AN IMPROVED ARRANGEMENT OF SLIDE VALVES FOR MOTIVE POWER ENGINES
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, EDWARD RICHMOND ALLFREY of South Eden Park, Beckenham in the
County of Kent, Engineer do hereby declare the nature of my invention for
AN IMPROVED ARRANGEMENT OF SLIDE VALVES FOR MOTIVE POWER ENGINES to
be as follows:—
This invention has for its object the improvement of slide valves for steam
engines and more particularly those of large size and using steam of high
pressures.
.
In order to relieve the pressure and consequent friction between the slide face
and the cylinder face, I place two slide valves of the ordinary single, double or
treble ported description back to back in one common slide box and I connect the
two slide, valves together at their backs by an intervening elastic metallic con-
necting piece, either circular, oval or rectangular (with rounded corners) formed'
either of copper, steel or other suitable sheet metal, by preference of copper, the
enclosed space being open to the exhaust. The slide valves may be kept up to
the cylinder face by spiral or other springs and the valves may be driven by single
or a pair of coupled rods.
By this arrangement it will be understood that while the valves are protected
from pressure on their backs they are still free to accommodate themselves to the
cylinder faces and a rapid supply of steam to and exhaust from the cylinder is
effected.
1
NEWTON & SON,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.}
"
I, EDWARD RICHMOND ALLFREY of South Eden Park, Beckenham, in the
County of Kent, Engineer do hereby declare the nature of my invention for
"AN IMPROVED ARRANGEMENT OF SLIDE VALVES FOR MOTIVE POWER ENGINES,”
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
The object of this invention is to improve the working of the slide valves of
steam engines, and more particularly of those of large size in which steam of high
pressure is used.
To this end I place two slide-valves, of the ordinary single, double, or treble
ported description, back to back, in one common slide box, and I connect the two
slide valves together at their backs by an interposed elastic metallic connecting
piece either circular, oval, or rectangular, with rounded corners formed either of
copper, steel, or other suitable sheet metal, by preference of copper, the enclosed
space being open to the exhaust.
In the accompanying Drawing
Fig: 1 is a sectional plan of a steam engine cylinder, shewing the adaptation of
my invention thereto and
Fig: 2 is a vertical section of the valve box with the slide valves in place, the
section being taken in the line 1. 2 of Fig: 1.
A is a cylinder, B the valve box, and CC a pair of double ported slide valves
set back to back. These valves are connected together by an elastic or corrugated
coupling piece D of thin sheet metal, and thereby form together a compound or
duplex valve.
The edges of this sheet metal are made fast to the backs of the valves by means
of gripping frames E E, which are secured to the valves by means of screws e, as
shewn best in the enlarged diagram Fig: 3. A chamber is thus formed between ·
the backs of the valves and the pressure, therefore, of the live steam upon the
valves is limited to the portion of the backs exposed to contact with the steam.
The limited pressure thus provided will in general suffice to hold the valves to
their seats, but this pressure may be supplemented, if desired, by springs inserted
in the chamber. c is a hole made through each valve to bring the chamber into
communication with the exhaust passages but the exhaust steam may be otherwise
admitted within the compound valve. The valves work over ports formed in the
ends of the valve box and communicating with the steam passages in the cylinder.
For working the compound or duplex valve, a forked valve rod, or two valve rods
connected by a cross head may be employed.
By the use of this arrangement of compound or duplex valve, it will be under-
stood that while the valves are protected from the undue pressure of steam upon
their backs they are still free to accommodate themselves to the cylinder faces and
a rapid supply of steam to and exhaust from, the cylinder is effected.

page_text: 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
Constructing compound or duplex slide valves in the manner and for the purpose
above described with reference to the drawing,