Year: 1898

page_text: I, JOHN GEORGE AULSEBROOK KITCHEN, of 44, Albert Road, Alexandra Park,
Manchester, in the County of Lancaster, Mechanician, do hereby declare the
nature of this invention to be as follows:-
This invention relates to improvements in pistons in which dished plates
capable of circumferential expansion are used instead of ordinary piston rings,
the object of this invention being to obtain a more perfect fitting piston.
In accordance with my invention, on the pressure acting side or sides of a
disc or block forming the body of the piston and in which is secured the piston
rod, or the connecting rod, a central boss is provided of a smaller diameter.
In the case of pistons having piston rods, the rod may form the boss and when
the piston is made for a double action cylinder the piston rod preferably passes
through the disc or block to the extent required. Upon the boss is arranged a
number of dished plates close together, each having a central hole large enough
to pass on to the boss and cach being slit through from the periphery to the
central hole. The plates are turned up together to fit the cylinder. They are
arranged upon the boss so that the slit in one plate does not come opposite that
in the next plate. To insure this a feather may be formed along the boss and
slots to fit the feather may be formed in the plates in different relative positions
to the slits aforesaid. Where, however, a large number of thin plates are
employed, it is found unnecessary to take this precaution. The plates are pre-
ferably disposed with their convex side to the disc or block, and the face of the
latter may be hollowed out so that the centre of the end plate next to the disc
rests against the disc next to the central boss while there is clearance at the
sides of the plates.
I mount a circular washer of smaller diameter than the plates upon the boss
so as to be capable of being pressed against the said plates by means of a nut
screwed upon the boss. By pressing upon the concave face of the plates by
means of this washer and nut the circumferential measurement of the plates
is increased.
:
At the end of the boss I may provide a cap preferably slightly smaller in
diameter than the plates, which bears against the concave side of the end plate
near its periphery and is immoveably secured in position against a shoulder by
a nut screwed upon the end of the boss or upon the piston rod as the case
may be.
When the plates are disposed with their concave face to the disc or block the
latter is formed with a convex face bearing against the plates. For the purpose
of expanding the plates a washer bears against their centre part and a nut
screwed upon the boss presses the plates against the convex face of the disc or
block aforesaid. A cap having a convex face the edge of which lightly touches
the end plate at or near its periphery may be fixed, clearance being provided

page_text: between the centre parts of the end plate and cap respectively, the cap being
immoveably secured by a nut against a shoulder upon the boss.
In each case circumferential expansion of the plates is effected in a similar
manner, that is by pressure upon their concave face while their central convex
portion is supported or vice versa.
The cap is in some cases pierced with holes near to its periphery to ensure
the plates receiving the force of the pressure tending to expand them.
Each plate is preferably in the form of a hollow frustrum of a straight sided
cone, but I have found that similar thin plates with curved sides will also
answer.
1
The plates are made preferably of thin sheet steel in pistons of the smaller
sizes, but the thickness will vary with the diameter and any suitable metal may
be used in their manufacture.
Dated this 25th day of November 1898.
R. J. URQUHART,
57, Barton Arcade, Manchester,
Harrington Chambers, 24, North John Street, Liverpool,
Consulting Engineer & Patent Agent.
I, JOHN GEORGE AULSEBROOK KITCHEN, of Heathwaite, Windermere, in the
County of Lancaster, late of 44, Albert Road, Alexandra Park, Manchester,
also in the County of Lancaster, Mechanician, 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:-
This invention relates to improvements in pistons in which dished plates
capable of circumferential expansion are used instead of ordinary cylindrical
piston rings, the object of this invention being, chiefly, to obtain a more perfect
fitting piston.
In the drawings attached hereunto which serve to illustrate this invention,
Figure 1 represents a longitudinal section of a piston made in accordance with
my invention, Figure 2 represents a plan of my improved dished ring plate,
Figure 3 represents a longitudinal section of a piston suitable for a double
acting cylinder made in accordance with my invention. Figure 4 represents a
part longitudinal section of my improved piston with the concave faces of the
ring plates to the piston body. In the several views similar parts are indicated
by like letters of reference.
Referring first to Fig. 1, I form the disc or piston body a with a boss or exten-
sion a¹, of less diameter than the body a and place round the said boss a¹ a
series or packet of thin metal plates b which I will now call "ring-plates," dished
so as to form frustrated cones preferably with an obtuse angle at the apex,
fitting one into the other and slit open on one side as shewn on Figure 2. In
Figures 1 and 3 ring-plates are placed with their smaller ends towards the piston
body and fit the boss a', and the end plate bears with its convex side against
a bead or rounded shoulder a² of the piston body, at about the middle of the
surface or somewhat nearer to the inner edge.
Against the concave side of the other end plate 12 a washer c bears near to
the outer edge of the plate, the edge of the washer being rounded or coned.
The washer is fixed to the piston body by means of a stud d and nut d' or by

page_text: equivalent means, and adjusted in its position relatively to the coned plates by
means of another washer e, which can be readily replaced by a thinner one.
The washer c in being fixed and draw into the packet of coned plates by the
nut expands the end plate 2 and this plate expands the next one and so on,
as the plates are divided on one side. At the same time in consequence of this
division and the thinness of the plates the cones are flattened out, the plates
being tilled on the bead or shoulder a² which acts as a fulcrum and are thus
expanded at their circumference and contracted and pressed against the boss a¹
at their inner edges, thus making a tight joint against the boss a¹.
In this way the diameter of the packet of plates can be enlarged to take up
the wear of the cylinder, and the latter rebored and the plates expanded and
turned or ground again to the enlarged size of the cylinder several times before
they have to be renewed. The fluid pressure which will get under the end
plate has the same effect of expanding the plates and flattening them and
thus keeps the piston tight.
In some cases the washer e is replaced by a spring washer or dispensed with,
in which case the fluid pressure on the washer e forces it at each stroke into the
coned plates and tightens them against the cylinder wall. The amount of this
tightening can be varied by reducing the angle and increasing the thickness of
the plates for higher pressure, and increasing the angle and reducing the thick-
ness of the plates for lower pressures.
The plates are so placed upon each other that the slit in one plate does not
come opposite that in the next plate as shewn on Figure 2. In order to insure
this a key way f is cut into the plates in different positions relatively to the slit
and a key f placed into the slot, either loosely or fixed to the boss kel. Where
the number of plates is large, this precaution may be omitted.
Figure 3 shows the improved conical packing plates applied to a double acting
piston, the disc or piston body a being formed with two reduced parts or bosses a¹
each of which receives a packet of conically dished rings or plates 6 preferably
placed as shewn with their larger ends towards the pressure side, and expanded
and flattened by means of the washers c¹ and the former of which is fixed by
the nut securing the piston rod g in the disc or body a and the latter by set
screws h.
Referring now to Figure 4 instead of placing the conically dished or ring
plates with their concave face towards the pressure side, as shewn on the
drawings in Figures 1 and 3, they may in some cases be reversed, and the bead
or shoulder a on the piston body a placed near to its circumference, and a
similar bead bearing upon the ring-plates nearer to their inner edge formed
on the washer e.
:
The plates may be made of steel, brass or other elastic metal according to the
fluid acting upon them.
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-
First. The improved construction of piston for reciprocating engines which
consists in providing the piston body with a central boss or stud, assembling
thereon a number of thin metal split ring plates forming hollow frustrums of
cones arranged so that the slit in the one plate does not come opposite that in
the next, and adjustably securing at the end of the central boss a washer which
can be pressed against the arrangement of plates, the pressure being applied
to act near to the periphery of the plates upon their concave side and near to
the central opening on their convex side so that the tendency is to flatten the
plates causing them to bear against the central boss and expand circumferen-
tially at the same time, substantially as and for the purpose hereinbefore
described and illustrated in the accompanying sheet of drawings.
Second. In pistons for reciprocating engines in which thin metal ring-plates

page_text: formed as split hollow frustrums of cones are employed in place of the ordinarily
known piston rings, the herein before described improvements which consist in
providing a raised annular bead or ridge upon the piston to bear against the
convex face of the packet of ring plates nearer to the axis of the plates and
act as a fulcrum for the plates to move upon when expanding circumferentially,
and a corresponding narrow annular ridge or edge to bear against the concave
face of the packet of ring-plates near to the periphery thereof substantially as
herein before described and illustrated in the accompanying sheet of drawings.
Third. The improved construction of piston for reciprocating engines sub-
stantially as described with reference to Figure 1 of the drawings.
Fourth. The improved construction of piston for reciprocating engines sub-
stantially as described with reference to Figure 3 of the drawings.
Tifth. The improved construction of piston for reciprocating engines sub-
stantially as described with reference to Figure 4 of the drawings.
Dated this 23rd day of September 1899.
R. J. URQUHART, C.E.,
Chartered Patent Agent, Manchester & Liverpool.