IMPROVEMENTS IN PISTON RINGS
Year: 1883

page_text: LETTERS PATENT to James Kerfoot of Rotherhithe in the County of
Surrey Marine Engineer, for an Invention of IMPROVEMENTS IN PISTON
PROVISIONAL SPECIFICATION left by the said 'James Kerfoot at the
Office of the Commissioners of Patents on the 11th October 1883.
JAMES KERFOOT, of Rotherhithe, in the County of Surrey, Marine Engineer,
"IMPROVEMENTS IN PISTON RINGS."
"J
My invention relates to the spring ring packing of steam or other pistons, and
it is designed to effect a regular and uniform spreading of the rings against the
interior surface of the cylinder, so as to make a good uniform steam or gas tight
joint, with a minimum amount of friction.
My invention consists in the combination of certain alternative forms of
segmental packing rings with spiral springs inserted between the butts thereof,
and in an automatic adjustment, through the piston junk ring or cover, being
provided if required.
My segmental rings may be divided preferably by three equidistant butt joints
in the circumference, overlapping tongues being fitted at the junctions to maintain
the steam joint.
The segmental packing ring may consist of one solid ring with recesses at the
inner side of the joints, to form shoulders against which the spiral spring between
the segments may re-act, end ways to the segments, thus uniformly pressing out
the rings against the inner surface of the cylinder. Alternatively my outer
packing rings may be two wedge shaped triangular complete rings, cut only in one
place covered with a tongue joint. Inside these wedge rings I place an inner V
segmental ring with the aforesaid spiral springs placed between each of the joints,
re-acting upon shoulders as before, so as to force the V ring uniformly outwards,
spreading the wedge rings both outwards, upwards, and downwards, against the
edges of the groove. Where three or more spiral springs are used between the
joints of the segments, I may insert a frame surrounding one of the spiral springs,

page_text: consisting of two caps (one at each end of the spiral spring) acting as nuts on two
right and left handed screws. Upon each of these screws is a worm wheel, so that
they can be rotated by an endless screw, fixed in the piston body, the head of
which projects through the junk ring, so that it can be rotated by a suitable
spanner when the back cylinder cover is removed.
This arrangement I consider especially valuable for long voyages, in which the the
elasticity of the spiral springs is likely to fail somewhat, in which case the screw
frame can be extended, and the segmental rings thus pressed home upon the other
spiral springs.
The shoulders against which the spiral springs re-act are preferably provided
with projections or studs, entering into the hollow centre of the spiral springs to
keep them in place.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Kerfoot in the Patent Office on the 10th April 1884.
JAMES KERFOOT, of Rotherhithe, in the County of Surrey, Marine Engineer,
"IMPROVEMENTS IN PISTON RINGS
"
My invention relates to the spring ring packing of steam or other pistons, and
it is designed to effect a regular and uniform spreading of the rings against the
interior surface of the cylinder, so as to make a good uniform steam or gas tight
joint, with a minimum amount of friction.
My invention consists in the combination of certain alternative forms of
segmental packing rings, with spiral springs inserted between the butts thereof,
and in an automatic adjustment, through the piston junk ring or cover being
provided if required.
My segmental rings may be divided preferably by three equidistant butt joints
in the circumference, overlapping tongues being fitted at the junctions to maintain
the steam joint.
The segmental packing ring may consist of one solid ring with recesses at the
inner side of the joints, to form shoulders against which the spiral spring between
the segments may re-act, endways to the segments, thus uniformly pressing out the
rings against the inner surface of the cylinder. Alternatively, my outer packing
rings may be two wedge shaped triangular complete rings, cut only in one place,
covered with a tongue joint. Inside these wedge rings I place an inner V
segmental ring with the aforesaid spiral springs placed between each of the joints,
re-acting upon shoulders as before, so as to force the V ring uniformly outwards,
spreading the wedge rings both outwards, upwards, and downwards, against the
edges of the groove. Where three or more spiral springs are used between the
joints of the segments, I may insert a frame surrounding one of the spiral springs,
consisting of two caps (one at each end of the spiral spring) acting as nuts on two
right and left handed screws. Upon each of these screws is a worm wheel, so that
they can be rotated by an endless screw, fixed in the piston body, the head of
which projects through the junk ring, so that it can be rotated by a suitable
spanner when the back cylinder cover is removed.
This arrangement I consider especially valuable for long voyages, in which the
elasticity of the spiral springs is likely to fail somewhat, in which case the screw
frame can be extended, and the segmental rings thus pressed home upon the other
spiral springs.
The shoulders against which the spiral springs re-act are preferably provided
with projections or studs, entering into the hollow centre of the spiral springs to
keep them in place.
In order that my invention may be the better understood, I now proceed to
describe the same with reference to the drawings hereto annexed and to the letters
and figures marked thereon. .
Figure 1 shows in plan and section my improved segmental packing ring where
a solid single ring is used. A AA are the segments preferably three in number
and of equal length. The butt joints are closed by lapping tongues B B to
maintain the steam joint. Recesses are made at the inner side of the joints to
permit of the introduction of the springs G G, which uniformly press out the
segments against the inner surface of the cylinder. Studs D D are provided or
fixed into the shoulders of the recesses, which, entering into the ends of the spiral
springs, keep them in place.
Figure 2 shows in plan and sectional elevation my alternative arrangement, in
which the outer packing rings E E are two wedge shaped triangular complete

page_text: rings, cut only in one place e, which is covered by a tongue joint. Inside these
wedge rings is an inner segmental V ring F, spiral springs G G as before described,
being placed between the different segments, spreading the wedge rings both
outwards, upwards, and downwards, against the cylinder and both edges of the
groove.
Figure 3 and 4 shows a detail in plan and sectional elevation of an adjustable
frame H surrounding the spiral spring K, which I place between two of the
segments when three or more segments are used.
The caps L L at each end of the spring K. have tapped holes fitting the right
and left handed screws H H. Upon these screws are fixed worm wheels N N into
which engages the screw P, the head of which projects through the junk ring.
On removal of the back cylinder cover, the screws can be rotated by a suitable
spanner, and the caps L L thus moved apart, pressing home the other segments
upon the spiral springs, when the latter have somewhat lost their elasticity through
wear.
2
Having now described and ascertained the nature of my invention and the
manner of carrying the same into effect, be it known that what I consider novel
and desire to protect & claim by Letters Patent is :-
First. The construction of a segmental solid packing piston ring, with spiral
or other elastic springs between the ends of the said segments, substantially as and
for the purposes described.
Second. In a piston the combination of two exterior wedge rings and an interior
segmental V ring, fitted with spiral or other elastic springs, between the ends of
the said segments, substantially as and for the purposes described.
Third. In a segmental piston ring packing, the combination of either of the
before claimed rings and springs with an adjusting piece, consisting of right and
left hand screws, tapped into end caps, adjustable by screw and worm wheels
through the junk ring, substantially as described with reference to figures 3 and 4.
In witness whereof I, the said James Kerfoot, have hereunto set my hand and
seal this thirteenth day of February in the year of our Lord one thousand
eight hundred and eighty four.
TAMEN
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