IMPROVEMENTS IN PISTONS
Year: 1858

page_text: LETTERS PATENT to John Sinclair, of the City of Dublin, Ireland, Turner
and Fitter, for the Invention of "IMPROVEMENTS IN PISTONS."
Sealed the 21st June 1859, and dated the 28th December 1858.
PROVISIONAL SPECIFICATION left by the said John Sinclair at the
Office of the Commissioners of Patents, with his Petition, on the
28th December 1858..
I, JOHN SINCLAIR, of the City of Dublin, Ireland, Turner and Fitter, do
hereby declare the nature of the said Invention of "IMPROVEMENTS IN
PISTONS," to be as follows, that is to say:-
This Invention relates to improvements in metallic pistons, such as are used
in steam engines, and aims at increased economy in their construction and
repair, and increased efficiency in their use. The Invention comprehends
improvements in various parts of the piston, and modifications thereof intended
for different sizes, or from which the constructor may in each case select
whichever he considers best.
A piston of the class to which the improvements are more particularly
applicable consists of a body piece fixed on the rod, and having a central boss,
an abutting ring or flange lying behind or within the packing ring, and a pro-
jecting retaining flange. The packing ring lies between this retaining flange
and a junk ring or plate bolted or otherwise secured to the body of the
piston.

page_text: In constructing a piston embodying the improvements constituting this
Invention, the piston rod, which is fitted to the boss with a taper, as is com-
monly practised, is fixed according to one modification by means of a nut
screwed upon it, being prevented from turning in the piston by means of a
key fitting into a key seat in the latter.
According to another modification the tapered part of the rod is very
accurately fitted into the piston boss, and is fixed by a nut as before, but a
shoulder or collar is formed on it to prevent its becoming jammed too firmly
in the boss. This sholder or collar may enter a recess in the bottom of the
piston so as to be countersunk. In fixing the rod by means of a nut screwed
upon it, it is preferred to place a brass washer between the nut and the junk
ring, and to make the nut of brass to facilitate its removal when repairs are
needed. After the nut is screwed up a pin is passed through it and the rod
to prevent it from loosening.
According to another modification the rod is fixed in the boss by means of
two keys. The key slot in the boss is not as long as that in the rod, and one
key is formed with a projection which is pushed down into the recess formed
by the extra portion of the slot in the rod, and which thus prevents this key
from getting loose, whilst the second key keeps the first one down, and is itself
kept in its place by the junk ring. In making a piston of large size the junk
ring is composed of two concentric rings, the outer one only requiring removal
for adjusting the packing details; the inner ring may either be fixed sepa-
rately, or the outer ring may be shaped so as when fixed itself to retain the
former, when the junk ring is fixed by screw bolts; these are prevented from
becoming loose by caps held upon their heads by blade springs contrived so as
to be easily removed when the bolts have to be unscrewed; if the bolt screws
are "right handed," the caps are formed with "left-handed" screws tapped
into their holders, or vice versa. Thus, whilst the caps can be adjusted to any
position of the bolt head, the counter arrangement of the screw threads will
prevent loosening. In the case of a small piston, the packing ring may be in-
a single main piece, a small space between the ends of this piece being occupied
by a small filling up piece, whilst the edges of each are step-shaped to prevent
the passage of steam when they are slightly separated. The small filling-up
piece is pressed outwards by a spring, which may consist of a couple of reversed
blades, whilst a long blade spring has its extremities bearing against the main.
piece, one beyond cach side of the filling up piece. It is, however, preferred
to make the packing ring in two main pieces with one filling-up piece; and in
the case of moderately sized and large pistons, it is preferred to make the packing.
ing of several pieces or segments alternated with filling-up pieces, the ends of

page_text: all being shaped step-ways to prevent the passage of steam across the joints.
It is preferred to shape these joint ends by sawing, the pieces or segments
being cut by the saw from rings turned and shaped entire.
With these arrangements repairs can be made with great facility; thus when
a ring has been so far expanded that a joint becomes open quite across, a
filling-up piece of an increased size can be substituted for the original one, and
steamers can carry with them extra rings, so that in case of emergency repairs
can be made without delay.
In constructing pistons for horizontal cylinders, provision is made to press.
out the packing ring on the lower side with extra force to compensate for the
weight of the piston; and it is preferred to make the springs by which this is
effected bear on two points, one on each side of the lowest point of the packing
ring, the springs being also prevented from moving round although the ring is
free to do so.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Sinclair in the Great Seal Patent Office on the
28th June 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JonN
SINCLAIR, of the City of Dublin, Ireland, Turner and Fitter, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-eighth day of December, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-second year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said John Sinclair, Her special licence that I, the said John Sinclair, my
executors, administrators, and assigns, or such others as I, the said John
Sinclair, my executors, administrators, or assigns, should at any time agrec
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 PISTONS," upon the
condition (amongst others) that I, the said John Sinclair, my executors or
administrators, by an instrument 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.

page_text: "
NOW KNOW YE, that I, the said John Sinclair, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, reference being had to the accompanying Drawings,
and to the letters and figures marked thereon, that is to say:-
My said Invention relates to improvements in metallic pistons, such as are
used in steam engines, and aims at increased economy in their construction
and repair, and increased efficiency in their use.
The Invention comprehends
improvements in various parts of the piston and modifications thereof intended
for different sizes, or from which the constructor may in each case select
whichever he considers best.
A piston of the class to which the improvements are more particularly
applicable consists of a body piece fixed on the rod, and having a central boss,
an abutting ring or flange lying behind or within the packing ring, and a
projecting retaining flange. The packing ring lies between this retaining
flange and a junk ring or plate bolted or otherwise secured to the body of
the piston.
In constructing a piston embodying the improvements constituting this
Invention, the piston rod which is fitted to the boss with a taper, as is
commonly practised, is fixed according to one modification by means of a nut
screwed upon it, being prevented from turning in the piston by means of a key
fitting into a key seat in the latter.
According to another modification the tapered part of the rod is very
accurately fitted into the piston boss, and is fixed by a nut as before, but a
shoulder or collar is formed on it, to prevent it becoming jammed too firmly
in the boss. This shoulder or collar may enter a recess in the bottom of the
piston so as to be countersunk. In fixing the rod by means of a nut screwed
upon it, it is preferred to place a brass washer between the nut and the junk
ring, and to make the nut of brass, to facilitate its removal when repairs are
needed. After the nut is screwed up a pin is passed through it and the rod
to prevent it from loosening.
According to another modification the rod is fixed in the boss by means of
two keys. The key slot in the boss is not as long as that in the rod, and one
key is formed with a projection, which is pushed down into the recess formed
by the extra portion of the slot in the rod, and which thus prevents the key
from getting loose, whilst the second key keeps the first one down, and is itself
kept in its place by the junk ring. In making a piston of large size the junk
ring is composed of two concentric rings, the outer one only requiring removal
for adjusting the packing details. The inner ring may either be fixed

page_text: "
separately, or the outer ring may be shaped so as when fixed itself to retain
the former. When the junk ring is fixed by screw bolts, these are prevented
from becoming loose by caps held upon their heads by blade springs contrived
so as to be easily removed when the bolts have to be unscrewed. If the bolt
screws are "right-handed," the caps are by preference formed with "left-
handed screws tapped into their holders, or vice versa. Thus, whilst the caps
can-be adjusted to any position of the bolt head, they will prevent loosening.
In the case of a small piston the packing ring may be in a single main piece,
a small space between the ends of this piece being occupied by a small
filling-up piece, whilst the edges of each are step shaped to prevent the passage
of steam when they are slightly separated. The small filling-up piece is pressed
outwards by a spring, which may consist of a couple of reversed blades, whilst
a long blade spring has its extremities bearing against the main piece, one
beyond each side of the filling-up piece. It is, however, preferred to make the
packing ring in two main pieces, with one filling-up piece. And in the case
of moderately sized and large pistons, it is preferred to make the packing ring
of several pieces or segments, alternated with filling-up pieces, the ends of all
being shaped step-ways to prevent the passage of steam across the joints. It
is proposed to shape these joint ends by sawing, the pieces or segments being
cut by the saw from rings turned and shaped entire. With these arrange-
ments repairs can be made with great facility. Thus, when a ring has been so
far expanded that a joint becomes open quite across, a filling-up piece of an
increased size can be substituted for the original one, and steamers can carry
with them extra rings, so that in case of emergency repairs can be made
without delay.
In constructing pistons for horizontal cylinders, provision is made to press
out the packing ring on the lower side with extra force to compensate for the
weight of the piston, and it is preferred to make the springs by which this is"
effected bear on two points, one on each side of the lowest point of the packing
ring, the springs being also prevented from moving round, although the ring is
free to do so.
And in order that my said Invention may be properly understood and
carried into effect, I have delineated upon a Sheet of explanatory Drawings
hereunto appended, and shall now proceed to describe, four examples of pistons
embodying various modifications of my improvements, premising that the
same reference letters mark the same or like parts in all the Figures.
Figure 1 is a face view of a piston, the junk ring or plate being removed;
and Figure 2 is a corresponding longitudinal section, these Figures showing
the first or smallest size of piston; Figure 3 is an edge elevation, Figure 4 is

page_text: a longitudinal section, and Figure 5 is a face view, the junk ring or plate
being removed, of a second size of piston; whilst Figures 6, 7, and 8 are
similar views of a third size of piston; and Figures 9, 10, and 11, of a fourth
size of piston; Figure 12 is a fragmentary plan, showing my bolt-holding cap
shown in elevation, Figures 9 and 10.
In all the Figures the rod is marked A, the body of the piston, B the
abutting ring C, the projecting part of the body forming the retaining
flange D, the junk ring or plate E, and the packing ring or its main
segments F..
In the first or smallest size of piston, Figures 1 and 2, the body B is solid,
and the packing ring F consists of a single main piece cut through at one
point, the ends being step-shaped (as best seen in Figures 6 and 9), and
having a filling-up piece G inserted between them. This portion is shown as
for working horizontally. Springs H are placed between the packing ring
and the abutting ring C, to press outwards the filling-up piece G, and the
contiguous ends of the ring F itself. Springs I, of extra strength, are applied
at the lower part of the packing ring, a little on each side of the lowest point,
to bear up the weight of the piston, these springs I being fixed in position
against the abutting ring C.
In the second size of piston, Figures 3, 4, and 5, the rod A is formed with
a tapered end fitting in a socket in the boss J of the piston body B. To
prevent the piston from turning on the rod a key K is inserted, as shown, and
the piston is held in its place on the rod by means of a nut L screwed upon
the rod. This nut L is made of brass, and a brass washer is placed under it
(or only the washer may be of brass), for the purpose herein-before explained.
In this example the nut L is made with a flange, and serves to hold down the
junk ring or plate E. The packing ring consists of two main segments F,
with step-shaped ends, and having a filling-up piece at G. The filling-up
piece and the contiguous ends of the segments F are pressed outwards by
springs H, and an additional spring h presses out the segments F at other
parts.
In the third size of piston, Figures 6, 7, and 8, the piston is fixed on the
rod in the same way as in the second size, but a collar a is formed on the
rod A, to prevent the tapered part getting jammed too firmly in the piston
boss J. In this example the packing ring consists of four main segments F,
filling-up pieces G being inserted at each joint.
In the fourth size of piston, Figures 9, 10, 11, and 12, the piston body B is
fixed on the rod A by means of two keys, one, M, of which is formed with a
step, which prevents it working loose, whilst the other, N, is inserted above

page_text: the first, M, to keep it in its place, the second, N, being prevented from
working loose by the inner edge of the junk ring or plate E. The junk ring
or plate is in two concentric pieces E, E', these being shaped so that the outer
one E' holds down the inner one E. If preferred the inner ring E may be
held down by screw bolts or otherwise, independently of the outer ring E'. In
this example the packing ring consists of six main segments F, filling-up
pieces G being inserted at each joint, whilst springs H are arranged to press
out both filling-up pieces and segments. In Figures 9, 10, and 12, are shown
my improved caps for preventing the loosening of the screw bolts P, which
hold down the junk ring E', two of these caps being shown in section in
Figure 10. The cap Q is made to fit upon the head of the screw bolt P, and is
screwed into the end of a spring holder R attached to the junk ring, as shown.
When the cap Q is adjusted to the position of the bolt head, it is firmly fixed
means of a small jam nut S. The screw bolts are easily got at by lifting
the caps off them, bending the spring holders for that purpose. If the bolts
are afterwards screwed back to their former positions the caps are replaced
upon them, without requiring further adjustment. If preferred, the bolts
and holding caps may be more or less recessed or sunk into the piston.
It will be obvious that the various piston details herein-before described are
susceptible of considerable modification within the scope of the Invention.
Where the packing ring consists of several segments, the filling-up pieces may
be inserted at only some of the joints, if preferred, and various kinds of springs
may be used for pressing out the segments and filling-up pieces. When the
packing ring is worn and the parts are pressed out so much as to become
considerably separated, larger filling-up pieces may be substituted for the
original ones, as indicated by dotted lines in Figure 9. Thin plates are
applied behind the joints of the packing rings, as shown, to prevent the passage
of the steam from one side of the piston through one part of a
joint to the
inside of the ring, and thence through the other part of the joint to the
other side of the piston. The piston rod may proceed either from the junk
ring side or from the other side of the piston, and either the narrow or the
broad part of the taper may be towards the end of the rod. The Figures are
all drawn to one scale, and show the proportions and sizes of details which I
consider to be best for the different sizes of pistons.
Having thus particularly described my said Invention, and the manner in
which the same is or may be used or carried into effect, I have to state
that I do not restrict myself to the precise details herein-before described
or delineated, and that I do not claim to have invented every separate detail
herein-before described and delineated; but that what I consider to be novel

page_text: and original, and claim as the Invention secured to me by the herein-before
in part recited Letters Patent, is,
First, the combining of the parts of pistons, substantially in the manners
herein-before described.
Second, the using of a brass washer between the nut, which fixes the piston
on the rod and the surface against which the nut bears, that is to say, the
using of a washer of a metal different from that of the surface against which
the nut bears.
Third, the fixing of the piston on its rod by means of keys, substantially of
the kind herein-before described and shown in Figures 10 and 11 of the
accompanying Drawings.
Fourth, the making of the junk ring in two pieces, substantially as herein-
before described.
Fifth, the preventing of the loosening of the screw bolts, by means of
a holding cap constructed and contrived substantially as herein-before
described.
Sixth, the using of packing rings composed of separate main segments and
filling-up pieces with step-shaped ends, the filling-up pieces occupying the
entire width of the ring, and the whole being pressed outwards by springs, but
not in themselves bending or yielding elastically, all substantially as herein-
before described.
In witness whereof, I, the said John Sinclair, have hereunto set my
hand and seal, this Twenty-second day of June, in the year of our Lord
One thousand eight hundred and fifty-nine.
JOHN SINCLAIR. (L.S.)