Piston-rod Packing.
Year: 1890

page_text: Date of Application, 7th Jan., 1890-Accepted, 8th Feb., 1890
COMPLETE SPECIFICATION.
[Communicated from abroad by FRANCIS PATRICK MARTIN, of Easton, County
Northampton, and State of Pennsylvania, United States of America,
Machinist.]
Piston-rod Packing.
I, JOHN IMRAY of No. 28 Southampton Buildings, Chancery Lane, in the County
of London, Consulting Engineer, and Patent Agent, do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
My invention relates to a simple and comparatively inexpensive packing for
piston rods, such that the packing is compressed on the rod by the pressure within
the cylinder and the rod is practically released by the packing when the pressure
is reduced, thus relieving the frictional resistance and lessening the wear and
tear.
Packing according to my invention can be applied without structural alteration
and without material expense to cylinders provided with ordinary stuffing boxes, and
with considerable reduction of wear and economy of lubricant, as I shall explain
referring to the drawings.
Fig. 1. is a central section shewing an ordinary stuffing box to which my invention
is applied.
Fig. 2 is a similar section shewing the application of the invention to a cylinder
having no stuffing box.
Fig. 3 is an end elevation of the casing or gland with the packing removed.
Fig. 4 is an elevation of one and a section of the other supporting annulus shewn
separately.
Fig. 5 is a plan of the annular cushion.
Fig. 6. is a perspective of one of the packing rings.
Fig. 7 is a transverse section of the ring-support taken in the plane of the steam
entrances.
1. is a cylinder cover having the usual stuffing box boss 2.
3 is a gland having a flange 4 secured to the cylinder cover by bolts 5. The hole 6
of the gland permits free passage of the piston rod 7.
The end of the gland 3 bears against an annular seat 8 faced steam tight both to
the cylinder cover and the end of the gland, the part of the seat within the gland
being of increased thickness, so as to form an annular rib 8ª within the open end of
the gland 3. Outside this rib 8ª are a set of small apertures 9, through the annular
seat opening into a circular channel 10 formed in the gland.
On the other face of the said seat is a raised face 10° surrounding the apertures
In the cover are formed
and ground to seat steam tight upon the cylinder cover.
a set of openings 12, coinciding with the apertures 9, or opening within the raised
surface 10. Fluid can pass from the cylinder, not only around the piston rod but
also through the apertures 12 with free access to the openings 9.
14 is a ring support made in two equal and similar halves. Each section has an
enlarged portion 15 fitting easily within the gland and an interior rib 16. fitting
easily to the piston rod. On each side of and between the ribs 16 are fitted
packing rings 17, and a third or intermediate ring 18. The parts 19 of the ring-
support being of less external diameter than the end parts 15 there is formed an
annular chamber 20, between the ring support and the interior of the gland. This
chamber might however be formed by internally hollowing the gland.
The packing rings 17 and 18 may be of any suitable metal or alloy or of hard
vulcanized rubber or other suitable elastic material. Each ring is cleft at one point
to form, preferably, a notched joint 21 or it might be an oblique cut. These rings

page_text: when placed within the ring support are so far compressed upon the piston rod as to
have only a slight frictional contact on it.
Behind the middle of each packing ring are holes 22 through the ring support these
holes communicating by slots 23 with the annular chamber 20 which communicates
by grooves 23ª with the chamber 10.
When the invention is adapted to cylinders having no stuffing box the gland 4 is
made of inverted form as shewn in Fig. 2 and is bolted directly to the cylinder
cover 1. The piston rod in this case passes through an inwardly turned flange 3, at
the outer end of the gland 3 which contains the packing as shewn in Fig. 2. A
shallow interior channel 24 may be formed behind each packing ring, so as to connect
all the fluid passages 22 and equalize pressure throughout.
The edges of the packing rings 17 and 18 and the shoulders between which they
lie, are all ground or fitted tight against leakage.
The operation is as follows: When there is pressure in the cy"nder the fluid flows
past the piston rod or through the apertures 12, into the annular chambers 10 and 20,
and thence through the openings 22. behind the packing rings 17 and 18 pressing
them against the rod. When the pressure in the cylinder is reduced, pressing force
upon the rings is also reduced, thus avoiding all needless wear of the parts, and the
additional power required to overcome friction of the stuffing.
The central packing ring 18 may be dispensed with and the ring support made in
a single piece or only a single packing ring may be employed without any material
alteration in the invention.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
A piston rod packing consisting of a gland, bearing against an annular seat in the
cylinder cover, within the gland a ring support or two of these, cleft packing rings
fitting internal recesses of the ring support, and channels and passages whereby fluid
under pressure in the cylinder can pass into the recesses behind the packing rings,
substantially as described.
Dated this 7th day of January 1890.
ABEL & IMRAY,
Agents for the Applicant.