Improvements in and connected with Equilibrium Slide Valves.
Year: 1894

page_text: Date of Application, 13th Apr., 1894-Accepted, 16th June, 1894
COMPLETE SPECIFICATION.
Improvements in and connected with Equilibrium Slide Valves.
I, JOHN MIDDLETON, of 8 Wood Street, Charlton, Dover, in the County of
Kent, Engineer, 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 :-
This invention relates to a method of balancing or putting slide valves in
equilibrium for the purpose of reducing friction between the bearing faces, and
consequent wear and tear of the working parts.
In the accompanying drawings which illustrate my invention as applied to an
ordinary single ported slide valve, Figure 1 being a longitudinal section, and
Figure 2 a transverse section, I have shown the relieving plate truly hung and
suitably adjusted on the back of the valve by four bolts, and in this case, in order
to ensure the plate being always in contact with the back of the valve, even when
steam is shut off, spiral springs, or their equivalent may be used.
My invention is applicable to slide valves of every description, and consists in
arranging on the slide A a rectangular plate B of relatively larger area than the
slide upon the back face of the valve, in such a manner, that the force with which
the steam pressure keeps the slide valve A up to its work can be reduced to the
lowest possible limit consistent with efficiency from outside the steam chest C by.
screwing up the four bolts D, D, D, D, (two of which only are shown) upon which
said rectangular plate B is hung.
Upon the inside of the steam chest cover E, brackets F are formed to engage
between ribs or projections G upon the plate B to prevent any end movement of
same during the action of the slide valve A which is caused to work between the
port faces H and the face of the rectangular plate B free of any excessive steam or
other pressure, the amount of pressure exerted by the rectangular plate B upon the
back face of the valve A to keep same up to the cylinder port face being regulated
by screw bolts D, D, D, D, that pass through stuffing boxes and glands in the
steam chest cover, the heads J, J, of the bolts being secured in undercut bosses K
on the back of said plate B.
In some cases, the bolts D, D, are encircled by spiral springs L that press.
against the plate B to keep the valve A up to its face when steam is turned off, and
also to prevent any chattering of the moving parts when working under reduced
pressure of steam.
When steam, or any other fluid is applied, the relieving plate B can be adjusted
to the greatest nicety, its under side being in communication with the exhaust
through the hole M.
The steam, or other fluid pressure on its upper side will force the plate against.
the back of the valve, but by screwing up the four lifting bolts D, D, D, D, the
valve A can be relieved of this pressure to any extent, and perfectly balanced.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. The method of suspending a relieving plate on the back of a slide valve for
the purpose and in the manner substantially as hereinbefore described and
illustrated in the accompanying drawings.
2. The arrangement of mechanism for relieving the pressure on the back of the
slide valve of any fluid pressure engine, and consisting of the relieving plate B in

page_text: combination with the relieving bolts D, D, D, D, substantially as described and
shown.
3. The combination of the relieving plate B and the relieving bolts D, D, D, D,
with the spiral springs L, or their equivalent.
Dated thin 12th der of April 1894
H.
GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said John Middleton.