IMPROVEMENTS IN BRIDGES
Year: 1860

page_text: LETTERS PATENT to William Turner and John William Gibson, of the
Hammersmith Works, Dublin, for the Invention of "IMPROVEMENTS IN
BRIDGES."
PROVISIONAL SPECIFICATION left by the said William Turner and
John William Gibson at the Office of the Commissioners of Patents,
with their Petition, on the 21st July 1860.
We, WILLIAM TURNER and JOHN WILLIAM GIBSON, of the Hammersmith
Works, Dublin, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN BRIDGES," to be as follows:-
This Invention relates to those descriptions of bridges known as platform or
ballanced, rolling, or sliding bridges, usually employed for crossing at right
angles railway lines, canals, dock entrances or locks, and in other situations,
and by its use or employment the roadway or platform may be perfectly level
instead of having a camber, and thus be available for supporting a line of
railway, and it may also be closed or opened by simply moving, sliding, or
rolling it back and forward in a level or horizontal position, and without
tipping or canting, or without raising or depressing the ends; and when the
platform is in position it is perfectly firm, steady, and secure for the purpose of
traffic.
For the purpose of constructing a bridge for enabling, say, a single line of

page_text: railway to cross a canal or other opening or passage way, we prefer to employ
longitudinal side girders, and frame them together with wrought-iron transverse
girders or bearers; and under this platforin we introduce guide and bearing
rails for running upon wheels or rollers, one set of which is made to support
the platform or roadway somewhere near the centre of its length, and one or
more sets of wheels or rollers may be interposed beneath the platform between
the centre and the end thereof, on the "land," "tail," or pit end." Theso
bearing rollers are mounted in carriages, one set of which may be fixed on the
centre pier or central bearing supporting the bridge, and one or more sets
similarly mounted should be placed in the pit, into or over which the one end
of the bridge is drawn or rolled back.
Instead of adopting any of the ordinary modes or plans beretofore in use
for making up level and flush with a general line of roadway or railway bars,
we for the purpose of enabling such bridges as those we have described to be
employed for railway purposes, mount pieces of rails upon beams or girders of
a length equal to the distance from the inner end of the pit to the end of the
bridge, so that when the bridge is in its place the roadway or line or lines of
railway bars are made continuous, of uniform guage, level, and perfectly rigid
and firm. Whilst these beams or girders are in place and each upright, the
bridge could not be rolled back, withdrawn, or opened, the end of each girder
being opposed to the end of the bridge, and may be locked thereinto by a
sliding bolt, locking catch, or other contrivance. Now, for the purpose of
enabling the bridge to be opened, we mount the short lengths of longitudinal
beams or girders in the pit, so that each is capable of being swung upon its
longitudinal axis, and thus may be turned down on its side, by which means
the obstruction to the opening of the bridge is withdrawn, and the platform or
tail end of the bridge passes over these beams or girders, each of which has a
metal railway bar or tram plate upon its upper edge, whilst upon its lower
edge a seating piece or curved bar is fitted, it being made to a suitable radius
to enable it to be swung into and out of a longitudinal bearing or saddle piece
running along the length of the pit for the purpose of giving uniform bearing
to each swinging beam or girder when it is upright and subject to bear a load.
By making these longitudinal bearings or saddle-pieces of an L shape, right
and left handed; they also act as stops or abutments or side bearing pieces,
by which the swinging longitudinal beams or girders are prevented being
thrust asunder, opened, or thrown out of guage, whilst they are free to swing
or turn the top of each inward or toward each other, and the bottoms of each
are thus thrown outward or from each other. These swinging longitudinal
beams or girders, with their rails, are so mounted that but little force is

page_text: required to turn them from the vertical to the horizontal, or from the
horizontal to the vertical position; and this may either be effected by means
of a quadrant rack fixed upon the end of each beam or girder, or by means of
levers and cranks, or by any other of the well-known means for giving the
required movement thereto, and which may be found most convenient.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Turner and John William Gibson in the Grent
Seal Patent Office on the 21st January 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
TURNER and JOHN WILLIAM GIBSON, of the Hammersmith Works, Dublin,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of July, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us,
the said William Turner and John William Gibson, Her special licence that
we, the said William Turner and John William Gibson, our executors,
administrators, and assigns, or such others as we, the said William Turner and
John William Gibson, our executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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," upon the condition (amongst others) that we,
the said William Turner and John William Gibson, our executors or adminis-
trators, by an instrument in writing under our, or one of our or their, or one
of their hands and seals, 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 we, the said William Turner and John William
Gibson, do hereby declare the nature of our said Invention, and in what
manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement in writing and accompanying
two Sheets of Drawings:-
This Invention relates to those descriptions of bridges, known as platform

page_text: or balanced rolling, or sliding bridges, usually employed for crossing at right
angles railway lines, canals, dock entrances, or locks, and in other situations
and by its use or employment, the roadway or platform may be perfectly level,
instead of having a camber, and thus be available for supporting a line of rail-
way; and it may also be closed or opened by simply moving, sliding, or rolling
it back and forward in a level or horizontal position, and without tipping or
canting, or without raising or depressing the ends, and when the platform is in
position, it is perfectly firm, steady, and secure, for the purpose of traffic.
For the purpose of constructing a bridge for enabling, say, a single line of
railway to cross a canal, or other opening or passage way, we prefer to employ
longitudinal side girders, and frame them together with wrought-iron trans-
verse girders or bearers, and under this platform, we introduce guide and
bearing rails for running upon wheels or rollers; one set of which is made to
support the platform or roadway somewhere near the centre of its length, and
one or more sets of wheels or rollers may be interposed beneath the platform,
between the centre and the end thereof on the "land," "tail," or "pit end.
These bearing rollers are mounted in carriages, one set of which may be fixed
on the centre pier, or central bearing supporting the bridge, and one or more
sets similarly mounted should be placed in the pit, into or over which the one
end of the bridge is drawn or rolled back.
Instead of adopting any of the ordinary modes or plans heretofore in use
for making up level and flush with a general line of roadway or railway bars,
we for the purpose of enabling such bridges as those we have described to be
employed for railway purposes, mount pieces of rails upon beams or girders of
a length equal to the distance from the inner end of the pit to the end of the
bridge, so that when the bridge is in its place, the roadway, or line or lines of
railway bars are made continuous, of uniform guage, level, and perfectly rigid
and firm. Whilst these beams or girders are in place, and each upright, the
bridge could not be rolled back, withdrawn, or opened, the end of each girder
being opposed to the end of the bridge, and may be locked thereiuto by a
sliding bolt, locking catch, or other contrivance. Now, for the purpose of
enabling the bridge to be opened, we mount the short lengths of longitudinal
beams or girders in the pit, so that each is capable of being swung upon its
longitudinal axis, and thus may be turned down on its side, by which means,
the obstruction to the opening of the bridge is withdrawn, and the platform or
tail end of the bridge passes over these beams or girders, cach of which has
a metal railway bar or tram plate upon its upper edge, whilst upon its lower
edge a seating piece or curved bar is fitted, it being made to a suitable radius
to enable it to be swung into and out of a longitudinal bearing or saddle-piece

page_text: running along the length of the pit, for the purposo of giving uniform bearing
to each swinging beam or girder when it is upright, and subject to bear a load.
By making these longitudinal bearings or saddle pieces of an L-shape right
and left handed; they also act as stops or abutments, or side bearing pieces,
by which the swinging longitudinal beams or girders are prevented being
thrust asunder, opened, or thrown out of guage, whilst they are free to swing
or turn the top of each inward or toward each other, and the bottom of each
is thus thrown outward, or from each other. These swinging longitudinal
beams or girders, with their rails, are so mounted that but little force is
required to turn them from the vertical to the horizontal, or from the hori
gontal to the vertical position, and, this may either be effected by means of a
quadrant rack fixed upon the end of each beam or girder, or by means of
levers and cranks, or by any other of the well-known means for giving the
required movement thereto, and which may be found most convenient.
Where the pit is limited in width at the surface, or in depth, or where from
any other reason it may be desirable, we mount the short lengths of longita-
dinal beams or girders carrying the continuation rails upon pedestals or bear-
ings, having the longitudinal axes thereof upon the innermost face, and at the
intersection of the horizontal line with the vertical line forming the internal
face of each beam or girder, or at the internal angle formed thereby, so that
when the bridge has to be opened, each girder and the rails supported thereon
is made to fall inwards, and towards each other in the manner of a hinge.
Counterbalance weights are added, and the two beams or girders may be con-
nected together by means of rods from each, extending to one or more double'
spanners mounted upon a horizontal shaft or shafts within the pit, and by
which motion is communicated simultaneously.
In the accompanying two Sheets of Drawings, I have illustrated two of the
modes in which our Invention can be applied in practice, Figure 1 being an
elevation partly in section; Figure 2, a plan view of a railway bridge with
wrought-iron side girders, and a single pair of railway bars upon the platform
of the bridge, the width of the rails being intended for the Irish guage;
Figure 8 is a transverse section to an enlarged scale of the bridge girders, and
the beams shewn in Figures 1 and 2; and Figure 4 is a transverse section of
a somewhat similar bridgo to that shewn in Figures 1, 2, and 8, but exhibits
another mode of mounting and working the longitudinal beams or girders
carrying the continuation rails.
We have shewn in Figures 1, 2, &c., the main girders of the bridge as
single plate girders, having top and bottom flanges, but they may be box
girders, or of any other convenient shape or construction; and instead of single

page_text: headed rails, such as are shewn in the Drawings, bridge rails or rails of any
form inay be adopted.
In each of the Drawings the same or like descriptions of letters refer to
like or corresponding parts in each Drawing.
In Figures 1 and 2, A is the water line of a canal or waterway over which
the bridge is shewn; B, the centre pier, upon the top of which are mounted
rollers or wheels mounted in carriages; C, one side of the canal; D, the
opposite side of the canal, or the side from which the bridge is withdrawn or
opened for the purpose of permitting the free passage between the pier B and
the land side C; E, the continuation rails, and their supporting beams; F,
F, F, are the bearing wheels or rollers upon which bridge is rolled back
and forth.
In Figure 3, which is a transverse section, and to an enlarged scale, a re-
prosents the masonry of the pit in which the extension rails are mounted, and
over which the tail end of the bridge is made to traverse when being opened
and closed; b, the longitudinal side or main girders of the bridge; c, the end
transverse joist or beam of the bridge; d, d, the two short longitudinal beams
or girders mounted in the pit as shewn, and carrying upon the top side of
cach the continuation rail e; t, t, two cast-iron saddle or bed pieces for sup-
porting the short girders in place when upright. The dotted lines shew the
position assumed by each of the short longitudinal girders when turned down
to allow the bridge to be opened or travel over the rails.
At each end of the beams or girders carrying the rails, there is intended to
be shown a casting with a square hole therein, for the purpose of receiving a
locking bolt or key, and this casting may also form the trunnions for supporting
the ends of the vibrating beams or girders d, d.
In Figure 4, a represents the section of the masonry (as in Figure 3);
b, the side or main girders of the bridge; c, the end transverse beam or joist
of the bridge upon which is shewn two stop brackets c'; d, d, the two shoit
longitudinal beams or girders mounted in the pit as shewn, and carrying upon
the top edge of each the continuation rail e; a wooden longitudinal sleeper or
blocking being in this case introduced on the top edge of each beam or girder;
ff, two sets of pedestals or bearing blocks arranged along cach side of the
pit for supporting and permitting to turn (in hinge fashion) each beam or
girder from its vertical to its horizontal position, and vice versa.
The dotted lines shew the position assumed by oach of the short longitu-
dinal beams or girders when turned down to allow the bridge to be opened or
travel over the rails; g, balance weights disposed at intervals along the length
of each swinging beam or girder, as shewn in the dotted lines; h, a shaft upon

page_text: which is mounted one or more double spanners or levers, from each end of
which connecting rods i, i, extend to the swinging beams for the purpose of
giving simultaneous motion thereto.
Having now described our Invention for improvements in bridges, and illus-
trated in the accompanying two Sheets of Drawings two modes or methods.
of applying the same in practice, we wish it to be understood that we do not
confine ourselves to the exact forms and arrangements of the several parts, or to
the dimensions, arrangement, or disposition thereof, either in relation to each
other, or to the whole structure, as such alterations, variations, or modifica
tions must be made in each case where our said Invention has to be applied
in practice as will best fit it or enable it to be adapted to the circumstances or
requirements thereof; but what we claim as our Invention is,-
First, the construction and mode of working bridges for railway and other
purposes of the kind or description herein set forth as in manner described.
Second, the modes or methods herein described of mounting or supporting,
and moving or working the continuation rails as herein described and illustrated.
Third, the modes or methods herein described of securely supporting, and
at the same time rendering readily easily moveable, when necessary, the con-
necting road pieces, rails, tram plates (or their equivalents), extending
between the land approach and the tail end of sliding or rolling bridges, so
as to enable such bridges to be constructed without a rising or cambered
Hoor; and also to avoid the necessity for tilting the tail end thereof.
In witness whereof, we, the said William Turner and John Wm. Gib-
son, have hereunto set our hands and seals, this Seventeenth day of
January, in the year of our Lord One thousand eight hundred &
sixty-one.
Witness,
DAVID FREEMAN,
WILLIAM TURNER.
(LB.)
JOHN WILLIAM GIBSON. (L.S.)
71, Queen St., Dublin.