IMPROVEMENTS IN METALLIC PACKINGS FOR PISTON RODS
Year: 1879

page_text: LETTERS PATENT to James Willard Preston, of Boston, in the County of Suffolk,
and State of Massachusetts, United States of America, for the Invention of
"IMPROVEMENTS IN METALLIC PACKINGS FOR PISTON RODS." A communi-
cation from Thomas Tripp, of East Stoughton, in the County of Norfolk, State
of Massachusetts. United States of America.
COMPLETE SPECIFICATION filed by the said James Willard Preston at the
Office of the Commissioners of Patents on the 5th April 1879.
JAMES WILLARD PRESTON, of Boston, in the County of Suffolk, and State of
Massachusetts, United States of America. "IMPROVEMENTS IN METALLIC PACKINGS
FOR PISTON RODS." A communication from Thomas Tripp, of East Stoughton,
in the County of Norfolk, State of Massachusetts, United States of America.
My present improvements relate to a class of sectional metallic packings for
piston rods, heretofore invented and patented by myself, the distinguishing feature
of which consists in the employment of a sectional ring enveloping the rod, such
ring being composed of twin semi-rings capable of sliding upon one another in a
plane at right angles to the axis of the rod, and being maintained in a uniform
plane by suitable guides, and crowded up to the rod from opposite sides by
means of which are controlled and adjusted from the outside of the cylinder
head; an important element in this class of packing being seen in the fact that
it is susceptible of lateral slip upon the cylinder head by and with any eccentric
movements of the rod should the latter become bent or out of true from any
cause. In my patented packing above referred to the rings are crowded up to
and enclose the rod from opposite sides by inclined planes or sloping cams
secured to an annular disc or collar sliding upon the rod, while the rings them-
selves are prevented from separation by pins and grooves properly arranged.
In my present packing I retain the twin rings and the annular disc, as shown in
my Patent above referred to, but discard the inclined planes or cams and substitute
for the latter two or more bolts screwing into the outer end of each ring and
swiveled to an ear projecting from the adjacent part of each opposite ring, while in
lieu of the pins and grooves employed in my Patent I make use simply of two lugs
projecting laterally inward from the inner face of the annular disc before named,
which encompasses the rod outside of the rings, an adjusting screw or its equivalent
being employed with each lug and bearing against the outer edge of each ring to

page_text: compel a close bearing between the sides of the peripheries of the ring and the rod
and to vary the degree of friction between them should it be found desirable. Or
in place of the lugs upon the disc an ear may be employed upon each ring over-
lapping the outside of the opposite ring and carrying a set screw to screw down
upon the latter. The Drawings which accompany this Specification and illustrate
my Invention represent in Figure 1 a longitudinal section and in Figure 2 a cross
section of a packing containing my improvements, while Figure 3 is a face view of
one of the section packing rings, and Figure 4 is a view of the modified con-
struction of the ring. In the above named Drawings it will be seen that the pair
of twin semi-rings are shown at A, A, as embracing opposite sides of the piston rod
which is shown at B, while C represents an annular disc loosely encompassing such
rod and confined or connected to an annular head D which also encompasses the rod
by two or more bolts a, a, while the_last_ named head D is rigidly bolted to the
cylinder head or to the outstanding flange b, in which such cylinder head usually
terminates. I term the sectional plates semi-rings for the reason that the corre-
sponding portions of metallic rod packings in general are-styled sectional rings and
because their united bores constitute a cylindrical bearing which embraces the rod.
In the present instance these rings A, A, are flat and practically triangular blocks
of metal of like size and shape, each having a semi-circular recess or depression c
in one corner and with straight parallel edges or faces d, d, which meet and slide
upon one another and provide a common circular opening to receive the piston rod,
such rings being enclosed between the disc C and head D and by them maintained
in a uniform common plane and prevented from separation endwise of the rod. The
rings A, A, are prevented from lateral spreading or separation with respect to each
other by lugs, f, extending inward from the disc C, and I prefer to employ ad-
justing screws g, g, or their equivalents with these lugs to vary the friction between
the sides of the rings and the rod and to compensate for wear should any occur at
this point. To crowd the rings A, A, end wise, as it may be termed, against opposite
sides of the rod, that is to say, in a direction at right angles to the direction of the
pressure exerted by the screws g, g, I employ with each a bolt h, which is swiveled
in any suitable manner to an ear i projecting laterally from the outer end of each
ring and screws into the adjacent part of the opposite ring, these bolts being disposed
upon diametrically opposite sides of the rod B, in order the better to exert a uniform
pressure or friction upon the circumference of the latter. In place of the lugs f,f,
a modification of this portion of my Invention would be to form upon each ear i a
lip or lug which shall be parallel with and overlap the outer edge m of the adja-
cent part of the opposite ring, while a screw n passes through each of these lips
and abuts against the said edge m, as seen in Figure 4 of the Drawings. By
screwing inward the screws n, n, the rings are crowded from opposite sides tightly
up to the rod. I here desire to call especial attention to the fact that the rings
A, A, are, by means of the disc C and head D maintained at all times in the same
plane with respect to each other longitudinally of the rod, or in other words are
always opposite each other. This is important for the reason that if these respective
positions should be changed an unequal strain and wear would eventuate upon the
rod. The bolts a, a, which confine the disc C to the head D are swiveled at their
outer ends or heads loosely in the head in order to be susceptible of certain freedom
of lateral motion or play to permit of a slight lateral movement or slip of the rings
upon the cylinder head in order that they and the disc may follow any eccentric or
abnormal movements of the rod, should the latter from any cause become bent or
"out of true" with the bore of the cylinder, and to maintain the rings always in a
position at right angles to the axis of the rod. This is a peculiar and valuable
feature of my packing and provides a complete relief from the unequal wear and
other injurious effects of the thrusts and strains to which metallic packings are
subjected. The bolts a, a, further serve to confine the rings to the cylinder head
with sufficient pressure to prevent escape of steam between the two. My present
packing is simpler, less expensive, and easier to adjust than that shown in my

page_text: Patent before cited; I dispense with springs now usually employed in packings of
his character and I obviate loosening or starting of the joints of the packing from the
rregular movements of the rod as the entire packing device follows the movements
of the rod and slides laterally upon the cylinder head without starting the joint
between them. The device is entirely outside of the cylinder and hence always
accessible.
rregular movements of the rod as the entire packing device follows the movements
of the rod and slides laterally upon the cylinder head without starting the joint
between them. The device is entirely outside of the cylinder and hence always
accessible.
CLAIMS.
First. The semi-rings having straight parallel sides and semi-circular recesses
which unitedly constitute a cylindrical box to encompass the rod, such rings being
constructed and adapted to move upon one another and close upon the rod (in com-
pensating for wear) always in the same plane longitudinally of such rod.
Second. The semi twin-rings closing upon opposite sides of the rod and crowded
up thereto by bolts or their equivalents, each bolt being swiveled to or passing
loosely through one ring and screwing or otherwise connected to the opposite ring,
and arranged upon diametrically opposite sides of such rod.
Third. The combination of the twin semi-rings, annular disc, and lugs, with or
without the adjusting screws of the latter.
Fourth. In combination with the rings A, A, disc C, and head D the bolts
a, a, as swiveled loosely in the said head to permit of lateral slip of the
rings and disc upon it by and with any eccentric or irregular movements of the
rod.
Fifth. The rings A, A, as encompassing the piston rod and enclosed between the
parts C and D, or the equivalents of the latter.
Sixth. The lips, l, and screws n, n, in combination with the rings A, A, rod B, and
bolts h, h.
In witness whereof, I, the said James Willard Preston, have hereunto set my
hand and scal, this Twenty second day of March 1879.
JAMES WILLARD PRESTON. (L.S.)