Improvements in Air Valves and their Seatings, especially applicable for use in Air-compressor Cylinder Covers.
Year: 1897

page_text: Date of Application, 5th Nov., 1897
Complete Specification Left, 6th May, 1898--Accepted, 4th June, 1898
Improvements in Air Valves and their Seatings, especially
applicable for use in Air-compressor Cylinder Covers.
I, ALFRED ERNEST MARKWICK, M.I. Mech. E., Engineer, of Karachi, in the Province
of Sind, in the Empire of India, do hereby declare the nature of this invention to be
as follows:-
The present invention relates to certain new and useful improvements in air valves
and their seatings and is especially applicable for use in air-compressor cylinder
covers; but also applicable to any other machinery whereby similar functions or
conditions are required to be fulfilled by the valves.
The valves are arranged preferably radially on each cylinder cover, the outlet ones
above and the inlets below the centre thereof; preferably five of the former to three
of the latter. As usual with permanent installations the covers are double with an
air space between them and the air supply is drawn from the top of an elevated shaft
to ensure freedom from dust and other impurities.
The valves are so arranged and constructed the air enters and is expelled at a pre-
determined angle preferably 30°. The seat for the inlet valve is simply a removable
washer made of any suitable material or composite structure but preferably leather,
its surface being accurately turned to the angle 30° to correspond with or fit the
taper periphery of the, preferably, cast steel, valve. This washer is held in position
by the bottom of the valve guide which presses it firmly against the shoulder of the
bushing or other equivalent guide-stop in the hole in the cover.
The valve itself, as above stated, is preferably of cast steel and of as light a design
as the pressure it has to sustain will admit of; and in cases where it has to withstand
heavy pressures the underside of the dome should be strengthened by webs carried
from the outer circumference to the centre.
There is provided an adjusting screw by which the "lift" of the valve can be
regulated or adjusted at will. A quarter-inch lift is found quite sufficient
generally.
An important part of my invention is the above-described removable washer valve
seat; it has the advantages of cheapness, can be quickly and easily renewed or
adjusted without removing the cylinder cover and is perfectly tight at all times
with ordinary attention." The valve does not stick, and opens with the
slightest vacuum and may be closed by a very weak spiral spring without the
slightest leakage.
The valve seat, spindle and buffer of the outlet valves are constructed on a
similar principle to those of the inlet valves. The "lift " can be adjusted without
stopping the engine, and the valve parts extracted without removing the cylinder
cover.
A similarly constructed valve seat might be useful in pumps, ball-cocks and other
like contrivances.
Finally the valve is or may be provided with an outer cover as usual when employed
on large machinery.
Dated the 5th day of November 1897.
PHILLIPS & LEIGH,
Agents for the Applicant.

page_text: Improvements in Air Valves
and their
Seatings, especially
applicable for use in Air-compressor Cylinder Covers.
I, ALFRED ERNEST MARKWICK, M.I. Mech. E., Engineer, of Karrachi, in the
Province of Sind, in the Empire of India, 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 :-
The present invention relates to certain new and useful improvements in air valves
and their seatings, and is especially applicable for use in air-compressor cylinder
covers, but also applicable to any other machinery wherein similar functions or
conditions are required to be fulfilled by the valves.
The following is a description of my invention as applied to an air-compressor
cylinder illustrated in and to be read together with the accompanying drawings, in
which-
Figure 1 is a vertical longitudinal section through an air compressor cylinder and
its covers fitted with my improved air valves.
Figure 2 is an end elevation of one of the cylinder covers.
Figure 3 is a plan of the valve guide.
Similar reference letters indicate the same parts throughout these drawings:
A A¹ A2 are the outlet valves considered as a whole, and B B1 B2 are the inlet valves
similarly considered. a is the valve proper, a¹ is the tapered periphery thereof;
b is the valve seating; c is the valve spindle; d is the adjustment screw; e is the
circular ledge on which the valve seat b rests; f is the bush sometimes employed
to line the hole in the cylinder cover. g is the valve guide casting; h are the webs
on the valve dome; is the adjustable nut on end of the valve spindle; ; is the
compression spring for automatically closing the valve and controlling its "lift"; k is
the valve spindle buffer of the outlet valves; m is the inspection cover over the
valves.
As is usual with permanent installations, the cylinder covers are made double or
hollow, with an air space between the back and front plates, and the air supply is
drawn from the top of an elevated shaft to ensure freedom from dust and other
impurities.
The valves and their seatings constitute the essential parts of my present invention;
they are constructed as follows:-
The valves are arranged, preferably radially, on each cylinder cover as shewn in
Figure 2; the outlet ones A, A1 and A2 above, and the inlets B, B1 and B2 below the
centre thereof. The total number of the valves and the relative proportion in each
set may vary, but generally speaking three inlets to five outlets will be found to
work well.
Referring to the inlet valves (see Figure 1) a is the valve proper made preferably
of cast steel with a tapered periphery a¹ as usual accurately turned to fit the seating b.
The other end of the spindle c of this valve is fitted with an adjustment screw das
The seat b
shewn, or it may be of any other convenient or ordinary type as desired.
on which this valve rests when in its closed position, is simply a washer of leather or
other like suitable material of appropriate dimensions. This seat is also accurately
turned or formed on its face, against which the valve comes in contact, to an angle
This
of 30°, to correspond with the tapered periphery a² of the said valve proper a.
seat b may rest on a circular ledge e formed simply out of the substance around the
hole in the back plate of the cylinder cover as shewn on the right hand side of
Figure ; or it may rest on a similar ledge or shoulder formed in a gunmetal or

page_text: other metal hush or well-fitting ring f inserted as a lining in the said hole as shewn
on the left-hand side of the same figure. g is the valve guide. This consists of a
metal (preferably gunmetal) casting of the form shewn, screwing into the cylinder
cover or bush as the case may be, and its bottom flat turned surface when it is
screwed down on to the seating, fixes the latter firmly against the shoulder or ledge e
on which it rests.
The valve itself a, is preferably of as light a design as is consistent with the
pressure it has to sustain, and in cases where the pressure is great, the underside of
the dome of the valve should be strengthened by webs h carried from the outer
circumference to the centre as shewn in the inlet valve on the left hand side of
Figure 1.
The inlet valves generally would have a "lift" of about a quarter of an inch, this
is found quite sufficient to fill the cylinder with air as desired.
In order that the "lift" may be altered to a greater or less one at will, some such
arrangement as that shewn at the rear end of the valve spindle, consisting of a screw
or stud d screwing into the end of the spindle c, the adjustment being made by the
nut against which one end of the compression spring ; bears.
This nut may be
screwed to-and-fro on the threaded end of the valve spindle, compressing or releasing
the spring more or less accordingly, which determines the amount of "lift" as
desired.
With inlet valves so constructed only the minimum amount of piston
clearance is necessary, as it allows of the piston being quite flat on each side.
As regards the outlet valves, they are constructed on the same principle as the
inlets just described. The valve seat b. and valve spindle end buffer k are preferably
composed of soft copper, but can be made of any other suitable material that will
withstand the heat and friction of the valve and passing air.
On the removal of the inspection cover m and adjustable screw i the valve can be
removed entirely without the necessity of first removing the cylinder cover, and the
lift of the valve be regulated even while the engine is running.
From the above it will be seen that the valves are so arranged and constructed that
the air both enters and is expelled at a predetermined angle preferably that of 300,
which experience has shown to be the best.
The operation of the engine is as follows:-In the drawings (Figure 1) the piston
is represented to be moving in the direction from left to right, the arrows indicating
the directions taken by both the incoming and outgoing air. The inlet valve at the
left-hand bottom corner of this figure is shewn open and admitting air, which it
continues to do until the piston arrives at the end of its stroke, and,
simultaneously the air behind the piston which was drawn into the cylinder, during
the previous stroke, through the inlet valve B¹ at the right-hand bottom corner of the
figure, is being compressed and forced out at an angle of 30° through the outlet
valve A2 at the top right-hand corner. On the return of the piston, air will be drawn
in through the inlet valve B¹ at the right-hand bottom corner, and the air previously
drawn in through B¹ at the left-hand bottom corner will now be expelled through the
outlet valve A2 at the left-hand top corner of the cylinder in question, and so on at
every stroke.
An important feature of the present invention is the above-described removable
washer valve seat; it has the advantage of cheapness, can be quickly and easily
renewed or adjusted without removing the cylinder cover, and is perfectly air-tight
at all times with but ordinary attention. The valve does not stick and opens with
the slightest vacuuin and may be closed by a very weak spiral spring. The spring j
shewn rests in a recess in the rear end of the valve guide casting g and, normally, is
under compression against the adjusting device i-d, the screwing up of which increases
the compression of the said spring.
The spring for the outlet valves is of course arranged between the internal surface
of the valve guide and the valve, because these valves open outwards, as distinguished
from the inlets which open inwards.

page_text: Should circumstances require that the angle be altered, this can of course be done
at the time of construction, and I do not confine myself to employ invariably an
angle of 30°.
Such a removable washer seat as herein described would also be useful in
pumps, ball and other valves or cocks and other like contrivances.
Finally, the valves are or may be provided with an outer cover such as m as is usual
when employed in large machinery.
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 valve for air-compressor cylinders, ball and other cocks and like contrivances,
consisting of a conical plug forming the valve proper, a loose or removable ring or
washer valve seat of leather or other suitable material, a valve guide encircling the
valve stem, adapted to screw down on to the valve seating, and having a recess at its
rear end containing a compression spring, and a screw adjustment regulating device
adapted to compress the said spring more or less, and so control the extent of the
"lift" or travel of the valve, substantially as described and illustrated in the
accompanying drawings.
2. The combination with the cylinder cover of an air-compressor cylinder of a valve
consisting of a conical plug forming the valve proper, a loose or removable ring or
washer valve seat of leather or other suitable material, a valve guide encircling the
valve stem, adapted to screw down on to the valve seating, and having a recess at its
rear end containing a compression spring, and screw adjustment regulating device
adapted to compress the said spring more or less, and so control the extent of the
"lift" or travel of the valve, substantially as described and illustrated in the accom-
panying drawings.
3. The combination with a pipe or other conduit of a valve consisting of a conical
plug forming the valve proper, a loose or removable ring or washer valve seat of
leather or other suitable material, a valve guide encircling the valve stem, adapted to
screw down on to the valve seating, and having a recess at its rear end containing a
compression spring, and a screw adjustment regulating device adapted to compress
the said spring more or less, and so control the extent of the "lift "or travel of the
valve, substantially as described and illustrated in the accompanying drawings.
4. A valve for air-compressor cylinders, ball and other cocks and like contrivances,
consisting of a conical plug forming the valve proper, a removable ring or washer
valve seat of copper, leather or other suitable material, a valve guide casting encircling
the stem of the valve, and adapted to screw down on to the valve seat, a compression
spring interposed between the said valve and valve guide in such manner as to exert
a pressure tending to separate these two parts or close the valve on its seat, and a
screw adjustment device acting against the rear end of the valve stem, for controlling
the "lift" or travel of the valve, substantially as described and illustrated in the
accompanying drawings.
5. The combination with the cylinder cover of an air-compressor cylinder, of a
valve consisting of a conical plug forming the valve proper, a removable ring or washer
valve seat of copper, leather or other suitable material, a valve guide casting encircling
the stem of the valve, and adapted to screw down on to the valve seat, a compression
spring interposed between the said valve and valve guide in such manner as to exert
a pressure tending to separate these two parts or close the valve on its seat, and a
screw adjustment device acting against the rear end of the valve stem, for controlling
the "lift" or travel of the valve, substantially as described and illustrated in the
accompanying drawings.
6. The combination with a pipe or other conduit, of a valve consisting of a conical
plug forming the valve proper, a removable ring or washer valve seat of copper
leather or other suitable material, a valve guide casting encircling the stem of the
valve, and adapted to screw down on to the valve seat, a compression spring interposed
between the said valve and valve guide in such manner as to exert a pressure tending

page_text: to separate these two parts or close the valve on its seat, and a screw adjustment
device acting against the rear end of the valve stem, for controlling the "lift" or
travel of the valve, substantially as described and illustrated in the accompanying
drawings.
7. A seat for a valve for air-compressor cylinders, ball and other cocks, consisting
of a loose or removable ring or washer of copper leather or other suitable material
with its acting surface accurately turned or bevelled to some predetermined angle,
substantially as described and illustrated in the accompanying drawings as set
forth.
8. In a valve for an air-compressor cylinder, ball and other cocks and like con-
trivances the combination with the valve plug, of a valve seat consisting of a loose
or removable ring or washer of copper, leather or other suitable material with its
acting surface accurately turned or bevelled to some predetermined angle to suit the
bevel of its complement the valve plug, substantially as described and illustrated in
the accompanying drawings as set forth.
PHILLIPS & LEIGH,
No. 22, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.