CERTAIN IMPROVEMENTS IN OR APPLICABLE TO TURN- TABLES TO USED ON OR IN CONNECTION WITH RAILWAYS
Year: 1845

page_text: MEMORANDUM OF ALTERATION.
SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
DUNN, of Manchester, in the County of Lancaster, Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Thirteenth day of March, in the eighth year of Her reign,
and in the year of our Lord One thousand eight hundred and forty-five, did
give and grant unto me, the said Thomas Dunn, my exors, admors, .and
assigns, Her special licence, full power, sole privilege and authority, that I
the said Thomas Dunn, my exors, admors, and assigns, and such others as I,
the said Thomas Dunn, my exors, admors, and assigns, should at any time
agree with, and no others, from time to time and at all times during the
term of years therein expressed, should and lawfully might make, use and
exercise and vend, within England and Wales and the Town of Berwick-upon-
Tweed, my Invention of "CERTAIN IMPROVEMENTS IN OR APPLICABLE TO TURN-
TABLES TO USED ON OR IN CONNECTION WITH RAILWAYS;" in which said
Letters Patent is contained a proviso obliging me, the said Thomas Dunn, to
particularize and ascertain the nature of my said Invention, and in what
manner the same is to be performed, by an instrument in writing-under, my
hand and seal, and to cause the same to be enrolled in Her Majesty's High
Court of Chancery within six calendar months next and immediately after
the date of the now reciting Letters Patent, as in and by the same, reference
being thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Dunn, do hereby declare the nature of my said Invention, to consist,-
First, in the application to such railway turntables only as have their plat-
forms at all times supported in a greater or less degree on friction rollers of
such apparatus as will, by being placed in contact with the platform, give
may have
support and stability to it where one or more of the friction rollers
become lower than the level of the rest, leaving the other parts of the
platform to be supported by the friction rollers, so that when a carriage passes
over the table the platform is prevented from shaking so violently, and from
making so loud and jarring a noise as those turntables do which are in general
use; and when it is required to turn such platform the apparatus is changed
in its position, so as to allow the platform to be turned on the rollers.
Secondly, in constructing the curb or stationary casing of the platform of a
turntable, and also the platform itself, which has to work in it in the form of a
ring, which form admits of a portion of the permanent line of railway being
left within the curb and platform, whereby the carriages of a train are less
liable to run off the line in case the rails on the platform are not left in a line
with the permanent rails on each side, and within the table, and by the plat-
form being so short in its bearings it is enabled to sustain a greater weight
than ordinary platforms are, without being otherwise damaged.
Thirdly, in constructing the general surface of the platform of a turntable
of metal on a level with the tops of the permanent rails, and in forming
grooves in the platform for the flanges of the wheels to pass into; so that if
the grooves. in the platform should not be in a position to receive the flanges
of the carriage wheels as they pass from the permanent rails, such wheels,
will have to mount on the surface of the table the height of the wheel flanges
only, and not the height of a rail, which is the case in turntables as at present
constructed. And,
Lastly, in the application of a guide ring or wheel placed on the surface
of the platform of a turntable, and in guide rings or wheels placed near to a
turntable within or outside of the rails of a line of railway, in such positions
that if the wheels of a carriage have only got a short distance off the rails-by
the platform not being in the position it ought to be for a train to pass over
it, such rings or wheels will guide them on to the rails again. And in further
compliance with the said proviso, I, the said Thomas Dunn, do hereby describe
the manner in which my Invention is to be performed by the following state-
ment thereof, reference being had to the Drawings annexed, and to the figures
and letters marked thereon, similar letters being used to denote similar parts
throughout the Drawings.

page_text: DESCRIPTION OF THE DRAWINGS.
In Sheet 1, Fig. 1 represents in section cut through the middle an ordinary
turntable, with part of my improvements attached for giving stability to the
platform whilst a train is passing over it. Fig. 2 is a plan of the curb shewn
in Fig. 1, with part of my improvements attached. Fig. 3 represents in section
cut through the middle an ordinary turntable platform, with a guide ring or
wheel placed on its surface. Fig. 4 is in plan a part of the platform shewn in
Fig. 3, with two guide rings or wheels placed within and two outside of the
rails of a line of railway near to the platform.
In Sheet 2, Fig. 5 represents in section an ordinary turntable cut through
the middle, with the platform steadied by cams according to my improve-
ments. Fig. 6 shews a part of a turntable in section, with the platform
steadied by the end of the rails outside the turntable, according to my improve-
ments. Fig. 7 represents a turntable in section cut through the middle, with
another variety of my improvements attached for steadying the platform by
wedges. Fig. 8 represents a turntable in section cut through the middle, with
another modification of my improvements attached for steadying the platform
by screws. Fig. 9 represents in plan the curb, screws, and chain shewn in
Fig. 8. Fig. 10 represents in section a turntable, with another modification
of my improvements attached. Fig. 11 represents in plan the turntable shewn
in Fig. 10, with the platform removed. Fig. 12 represents in section a turn-
table, with another modification of my improvements attached. Fig. 13 repre-
sents in plan a part of the table shewn in Fig. 12, with the platform removed.
In Sheet 3, Fig. 14 is a side representation of the curb and platform of a
turntable, in which a portion of the permanent line of railway is left in the
middle. Fig. 15 is a plan of the table shewn in Fig. 14. Fig. 16 represents
in section part of the table shewn in Fig. 14. Fig. 17 represents a plan of
the curb shewn in Figs. 14, 15, and 16, with the rollers on which the platform
works when it is required to turn a carriage from one line of rails to another,
with my improvements for steadying the platform attached to it.
In Sheet 4, Fig. 18 represents in plan of my improved platform made in.
the form of a ring and resting upon ordinary rollers, with a great number of.
grooves sunk below the metallic surface to receive the flanges of the carriage
wheels. Fig. 19 represent a section of the same platform. Fig. 20 repre-
sents a side view of the ring table shewn in Figs. 18 and 19. And Fig. 21
represents in plan the ring, curb, and also the rollers on which the ring.
platform rests entirely when turning.
In Fig: 1, Sheet 1, a represents a rail as it is placed on an ordinary turn-
table; b represents the platform; c the centre pin, with the ordinary adjusting

page_text: screws; d, the rollers on which the platform works whilst it is being turned;
e, a shaft working through three stationary bearings .f. This shaft e has a
handle hand two short levers g keyed upon it. Through the top end of the
levers a pin is fixed, on which pin two links i are passed at the top side, so
as to work-freely, and at the other end these links are by another pin united
to a wedge j: The pin at the bottom end of the lever g unites it to the
forked end of a long rod k, which rod at its other extremity is by a forked end
and pin united to another wedge j: In Fig. 3, u represents a guide roller
placed on the surface of the platform; and in Fig. 4; v represents two guide
rollers placed within the rails of a line of railway near to a turntable; and tu
represents two guide rollers placed outside of the rails of a line of railway,
also near to a türntable, for the purpose of guiding the wheels of a carriage
if they should get off the rails on the table: My improvements as regard
the steadying apparatus are shewn in Figs. 1 and 2 to be in a position
to keep the platform steady for a train to pass over it, by the wedges having
been brought in contact with the under side of the platform by having been
passed towards the centre of the table. If, however, a carriage were upon the
table which required to be passed upon another line of rails, by raising the handle
h and thereby partially turning the shaft e; the wedges j; by the levers; pins,
links; and röds; before described, would be forced outwards; and the platform
and carriage upon it might in consequence be turned to the required distance.
In Fig. 5, Sheet 2, h represents the handle keyed upon the shaft.e, upon
which shaft are fixed two cams 7, one only of which can be seen in this
Figure: Another shaft e is placed parallel to the first shaft, which has also
two cams upon it, and each cam is united to the one opposite to it by a
rod m, which unites them on the under side, as seen in this Figure. The
platform of this table is shewn to be held steady for a train to pass over it by
the cams 1 being in contact with the under side of the platform. By raising
the handle h the cams l, by being partially turned on their axes, allow the
platform to turn on the rollers, which, however, are not shewn in this
Drawing, as they are well known to exist under the platforms of ordinary
turntables. In-Fig.-6-my-improvements consist-in-using-a-portion-of-the-rails
on the outside of the turntable; to give stability to the platform when it is
required; n represents a portion of the main rail jointed and attached by a pin
to the chair o. That end of the rail which is next to the turntable is notched
out so as to páss under the rail on the table, and a cam 7 on the shaft e-forces
the end of the main rail, which is made moveable. or jointed for the
purpose, under the rail on the table when it is required to give stability to the
table for a train to pass over it. There are four such jointed ends of

page_text: the main rails with a cam working under each, though one only is
shewn in this Figure. The four cams may be united in a manner similar to
that described in Fig. 5, and they are used in a similar way and produce
similar effects. In Fig. 7 is shewn another mode of moving the wedges.
p. p, are two pedestals bolted to beams which extend under the curb. q is a
bevil wheel attached to a boss, which is supported by and turns round in the
pedestal p. On the boss are two shoulders to prevent the wheel and boss
moving backwards or forwards. A female screw is cut in the boss of each of
the. bevil wheels, in which a male screw works, which male screw is cut on
one end on each of the rods k, and the other end of each of the rods is
attached to one of the wedges. Another bevil wheel, which is fixed upon a shaft
supported by pedestals, takes into the two bevil wheels last mentioned; and
when this shaft which extends outside the table is turned sufficiently by any
known mechanical means, the wedges may be forced under the platform-to
give stability to the table whilst a train passes over it, or they inay be with-
drawn from under the platform so as to admit of its being turned on the
rollers. In this Drawing I have not shewn the rollers, as their position'
is well known, nor have I been enabled to shew a second bevil wheel whichi
is keyed on the same shaft as the middle wheel here shewn, and which
works. two other wedges by exactly the same means as those I have shewn in
this Figure. In Fig. 8 is shewn another mode of giving stability to the table...
r represents a number of screws, each having a cup on the top of it, in which
a piece of wood is fitted to act against the platform. A notched recess or
pulley groove is cut in the head of each screw for a chain to work-in. These
screws, each of them, work in a female screw fixed in the curb of the table:
The chain; which is an endless chain, works in the pulley groove of each of
the: screw heads, and passes partly round a wheel-placed outside of the table,
as shewn in Fig. 9, by which wheel. the chain is moved, so that by its action
it moves all the screws up or down at the same time. The screws against
which the chain acts in the inside have their threads cut in a contrary direc
tion to those against which the chain acts on the outside. When it is
required to steady the platform of this table for a train to pass over it, the
screws are forced upwards against it; but when it is required to turn the plat-
form, the screws are lowered down so as to admit of its being turned on
the rollers. In Fig. 10 and 11 I move the wedges j.backwards and forwards
for the purposes before described, by the rule joints s and the rods connecting
them to the wedges. In Figs. 12 and 13 I move the wedges j backwards and
forwards for the purposes before described, by the bell-crank levers t and the
rods connecting them to the levers. .

page_text: .
.
In Sheet 3, Fig. 14, A represents the outside of the stationary ring, curb,
or bearing. B are stone blocks, on which the curb rests. C is the moveable
ring platform, the general metallic surface of which is on a level with the
rails, with grooves in it to receive the flanges of the wheels, clearly shewn in
Fig. 15, in which D represents a portion of permanent road, and E short
lengths of permanent rails. On the ring platform it will be observed that the
general metal surface of the table is on a level with the top of the wrought-
iron rails, which are let into it. In Fig. 16 the ring platform C is shewn in
section and the space within the curb is shewn without any soil or ballast being
put into it. One of the permanent rails E is also shewn, fixed to a covering
plate F, which plates are made so that they may be removed when required to
adjust the rods k below them by a right and left hand screw, and thereby also
adjust the double wedges j, shewn in this Figure. It will not be needful here
to again explain how these wedges give stability to the platform for a train to
pass over it, as they act in a similar manner to those already explained, which
belong to the first part of my improvements. I would however remark, that
there are two wedges j on the same piece of metal, which constitutes the only
difference between these wedged pieces and those before described. In
Fig. 17 my improved ring table is shewn with the platform removed, and
the rollers d are shewn placed in the bottom of the curb or bearing ring. The
handle, shaft, levers, links, wedges, and rods are also shewn, by which the plat-
form is made steady, or allowed to turn on the rollers d, as explained already:
In Sheet 4, Fig. 18 represents a plan of a ring platform G, which is formed
entirely of cast iron. The general surface of this platform is on a level with
the rails. The flanges of the wheels work in the grooves, and their peripheries
work on the surface of the platform, there being no wrought-iron rails let into
it. It will be observed, that there are a number of parallel grooves on this
platform; so that when the surface is worn down by the sides of one pair of
grooves another part of the table may be substituted for that which is so worn..
Fig. 19 is a section of the table shewn in Fig. 18.
"
Having now described the nature of my Invention, and the manner in
which it is carried into effect, I hereby claim,―
First, the application to such railway turntable as I have shewn and
described in this my Specification of such moveable apparatus for giving
stability to a platform whilst a carriage is passing over it, as I have also herein
shewn and described. But I desire it to be distinctly understood, that I do
not claim the application of such apparatus to those turntables whose plat-
forms are supported each on a central column, and which are devoid of the
ordinary friction rollers on which ordinary platforms are turned, as I am

page_text: aware that cams have for some years been used to give support and stability to.
the platforms of turntables known as Captain Handcock's Patent Turntables,.
and which rest each on a central column.
Secondly, in constructing the curb and platform of a turntable in the form
of a ring, whereby the bearings are shortened, and a space is left in the middle.
of the table for a portion of a permanent line of railway.
Thirdly, in constructing the general surface of the platform of a turntable,
whether such platform consists of one entire disc, or of a ring on a level with
the permanent rails, and with grooves in it to receive the flanges of the wheels,
so that if the platform is not in the position it ought to be when a train
passes
over it the carriage wheels will not have to rise higher than the distances that
the flanges of the wheels extend beyond their peripheries; and in a ring plat
form they will not have to move far without again arriving upon the permanent
rails. And,
Lastly, in the application of a guide ring or wheel placed on the surface
of the platform of a turntable, and in guide rings or wheels placed near to a
turntable within or outside of the rails of the permanent line of railway in such
positions that if the wheels of a carriage have only got a short distance off the
rails by the platform not being in the position it ought to be for a train to pass
over it, such rings or wheels will guide them on to the rails again.
And such my Invention being, to the best of my knowledge and belief,
entirely new, and never before used within that part of Her said Majesty's
United Kingdom of Great Britain and Ireland called England, Her Dominion
of Wales, and Town of Berwick-upon-Tweed, I do hereby declare this to be
my Specification of the same,-and that I do verily believe that this my said
Specification doth comply in all respects, fully and without reserve or disguise,
with the proviso in the said herein-before recited Letters Patent contained.
Wherefore I do hereby claim to maintain exclusive right and privilege to the
said Invention.
In witness whereof, I, the said Thomas Dunn, have hereunto set my
hand and seal, this Twelfth day of September, in the year of our
Lord One thousand eight hundred and forty-five.
Signed, sealed, and delivered, being first
duly stamped, by the within-named
Thomas Dunn, in the presence of
THOMAS (L.S.) DUNN.
G. B. WITHINGTON,.

page_text: AND BE IT REMEMBERED, that on the Twelfth day of September,
in the year of our Lord 1845, the aforesaid Thomas Dunn came before
our said Lady the Queen in Her Chancery, and acknowledged the Specifi-
cation aforesaid, and all and every thing therein contained and specified in
form above written. And also the Specification aforesaid was stamped
according to the tenor of the Statute made for that purpose.
Enrolled the Thirteenth day of September, in the year of our Lord One
thousand eight hundred and forty-five.

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
DUNN, of Manchester, in the County of Lancaster, Engineer, send
greeting.
TO
WHEREAS Her most gracious Majesty Queen Victoria, by Her Letters
Patent, under the Great Seal of Great Britain, bearing date the Thirteenth
day of March, in the year of our Lord One thousand eight hundred and
forty-five, did give and grant unto me, the said Thomas Dunn, my exors,
adiiors, and assigns, Her especial licence, full power and sole authority, that
I, the said Thomas Dunn, and my exors, adñiors, and assigns, and such
others as I should at any time agree with, and no others, from time to:
time and at all times thereafter during the term of years therein expressed,
should and lawfully might make, use, exercise, and vend as therein men-
tioned, my Invention of "CERTAIN IMPROVEMENTS IN OR APPLICABLE
TURNTABLES, TO BE USED ON OR IN CONNECTION WITH RAILWAYS;" And
whereas, in pursuance of a proviso in the said Letters Patent contained,
I caused a particular description of the nature of my said Invention, and in
what manner the same is to be performed, by an instrument in writing
under my hand and seal, to be inrolled in Her said Majesty's High Court of
Chancery, and commonly called a Specification; And whereas I am desirous,
for reasons herein-after mentioned, to enter a Disclaimer of part of the said
Specification, and a Memorandum of Alteration of part thereof, and have
obtained leave of Her Majesty's Attorney General, certified by his fiat and
signature, according to the form of the Statute in such case made and
provided:
KNOW YE THEREFORE, that I do hereby disclaim the following parts of
the said Specification and of certain plans annexed to and forming part of the
said Specification; that is to say, I disclaim the part following of the said
Specification :-
"In Sheet 2, Fig. 5 représents in section an ordinary turntable cut through
the middle, with the platform steadied by cams according to my improvements.
Fig. 6 shews a part of a turntable in section, with the platform steadied by the
end of the rails outside the turntable according to my improvements. Fig. 8
represents a turntable in section cut through the middle, with another
modification of my improvements attached for steadying the platform by
screws. Fig. 9 represents in plan the curb, screws, and chain, .shewn iu
Fig. 8. And I disclaim the said Figures 5 and 6, and 8 and 9.

page_text: I also disclaim-In Fig. 5, Sheet 2, h represents the handle keyed upon the
shaft e, upon which shaft are fixed two cams 1, one only of which can be seen in
this Figure. Another shaft e is placed parallel to the first shaft, which has also
two cams upon it, and each cam is united to the one opposite to it by a rod
m, which unites them on the under side, as seen in this Figure. The platform
of this table is shewn to be held steady for a train to pass over it, by the
cams being in contact with the under side of the platform. By raising the
handle h the cams 7, by being partially turned on their axis, allow the platformı
to turn on the rollers, which, however, are not shewn in this Drawing, as they
are well known to exist under the platforms of ordinary turntables.. In
Fig 6, my improvements consist in using a portion of the rails on the outside
of the turntable to give stability to the platform when it is required; n repre-
sents a portion of the main rail jointed and attached by a pin to the chair o.
That end of the rail which is next to the turntable is notched out, so as to pass
under the rail on the table, and a cam l on the shaft e forces the end of the
main rail, which is made moveable or jointed for the purpose, under the rail
on the table when it is required to give stability to the table for a train
to pass over it. There are four such jointed ends of the main rails with a
cam working under each, though one only is shewn in this Figure. The four
cams may be united in a manner similar to that described in Fig. 5, and they
are used in a similar way and produce similar effects."
"
66
I also disclaim:-"In Fig. 8 is shewn another mode of giving stability to the
"table.
represents a number of screws each having a cup on the top of it,
" in which a piece of wood is fitted to act against the platform. A notched
"recess or pulley groove is cut in the head of each screw for a chain to
work in. These screws, each of them, work in a female screw fixed in
"the curb of the table. The chain, which is an endless chain, works in the
pulley groove of each of the screw heads, and passe partly round a
"wheel placed outside of the table, as shewn in Fig. 9, by which wheel the
"chain is moved so that by its action it moves all the screws up or down at
"the same time. The screws against which the chain acts in the inside have
"their threads cut in a contrary direction to those against which the chain
"acts on the outside. When it is required to steady the platform of this
table for a train to pass over it, the screws are forced upwards against it;
"but when it is required to turn the platform, the screws are lowered down so
"as to admit of its being turned on the rollers."
66
And also that I do hereby enter the following Memorandum of Alteration;
that is to say, in the said Specification and in that part of it in which the
nature of my Invention is described, after stating therein "I, the said Thomas

page_text: "Dunn, do hereby declare the nature of my said Invention to consist, first, in
"the application to such railway turntables only as have their platforms at all
"times supported in a greater or less degree on friction rollers,". I insert the
words "and as are placed within a curb." And in that part of it in which
the manner in which my Invention is to be performed, after stating therein My
improvements as regard the steadying apparatus are shewn in Figs. 1 and 2
to be in a position to keep the platform steady for a train to pass over it, by
the wedges having been brought in contact with the under side of the
platform by having been passed towards the centre of the table, I add the
words:"And by their working through mortices or other holes or bearings
formed through or in the curb, as shewn in those Figures, so that they rest
firmly on and are supported by the lower parts of those mortices, holes, or
bearings, and are kept steady and prevented from moving sideways. or
shaking to any considerable extent, by the sides of those mortices, holes, or
bearings. And in that part of it in which it is stated what I claim, after
stating "I do not claim the application of such apparatus to those turntables
"whose platforms are supported each on a central column, and which are
"devoid of the ordinary friction rollers on which ordinary platforms are turned,
as I am aware that cams have for some years been used, to give support
"and stability to the platforms of turntables known as Captain Handcock's
"Patent Turntables, and which rest each on a central column," I add the
words: "And that I do not claim the application of such apparatus to such
turntables as are not within curbs."
6:
And I do also hereby declare that my reasons for making and entering
the said Disclaimer and Memorandum of Alteration are as follows; that is to
say, that since the making and inrolling the said Specification I have discovered
that there is reason to doubt whether the use of wedges and the like, without
acting in connection with the curb, was new at the time of the grant of the
said Letters Patent. And I hereby further declare that the above Disclaimer
and Memorandum of Alteration is not such Disclaimer or such Alteration as
will extend the exclusive right granted by the said Letters Patent.
In witness whereof, I have hereunto set my hand, this Twenty-sixth
day of March, in the year of our Lord One thousand eight hundred
and forty-seven:
35
THOMAS
(L.S.) DUNN.
To the Clerk of the Patents of England.
This is to certify, that Thomas Dunn, of Manchester, in the County of
Lancaster, Engineer, has applied to me for leave to enter with you the above-

page_text: written Disclaimer and Memorandum of Alteration of a certain Invention
for which Letters Patent were duly granted to him, under the Great Seal,
date the 13th day of March, 1845, and to which the Specification was duly]
enrolled, and on considering of the said application I directed him to advertise
the said Disclaimer and Alterations in the London Gazette, and in the Times
and Morning Chronicle and Manchester Guardian Newspapers; and such
advertisements have been duly made in the said papers, and no objection
having been made to the said application, I have accordingly granted leave
to the said Thomas Dunn to file his said Disclaimer and Alterations pur-
suant to the Statute passed in the 5th & 6th years of the reign of His late
Majesty, entitled "An Act to amend the Law touching Letters Patent for
Inventions
AND BE IT REMEMBERED, that on the Twenty-sixth day of March, in
the year of our Lord 1847, the aforesaid Thomas Dunn came before our said
Lady the Queen in Her Chancery, and acknowledged the Disclaimer aforesaid,
and all and every thing therein contained and specified, in form above written.
And also the Disclaimer aforesaid was stamped according to the tenor of the
Statute made for that purpose.
Enrolled the Thirtieth day of March, in the year of our Lord One
thousand eight hundred and forty-seven.