Improvements in Valves and Metallio Packing in Single Acting Engines.
Year: 1893

page_text: Date of Application, 17th June, 1893
Complete Specification Left, 19th Mar., 1894-Accepted, 12th May, 1894
PROVISIONAL SPECIFICATION.
Improvements in Valves and Metallio Packing in Single Acting
Engines.
We, MARK HEATON ROBINSON, MATTHEW HENRY PHINEAS RIALL SANKEY
and WILLIAM HOPE WILSON, all of Ferry Works, Thames Ditton in the County
of Surrey, Engineers, do hereby declare the nature of this invention to be as
follows:-
This invention relates to packing for pistons and piston rods in single acting
engines, in which the fluid pressure is at some times equal on the two sides of the
packing, and at other times differs but so that the greater pressure is still on the
same side.
One of the plane sides of the groove or recess in which the packing rings lie is
made in the form of an elastic metallic plate, which is pressed against one of the
plane sides of the rings by its own elasticity. The moveable or elastic side of the
groove or recess is that which is exposed to the greater pressure.
Provision is made to admit the pressure to the back of the rings, thus forcing
them outward against the cylinder walls, or inward against the piston rod. The
pressure of the elastic plate end ways against the rings, combined with the pressure
of the fluid upon them, keeps the other side of the rings in-contact with the fixed
part of the piston or gland box, aud prevents the passage of fluid from behind the
rings in a radial direction.
In the figure a set of piston rings is shewn at B B the lower sides of which are
pressed against the lower side of the groove (i.e. the fixed portion of the piston) by
the downward pressure of the spring plate (preferably of steel) C C-the plate is
secured to the body of the piston by bolts D D, and it is so formed and fixed that
it exerts a constant pressure upon the upper side of the rings, so that as the latter
wear thinner, the plate follows up the wear and prevents end play. (It is to be
observed however, that owing to the absence of any initial clearance between the
rings and the sides of the groove in which they fit, end play should never arise and
the end wear of the rings is extremely small.) The arrangement is of course
applicable only in a single acting engine, where the pressure below the piston does
not ordinarily exceed that above it. The steel plate may be partially divided by
radial saw-cuts to increase its elasticity.
The arrangement is shown at F F in the figure applied to a gland ring.
Here E E are the rings (springing inward). F F is the spring plate, held down
by studs and nuts to the body of the gland-box which is very slightly shallower
than the rings (i.e. in a vertical direction); consequently when the nuts which hold
The same
down the spring plate are tightened it presses upon the rings.
arrangement is also shewn at G G.
In both these cases the fluid pressure is admitted to the back of the rings,
keeping them pressed against the cylinder, or the piston rod, as the case may be.
The fluid pressure (as well as the spring pressure) also acts upon the top of the
rings, keeping their lower sides close against the piston or gland box.
The drawing Figure 1 illustrates a vertical single acting engine, in which the
upward
down stroke is the effective or working stroke. It is obvious that with "
pressure substituted for "downward pressure" the same description will apply to
an engine in which the upstroke is the effective stroke. It is also obvious that the
same system of packing may be applied to horizontal single acting engines.

page_text: The invention also relates to the distribution of the fluid pressure in a single
acting engine of the central-valve type, such as is described in the English Letters
Patent Nos. 13769 of the year 1884 and 1852 of the year 1885, granted to Peter
William Willans. Such engines are sometimes arranged not to pass the exhaust
fluid directly from the working cylinder to the exhaust, but first from the working
end of the cylinder to the other end, and then, on the succeeding stroke, from the
cylinder to the exhaust.
The central valve engine of which a portion is shown in the figure is thus
arranged. Just before the pistons reach the bottom of their stroke the valve V₁
passes above the ports P' and places them in communication with the ports P2², thus
allowing the working fluid to pass from the upper or working end of the cylinder
to the lower end. During the greater part of the upstroke it is so transferred,
without substantial change of volume, communication between P and P being
closed only just before the completion of the upstroke. Immediately afterwards
the descent of the hollow piston valve V³, and of V, opens the ports P³ and P³,
and thus places P2, and the lower part of the cylinder X in communication with
the space Y, from which the exhaust pipe opens.
Now it will be observed that the action of the valves V and V is an exhaust
action, but that it takes place while the line of valves of which they form part is
giving admission to the working end of the cylinder. This tends to neutralise the
advantage which ordinarily belongs to the valves of a single acting engine, viz. that
their motion may be directed to alternately admitting and exhausting and not to
both functions at once which renders it difficult to obtain a sufficiently free
exhaust. By this invention this difficulty is met by using two (or more) rows of
exhaust ports at P3 and P*, and covering and uncovering them by two (or more)
valves Vand V, of which the upper one is hollow and gives passage for the
exhaust fluid to the lower one. Thus a sufficient port area is obtained without
enlarging the hollow piston-rod.
Dated this 16th day of June 1893
MARK H. ROBINSON.
M. H. P. R. SANKEY.
W. H. WILSON.
COMPLETE SPECIFICATION.
Improvements in Valves and Metallic Packing in Single Acting
Engines.
We, MARK HEATON ROBINSON, MATTHEW HENRY PHINEAS RIALL SANKEY,
and WILLIAM HOPE WILSON, all of Ferry Works, Thames Ditton, in the
County of Surrey, Engineers, 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 packing for pistons and piston rods in single acting
engines, in which the fluid pressure is at some times equal on the two sides of the
packing, and at other times differs but so that the greater pressure is always on
the same side.
One of the plane sides of the groove or recess in which the packing rings lie is
made in the form of an elastic metallic plate which is pressed against one of the
plane sides of the rings by its own elasticity. The moveable or elastic side of the
groove or recess is that which is exposed to the greater pressure.
Provision is made to admit the pressure to the back of the rings, thus forcing
them outward against the cylinder walls, or inward against the piston rod. The
pressure of the elastic plate end ways against the rings, combined with the pressure
of the fluid upon them, keeps the other side of the rings in contact with the fixed

page_text: part of the piston or gland box, and prevents the passage of fluid from behind the
rings in a radial direction.
In the figure a set of piston rings is shown at B B the lower sides of which are
pressed against the lower side of the groove (i.e. the fixed portion of the piston) by
the downward pressure of the spring plate (preferably of steel) C C-the plate
is secured to the body of the piston by bolts D D, and it is so formed and fixed
that it exerts a constant pressure upon the upper side of the rings, so that as the
latter wear thinner, the plate follows up the wear and prevents end play. (It
is to be observed however, that owing to the absence of any initial clearance
between the rings and the sides of the groove in which they fit, end play should
never arise and the end wear of the rings is extremely small.) The arrangement is
of course applicable only in a single acting engine, where the pressure below the
piston does not ordinarily exceed that above it. The steel plate may be partially
divided by radial saw-cuts to increase its elasticity.
The arrangement is shewn at F F in the figure applied to a gland ring. Here E E
are the rings (springing inward). F F is the spring plate, held down by studs and
nuts to the body of the gland-box which is very slightly shallower than the rings
(i.e. in a vertical direction); consequently when the nuts which hold down the
spring plate are tightened it presses upon the rings. The same arrangement is
also shown at G G.
In both these cases the fluid pressure is admitted to the back of the rings,
keeping them pressed against the cylinder, or the piston rod, as the case may be.
The fluid pressure (as well as the spring pressure) also acts upon the top of the
rings, keeping their lower sides close against the piston or gland box.
"
The drawing illustrates a vertical single acting engine, in which the down stroke
is the effective or working stroke. It is obvious that with "upward pressure'
substituted for "downward pressure "the same description will apply to an
engine in which the upstroke is the effective stroke. It is also obvious that the
same system of packing may be applied to horizontal single acting engines.
The invention also relates to the distribution of the Huid pressure in a single
acting engine of the central-valve type, such as is described in the English Letters
Patent Nos. 13769 of the year 1884 and 1852 of the year 1885, granted to
Peter William Willans. Such engines are sometimes arranged not to pass the
exhaust fluid directly from the working cylinder to the exhaust, but first from the
working end of the cylinder to the other end, and then, on the succeeding stroke,
from the cylinder to the exhaust.
The central valve engine of which a portion is shown in the figure is thus
arranged. Just before the pistons reach the bottom of their stroke the valve V₁
passes above the ports Pl and places them in communication with the ports P, thus
allowing the working fluid to pass from the upper or working end of the cylinder
to the lower end. During the greater part of the upstroke it is so transferred,
without substantial change of volume, communication between P' and. P² being
closed only just before the completion of the upstroke. Immediately afterwards the
descent of the hollow piston valve V³, and of V, opens the ports P and P₁, and
thus places P' and the lower part of the cylinder X in communication with the
space Y, from which the exhaust pipe opens.
Now it will be observed that the action of the valves V³ and V is an exhaust
action, but that it takes place while the line of valves of which they form part is
giving admission to the working end of the cylinder. This tends to neutralise
the advantage which ordinarily belongs to the valves of a single acting engine
viz. that their motion may be directed to alternately admitting and exhausting and
not to both functions at once which renders it difficult to obtain a sufficiently free
exhaust. By this invention this difficulty is met by using two (or more) rows of
exhaust ports at P³ and P, and covering and uncovering them by two (or more)
valves Vand V, of which the upper one is hollow and gives passage for the exhaust
fluid to the lower one. Thus a sufficient port area is obtained without enlarging
the hollow pistou rod.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is
1. A piston packing suitable for a single acting engine, such packing consisting
of piston rings fitting the cylinder-a plane surface on the piston supporting the
rings a spring cover plate secured by bolts to the pressure side of the piston
which by its elasticity exerts a constant pressure on the rings and retains them
in contact with the plane surface, and openings for admission of steam to the
back of the piston rings from the pressure side of the piston substantially as
.described.
2. A gland packing substantially as described suitable for a single acting engine,
such packing consisting of rings encircling the rod, a plane surface in the gland
box supporting the rings, a spring cover plate which is secured by bolts to the
pressure side of the gland box and which by its elasticity exerts constant pressure
on the rings and retains them in contact with the plane surface, and openings for
admission of steam to the back of the rings from the pressure side, substantially
as described.
3. A single acting central valve engine, substantially as described, and having
double or multiple exhaust passages P³ and P, formed in the hollow piston rod and
double or multiple exhaust valves V3 and V* working over the said exhaust passages
within the hollow rod.
Dated this 19th day of March 1894
MARK HEATON ROBINSON.
MATTHEW HENRY PHINEAS RIALL SANKEY.
W. H. WILSON.