IMPROVEMENTS IN ROLLING BRIDGES
Year: 1861

page_text: LETTERS PATENT to William Turner and John William Gibson, of
Hammersmith, in the County of Dublin, Engineers, for the Invention
of "IMPROVEMENTS IN ROLLING BRIDGES."
Sealed the 24th June 1862, and dated the 27th December 1861.
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 27th December 1861.
We, WILLIAM TURNER and JOHN WILLIAM GIBSON, of Hammersmith, in
the County of Dublin, Engineers, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN ROLLING BRIDGES," to be as follows:-
This Invention relates to that class of bridges in which the length of road-
way of necessity exceeds the width of the opening which they are employed to
span, and which bridges are withdrawn longitudinally in the direction of the
roadway for the purpose of enabling greater height to be obtained below, and
also to permit of a clear passage being effected along the line of way spanned
by the bridge when closed. These bridges are usually designated as sliding
or rolling bridges, and are substituted for swing or swivel bridges.
In constructing bridges according to our present Invention the chief objects
to be attained, are a reduction in the power and time required to open and
close such bridges, and to take full advantage of the balance principle of
construction.

page_text: We construct the platform or roadway by combining two or more trussed
girders, by preference of wrought iron or of wrought and cast iron combined,
although they may be constructed of wood and iron plated. The under side of
the girders form longitudinal rails which run upon bearing rollers erected
upon a centre pier or quay wall about the middle of the length of the bridge
or on the tail-pit side of the opening spanned by the bridge. Thus instead
of the rails being laid in the pit and the bearing wheels and their carriages
being attached to the bridge, and the whole being made to move back and
forth on the bearing rails in, the pit.in manner described in the Specification
of a Patent granted to Michael Kenney, dated December 22nd, 1858, No.
2924, we mount the bearing wheels, whether there be two, three, or more
of them, in the width of the bridge, on a pier or other suitable foundation in
such position as to be about the centre of the length of the bridge, or rather
nearer to the overhanging or forward end of the platform, and by means of
longitudinal bearing rails, of suitable section fixed to the under side of the
bridge platform at such an angle or inclination as shall best suit the particular
application or the dimensions of the bridge, these rails support the overhanging
end of the bridge, whilst a rack (or there may be more than one) is'fixed
parallel with the bearing rails, and at the same angle or inclination.
?
For the purpose of opening and closing the bridge or moving the platform
backward and forward, a pinion mounted upon a horizontal shaft is made
to take into the rack, and motion is communicated to the horizontal pinion
shaft by any of the ordinary wheel gearing or arrangements used for such
purpose, so that the bridge may be opened from any convenient position.
The position of the pinion for operating on the rack should be before or
in advance of the bearing rollers and their carriages, and the rack need only
extend from the extreme fore-end of the bridge to somewhere about the
middle of the length of the platform, but for the purpose of further facilitating
the opening and closing of the bridge, a rack or racks may also be added to
the underside of the tail-end of the bridge, as also there may be added bearing
rails and additional bearing wheels at the extreme end of the tail-pit. The
bearing rails applied to the under side of the fore-end of the bridge platform
should by preference be curved at their inner ends so that they may rest upon
the bearing wheels and form a stop or check when the bridge has been
projected across the opening to be spanned.
When the platform having been withdrawn has to be projected across the
opening or passage way, motion is given to the pinion, and the bearing rails
and rack or racks are then-level, and the overhanging end of the bridge and
the platform is correspondingly depressed until it has been entirely projected

page_text: across and come to rest on a bearing provided for it on the opposite side of
the opening, when the point of the platform is raised and held securely at
its proper level, so that the level of the roadway coincides with the level
of the approach. Thus whilst the one end of the platform is raised as just
described, the opposite end is depressed within the pit, so that the level of the
roadway at the tail end of the platform is also made to coincide with its
approach, each end is then securely supported.
When the bridge platform is wide, or has a double road or carriage way in
addition to foot ways, we prefer to employ a central longitudinal girder, and to
have a central bearing rail, and instead of employing a single rack, we prefer
to employ two racks, which may either be fitted one on each side of and close
I to the central bearing rail beneath the middle longitudinal girder, or between
the middle and each of the outside longitudinal girders, if the strength of the
.platform is such as to admit of the latter plan being employed.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Turner and John William Gibson in the Great
Seal Patent Office on the 27th June 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
TURNER and JOHN WILLIAM GIBSON, of Hammersmith, in the County of
Dublin, Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of December, in the year of our
Lord One thousand eight hundred and sixty-one, in the twenty-fifth 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 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 "Iш-
PROVEMENTS IN ROLLING BRIDGES," upon the condition (amongst others) that
we, the said William Turner and John William Gibson; our executors. or
administrators, by an instrument in writing under our, or their, or one
of their bands and seals, should particularly describe and ascertain the

page_text: nature of the said Invention, and in what manner the same was to be per-
formed, 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
ascertained in and by the following statement in writing, and on reference
to the accompanying Drawings, that is to say:-
This Invention relates to that class of bridges in which the length of road-
Iway of necessity exceeds the width of the opening which they are employed
to span, and which bridges are withdrawn longitudinally in the direction of
the roadway for the purpose of enabling greater height to be obtained below
and also to permit of a clear passage being effected along the line of way,
spanned by the bridge when closed. These bridges are usually designated as
sliding or rolling bridges, and are substituted for swing or swivel bridges.
In constructing bridges according to our present Invention the chief objects
to be attained are a reduction in the power and time required to open and
close such bridges, and to take full advantage of the balance principle of con-
struction.
We construct the platform or roadway by combining two or more trussed
girders, by preference of wrought iron or of wrought and cast iron combined,
although they may be constructed of wood and iron plated. The under side of
the girders form longitudinal rails, which run upon bearing rollers erected
upon a centre pier or quay wall about the middle of the length of the bridge
or on the tail pit side of the opening spanned by the bridge. Thus instead of
the rails being laid in the pit and the bearing wheels and their carriages being
attached to the bridge, and the whole being made to move back and forth on
the bearing rails in the pit, in manner described in the Specification of a
Patent granted to Michael Kenny, dated December 22nd, 1858, No. 2924,
we mount the bearing wheels whether there be two, three, or more of them in
the width of the bridge, on a pier or other suitable foundation, in such
position as to be about the centre of the length of the bridge, or rather nearer
to the overhanging or forward end of the platform, and by means of longi-
tudinal bearing rails of suitable section fixed to the under side of the platform
at such an angle or inclination as shall best suit the particular application or
the dimensions of the bridge. These rails support the overhanging end of the
bridge, whilst a rack (or there may be more than one) is fixed parallel with
the bearing rails, and at the same angle or inclination.

page_text: For the purpose of opening and closing the bridge or moving the platform
backward and forward, a pinion mounted upon a horizontal shaft is made to take
into the rack, and motion is communicated to the horizontal pinion shaft by
any of the ordinary wheel gearing or arrangements used for such purpose, so
that the bridge may be opened from any convenient position.
The position of the pinion for operating on the rack should be before or in
advance of the bearing rollers and their carriages, and the rack need only
extend from the extreme fore end of the bridge to somewhere about the middle
of the length of the platform; but for the purpose of further facilitating the
opening and closing of the bridge or rack or racks may also be added to the
under side of the tail end of the bridge, as also there may be added bearing
rails and additional bearing wheels at the extreme end of the tail pit. The
bearing rails applied to the under side of the fore end of the bridge platform
should by preference be curved at their inner ends so that they may rest upon
the bearing wheels and form a stop or check when the bridge has been pro-
jected across the opening to be spanned.
When the platform, having been withdrawn, has to be projected across the
opening or passage way, motion is given to the pinion, and the bearing rails,
rack or racks, are then level, and the overhanging end of the bridge and plat-
form is córrespondingly depressed until it has been entirely projected across
and come to rest on a bearing provided for it on the opposite side of the
opening, when the point of the platform is raised and held securely at its
proper level, so that the level of the roadway coincides with the level of the
approach. Thus, whilst the one end of the platform is raised as just described,
the opposite end is depressed within the pit, so that the level of the roadway at
the tail end of the platform is also made to coincide with the approach; each
end is then securely supported.
When the bridge platform is wide or has a double road or carriage way in
addition to footways, we prefer to employ a central longitudinal girder, and to
have a central bearing rail, and instead of employing a single rack we prefer to
employ two racks, which may either be fitted one on each side of and close to
the central bearing rail beneath the middle longitudinal girder or between the
middle and each of the outside longitudinal girders, if the strength of the
platform is such as to admit of the latter plan being employed.
In the accompanying Drawings, Figures 1, 2, and 3, are views of a bridge
constructed according to our Invention; Figure 1 being a longitudinal section
taken on the line A, B, of Figure 2; Figure 2 being a general plan of the
roadway, the approaches and the canal or waterway which the bridge is
employed to span; Figure 3 is a transverse section through the line C, D.

page_text: In each Figure corresponding parts have the same letters of reference written
'thereupon.
a is the waterway; b, b, are the two quay walls; 61, the approach behind
the pit, c being the pit for receiving the tail end of the bridge; d are the
bearing wheels near the quay wall; e are the toothed bearing wheels. for
:supporting the tail end of the bridge, and by means of which, motion being
communicated thereto, the bridge is moved back and forth; f, the driving
pinion acting upon the gearing connected with the moving apparatus,
which it causes to rise into the position shown by the dotted lines when the
counter-balanced tilting gear has been brought into action, and the tail end of
the platform is thus raised sufficiently high to clear the approach; h is a
horizontal shaft, upon which is mounted the counterbalanced tilting gear,
which also carries the toothed gearing wheels e for working into the racks on
the under side of the bridge, causing them to perform a fourth of a revolution
from the time the bridge is at rest until it is ready to be moved longitudinally;
i, i, are the handles by which motion is communicated to the gearing below;
k being a cast-iron standard or pillow within which the gearing is protected,
.one handle may be employed for working the tilting apparatus and the other
for the longitudinal mevement, or both handles may be employed for each
purpose alternately, as by means of a clutch the lever lifting or the moving
gear may be brought into or out of action; 7, the locking cams for supporting the
overhanging end of the bridge, to which cams motion is communicated by
means of a lever handle and pinion worked from the standard or pillar m. The
rack or racks on the under side of the tail end of the bridge take into the
toothed wheels by which motion is communicated, and when the locking cams
are lowered the counterbalanced tilting gear is brought into play and
the tail end raised sufficiently high to allow of its passing over the
approach.
The construction of the bridge and the arrangement and disposition of
materials therein are so clearly shown in the several views of the accom-
panying Drawing and also herein-before described, that it is unnecessary
to enter into a description of the several parts thereof aided by letters of
reference.
The dotted lines in Figure 1, representing the longitudinal section of the
bridge, are intended to represent the position it would assume whilst being
opened to, the extent of about one-third its travel.
Instead of applying racks to the under side of the tail end of the bridge
alone and applying the moving gear and pinion at the extreme end as shown
in Figure 1, racks may be applied to the under side of the overhanging end,

page_text: and the pinion and moving gear be applied close to the quay line or the fore
end of the pit, and, if preferred, independent racks may be applied to
both ends of the bridge and two sets of moving gear and pinions be
employed.
Having now described our Invention of improvements in rolling bridges
and in the accompanying Drawing shown one of the modes or methods in
which we apply the same in practice, we claim,-
First, the mode or method of constructing and working rolling bridges as
herein set forth.
Second, the modes or methods herein described for securely supporting and
at the same time rendering easily moveable when required the bridge or
platform.
Third, the arrangement and mode of working the counterbalanced tilting
gear and moving or traversing apparatus herein-before described and as
illustrated in the accompanying Drawing, and whether the same be
applied to bridges generally of the construction shown and described, or to any
other description or arrangement of rolling or traversing bridge.
In witness whereof, I, the said John William Gibson, on behalf of
myself and the said William Turner, have hereunto set my hand
and seal, this Twenty-seventh day of June, One thousand eight
hundred and sixty-two.
JOHN WILLIAM GIBSON.
(L.S.)