IMPROVEMENTS IN RAILWAY AND OTHER CARRIAGE SPRINGS, AND IN THE MACHINERY OR APPARATUS POR MANUFACTURING THE SAME
Year: 1868

page_text: LETTERS PATENT to Joseph Mitchell, of Sheffield, in the County of
York, Spring Manufacturer, for the Invention of "IMPROVEMENTS IN
RAILWAY AND OTHER CARRIAGE SPRINGS, AND IN THE MACHINERY OR
APPARATUS POR MANUFACTURING THE SAME."
Sealed the 24th July 1868, and dated the 18th May 1868.
PROVISIONAL SPECIFICATION left by the said Joseph Mitchell at the
Office of the Commissioners of Patents, with his Petition, on the
18th May 1868.
I, JOSEPH MITCHELL, of Sheffield, in the County of York, Spring
Manufacturer, do' hereby declare the nature of the said Invention for
"IMPROVEMENTS IN RAILWAY AND OTHER CARRIAGE SPRINGS, AND IN THE
MACHINERY OR APPARATUS FOR MANUFACTURING THE SAME," to be as
follows:-
My Invention of improvements in railway and other carriage springs
has for its object to construct flat or elliptical springs in such a manner
that they will be stronger and less liable to break than springs of the
ordinary construction. The result of the use of my improvements will

page_text: be not only that the strength and durability of the spring will be
increased, but also that the cost of manufacture will be considerably
diminished. In ordinary flat or elliptical carriage springs the several
plates composing the same have a hole punched or bored through the
centre to receive a bolt, whereby they are held together and prevented
from shifting out of their place. It has been found that these springs
are extremely liable to fracture across the line of the bolt holes, that
being the weakest part of the spring.
In carrying out my Invention I altogether dispense with these bolt
holes, and in order to prevent the plates of which the spring is composed
from shifting on one another I form a corrugation or indentation across
the central part of each plate, and these corrugations or indentations are
made to fit into each other. The several plates are held together by
means of a square metal box or collar, through which is passed a cross
pin or bolt which fits snugly into the concave recess of one of the
outermost plates.
As a modification of the above indentations or notches may be made
in the edges of the plates for the purpose of receiving ribs formed
on the clip plates or vertical bolts passed through the clip plates which
embrace the spring plates. These bolts being screwed up will secure
the spring plates together.
The machinery or apparatus for manufacturing these springs forms the
second part of the Invention, and will enable the springs to be made
with unskilled labour. The machinery consists of a strong press provided
with a die and counter die, whereby the corrugation is produced in the
plate.
In carrying out the Invention the steel bars are cut up into plates
of proper lengths, according to the size and kind of spring it is intended
to produce. These plates are heated and while red hot are placed in the
press, and by bringing the central part of the plate between the dies
the corrugation or indentation is made therein at one blow. The die
may be actuated either by a cam, crank, or excentric, or by a screw, and
for heavy plates I use hydraulic power. When the edges of the plates
are to be indented punches or cutters are substituted for the moving
die.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Joseph Mitchell in the Great Scal Patent Office on
the 18th November 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
MITCHELL, of Sheffield, in the County of York, Spring Manufacturer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of May, in the year of
our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Joseph Mitchell, Her special licence
that I, the said Joseph Mitchell, my exccutors, administrators, and
assigns, or such others as I, the said Joseph Mitchell, my 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 "IMPROVEMENTS IN RAILWAY
AND OTHER CARRIAGE SPRINGS, AND IN THE MACHINERY OR APPARATUS FOR MANU-
FACTURING THE SAME," upon the condition (amongst others) that I, the said
Joseph Mitchell, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and scals, 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 Joseph Mitchell, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawing hereunto
annexed, and to the letters and figures marked thereon (that is to
say)-
My Invention of improvements in railway and other carriage
springs has for its object to construct flat or elliptical springs in
such a manner that they will be stronger and less liable to break

page_text: than springs of the ordinary construction. The result of the use of
my improvements will be not only that the strength and durability of
the spring will be increased, but also that the cost of manufacture will
be considerably diminished. In ordinary flat or elliptical carriage
springs the several plates composing the same usually have a hole
punched or bored through the centre to receive a bolt, whereby they
are held together and prevented from shifting out of their place. It
has been found that these springs are extremely liable to fracture
across the line of the bolt holes, that being the weakest part of the
spring.
By my Invention I altogether dispense with these bolts and holes,
and in order to prevent the plates of which the spring is composed
from shifting on one another I form a corrugation or indentation
across the central part of each plate, and these corrugations or inden-
tations are made to fit into each other. The several plates having
been placed one on the other in proper order, and with the convex
protuberance of each plate fitting into the corresponding corrugation,
indentation, or recess of the contiguous plate, they are held together
by means of a square metal box or collar, through which is passed a
cross pin or bolt which fits snugly into the concave recess of one of the
outermost plates, either the topmost or the lowermost plates.
In the accompanying Drawing Fig. 1 is an elevation of an elliptic or
flat bearing spring constructed according to my Invention, and con-
sisting of several plates a, a; the square metal box or collar b which
holds the plates a together being shewn in section; Fig. 1 is an end
view of the same; Fig. 1B is a plan view, and Fig. 1° an edge view of
one of the plates a detached, shewing the corrugation a* made therein.
Figures 1º are front and sectional views of the box or collar 6 in which
the plates a are secured by the cylindrical or semi-cylindrical cross
pin c, as shewn at Fig. 1.
Fig. 2 is a sectional elevation of a modification of the above, the only
difference being that the corrugations a* at the central part of the
spring plates are in a reverse position to that shown at Fig. 1.
Figures 3, 34, and 3B are side elevation, plan, and end views of a
bearing spring for a bogie carriage, or it may be used as a buffer spring.
These Figures also shew another mode of holding the plates a¹ together.
In this instance the spring plates a¹ are held between two plates b¹
technically called butterfly plates, and are secured between the butterfly

page_text: plates by bolts 62, which are held firmly in place by screw nuts, as
shewn in the Drawing; or a single butterfly plate may be used and
secured in place by U-straps or bolts &, as shewn at Fig. 3°.
As a modification of the above indentations may be made in the
centre of the plates, as shewn in the plan view, Fig. 4, and sectional
views, Figs. 4 and 4; these indentations will fit one in the other, and
will prevent the spring plates a from moving longitudinally on each
other.
As a further modification notches may be made in the edges of the
spring plates, as shewn at d in the plan view, Fig. 5 and Fig. 6", for the
purpose of receiving ribs formed on clip plates d, Fig. 5, which are
held firmly to the sides of the spring plates a, either by bolts, as shewn
in the Drawing, or by a sling or collar, which may be attached to the
draw bar, as shewn at Fig. 5° and Fig. 5°; or vertical bolts 6³, Fig. 6,
may be passed through two butterfly plates 65, 6, which embrace the
spring plates a at top and bottom, as at Figures 6 and 6, and also at
Fig. 3. The bolts 63, in Figures 5 and 5*, being screwed up will hold the
clip plates d of Figures 5 and 5* or the butterfly plates 6s of Fig. 6, and
will secure the spring plates a together; or a single butterfly plate. 6'
with U-bolts 6s may be used, as at Fig. 3º, for the purpose of securing
the spring plates a together.
The machinery or apparatus for manufacturing these springs forms
the second part of the Invention, and is shewn in Sheet II. of the
Drawings. By means of this machinery the springs may be made with
unskilled labor, consequently much quicker and cheaper than heretofore.
The machinery consists of a strong press of any convenient construction
and provided with a die and counter die, whereby the corrugation is
produced in the plates a, a, of which the spring is to be made.
In carrying out the Invention steel bars of suitable thickness are cut
up into plates of proper lengths according to the size and kind of spring
it is intended to produce. These plates are heated and while red hot are
placed on the bed g of a press, as shewn at Fig. 7, and by bringing
the central part of the plates a, a, between the fixed die g¹ and the
plunger which carries the moveable die ', the corrugations or inden-
tations, as shewn at Figures 1, 2, 3, and 4 in Sheet I., are made therein
at one blow. The moveable die h may be actuated either by a cam,
crank, or excentric, or by a screw, but for heavy plates I prefer to use
hydraulic power. When the edges of the plates are to be indented, as

page_text: shewn at Figs. 5, 6, and 6³, punches or cutters are substituted for the
moving die h. The spring plates a, a, having been indented in the
manner shown they must be bent to the proper curves, so as to cause
them to fit and bed properly one on the other. To this end they are
placed on the bed of a hydraulic press against a curved block i, as
indicated by dots in Fig. 8, which is a sectional plan view of the
apparatus, Fig. 9 being a side elevation of the same, and by means of
the plunger of the hydraulic cylinder j, which is connected by links
1, k¹ to a pair of spring arms k, k, I cause the rollers at the ends of the
arms k to bear against the outer faces of the plates a, a, so that by the
advance of the plunger and arms the extreme ends of the plates a
will one by one be forced back against the fixed curved block i, and thus
made to assume the curved shape desired, as indicated by dotted lines in
Fig. 8, and all the several plates will be made to fit snugly on each other
and will only need to be secured in the manner shewn in the several
Figures in Sheet I.
Having now described my Invention of "Improvements in Railway
and other Carriage Springs, and in the Machinery or Apparatus for
Manufacturing the same," and having explained the manner of carrying
the same into effect, I claim under the herein-before in part recited
Letters Patent making springs of plates in which are made corruga-
tions or indentations, as herein set forth, for the purpose of preventing the
several plates from moving or slipping on each other.
In witness whereof, I, the said Joseph Mitchell, have hereunto
set my hand and scal, the Sixteenth day of November, in the year
of our Lord One thousand eight hundred and sixty-eight.
Signed and sealed in the
presence of
HENRY HORNER,
Estate Agent,
JOSEPH MITCHELL. (L.S.)
56, Norfolk St., Sheffield.