IMPROVEMENTS IN METALLIC PACKINGS FOR PISTON AND OTHER RODS
Year: 1880

page_text: LETTERS PATENT to James Willard Preston, of Boston, in the County of
Suffolk, State of Massachusetts, U. S. of America, for the Invention of
"IMPROVEMENTS IN METALLIC PACKINGS FOR PISTON AND OTHER RODS." A
communication by Thomas Tripp, of East Stoughton, in the County of Norfolk,
State of Massachusetts, U.S. A.
Sealed the 5th March 1880, and dated the 10th January 1880.
COMPLETE SPECIFICATION filed by the said James Willard Preston at the
Office of the Commissioners of Patents on the 10th January 1880.
JAMES WILLARD PRESTON, of Boston, in the County of Suffolk, State of Massa-
chusetts, U. S. of America. "IMPROVEMENTS IN METALLIC PACKINGS FOR PISTON
AND OTHER RODS." A communication by Thomas Tripp, of East Stoughton, in the
County of Norfolk, State of Massachusetts, U.S. A.
These improvements relate to a class of sectional metallic packings for piston or
valve rods of steam engines, etc., shewn and described in Royal Letters Patent issued
to myself on the 5th day of April, A.D. 1879, and numbered 1370, the distinguish-
ing features of which consist in the employment 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 which are controlled and adjusted from the outside of the
cylinder head, an important element in this class of packings 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 said patented device the sectional or semi-rings are crowded up to the rod
from opposite sides by bolts screwing into the outer end of each ring and swivelled
to a suitable part or projection of the opposite sides by bolts screwing into the outer
end of each ring and swivelled to a suitable part or projection of the opposite ring,
while to prevent separation of the rings I employ two lugs projecting laterally
inward from the inner face of the annular disc which encompasses the rod outside of
the rings, and an adjusting screw or its equivalent being employed with each lug,
and bearing against the outer edge of each ring to compel a close bearing between the
D077

page_text: sides of the periphery of the ring and the rod, and to vary the degree of friction
between them, should it be found necessary or desirable.
The Drawings accompanying this Specification represent in Figure 1 end view
outer plate removed; Figure 2, a section through rings shewing joint; Figure 3,
section of packing, and Figure 4 section of packing also. My present devico is
constructed as follows:-A represents the sectional rings as embracing opposite
sides of the piston rod, which is shewn 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 in which such
cylinder head usually terminates. I term the sectional packing platos semi-rings,
for the reason that the corresponding portions of metallic rod packings in general
are styled sectional rings, and because their united bores constitute a cylindrical
bearing which embraces the rod. Between the disc C and head D, and securely
confined therein by the bolts a, a, I place a cylinder A*, which with the disc and
head constitutes a box or case to enclose the various parts of the packing, and
protects them from dust or dirt, and to receive such small amount of condensed
water as may find its way to this point, but more especially to prevent the bolts
when screwed up tight from unduly binding the packing rings between the said
disc and head. Upon the outside of the rings A, A, and between them and the disc
C, I encompass the rod with a flat metallic ring B' which contains in a rebate C
formed in it an elastic or soft packing ring D, which tightly encircles the rod and
prevents escape of such minute portions of steam as may pass the packing rings.
In practice the ring D' will probably not be needed, but I add it as an extra
precaution.
The packing rings A, A, are flat upon their end faces, and between them and the
head D I interpose a washer or annulus E, which closely encircles the rod and is let
into a rebate a¹ of larger diameter created in the head in order that the annulus,
and with it the rings A, A, may be permitted lateral slip to accommodate any
irregular or eccentric movements of the piston rod, and thereby relieve the packing
from thrusts and strains which would otherwise devolve upon it in case of bending
or other injury to the rod. The annulus serves to maintain a steam tight joint
between the head or exterior of the cylinder and the rings, and yet permit of the
lateral play last named. In the present instance the rings A, A, are each formed in
two parts or halves c³, c³, and 6, 62, the ring 62, 63, being enclosed between and
sliding within the arms of the ring c², c³, the two rings being crowded up to the rod
B, and so as to hug it closely by springs ff, which are disposed upon opposite sides
of the ring c³, c, and encircles the ends of the bolts g, g, which latter pass loosely
through the said ring c², c², and screws into the ring b², 6, the springs exerting their
stress between the said ring c², c³, and the heads of the bolts, thereby drawing the
two rings together upon opposite sides of the rod B.
The outer ends of the halves b2, 62, or c³, c³, of each ring are confined together by
a bolt d or e which passes at its head end loosely through one of the rings and
screws into the other, in order that a slight rocking motion may be permitted
between the said two halves 62, 63, or c³, c², of the rings to enable their common bore
to be contracted if occasion requires.
To effectually seal the joint between the two parts of each ring and the rod B, I
employ an intermediate block h of soft or hard metal or other material let into the
bore of the ring, and I secure this block tightly to one half of the ring, as shewn at
i, i, i, and so that it shall be a permanent part of the latter and move with it toward
or away from the other half in the event of separation or contraction of the arms or
sides of the ring, but in order that a tight joint may be secured between the two
halves of the ring, and yet permit of these movements, I form the meeting faces of
the intermediate block and the opposito half of the ring with one or more indenta-
tions and spurs ; or k, in order to provide lateral bearings or joints 1, l, see Figure 2
of the Drawings, which shall be steam tight under all circumstances.
Furthermore, the outer edge m of each block h which is in contact with the

page_text: opposite half of the ring should be a close joint with that part n of the latter
with which it is in contact, see Figure 1, and this joint should be as nearly as
possible such an arc of a circle as shall permit of separation or contraction of the
halves of the ring, or rocking movements of the ends thereof, without separation of
the parts m and n before described.
The block h may be dispensed with and the spurs and indentations ; and k formed
directly upon the halves of the ring, but I prefer to employ a soft metal block in
this locality.
In lieu of making the packing rings in balves jointed together, with provisions
for loose rocking motion or contraction and expansion, such rings may be in one
entire piece, and the necessary expansion or contraction obtained by the inherent
elasticity or spring of the metal.
In order that the two sides of the outermost or larger ring c³, c³, may closely hug
the rod B as well as the sides of the ring 63, 6%, under all circumstances, I employ
with each side of said ring c³, c³, a spring o which exerts its stress between the
outside of the ring and the inner periphery of the cylinder or case Aª
By my construction as above described the bore of any given packing may be
reduced in diameter if desired; to accomplish this it is only necessary to file down
the meeting faces of the halves of the ring, which will contract the bore, and the
bore may then be rebored to a true circle, or if the bore of any packing should
become scratched or otherwise injured it may be rebored by pursuing the same