chord ; and it is not intended
to limit the invention to any particular form of parts, or manner of joining them,
which combine to form said trough shaped chord, or to any form of truss.
It will be seen from the drawing-figure 1-that the formation of the truss is novel
in its manner of bracing and tying between the top and bottom chords the essential
feature of which lies in the arrangement of each end tie in such a way that it extends
to the apex of a triangle formed by itself, the intermediate web braces and the top
chord B, the special advantages thereof consisting in providing more numerous
supports to the top chord which its action as a stringer makes desirable.
The advantages of a railway constructed substantially in accordance with the
present invention are manifest, but among them may be mentioned that wooden cross
ties and guard rails as at present employed are entirely dispensed with and there is
the least obstruction of light to the street below, and the heavy shadows and tunnel
like appearance given to the street are avoided, a great desiratum in a city.
The repairs are reduced to a minimum, and may be made with much greater case
than in the present structures. The chords in the different trusses are connected by
lateral diagonal bracing F, whereby the same stiffness is secured to the structure that
is secured by the use of cross-ties and wood is used in the present truss in a minimum
and merely as cushions for the rails and may be replaced at slight expense and
inconvenience.
The safety of the railway is ensured, the wheels running in iron troughs are
prevented from leaving the rails and in the event of a broken wheel or axle the truck
drops upon the top of the sides H, of the trough, which is in effect the same as a pair
of skids.

page_text: The structure is much more readily cleaned of snow; and the space between the
trusses allows ample room for pulleys of a cable, which is not easily secured where
cross-ties are employed.
The main advantage however consists in making the floor system an integral part
of the truss through which great economy of cost and construction and insurance of
durability are secured.
The use of the pin connection in place of the present riveted connection secures
much greater safety and durability in the structure. The pins allow a deflection of
the parts without injury to the joints and when worn they may be readily replaced,
while in the use of rivets it is found impossible to keep the rivets tight, and cutting
out and replacing a loose rivet injures the material and is apt to loosen the other
rivets.
I am aware that the use of the top chord of a truss in the double duty of top chord
and stringer is not new. I am also aware that the double duty of a stringer as a
stringer and wheel guard is not new and neither of these things distinct and in itself
do I claim but the invention resides essentially in a construction whereby the top
chord of the truss is made to perform the three functions of top chord, stringer and
wheel guard.
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
1st. A truss for elevated railways and other purposes, having the top chord of the
truss constructed in the form of a trough serving as a support for the rails and as
guards for the car-wheels substantially as described for the purposes specified.
2nd. A truss for an elevated railway, etc., its top chord made of parallel longitudinal
pieces II, H. and horizontal plates J, joined together in a manner to form in substance
a trough substantially as described for the purposes specified.
3rd. A trough chord formed substantially as described in combination with braces
and ties to form a truss for elevated railroads or other purposes.
4th. A truss for elevated railways, etc., having its top chord made of parallel
longitudinal pieces H, H, and a series of horizontal plates J, at intervals, with spaces
between them, joined together in a manner to form, in substance, a trough, subsian-
tially as described for the purposes specified.
5th. In an elevated railway etc., a truss having its top chord made of parallel
longitudinal pieces H, H, and horizontal plates, J, joined together in a manner to
form a trough, and having blocks, K, resting on said horizontal plates, J, substan-
tially as described for the purpose specified.
6th. The combination with the trough chord B, enclosing and supporting the
rail, L, of the braces, E, bottom chord, C, and ties, D, to form a truss for elevated
railroads and other purposes substantially as described.
7th. The combination with the trough chord, B, enclosing and supporting the
rail L, of the braces E, the tie bars, C, and D, and the transverse and lateral
bracing, F, and G, to form a bridge for elevated railroads and other purposes substan-
tially as described.
8th. A truss for.elevated railways and other purposes in which each end tie D
extends to the apex of a triangle which is formed by said tie, the intermediate web
braces and the top chord B substantially as set forth.
9th. The combination with the top chord B the braces E, ties D, bottom chord C,
and pins, p, to form a truss substantially as described for the purposes specified.
Dated this 23rd day of Fabrum 1007