A BALANCED SLIDE VALVE
Year: 1885

page_text: COREL DELE
I, ALEXANDER HENRY REED, of 90 Cannon Street in the city of London,
Engineer, do hereby declare the nature of the said invention. for A BALANCED
SLIDE VALVE and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
The invention relates to a slide valve to which is firmly connected a counter
balance plate which is exposed to the atmospheric pressure, so that the pressure
exerted by the live steami on the slide valve and also the pressure exerted thereon
by the exhaust steam are counter-balanced, the former by the pressure of the live
steam on the counter balance plate, and the latter by the atmospheric pressure
acting on said counter balance plate. The seat of the counter balance plate is
provided with an elastic support so that the same can be adjusted and by its
adjustment both valves can be correctly seated.
In the accompanying drawing
Fig 1 represents a longitudinal section of a steam cylinder provided with the
improved balance valve."
Fig 2 is a face view of the cover of the valve chest detached.
Similar letters indicate corresponding parts.
In this drawing the letter A designates the cylinder of a steam engine, B is the
valve chest and C is the slide valve. The slide valve is seated on the bottom of
the valve chest and steam is admitted to it through a pipe D which enters at any
suitable point. E is the exhaust port, and F, F¹ are the steam ports. With the
slide valve C is combined a counterbalance plate G which has its seat on the
cover of the valve chest. Said counterbalance plate is connected to the slide
valve by one or more columns a which are provided with top and bottom
flanges b, c, and secured to the slide valve by screws d and to the counterbalance
plate by screws e. Said columns extend through a slot f in the cover of the valve
chest so that they do not interfere with the movement of the slide valve. By
referring to fig. 1 it will be seen that the inner surface of the counterbalance plate
is exposed to the action of the live steam which also acts upon the back of the slide
valve and if the area of the exposed inner surface of the counterbalance plate is

page_text: equal to the area of the back of the slide valve, the latter is balanced against the
action of the live steam. At the same time the outer surface of the counterbalance
plate is exposed to the pressure of the atmosphere and the inner surface of the
slide valve is exposed to the pressure of the exhaust steam so that the action of the
exhaust steam on the slide valve is counterbalanced by the action of the atmosphere
on the counter balance plate or nearly so.
Of course the area of the counterbalance plate must be changed according to the
nature of the engine. If my slide valve is used for a low pressure engine, the area
of the exposed inner surface of the counterbalance plate must be somewhat larger
in proportion to the exposed area of the slide valve than it is if the slide valve is
used for a high pressure engine but it will be readily seen from the foregoing
description that by properly guaging the area of the counter balance plate G, the
slide valve can be balanced in regard to the pressure of the live steam as well as in
regard to the action of the exhaust. The counter balance plate is made detachable
from the slide valve so that the valve and plate can be ground down upon their
seats independent of each other.. In order to be able to seat the valve and plate
correctly I provide the cover H with a recess into which is placed a sheet g of
india rubber and a metallic plate 7, which latter forms the seat for the counter-
balance plate: The plate his secured to the cover H by screws i and by means
of these screws and the elastic support the plate h can be so aljusted, that both
the slide valve and the counterbalance plate are correctly seated.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1 The combination with the slide valve C and the exhaust port E situated
beneath said slide valve and with the counterbalance plate which is firmly
connected to the slide valve of a yielding seat for said counterbalance plate
arranged on the outside of the valve chest substantially as and for the purpose
described.
2. The combination substantially as hereinbefore described, with the slide valve
and with the counterbalance plate firmly connected to the slide valve of the
metallic plate h secured to the valve chest and forming the seat for the counter-
balance plate and of the elastic support g placed beneath said metallic plate.
Dated this twentyfourth day of February 1885