IMPROVEMENTS IN APPARATUS FOR EQUALIZING OR COUNTER- BALANCING THE PRESSURE UPON SLIDE OR OTHER VALVES
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Edmund Edwards at the Office of
the Commissioners of Patents on the 18th December 1883. A communication
to him from abroad by Abraham Zalm of Rotterdam in the Kingdom of
Holland
EDMUND EDWARDS, of the firm of Edwards and Co:-Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of
Middlesex "IMPROVEMENTS IN APPARATUS FOR EQUALIZING OR COUNTER-
BALANCING THE PRESSURE UPON SLIDE OR OTHER VALVES" [a communication to
him from abroad by Abraham Zalm of Rotterdam in the Kingdom of Holland]
This invention has for its object a novel method of construction and arrangement
of apparatus for the purpose of counteracting the varying pressure under valves
used for closing ports or passages through which high pressure steam or other
elastic fluid is passing.
Assuming that the improved apparatus is to be applied to a disc valve of the
ordinary well known kind fitting upon a seat so as to close an aperture through
which high pressure steam is passing, I arrange the valve in an ordinary valve
box the upper part of which is closed by a cover and an ordinary stuffing-box
through which passes a central spindle rising from the top of the valve. Above
the stuffing-box the spindle passes through a horizontal guide plate the height of
which can be adjusted as desired by means of two vertical screwed bars fixed to
the top of the valve box and passing through holes in the ends of the plate, nuts
being fitted upon the bars above and below the plate, so that the latter can be
fixed in its required position.
Above the plate is arranged a helical spring surrounding the spindle and its
upper end pressing against a horizontal disc screwed upon the spindle and held
down by a second upper horizontal plate also adjustable by nuts upon the vertical
fixed bars already described. The strength of the spring is sufficient to lift the
weight of the valve with its spindle and disc, and is of such length that it can be
compressed for at least the length of the stroke of the valve.
Above the upper horizontal plate described is a third similar horizontal plate
also capable of being adjusted and fixed in position by means of nuts upon the two

page_text: vertical screwed bars, and at the centre of the upper plate is an eye or attachment
from which can be suspended a second helical spring the lower end of which has a
hook which can be inserted into a vertical slot in a plate or bracket upon the
upper side of the disc which is screwed upon the upper end of the valve spindle.
The second spring is of such strength that it requires a weight about equal to
the greatest pressure upon the valve to extend it to the length of stroke of the
latter.
The vertical slot into which the lower end of the upper spring is hooked has a
depth about equal to the length of stroke added to the thickness of the hook
itself, and the two lower horizontal plates are so adjusted that the valve can rise
from its seat for its full stroke without the lower edge of the slot touching the
hook. The upper crossbar is then gradually raised, lifting with it the upper spring,
until a point is reached at which the operation of the two springs upon the valve in
conjunction with the decrease of pressure below it will be such that in shutting it
will just touch its seat.
If it be desired that the valve should be held with some force upon its seat the
upper crossbar is brought somewhat lower so that the action of the upper spring
is reduced. In the way described valves such as those of large pumping Engines,
which are ordinarily forced down with great pressure, can be operated with very
much less power than is usually the case.
In cases where the valves are not required to close with such accuracy upon their
seats, the valve may be made to pass down more or less into the cylindrical
opening which it is to close, instead of closing upon a seat; and in this way any
accidentally increased pressure upon the valve is balanced, whilst the closing of the
lower spring will prevent the valve from being forced down too far. The novel
combination of springs as described may be applied to slide or other valves as well
as to disc valves, where their thickness of metal is sufficient to cause considerable
pressure upon them.
Elliptic, flat, or other springs, may be used instead of helical ones as above
described, and the relative position of the two springs may be inverted or otherwise
varied to suit the circumstances in which they are to be applied.
Or sometimes more than two springs may be used in the manner described,
working together or separately, or arranged to come into operation one after
another at different parts of the stroke of the valve, so as to counterbalance wholly,
or partly the varying pressure upon the latter.