IMPROVEMENTS IN PNEUMATIC SPRINGS, SPECIALLY APPLICABLE TO RAILWAY ROLLING STOCK
Year: 1867

page_text: LETTERS PATENT to John Piddington, Patent Agent, of 53, Gracechurch
-
Street, in the City of London, for the Invention of "IMPROVEMENTS IN
PNEUMATIC SPRINGS, SPECIALLY APPLICABLE TO RAILWAY ROLLING STOCK."-
A communication from abroad by Joseph Dauley, Ironmaster, of Aiseaux,
in the Kingdom of Belgium.
Sealed the 31st March 1868, and dated the 5th October 1867.
PROVISIONAL SPECIFICATION left by the said John Piddington at the
Office of the Commissioners of Patents, with his Petition, on the
5th October 1867.
I, JOHN PIDDINGTON, Patent Agent, of 53, Gracechurch Street, in the City
of London, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN PNEUMATIC SPRINGS, SPECIALLY APPLICABLE TO RAILWAY ROLLING STOCK,"
a communication to me from abroad by Joseph Dauley, Ironmaster, of
Aiseaux, in the Kingdom of Belgium, to be as follows:-
This Invention consists in employing the elasticity of air for the construction
and arrangement of springs suitable for any kind of industrial requirement,
but chiefly for the rolling stock of railways, buffers, drawing and bearing
springs. A cylinder closed at one end, and the inner surface of which is
turned so as to be perfectly smooth, is made of such strength as to
contain air at any fixed rate of pressure, an air-tight piston being so arranged
as to work in the cylinder. If by the force of any weight or sudden shock

page_text: the piston is driven back into the cylinder the pressure of the air increases
in proportion to the decrease of volume thus produced, and upon the force
being entirely or partially removed the elasticity of the air restores the piston
to its original position, or to a position proportionate to the remaining
weight or force to be sustained or resisted. The compressibility and elas-
ticity of the air thus present the qualities of a spring of regularly progressive
resistance, and by varying the dimensions and strength of the cylinder the
extent and conditions of its resisting power and the action of the spring may
be regulated as desired.
In cases in which the cylinder is of comparatively slight thickness, and in
which it is necessary to avoid the limit of resistance to the weight or force
employed being passed, this object may be effected by forming either inside
the piston or in the bottom of the cylinder a hollow or recess of such
calculated capacity as may be sufficient to receive the air at a limited pressure.
Thus when the outward pressure has attained its proper limit and the piston
has reached the bottom of the cylinder (an elastic substance being interposed
if considered desirable), and as the volume of air can then be no further
diminished, the pressure cannot consequently be increased. The initial or
normal pressure of air in the interior of the cylinder required to overcome
friction or to increase the original force of the spring may be obtained in
various ways, as, for instance, by so constructing the apparatus that the piston
when at rest shall partially enter the cylinder, thus producing a certain amount
of pressure, or by causing the piston to be pressed upon by an additional
piece fitting the cylinder into which the air which it contains is forced, or by
the use of a forcing pump.
.
In order to prevent the passage of the air between the piston and the wall
of the cylinder any of the well-known methods of securing air-tightness may
be adopted, but by preference the following arrangement is used:-Upon the
inner surface of the piston is placed a ring of india-rubber or of any suitable
semi-elastic material, the external diameter thereof being exactly equal to the
internal diameter of the cylinder; this ring is kept in position by a metal
washer fastened to the piston by screws, but so that it can move freely towards
the latter. The pressure of the air acting upon the water will tend to force
it towards the piston, thus compressing the india-rubber or semi-elastic ring,
which will therefore expand laterally, thus forming a joint of which the
closeness will increase in proportion to the pressure of the air.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Piddington in the Great Seal Patent Office on the
4th April 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
PIDDINGTON, Patent Agent, of 58, Gracechurch Street, in the City of London,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourth day of October, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said John Piddington, Her special licence that 1, the said John Piddington,
my executors, administrators, and assigns, or such others as I, the said John
Piddington, 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
PNEUMATIC SPRINGS, SPECIALLY APPLICABLE TO RAILWAY ROLLING STOCK," a com-
munication to me from abroad by Joseph Dauley, Ironmaster, of Aiseaux, in
the Kingdom of Belgium, upon the condition (amongst others) that I,
the said John Piddington, my executors or administrators, by an instru-
ment in writing under my, 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 I, the said John Piddington, 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 accompanying Drawing, and to the letters marked
thereon, that is to say :-
My said Invention consists in employing the elasticity of air for the
construction and arrangement of springs suitable for any kind of industrial
requirement, but chiefly for the rolling stock of railways, as buffers, drawing
and bearing springs. A cylinder closed at one end, and the inner surface of
which is turned so as to be perfectly smooth, is made of such strength as to
contain air at any fixed rate of pressure, an air-tight piston being so arranged
as to work in the cylinder. If by the force of any weight or sudden shock

page_text: the piston is driven back into the cylinder the pressure of the air increases in
proportion to the decrease of volume thus produced, and upon the force being
entirely or partially removed the elasticity of the air restores the piston to its
original position, or to a position proportionate to the remaining weight or
force to be sustained or resisted. The compressibility and elasticity of the air
thus present the qualities of a spring of regularly progressive resistance, and
by varying the dimensions and strength of the cylinder the extent and con-
ditions of its resisting power and the action of the spring may be regulated as
desired.
In cases in which the cylinder is of comparatively slight thickness, and it is
necessary to avoid the limit of resistance to the weight or force employed
being passed, this object may be effected by forming either inside the piston
or in the bottom of the cylinder a hollow or recess of such calculated capacity
as may be sufficient to receive the air at a limited pressure. Thus when the
outward pressure has attained its proper limit and the piston has reached the
bottom of the cylinder (an elastic substance being interposed if considered
desirable), and as the volume of air can then be no further diminished, the
pressure cannot consequently be increased. The initial or normal pressure of
air in the interior of the cylinder required to overcome friction or to increase
the original force of the spring may be obtained in various ways, as, for
instance, by so constructing the apparatus that the piston when at rest shall
partially enter the cylinder, thus producing a certain amount of pressure, or
by causing the piston to be pressed upon by an additional piece fitting the
'cylinder, into which the air which it contains is forced, or by the use of a
forcing pump.
In order to prevent the passage of the air between the piston and the wall
of the cylinder any of the well-known methods of securing air-tightness may
be adopted, but by preference the following arrangement is used:-Upon the
'inner surface of the piston is placed a ring of india-rubber, or of any suitable
semi-elastic material being air and water tight, the external diameter thereof
being exactly equal to the internal diameter of the cylinder; this ring is kept
in position by a metal washer fastened to the piston by screws, or in any other
suitable manner, but so that it can move freely towards the latter. The
pressure of the air acting upon the washer will tend to force it towards the
piston, thus compressing the india-rubber or semi-elastic ring, which will
therefore expand laterally, thus forming a joint, the closeness of which will
increase in proportion to the pressure of the air.
My Invention will be more clearly understood by reference to the annexed
'Drawing, which represents a buffer spring to which it is applied.

page_text: B is the cast-iron cylinder with a bottom thereto; P is a wrought-iron
piston the rod of which works in the cylinder with a slight friction; A is the
india-rubber ring; R is a metal washer which holds the ring against the
bottom of the piston by means of the screw V; C is an iron stem or pin which
crosses the diameter of the cylinder and piston; a, b, is a longitudinal groove
of the width of the pin C formed in the surface of the piston. The same
groove exists upon the opposite side of the piston, where it is traversed by
the pin, the two maintaining the piston in its right position when at rest, but
allowing free action as a spring.
Having thus described and ascertained the nature of my said Invention,
and the manner in which it is to be performed, I would observe in conclusion
that what I consider novel and original, and therefore claim as consti-
tuting the Invention secured to me by the said herein-before in part recited
Letters Patent is, the arrangement and combination of parts and mechanism
for the purposes of obtaining a perfectly elastic spring of progressive resisting
power and of any desired strength, substantially herein-before described and
set forth, or any mere modifications thereof.
In witness whereof, I, the said John Piddington, have hereunto set my
hand and seal, this Fourth day of April, in the year of our Lord
One thousand eight hundred and sixty-eight.
Witness,
R. S. MORDAUNT VAUGHAN,
54, Chancery Lane, W.C.
JOHN PIDDINGTON. (L.s.)