IMPROVEMENTS IN BRIDGES AND VIADUCTS, AND IN MACHINERY OR APPA- RATUS CONNECTED THEREWITH
Year: 1872

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of
"IMPROVEMENTS IN BRIDGES AND VIADUCTS, AND IN MACHINERY OR APPA-
RATUS CONNECTED THEREWITH."-A communication from abroad by
Thomas Curtis Clarke, of Philadelphia, Pennsylvania, and Adolphus
Bonzano, and John Griffin, of Phoenixville, Chester County, Penn-
sylvania, all of United States, America.
Scaled the 31st December 1872, and dated the 11th September 1872.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 11th September 1872.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
5 of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN BRIDGES AND VIADUCTS, AND IN MACHINERY
OR APPARATUS CONNECTED THEREWITH," a communication to me from abroad
by Thomas Curtis Clarke, of Philadelphia, Pennsylvania, and Adolphus

page_text: Bonzano and John Griffin, of Phoenixville, Chester County, Penn-
sylvania, all of United States, America, to be as follows:-
This Invention consists,-
:-
First, of a peculiar truss frame bridge constructed of wrought iron or
steel, with the view to the attainment of lightness, strength, facility of a
erection, and economy of construction.
Secondly, of a peculiar truss frame bridge or viaduct having a
roadway on the top, and possessing many of the features to be found
in the bridge which forms the subject of the first part of the Invention.
Thirdly, a peculiar pivot bridge made of wrought iron or steel, the
said bridge being constructed in such a manner that the lower chord
shall be a compression member when the bridge is clear of its end
bearings, the upper chord becoming a compression member when the
bridge is adjusted to form a roadway for the passage of trains.
Fourthly, of a peculiar turntable for supporting the above-mentioned
pivot bridge, whereby the ready vertical adjustment of its rim is
obtained without disturbing its integrity and concentricity with the
.pivot.
And fifthly, of certain peculiar mechanism connected with the pivot
bridge for readily elevating the same from-its end bearings when it has
to be turned, and as readily readjusted to its end bearings when the
'bridge has to be adjusted for the passage of trains.
The bridge as constructed according to the first part of this Invention,
consists of two trusses, each truss being composed of an upper chord, a
lower chord, inclined end posts, and verticals, and the diagonals and
counter diagonals referred to hereafter.
The upper chord, end posts, and verticals are all composed of wrought-
iron tubes composed of a group of rolled bars of wrought iron, so shaped
that a combination of the bars will form a tube, the bars having flanges
through which pass bolts or rivets. While these wrought-iron tubes are
remarkably light, they are capable of resisting great end strain, and
hence are especially applicable as compression members to the con-
struction of truss frame bridges and viaducts generally.
The method of connecting the inclined end post to the upper chord
connecting ninna
Atzon
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annular proination
An

page_text: The
which fits the upper end of the inclined end post, and the end of the
upper chord tube, a pin passing through the connecting piece and
through eyes at the upper end of ties bars referred to hereafter.
lower end of the end post fits over an annular projection on the
pedestal, through which and through the eyes at the ends of the lower
chord rods pass bolts, the pedestal resting on a series of rollers
connected to a frame, and these rollers bearing on a foundation plate
which is secured by anchor bolts to one of the piers of the bridge.
The method of connecting the upper chord tube, the verticals, the
diagonals, and the counter diagonals together, consists as follows:-The
ends of the upper chord tubes are fitted over annular projections on a
cast-iron connecting piece, at the lower end of which is a third annular
projection fitting into the top of the vertical, which, as before remarked,
consists of a group of wrought-iron bars rivetted together. A bolt
passes through the cast-iron connecting piece through the eyes of the
diagonals and through loops in the adjustable counter diagonals. More
particular allusion will be made heareafter to the peculiarity of these
counter diagonals.
The mode of connecting together the verticals, lower chords, diagonals,
counter diagonals, and floor beams, consists as follows:-A bolt passes
directly through the vertical near the lower end of the same, where it
is reinforced in thickness internally, the bolt also passing through the
eyes of the lower chord rods, through those of the diagonals, and
through the loops of the counter diagonals. Strap bolts also pass over
the last-mentioned bolts, the threaded ends of the strap bolts passing
through a plate, between which and a second plate fitted to the lower
end of the vertical, is confined the floor beam by nuts adapted to the
said threaded ends of the strap bolts, the floor beam being of wrought
iron of a I sectional form, or of any other equivalent form.
In order to connect the two trusses together so as to form the desired
bridge, the lower portion of the trusses are connected together by
the floor beams and by lower horizontal diagonal tie rods, which are
connected to the webs of the beams, as explained hereafter.
:-
The trusses are connected together at the upper end in the following
manner Each intermediate cast-iron connecting piece and each end
connecting piece has a cylindrical projection, and from the projection
of one truss to that of the other extends a transverse tubular stay

page_text: composed of a group of rolled bars in the same manner as the verticals
and upper chords, and through the projections pass the ends of
horizontal diagonal tie rods, the tightening of these rods resulting in the
effective connection of the upper chords of the two trusses together.
The lower horizontal diagonal tie rods above alluded to are connected
to the webs of the floor beam in the following manner:-A circular
opening is formed in the web of the beam for the reception of
projections on corresponding opposite triangular blocks, through which
pass the ends of the said tie rods. In tightening the nuts of these
rods the blocks will be firmly bound to the web of the beam, which
will resist the strain imparted by the rods. This is both an economical
and secure mode of connecting the tie rods to the beam.
Allusion has been made to the construction of the adjustable counter
diagonals. Each adjustable counter diagonal before referred to consists
of one plain rod with a loop at each end, one loop being adapted to the
pin of the lower chord, and the other to the pin of the upper chord.
One end of the rod has a right-handed thread adapted to one loop, and
the other end of the rod a left-handed thread adapted to the other loop,
so that by turning the rod the counter diagonal may be lengthened and
shortened at pleasure. These counter diagonals are not only economical
in construction, but they afford better means of adjustment than the
ordinary screw couplings.
In the bridge constructed according to the second part of this
Invention, there are two trusses, each being composed of an upper
chord, a lower chord, posts or verticals at suitable intervals, diagonals,
counter diagonals, and end diagonals. The upper chord, as in the
former case, consists of a series of wrought-iron tubes, each tube being
composed of a number of flanged bars (eight in the present instance)
rivetted together, the posts or verticals consisting of similar tubes.
The method of connecting the post and upper chord together consists
of a cast-iron connecting piece over projections on which fit the chord
tubes, a similar projection fitting into the upper end of the post. A bolt
passes through the connecting piece through the eyes of the diagonals,
and where counter diagonals occur through the loops of the same. The
lower ends of the posts, the lower chord rods, the diagonals, and the
counter diagonals are connected, together by a pin passing through the

page_text: post through the eyes of the lower chord bars, those of the diagonals and
through the loops of the counter diagonals.
The two trusses are connected together in the following manner:- -A
transverse beam extends from truss to truss immediately above the posts,
the lower edge of each beam resting on the cast-iron connecting piece
before mentioned, to which it is confined by bolts and a plate. Diagonal
tie rods extend horizontally from truss to truss and pass through and
are connected to the beam; between the opposite posts of the trusses
extend wrought-iron tubes similar in character to but much lighter than
the tubes of the chords, and the opposite posts of the trusses are further
connected together by diagonal tie rods. A series of longitudinal beams
extend from one transverse beam to another, and on these longitudinal
beams rest the floor beams for supporting the rails of the two tracks.
The bridge is supported on pedestals secured to a pier, and to these
pedestals are connected the end diagonals and adjoining diagonals, the
pedestals also supporting a transverse beam similar to those above the
posts.
In constructing a truss frame pivot bridge according to the third part
of this Invention the upper chord of each truss consists of two series of
spliced channel bars connected together at the top by plates, and at
intervals by stays and bolts, and at the bottom by lattice work. A series
of posts or verticals are connected to this upper chord, and through the
post passes a bolt as well as through the ends of the diagonals and counter
diagonals. The lower chord also consists of two sets of channel bars
connected together by plates and by latticework at the top, a bolt
passing through the channel bars through the post near the lower end
of the same, and through the ends of the diagonals and counter diagonals.
The verticals as well as the end posts are made of flanged bars of rolled
iron revetted together as in the above described bridges. The two trusses
are connected together at the top by transverse tubes of wrought iron
and by diagonal stays, and at the bottom by transverse beams, each end
of each beam being secured to the under side of one of the lower chords
by strap bolts passing over the bolt before mentioned as passing through
the channel bars, the threaded ends of the strap bolts passing through
a plate confined to the under side of the transverse beam by ordinary.
nuts. A series of longitudinal beams extend between the transverse
beams, and on these longitudinal beams are secured these sleepers to
which the rails of the track are secured.

page_text: The bridge is designed as a continuous girder extending over twO*
spans, and is arranged to turn on a central pivot on a supporting pier,
but when adjusted for the passage of trains bears with its opposite ends
on two other piers.
It will be seen that the upper and lower chords are alike, and this is
essential to the proper construction of the bridge, for when the latter is
swung round clear of its bearings the lower chord becomes the com-
pression member, and when the bridge is adjusted to its bearings for
the passage of trains the upper chord becomes the compression member.
The turntable which constitutes the fourth part of this Invention and.
which serves to support the above described pivot bridge consists of a
disc of cast iron so fitted to a pivot that it can slide freely therein, and
this disc is suspended by bolts to the base of an upright pillar, to the top
of which is secured another disc, and through the flange of the latter
and through the rim or annular girder of the turntable extend a series-
of radial tie bolts. The upper end of the pivot above referred to terminates
in the base, and its lower rounded end rests on the rounded surface of a
steel block in a recess in the foundation plate, the latter being secured to
the supporting pier. A series of radial struts extend in an inclined
direction from the lower disc as an abutment to the rim of the turntable,
each strut being furnished at its upper end with an adjusting screw.
The struts consist by preference of wrought-iron tubes similar to those
of which the posts and other compression members of the above described
bridges are employed. The rim of the turntable bears on rollers, the
pins of which are carried by an annular frame connected by a series of
rods to the flange of a bottom disc, which is so adapted to the foundation
plate that it can turn freely thereon: By means of screws on the struts
and by tie bolts the rim of the turntable is made perfectly true and
concentric with the pivot in the first instance, after which whenever the
rim requires elevating so that it cannot bear with greater force on the
rollers than is necessary to simply steady the turntable, all that is
required is to turn certain nuts on bolts and thereby elevate the first
mentioned disc, and consequently the rim, and this elevation or any
lowering of the rim is accomplished without disturbing its integrity or
its proper concentricity with the pivot. The annular track on which
the rollers bear is secured to the pier, and is furnished with an annular
rack into which gears a pinion to be operated by any suitable appliances

page_text: when the turntable and its superincumbent bridge have to be turned.
The bridge is so adjusted on and secured to the turntable that three of
the transverse beams of the bridge shall bear upon the rim.
The fifth part of this Invention, which relates to the ready withdrawal
of the corner supports of the pivot bridge when the latter has to be
turned and to the ready restoration of the supports, consists of two.
transverse parallel beams at one end of the bridge, these, together with
other transverse beams of like character, serving to support the longi-
tudinal beams, across which extend the sleepers for carrying the rails.
The transverse beams are secured to the lower chord beams by suspension
bolts, this lower chord forming part of a truss frame of which the above-
described pivot bridge is composed. To the transverse beam are hung
by a pin four links, and to the latter are hung by means of another pin
a series of similar links, and to a pin passing through the lower ends of
the latter series of links are hung two rollers, which are guided vertically
by brackets secured to the under side of the transverse beam. The two
sets of links, as will be seen hereafter, form a knee joint to the central
pin, of which two rods are jointed, the opposite ends of these rods being
connected to the lower end of an arm, which is hung to the transverse
beams, and this arm is connected by a rod to lugs on a nut, which is
adapted to vertical girders arranged between the two parallel transverse
beams, the said nut being also connected by similar appliances to knee
joint links arranged at the opposite corner of the bridge. This nut is
controlled by a vertical screw, so confined to suitable bearings that while
it can turn easily it is incapable of vertical movement. The said screw
may be operated by any suitable mechanism, but it is preferable to
operate it from a central point on the pivot bridge, and to connect the
operating mechanism by means of a horizontal shaft extending along the
bridge beneath the ties, one end of the shaft being geared by bevel
wheels to a screw at one end of the bridge, and the opposite end to a
similar screw at the opposite end of the bridge, so that the knee joint
links at all four corners of the bridge may be operated simultaneously
from one point.
The outer ends of the rails at each end of the bridge admit of being
raised and lowered by the same mechanism which opèrates the knee
joints. Thus the rails are connected by rods to other rods, and these
rails are adapted to chairs which are secured to the permanent roadway ör
permanent part of the bridge, and which receives the permanent rails of

page_text: the track, the chairs thus insuring the coincidence of the rails of the
pivot bridge with those of the permanent track. When the bridge is
closed and free for the passage of trains; the rollers at the lower ends
of the knee jointed links at each corner of the bridge bear in a cavity in
the top of a plate secured to the foundation or pier, and the pins of the
knee jointed links being in the same vertical line the links afford a
steady support for the bridge at each of its four corners.
When it is necessary to swing the bridge round the rollers are
elevated in their guides, and this is continued until the bridge is in the
first instance lowered and supported on its central pivot only, and after-
wards until the rollers are clear of their bearings. Simultaneously with
this movement of the knee jointed links and rollers the outer ends of the
rails are also elevated clear of the chairs on the permanent track, and
consequently the bridge is free to be turned on its pivot. In restoring.
the bridge to its original position it is turned round until the rollers are
above the cavity of the foundation plate. It is very rarely however that
the bridge can be arrested in its movement at a point where the said
rollers are directly above the centre of this cavity, but as soon as the
screws are operated to straighten the knee joint links and the rollers
begin to bear upon the plate, the weight on the rollers will induce them
to descend into the cavities of the plates, and hence as the straightening
of the knee joints is continued the bridge will be slightly turned until
their pins are in the same vertical line.
After the bridge has adjusted itself in the manner described during
the preliminary straightening of the links, and this straightening being
continued the rails on the bridge descend until they rest in and are
confined laterally by the chairs of the permanent track. It will be seen
therefore that by connecting these rails to the mechanism which operates
the knee joints the said rails are elevated out of the chairs. simul-
taneously with the releasing of the bridge from its corner bearings, and
when the knee joints become the corner bearings the rails are lowered
into the chairs, and their coincidence with the rails of the permanent
track is thereby insured.
In reference to the above-described bridges it will be observed that a
principal feature of the Invention is the employment for compression
members of tubes composed of rolled bars of wrought iron. It should be
understood however that I do not desire to confine myself to any specific

page_text: sectional form of tube or of the bar composing the same, for the tubes
may be square or many sided, and groups of bars of different form may
be combined to form a tube.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 10th March 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eleventh day of September, in the year
of our Lord One thousand eight hundred and seventy-two, in the 36th
year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said John Henry Johnson, Her special license
that I, the said John Henry Johnson, my executors, administrators; and
assigns, or such others as I, the said John Henry Johnson, my executors,
administrators, or assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN BRIDGES
AND VIADUCTS, AND IN MACHINERY OR APPARATUS CONNECTED THEREWITH," a
communication to me from abroad by Thomas Curtis Clarke, of
Philadelphia, Pennsylvania, and Adolphus Bonzano, and John Griffin,
of Phoenixville, Chester County, Pennsylvania, all of United States of
America, upon the condition (amongst others) that I, the said John
Henry Johnson, my executors or administrators, by an instrument in
writing under my hand and seal, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
T..
1

page_text: The said Invention consists,―
First, of a peculiar truss frame bridge constructed of wrought iron or
steel, in the peculiar manner fully described hereafter, with the view
to the attainment of lightness, strength, facility of erection, and economy
of construction.
Secondly, of a peculiar truss frame bridge or viaduct having a road-
way on the top, this bridge possessing many of the features to be found
in the bridge which forms the subject of the first part of the Invention.
.
Thirdly, of a peculiar pivot bridge made of wrought iron or steel, in
the manner described hereafter, the said bridge being constructed in
such a manner that the lower chord shall be a compression member
when the bridge is clear of its end bearings, the upper chord becoming a
compression member when the bridge is adjusted to form a roadway for
the passage of trains.
Fourthly, of a peculiar turntable for supporting the above-mentioned
pivot bridge, the said turntable being constructed in the peculiar manner
described hereafter for the ready vertical adjustment of its rim without
disturbing its integrity and concentricity with the pivot.
And fifthly, of certain peculiar mechanism, described hereafter, as con-
nected with the pivot bridge for readily elevating the same from its end
bearings when it has to be turned, and as readily readjusted to its end
bearings when the bridge has to be adjusted for the passage of trains.
The first part of the Invention is illustrated in Sheet 1 of the Drawings
annexed, where,-
Figure 1 is a side view of one truss of a bridge made in accordance
with the first part of the Invention.
Figure 2, a side view of part of Figure 1 drawn to a larger scale.

page_text: Figure 5, a plan view of the bridge as arranged for a double track.
Figures, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 illustrate the detailed
construction of the bridge.
This bridge consists of two trusses, cach truss being composed of the
upper chord A, lower chord B, inclined end posts D, and verticals E,
and the diagonals and counter diagonals referred to hereafter. The con-
struction and mode of connecting the several parts of the truss together
will be best explained in connection with the detailed views, Figures 6
to 15 inclusive.
It may be remarked in the outset that the upper chord, end posts, and
verticals are all composed of wrought-iron tubes of the sectional form
best observed in Figure 6, where x represents a section of one of the
inclined end posts, the latter consisting of a group of rolled bars of
wrought iron so shaped that a combination of the bars will form a tube,
the bars having flanges through which pass bolts or rivets. While these
wrought-iron tubes are remarkably light; they are capable of resisting
great end strain, and hence are especially applicable as compression
members to the construction of truss frame bridges and viaducts
generally.
upper
The method of connecting the inclined end post D to the upper
chord A will be best observed in Figures 6 and 7, where G represents a
cast-iron connecting piece over an annular projection on which fits the
end of the inclined end post D, and the end of the
upper
chord
tube A, a pin a passing through the connecting piece and through eyes
at the upper end of the rods H, I, and J, referred to hereafter. The
lower end of the end post D fits over an annular projection on the
pedestal K, Figure 11, through which and through the eyes at the ends
of the lower chord rods B pass bolts b, the pedestal resting on a series of
rollers connected to a frame, and these rollers bearing on a foundation
plate K' which is secured by anchor bolts to one of the piers of the
bridge.
The method of connecting the upper chord tube A, the verticals E,
diagonals L, and counter diagonals M together will be best observed in
Figures 8 and 9. The ends of the upper chord tubes are fitted over
annular projections on the cast-iron connecting piece N, at the lower end
of which is a third annular projection fitting into the top of the vertical E
which, as before remarked, consists of a group of wrought-iron bars

page_text: rivetted together. A bolt d passes through the cast-iron connecting
picce N, through the eyes of the diagonals L, and through the loops c of
the adjustable counter diagonals M. More particular allusion will be
made hereafter to the peculiarity of these counter diagonals.
Figures 12 and 13 illustrate the mode of connecting together the
verticals, lower chords, diagonals, counter diagonals, and floor beams.'"
A bolt passes directly through the vertical E near the lower end of the
same, where it is reinforced in thickness internally, the bolt also passing
through the eyes of the lower chord rods B, through those of the
diagonals L, and through the loops of the counter diagonals M. Strap
bolts also pass over the bolts f, the threaded ends of the strap bolts
passing through a plate P between which and a plate P¹ fitted to the
lower end of the vertical E is confined the floor beam Q by nuts adapted
to the said threaded ends of the strap bolts h, the floor beam being of
wrought iron of the sectional form illustrated in Figure 12, or of any
other equivalent form.
Having now explained the manner of constructing each truss I will
proceed to describe the mode of connecting the two trusses together so as
to form the desired bridge. The lower portion of the trusses are connected
together by the floor beams Q, as shewn in Figures 12 and 13, and in
Figure 4, and by the diagonal tie rods i, i, which are connected to the
webs of the beams in the manner shewn in Figures 14 and 15, and
explained hereafter. The trusses are connected together at the upper
end in the manner best observed in Figures 8 and 9. Each cast-iron
connecting piece N and each connecting piece G has a cylindrical pro-
jection m, and from the projection of one truss to that of the other
extends a transverse tubular stay R composed of a group of rolled bars
in the same manner as the verticals and upper chords, and through the
projections pass the ends of diagonal tie rods n, shewn in Figures 3, 4, 8,
and 9, the tightening of these rods resulting in the effective connection
of the upper chords of the two trusses together.
The diagonal tie rods i, i, above alluded to are connected to the webs
of the floor beam Q in the manner best observed in Figures 14 and 15.
A circular opening is formed in the web of the beam for the reception of
projections on the opposite triangular blocks q, q, through which pass
the ends of the tie rods i, i. In tightening the nuts of these rods the
blocks will be firmly bound to the web of the beam, which will resist

page_text: the strain imparted by the rods. This is both an economical and secure
mode of connecting the tie rods to the beam.
Allusion has been made to the construction of the adjustable counter
diagonals M. On referring to Figures 8 and 11 it will be observed that
each counter diagonal consists of one plain rod with a loop at each end,
one loop being adapted to the pin f of the lower chord, and the other to
the pin d of the upper chord. One end of the rod has a right-handed
thread adapted to one loop, and the other end of the rod a left-handed
thread adapted to the other loop, so that by turning the rod the counter
diagonal may be lengthened and shortened at pleasure. These counter
diagonals are not only economical in construction, but they afford better
means of adjustment than the ordinary screw couplings.
The second part of the Invention, illustrated in Drawing No. 2, relates
to the construction of that class of truss frame bridges and viaducts in
which the roadway is on the top of the trusses.
Figure 1 is a side view of a portion of a deck bridge made in accordance
with this portion of the Invention; Figure 2, a plan view of the same;
Figure 3, a plan of a portion of the lower chord system; Figure 4, a
transverse section; and Figures 5, 6, 7, and 8, views illustrating the
detailed construction of the bridge.
In this bridge there are two trusses, each being composed of upper
chord A, lower chord B, posts or verticals D, diagonals E, counter
diagonals F, and end diagonals G.
The upper chord A, as in the former case, consists of a series of
wrought-iron tubes, each tube being composed of a number of flanged
bars (eight in the present instance) rivetted together, as best observed in
Figure 5, the posts D consisting of similar tubes.
The method of connecting the post and upper chord together is
illustrated in Figures 5 and 6; where K represents a cast-iron connecting
piece over projections on which fit the chord tubes, a similar projection
fitting into the upper end of the post. A bolt a passes through the con-
necting piece, through the eyes of the diagonals E, and where counter
diagonals F occur through the loops of the same. The lower ends of
the posts, lower chord rods B, diagonals, and counter diagonals are
connected together in the manner illustrated in Figures 7 and 8, a pin h
passing through the post, through the eyes of the lower chord bars,
those of the diagonals, and through the loops of the counter diagonals. ·

page_text: The two trusses are connected together in the following manner :—
A transverse beam I extends from truss to truss immediately above the
posts, the lower edge of each beam resting on the connecting piece K to
which it is confined by bolts d, d, and a plate e, as shown in Figures 5
and 6; diagonal tie rods J extend horizontally from truss to truss, see
Figure 2, these rods passing through and being connected to the beam
as shown in Figure 5; between the opposite posts D of the trusses
extend wrought-iron tubes K, similar in character to but much lighter
than the tubes of the chords;. and the opposite posts of the trusses are
further connected together by diagonal tie rods L, L, shown in Figure 4,
and also in Figures 5, 6, 7, and 8; a series of longitudinal beams M
extend from one transverse beam to another; and on these longitudinal
beams rest the floor beams N for supporting the rails of the two tracks,
see Figure 2. The bridge is supported on pedestals F, Figure 1, secured
to the pier Q; and to these pedestals are connected the end diagonals G
and adjoining diagonals E, the pedestals also supporting a transverse
beam I similar to those above the posts.
The third part of the Invention relates to the construction of a truss
frame pivot bridge, and is illustrated in Drawing No. 3, in which Figure 1
is a side view of the pivot bridge; Figure 2, a plan view; Figures 3, 4,
5, and 6 views illustrating the detailed construction of the bridge..
In this case the upper chord A of each truss consists of two series of
spliced channel bars a, a, connected together at the top by plates h, and
at intervals by stays and bolts f, f, Figure 4, and at the bottom by lattice
work. A series of posts or verticals D are connected to this upper chord,
and through the post passes a bolt d, as well as through the ends of the
diagonals and counter diagonals, see Figures 3 and 4. The lower chord B
also consists of two sets of channel bars e, e, Figure 6, connected
together by plates f, and by latticework at the top, a bolt 7 passing
through the channel bars, through the post near the lower end of the
same, and through the ends of the diagonals and counter diagonals.
The verticals D as well as the end posts F are made of flanged bars of
rolled iron, rivetted together as in the above described bridges. The two
trusses are connected together at the top by transverse tubes x of
wrought iron, and by the diagonal stays I, I, as shown in Figure 2;
and at the bottom by transverse beams K, each end of each beam being
secured to the under side of one of the lower chords by strap bolts i, i,
passing over the bolt h, as shown in Figures 5 and 6, the threaded ends

page_text: of the bolts passing through a plate m confined to the under side of the
transverse beam by ordinary nuts. A series of longitudinal beams M
extend between the transverse beams, and on these longitudinal beams
are secured the sleepers N, to which the rails of the track are secured.
The bridge is designed as a continuous girder extending over two
spans, and is arranged to turn on a central pivot on the pier F, but
when adjusted for the passage of trains bears with its opposite ends or
piers Q.
It will be seen that the upper and lower chords are alike, and this is
essential to the proper construction of the bridge, for when the latter is
swung round clear of its bearings the lower chord becomes the com-
pression member, and when the bridge is adjusted to its bearings for
the passage of trains the upper chord becomes the compression member.
The turntable which constitutes the fourth part of the Invention is
illustrated in Sheet 4, Figure 1 being a vertical section of the turn-
table for supporting the above described pivot bridge, and Figure 2 a
plan view of one half of the turntable.
A disc A. of cast iron is so fitted to the pivot a that it can slide freely
therein, and this disc is suspended by bolts b, b, to the base E of the
pillar B, to the top of which is secured a disc D; and through the
flange i of the latter and through the rim or annular girder F of the turn-
table extend a series of radial tie bolts d. The upper end of the pivot
terminates in the base E, and its lower rounded end rests on the rounded
surface of a steel block in a recess in the foundation plate G, the latter
being secured to the pin X. A series of radial struts extend in the
inclined direction shown in Figure 1, from the disc A, as an abutment
to the rim F of the turntable, each strut being furnished at its upper
end with an adjusting screw m.
The struts consist by preference of wrought-iron tubes, similar to
those of which the posts and other compression members of the above-
described bridges are employed.
The rim of the turntable bears on
rollers I, the pins of which are carried by an annular frame connected
by a series of rods J to the flange of a disc K, which is so adapted to the
foundation plate G that it can turn freely thereon. By means of
screws m of the struts X and the tie bolts d the rim of the turntable is
made perfectly true and concentric with the pivot in the first intance,
after which, whenever the rim demands elevating so that it cannot bear

page_text: with greater force on the rollers than is necessary to simply steady the
turntable, all that is required is to turn the nuts of the bolts b, and
thereby elevate the disc A, and consequently the rim, and this elevation
or any lowering of the rim is accomplished without disturbing its
integrity or its proper concentricity with the pivot. The annular
track K, on which the rollers bear, is secured to the pier X, and is
furnished with an annular rack n, into which gears a pinion to be
operated by any suitable appliances when the turntable and its super-
incumbent bridge have to be turned. The bridge is so adjusted on and
secured to the turntable that three of the transverse beams K of the
bridge shall bear upon the rim F.
The fifth part of the Invention, which relates to the ready withdrawal
of the corner supports of the pivot bridge when the latter has to be
turned, and to the ready restoration of these supports, is also illustrated
in Sheet No. 4, Figure 3, representing a portion of the end of the pivot
bridge; Figure 4, a side view of a portion of one end of the bridge;
Figure 5, a plan view; Figure 6, a section on the line 3, 4; and
Figure 7, a section on the line 1, 2.
A and A¹ are two transverse beams at one end of the bridge, these,
together with other transverse beams of like character, supporting the
Jongitudinal beams, across which extend the sleepers D for supporting
the rails a, a.
The transverse beams A are secured to the lower chord
beams F by suspension bolts e, this lower chord forming part of a truss
frame, of which the above-described pivot bridge is composed. To the
transverse beam A are hung by a pin f, links i, i, i, i, and to the latter
are hung by means of a pin ja series of similar links m, and to a pin
passing through the lower ends of the latter series of links are hung two
rollers p, p, which are guided vertically by brackets q, q, secured to the
under side of the beam A. The two sets of links, as will be seen here-
after, form a knee joint to the central pin j, of which two rods G, G, are
jointed, the opposite ends of these rods being connected to the lower end
of an arm H, which is hung to the transverse beams, and this arm is
connected by a rod I to lugs on a nut J, which is adapted to vertical
girders arranged between the two beams A, A', Figure 6, the said nut
being also connected by similar appliances to knee-joint links arranged
at the opposite corner of the bridge, which is not shewn in the Drawing.
The nut J is controlled by a vertical screw Y, so confined to suitable
bearings h, h, that while it can turn easily it is incapable of vertical

page_text: movement. This screw may be operated by any suitable mechanism,
but it is preferable to operate it from a central point on the pivot bridge,
and to connect the operating mechanism by means of a horizontal
shaft X extending along the bridge beneath the ties, one end of the
shaft being geared by bevel wheels to the screw K at one end of the
bridge, and the opposite end to a similar screw at the opposite end of
the bridge, so that the knee-joint links at all four corners of the bridge
may be operated simultaneously from one point.
The outer ends of the rails a, a, at each end of the bridge admit of
being raised and lowered by the same mechanism which operates the
knee joints. Thus the rails a, a, in Figure 3, are connected by rods y, y,
to the rods I, I, and these rails are adapted to chairs which are secured
to the permanent roadway or permanent part of the bridge, and which
receives the permanent rails of the track, the chairs thus insuring the
coincidence of the rails of the pivot bridge with those of the permanent
track. As seen in Figure 3 the bridge is supposed to be closed, and
free for the passage of trains, the rollers p at the lower ends of the
knee-jointed links at each corner of the bridge bearing in a cavity in the
top of a plate t secured to the foundation or pier, and the pins of the
knee-jointed links being in the same vertical line the links afford a
steady support for the bridge at each of its four corners.
When it is necessary to swing the bridge round the screw Y at each
end of the bridge is turned so as to elevate the nuts J. This consequently
draws the rods G and I in the direction of the arrows, and therefore so
acts on the knee-jointed links as to elevate the rollers p, p, in their
guides, and this is continued until the bridge is in the first instance
lowered and supported on its central pivot only, and afterwards until the
rollers are clear of their bearings. Simultaneously with this movement
of the knee-jointed links, the outer ends of the rails owing to their
connections with the rods I, I, were elevated clear of the chairs on the
permanent track, and consequently the bridge is free to be turned on its
pivot. In restoring the bridge to its original position it is turned round
until the rollers p, p, are above the cavity of the foundation plate t. It
is very rarely however that the bridge can be arrested in its movement
at a point where the said rollers are directly above the centre of this
cavity, but as soon as the screws Y are operated to straighten the knee-
joint links and the rollers q begin to bear upon the plate t the weight on
the rollers will induce them to descend into the cavities of the plates,
B

page_text: and hence as the straightening of the knee joints is continued the bridge
will be slightly turned until their pins are in the same vertical line as
shewn in Figure 3.
After the bridge has adjusted itself in the manner described during
the preliminary straightening of the links, and this straightening was
continued, the rails a, a, on the bridge descended until they rested in and
were confined laterally by the chairs of the permanent track. It will be
scen therefore that by connecting these rails a, a, to the mechanism
which operates the knee joints, the said rails are elevated out of the
chairs simultaneously with the releasing of the bridge from its corner
bearings, and when the knee joints become the corner bearings the rails
are lowered into the chairs, and their coincidence with the rails of the
permanent track is thereby insured.
In reference to the above-described bridges it will be observed that a
principal feature of the Invention is the employment for compression
members of tubes composed of rolled bars of wrought iron.
It should be understood that the Inventors do not desire to confine
themselves to any specific sectional form of tube or of the bar composing
the same, for the tubes may be square or many sided, and groups of bars
of different form may be combined to form a tube.
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 carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,―—
First. The employment in truss frame bridges as compression mem-
bers of wrought-iron tubes composed of groups of rolled bars, substan-
tially as set forth.
Second. A truss composed of the chord tubes A, tubular end
posts D, tubular verticals E, lower chord rods B, and the system of
diagonals and counter diagonals, all substantially as illustrated in
Sheet 1 of the Drawing.
Third. The method substantially as described and illustrated in
Figures 8 and 9, Sheet 1, of connecting the upper chord verticals and
diagonals together.

page_text: wwyco w
Fourth. The method substantially as described and illustrated in
Figures 12 and 13, of connecting the posts, lower chord rods, and
diagonals together.
Fifth. The method of connecting the floor beams Q to the posts by
strap bolts n, (Figures 12 and 13.)
Sixth. The combination of the projections m on the top of the con-
necting pieces N, the cross stays R, and diagonal tie rods n, n.
Seventh. The mode described and illustrated in Figures 14 and 15 of
connecting diagonal tie rods to the beams.
Eighth. The application to truss frame bridges of counter diagonals M,
each consisting of a rod with two loops adapted to the pins of the upper
and lower chords.
Ninth. The within-described truss deck bridge composed of the upper
chord tubes, tubular posts, lower chord rods, diagonals, and counter
diagonals, all substantially as described and illustrated in Sheet 2.
Tenth. The mode substantially as described and illustrated in
Figures 5 and 6 of connecting together the upper chord verticals and
diagonals.
Eleventh. The combination of the posts, upper chord, floor beams, all
substantially as shown in Figures 5 and 6.
Twelfth. The mode substantially as described and illustrated in Figures
7 and 8, Sheet 2, of connecting together the posts, lower chord rods, and
diagonals and counter diagonals.
Thirteenth. The pivot bridge, substantially as described and illustrated
in Sheet 3, and composed of similar upper and lower chords, verticals,
and diagonals.
Fourteenth. The upper and lower chords composed of channel iron
connected together, substantially as shown and described.
Fifteenth. The mode substantially as described and shewn in Figures
3 and 4, of connecting together the upper chord posts, and diagonals,
and counter diagonals.
Sixteenth. The mode substantially as described and illustrated in
Figures 5 and 6, of connecting together the posts, lower chord, and floor.
beams.

page_text: Seventeenth. A turn-table, in which an annular girder or rim F is
connected to a nave by radial rods d and by struts H fitted at one end
directly to the girder F, and at the other end directly to a vertically
adjustable portion A of the nave, as set forth.
Eighteenth. The within-described naved consisting of the disc K
adapted to the foundation plate G, the pivot a supporting the casting E,
post B, and disc H, and the disc K forming abutments for the struts Q,
and rendered vertically adjustable on the pivot, all substantially as set
forth.
Nineteenth. The rim J bearing on rollers I connected by inclined
radial rods to a flanged disc K, arranged to turn on the central pivot
plate I.
Twentieth. The combination with a pivot bridge, substantially as
described, of knee joint supports, and the mechanism described or any
equivalent to the same for operating the said joints.
-Twenty-first. In combination with a pivot bridge having moveable.
links as supports, plates t, constructed substantially as described so as to
render the bridge self-centering.
In witness whereof, I, the said John Henry Johnson, have to this
my Specification set my hand and seal, the Tenth day of March,
One thousand eight hundred and seventy-three.
J. HENRY JOHNSON. (L.S.)