Improvements in Valves for Steam Engines.
Year: 1889

page_text: Date of Application, 23rd May, 1889-Accepted, 29th June, 1889
COMPLETE SPECIFICATION.
Improvements in Valves for Steam Engines.
We, DAVID CARMICHAEL, of Ward Foundry, Dundee, in the County of Forfar,
North Britain, Engineer, and ALEXANDER MACKIE, of the same place, Draughtman,
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, that is to say :-
This Invention relates to improvements designed to be used with the improvements
in valves and valve gear described in our Patent Specification No. 5834 of 1889 ; but
which are also applicable with other modifications of Corliss valves and valve gear.
Our present Invention comprises an improved construction applicable to admission
and exhaust valves of the Corliss type and it consists principally in making each
valve and its spindle of forms such that the centre of gravity is in the axis of the
valve and spindle and so that there is no unbalanced weight tending to resist or to
induce movement of the valve in whatever position it may be. The improved
construction is, at the same time, such as to diminish the amount of clearance space
and save steam. In carrying out our Invention we prefer to construct and adapt
the valves for double ports and passages such as are described in our earlier
Specification hereinbefore referred to.
On an accompanying sheet of explanatory drawings, figure, 1, is a side elevation
of a horizontal steam-engine cylinder as provided with our improvement the
admission and exhaust valve boxes, valves, ports and passages, being shown in
vertical section at one end of the cylinder the cylinder lining being partly broken away.
Figure, 2, is a plan of one of the valves, and figures, 3, and 4, are a side view and an
edge view of the valve spindle.
Each valve, A, or E, is of a shape, in cross section, obtainable from a solid
cylinder by forming two passages, 41, 42, through or across it on opposite sides of a
diameter. When the admission valve, A, is in the open position the lower ends or
ports of its passages, 41, 42, coincide with the ports, 28, 29, through which the
steam finds its way into the cylinder; and at the same time the upper ends or ports
of the valve passages, 41, 42, coincide with ports, 43, 44, by which the steam enters
the valve box and valve. In a similar way when the exhaust valve, E, is open as
shown, the upper ends or ports, of its passages, 41, 42, coincide with ports, 45, 46,
by which the steam leaves the cylinder; and the lower ends or ports of the valve
passages, 41, 42, coincide with ports, 31, 32, by which the steam passes from the
valve box to the exhaust pipe. When either valve is in its closed position it covers
all the ports in its valve box. The valves, A, E, are formed with strengthening bars
across the ends of their ports or passages, 41, 42, as shown in figure, 2. The
spindle, 47, by the rocking movements of which each valve is worked, extends
completely through the valve longitudinally and is made with a journal, 48, at the
further end, whilst the part, 49, which is between the ends is in the form of a broad
plate extending symmetrically on opposite sides of the axis, its end parts, 50, 51,
itting in slots made for them in the ends of the valve, which is consequently equally
cted on at both ends and is not subjected to torsion.
Valves of our improved construction, and especially when double-ported and
consequently requiring a diminished oscillatory movement, can be safely and
atisfactorily driven at a greater speed, that is with a greater number of strokes
er minute than Corliss valves as heretofore constructed and worked. As the
alves close both the inlet and egress openings of the valve boxes the spaces in
hese boxes do not require to be reckoned as parts of the clearance spaces, and, in
he case of the exhaust valves more particularly, there is in consequence some saving
f steam.

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 :-
The improved construction of Corliss valves for steam engines, each valve being
made of a form obtainable from a solid cylinder, by forming one or two passages
through it, and the valve being arranged to work in connection with ports and
passages at both the inlet and egress sides of the valve box, substantially as herein-
before described and as shown in the accompanying drawings.
Dated this Twenty-second day of May 1889.
EDMUND HUNT.
Applicants' Agent.