Improvements in Balanced Slide Valves for Steam Engines.
Year: 1898

page_text: Date of Application, 29th Dec., 1898-Accepted, 4th Feb., 1899
COMPLETE SPECIFICATION
Improvements in Balanced Slide Valves for Steam Engines.
I, SAMUEL SMITH YOUNGHUSBAND, of Granville Terrace, Woodlands Road,
Darlington, in the County of Durham, Engineer, do hereby declare the nature
of this invention and in what manner the same 18 to be performed to be parti-
cularly described and ascertained in and by the following statement. -
This invention relates to balanced slide valves for locomotive and other steam
engines, and consists in an improved design and simple construction whereby
the balancing of the valve is ensured by steam pressure alone without the aid of
springs which are liable to fail and whereby both of a pair of valves working
back to back in the same steam chest are balanced by one and the same means.
According to this invention the valve is provided with a self-adjusting displacer
held by steam pressure to work against the cover of the steam chest or against the
back of another valve in the case of a pair of engines whereof the valves work
back to back as in some inside cylinder locomotives
The invention will be described with reference to the accompanying drawings
forming part of this specification wherein Figure 1 18 a real face view of a
balanced slide valve. Figure 2 18 a longitudinal section of the same on line 2-2
Figure 1, shewing the self-adjusting displacement device which may be either
on the valve chest cover or on the back of another valve shewn in dotted lines,
the two valves working back to back, and Figure 3 is a transverse section taken
on line 33, also shewing two valves back to back The same letters of refer-
ence indicate the same parts in all the Figures
In the back of the valve A there is fitted a displacement device consisting of
two rings B B united in one piece substantially in the form of a figure of 8 of
which the two loops fit as pistons in a correspondingly shaped cavity or groove (
in the back of the valve from which the working face of such displacer pro-
jects so as to work against a seat G, the working face b being preferably counter-
sunk at the middle or transverse portion in order to reduce friction
The
breadth of the cavity C 18 greater than that of the displacer B so as to enable
the difference of effective area hereafter referred to, to be obtained and the dis-
placer B 18 kept steam tight in its cavity C by means of two pans of split packing
rings D and E for each loop of the displacer The packing rings D of each such
loop work steam tight against the inner wall of cavity C and are sprung into
a groove of recess d formed in the inner wall of the displacer B in which the
said packing rings fit steam tight so that the packing rings D virtually form
part of the displacer B, in 80 far that they expose an area of surface to steam
pressure within the cavity C additional to that exposed by the displacer B itselt.
The packing rings E, on the contrary, work steam tight against the inner side
of the displacer B and are held in a recess formed or enclosed by a flanged junk
ring by which the rings E are made steam tight and are secured to the
valve A By this arrangement the effective areas of the two surfaces of the

page_text: displacer ring B are different, that of the rear surface, plus the area of the
packing rings D, being greater than that of the face of the displace which
works against the seat G
The cavity C 1s constantly supplied with steam from the steam chest through
inlet passages c and the displacer B 18 prevented from bottoming in the cavity C
by projecting studs b so that steam can always enter behind at By this means
the displacer B is constantly pressed outwards so as, in participating in the
travel of the valve A, to work steam tight against the seat G.
In order to permit the escape of any steam which might leak into the spaces I
at the back of the valve A enclosed by the loops of the displacer B, relief
valves II are seated over thoroughfares J opening from the said spaces I into the
exhaust cavity K of the main slide valve A each rehef valve being held closed
to its seat by a spiral spring contained within a cylindrical chamber in the
boss h¹ of the valve H the spring being confined between the inner end of the
boss and the head h³ of a fixed guide pin h upon which the valve boss h¹ slides,
the head of the pin fitting as a piston in the bore of the chamber h¹ The
guide pin h² 18 fixed centrally in the thoroughfare J and is carried by cross bars
at the rear end of the said thoroughfare fixed to or formed with the valve A and
the hollow boss A¹ 18 enclosed on the back of the relief valve H by a screw
cap * removable to admit of the insertion and adjustment of the spring h
The construction and operation are similar whether in the case of one slide
valve working against a seat G on the valve chest cover or for a pair of slide
valves working back to back in the same steam chest as in Figures 2 and 3 in
which case only one of auch valves would be provided with the displacer Bas
above described the other valve carrying the seat G The steam enters the
cavity or steam way C through the inlets (which open through the edges of the
slide valve A clear of the buckle or strap L attached to the valve rod M) and
acting on the rear face of the displacer B of larger area than the working face b,
the latter will be pressed against the seat G whether such seat be carried on the
valve chest cover or on the back of a partner valve such as A' so that the back
of the valve A or the backs of the two valves A A', in the case of a pair, will
be relieved of steam pressure over the areas enclosed by the displacer whereby
the said valve or valves will be approximately balanced.
Owing to the oblong form of the slide valve A it is necessary, in order to
enclose and elieve from steam pressure a sufficient area of its back surface, to
employ either a single displacer of oblong form or two separate displacers And
in order to enable a steam tight fitting of such displacer or displacers to be easily
made and maintained by means of packing rings as herein described, it is neces-
sary that the surfaces against which such packing rings fit should be cylindrical.
It is preferred to employ but a single displacer and this is made in the form of
two substantially circular rings united (in the form of a figure of 8), fitting in
a groove or cavity of corresponding shape the packing rings fitting against
cylindrical surfaces formed by the inner walls of the groove and displacer as
described, but it will be obvious that the displacer might be formed of two
separate circular rings fitting in separate circular grooves or cavities and each
packed by rings C and D as herein described
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. A slide valve balanced by means of a displacer substantially of the form
described fitted piston-like in a corresponding cavity or steam way in the back
of the valve and in communication with the steam chest and wherein the ring
18 made steam tight by means of packing ungs arranged as described so as to
ensure a differential steam pressure whereby the displacer will be maintained
in steam tight working contact with a corresponding seat on the steam chest
cover so as to relieve the back of the valve of steam pressure as described

page_text: 2 A slide valve balanced by means of a displacer of the form, and fitted in
the manner described so as to be acted on by steam pressure as set forth and
fitted with spring pressed relief valves adapted to open from the spaces enclosed
by the displace, into the exhaust cavity of the valve to permit the escape of
any steam that may leak into such spaces, as specified
3. A pair of slide valves working back to back in the same steam chest and
balanced by means of a single displacer fitted to one only of said valves by
means of parking rings as described, so as to be acted on by steam pressure and
maintained in steam tight working contact with a seat on the back of the other
valve as described.
1000
A. M & WM CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
A. M & WM CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.