IMPROVEMENTS IN PACKINGS FOR PISTONS, PISTON RODS, AND ANALOGOUS MOVING PARTS
Year: 1884

page_text: I, MATHIAS VITAL SCHILTZ, Doctor of Medicine, of Cologne, Germany, do
hereby declare the nature of my Invention for IMPROVEMENTS IN PACKINGS FOR
PISTONS, PISTON RODS, AND ANALOGOUS MOVING PARTS, and in what manner
the same is to be performed, to be particularly described and ascertained in
and by the following statement:-
This Invention relates to that kind of packings, in which the pressure of the
fluid is utilized for producing an intimate contact between the movable part and
the pack ng material. Such packings are frequently found in ordinary pumps and
fire engines and are usually constructed so as to admit liquid under pressure behind
a packing ring or band of leather and to press the same tightly against the walls
of the cylinder.
My Invention has for its object to adapt the same principle of construction to
metallic packings.
In order to obtain the necessary elasticity or capacity of expansion and
compression, I provide the metallic packing ring or cup with several slits parallel
with the axis of the piston, so as to form a number of parallel flaps, each of which
has sufficient elasticity or flexibility to yield to the pressure of the liquid, as much
as is required to form a tight fit.
In further describing this Invention reference will be made to the accompanying
Drawings, of which Fig. 1 is an axial section of a piston K and stuffing box B
embodying my Invention, Fig. 2 a cross section through the piston packing, and
Fig. 3 a cross section through the stuffing box (along line w z of Fig. 1). Fig. 4
is a side view of the piston, and the remaining Figures illustrate modifications.
The piston packing may be made one sided, or symmetrical, as shown in Fig. 1.
Each packing consists substantially of an outer ring, or sheet m and one or more
inner rings n and o divided and placed in such a manner, that the slits of any
ring are covered by the flaps of the contiguous ring or rings, as shown in Fig. 2..
If a fluid under pressure is admitted to the piston, all the flaps will be pressed
outward against the inner surface of the cylinder and the slits between the flaps
will be widened, without causing leakage owing to the grease which fills out the
openings.
The outer ring m, which is exposed to wear on the cylinder wall, may be formed
or finished on the lathe from steel, or soft metal (such as German silver). Instead
of making the ring of one piece, as indicated by the left half of Fig. 4, it

page_text: may be composed of several pieces attached by screws or other suitable means,
as indicated by the right,half of Fig. 4. The inner rings n and c, which are not
subject to great wear, may be made of thin sheets of any desired metal. The
average width of each open slit is equal to the inner circumference of the cylinder C,
less the outer circumference of the ring before expansion divided by the number
of flaps in a ring.
The gap formed by the joints may be still more diminished by making the slits
not-radial, as in the left half of Fig. 2, but oblique as shown in the right half of
.the same Figure, so as to form tangents to a given circle.
The expansion of the split joints may also be rendered harmless, by fitting all
the outside flaps with tongues F, Figure 7, in the same manner as applied to
common piston rings, or by fitting small rectangular keys R, Fig. 7, into suitable
transverse grooves or recesses at the joints of the flaps; or these joints may be
toothed, as illustrated by Fig. 8.
Fig. 5 and 6 show how axially split rings of my system may be combined with
the usual outside packing of pistons, consisting of ordinary piston packing rings a
or asbestos.
Projections b are secured to the outer surface of the flaps to prevent the packing
from being stripped off.
The application of metallic rings, split into a sufficient number of flaps or
segments, for obtaining a (variable) pressure in stuffing boxes, represented at B
in Figure 1. A double packing ring, that is to say, an inner and and outer ring
is in this case not necessary, as the pressure of the fluid acts radially upon the
outer surface of the flaps m and n, so as to contract the openings or slits, and the
gaps are covered from inside by the usual packing a coiled round the piston rod k.
The ring is split into flaps m and n, as shown in cross section Fig. 3 and
provided with inside lugs or projections b which form a ring and nearly touch the
piston rod. They serve to hold between themselves and the screw cap D the
asbestos or other packing material a, coiled round the piston rod k. This packing a
is to be pressed, by the concentric pressure of the fluid acting on the flaps or
segments; against the piston rod K, as soon and so long as the liquid or gaseous
fluid under pressure communicate with the annular opening e between the flaps m, n
and the packing receptacle c.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is :-
1. A packing for pistons and stuffing boxes, comprising in its construction oné
or more metallic rings split into parallel segments or flaps and exposed on the
inner or outer surface to the radial pressure of the fluid towards the surface to be
packed, the superposed flaps or segments being arranged to break joint.
2. The combination of a longitudinally split metallic ring, of the kind described,
with an inside or outside packing a, as illustrated.
3. A longitudinally split metallic ring of the kind described, provided in the
joints with transverse grooves and keys, or with toothed edges, as illustrated by
Fig. 7 and 8.
A