IMPROVEMENTS IN METALLIC PISTON AND AIR PUMP PACKINGS AND IN PISTON HEADS
Year: 1885

page_text: In 180
I GEORGE MURDOCH of Princes and Clarendon Dock Belfast in the County of
Antrim in Ireland Engineer do hereby declare the nature of my invention for
IMPROVEMENTS IN METALLIC PISTON AND AIR PUMP PACKINGS AND IN PISTON
HEADS to be as follows:-
I employ two light and elastic metallic packing rings each having a transverse
oblique division and a continuous or indented internal flange at one edge to enclose
the spring or springs hereinafter mentioned. These rings are placed together so
that the flanges are at the opposite edges thereof and a three sided rectangular
enclosure is formed for the spring or springs-Within this enclosure I place an
annular spring, part of which is waved so as to press the flanges of the packing
rings alternately in the direction of a line parallel to the piston shaft and keep
them in close and constant contact with the flange of the piston head and the
remaining part of which is an oval spiral (having a long and a short diameter at
right angles to each other) in order to adjust or equilibriate the action of the
waved part and to aid it in distending the packing rings in an outward direction
(circumferentially) and keeping them in close and constant contact with the walls
of the cylinder whereby waste of steam is prevented.
For large pistons I modify the above arrangement and employ compound springs
of the same character which consist of two wave springs, one within each packing
ring and alternately pressing the flange of the packing ring encircling it and the
wave spring encircled by the adjoining packing ring, and both adjusted or
equilibriated and aided by a common oval spiral spring, to each end of which
their contiguous ends are attached, a washer being interposed between the wave
springs and the spiral to regulate their reciprocal pressures.
I also construct the piston head in halves cut horizontally and fitted together, at
the axis, with an internal and an external joint and held in position by the piston
rod passing through the axis so that the packing rings may be introduced into the
recess in the piston head in a similar manner as heretofore effected by the removal
of the junk rink, the junk ring and bolts being dispensed with.
Dated this 6th dow of March 1885
HYNDMAN & DICKSON,
Agenta.

page_text: COMPLETE SPECIFICATION.
"
Improvements in Metallic Piston and Air Pump Packings and
in Piston Heads.
I GEORGE MURDOCH of Princes and Clarendon Dock, Belfast in the County of
Antrim in Ireland, Engineer, do hereby declare the nature of my invention for
IMPROVEMENTS IN METALLIC PISTON AND AIR PUMP PACKINGS AND IN PISTON
HEADS" and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
For average sized Pistons I employ two light and elastic metallic Packing rings,
each having a transverse oblique division, cut right through it, so as to admit of
the distension of the ring and its adjustment to 'the circle of the cylinder. Upon
one edge of each of these rings I form a continuous or indented internal flange
(but cut through opposite the transverse oblique division of the ring) to enclose
and retain the spring or springs hereinafter mentioned and I place internally
across the transverse oblique division or cut, in order to prevent the passage of
steam into the recess in the Piston head, a tongue-piece furnished with snugs
which pass through corresponding slots provided for the purpose in the face and
flange of the ring respectively and hold the tongue-piece in position. The flanged
Packing rings are placed together so that the flanges are at the opposite edges
thereof and a three sided rectangular enclosure is formed for the retention of the
spring or springs already referred to.
Within this rectangular enclosure I place an annular spring, part of which is
waved and comes into contact with the flanges of the Packing rings alternately so
as to press them apart in the direction of a line parallel to the Piston-shaft and to
keep them in close and constant contact with the flange of the Piston-head. The
remaining part of the annular spring is spiral, of an oval form, having a long and
a short diameter crossing each other at right angles, in order to adjust and equi-
libriate the action of the waved part and to aid it in distending the Packing-rings
in an outward direction (circumferentially) and in keeping them in close and
constant contact with the walls of the cylinder, whereby waste of steam is more or
less effectually prevented. The springs are maintained in position and prevented
shifting by means of pins or bolts driven into the rings, at intervals, preferably
within the lobes of the wave-spring.
For large Pistons I modify the arrangement I have described and employ
compound springs of the same character as those which I introduce into the
Packing rings in a Piston of the average size.
L
The springs in this arrangement consist of two separate, wave springs and a
common oval spiral spring, to each end of which the contiguous ends of the
separate wave springs are attached-Each of these wave springs is placed within
a Packing ring and presses alternately the flange of the ring which encircles it and
the other wave spring encircled by the adjoining ring and both wave springs are
adjusted or equilibriated by the common oval spiral spring to which they are
attached. A washer is interposed between the ends of the Wave. springs and

page_text: the common oval spiral spring at either or each side to regulate their reciprocal
pressures.
But instead of the compound springs last above described I may employ for
large Pistons two annular springs of the same construction as that first herein before
described and in either of these arrangements I prefer to place a flat ring or
washer between the springs or as much thereof as is waved so that the pressure of
the springs may not be acting directly against each other but against such flat ring
or washer and that loss of power by the springs shifting on their opposing lobes or
curves may be avoided.
And for small Pistons I may construct the springs from a ring or band of steel
placed on edge and having a portion thereof formed into waves by cutting a series
of oval or lance shaped openings or perforations along its centre line and by
shaping the edges with corresponding curves, the extremities of the portion so
formed into waves being connected adjusted and equilibriated by an oval spiral
apring as above described.
J
I also construct the Piston-head in halves cut horizontally and fitted together at
the axis with an internal and an external joint, and I dispense with the use of a
junk ring and bolts. The halves of the Piston-head are held in position by the
Piston rod which passes through them and is furnished with a threaded end and
screw nut. The halves may thus be separated and the Packing rings may be
introduced into and removed from the recess in the Piston-head in a similar
manner as heretofore has been effected by the removal of the junk-ring.
And in order that my said invention may be more fully understood I shall now
proceed to describe the drawings upon the sheet hereunto annexed, the same letters
of reference indicating the same or corresponding parts of my said arrangements
throughout all the figures upon said sheet.
Fig. I is a plan of a divided Piston-head with a portion of one of the halves
removed and showing the annular spring with a portion of the spiral part thereof.
Fig. II is a section of the Packing rings showing portions of two wave springs
and the common oval spiral spring between their extremities and an intervening
washer.
Fig. III is an elevation of the Piston-head, partly in section, shewing portions of
the flanged Packing rings with the transverse oblique division or cut in one of
them and a longitudinal slot across the division or cut to receive one of the snugs
on the tongue piece and also portions of two wave springs with a ring or washer
between them.
Fig. IV is an elevation of the Packing-rings, partly in section, removed from the
Piston-head showing two compound annular springs with the intervening ring or
washer and each having its separate spiral.
Fig. V is an elevation of the same parts for a Piston-head of average size
shewing the application of one annular spring only.
Figs. VI and VII are details of a Packing ring shewing the transverse oblique
division or cut and the longitudinal slot and the curved slot in the flange with the
snugs on the tongue piece inserted.
Figs. VIII and IX are a plan and elevation of the Tongue pieces.
Fig. X is a plan of a small Piston-head with a portion of one of the halves
removed and showing the spring constructed from a ring or band of steel with a
portion of the spiral part thereof.
Fig. XI is a plan of the spring partly shewn in Fig. X.
Fig. XII is an elevation of the Piston-head, partly in section, shewing portions
of the flanged Packing rings with the spring shewn in Fig. XI and
Fig. XIII is an elevation of the Packing rings in section removed from the
Piston-head shewing portion of the same spring.
A is the divided Piston head; B. B. are the Packing rings; C is the annular
spring; D is the washer placed between the wave and spiral parts of the spring C;
E is the Piston rod; F is the nut holding the halves of the Piston head together;
G is the transverse oblique cut in the Packing-rings; H is the tongue piece fitted

page_text: into the longitudinal slot and having a snug I passing through the flange of the
Packing ring; and K is the ring or washer placed between the annular springs C, C,
or the waved parts thereof.
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. The use, in Piston and air pump Packing rings, of a combined wave and spiral
annular spring constructed and employed substantially in the manner and for the
purposes hereinbefore described and shewn in the drawings, hereunto annexed.
2. The use, in Packing rings, of an annular spring or annular springs arranged
with an intervening washer or intervening washers constructed and employed
substantially in the manner and for the purposes hereinbefore described and shewn
in the drawings hereunto annexed.
3. The use, in Packing-rings, of a ring or band of steel arranged with openings
or perforations and a spiral spring constructed and employed substantially in the
manner and for the purposes hereinbefore described and shewn in the drawings
hereunto annexed.
4. The use, in motive Engines and Air pumps, of Piston-heads divided hori-
zontally and arranged, constructed and employed substantially in the manner and
for the purposes hereinbefore described and shewn in the drawings hereunto
annexed.
5. The combination and arrangement of parts constituting my improved Elastic
Metallic Packings constructed and employed substantially in the manner and for
the purposes hereinbefore described and illustrated by the drawings hereunto
annexed, and
6. The combination and arrangement of parts constituting my improved divided
Piston-head constructed and employed substantially in the manner and for the
purposes hereinbefore described and illustrated by the drawings hereunto annexed.
Dated this 5th day of December 1885.
HYNDMAN & DICKSON,
Agents for said George Murdoch.