Improvements in and connected with Slide-valves of Steam and other Fluid-pressure Engines or Machines.
Year: 1890

page_text: Date of Application, 21st Jan., 1890-Accepted, 22nd Feb., 1890
COMPLETE SPECIFICATION.
Improvements in and connected with Slide-valves of Steam and
other Fluid-pressure Engines or Machines.
I, WILLIAM HOLKER, of 5, Victoria Road, New Brighton, in the County of Chester,.
Engineer, do hereby declare the nature of my said 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 has reference generally to slide valves of steam and other fluid
pressure engines or machines, but it is more particularly applicable for use in steam
engines and especially those in which high pressure steam is employed.
The object of my Invention is, chiefly, to prevent the slide valves of engines and
machines being pressed upon their seats by the steam or other fluid to such an extent as
to cause great friction and wear upon the faces of both the valve and cylinder, and
my Invention consists mainly in the employment of slide valves having a triangular
figure in cross section and using, in connection therewith, plates applied to the
inclined or pitched back of the valve, fixed to the valve case, and adapted to
prevent the fluid pressure from acting upon the back of the valve, or limiting that
pressure.
In order that my Invention may be clearly and exactly understood I will proceed
to describe it with the aid of the drawings hereto annexed. These drawings illustrate
slide valves such as are ordinarily used in locomotives and other analogous engines.
They constitute one example according to the invention; and for the sake of
simplicity the description of the invention will be made with reference to this
example. From this example it will be plainly seen how the invention may be
applied to various other types. of slide valves of fluid pressure engines and
machines.
In the Drawings, Figure 1 is a cross section through a valve chest, showing, in
end view, a valve and relief plates according to the invention; Figure 2 is a plan of
the back of the valve; and Figure 3 is a plan of the cylinder valve face.
Figure 4 shows in end view two slide valves arranged back to back working on
two cylinder valve faces.
Figure 5 shows in end view a modification of the arrangement illustrated in
Figure 4 and Figures 6, 7 and 8 are details thereof.
With reference to the Drawings A designates the slide valve which is of the
triangular figure in cross section; B is the cylinder valve face; C is the valve chest ;
D are the relief plates; and E the bolts by which the plates D are held in position
when adjusted.
In Figure 1 it will be seen the relief plates D are of angular shape, one of the sides
thereof being secured to the side of the valve chest C by the bolts E, which are fixed
therein and pass through the plate. The apertures in the plates through which the
bolts E pass are slotted so as to provide for adjustment to any required extent.
When the plates D are properly adjusted up to the back of the valve, it will be
obvious the steam can then only act and press upon that portion of its surface not
covered by the plates, and this need only be sufficient to keep the valve properly
upon its seat; thus the valve is relieved of a very large proportion of its pressure
which otherwise it would be subjected to, as in ordinary practice.
In Figure 4 the relief devices are four in number, and are made triangular in cross
section and hollow. In this case they are separated by a central web or plate F; this
plate forming the means by which the devices D are kept in position when adjusted. Both
the plate and devices are provided with slotted apertures for receiving the adjusting
bolts E; and when the devices are set or adjusted onto the back of the two valves, each
pair of such devices are moved towards each other until their inclined surfaces touch the

page_text: back of the valves (the valve of course being upon the seats on the cylinder valve
faces), when the bolts E are tightened up and the adjustment is complete.
A similar arrangement and mode of adjustment to that just described with reference
to Figure 4 is also illustrated in Figures 5 to 8 but in this case two relief devices D
are used instead of four and these are adjusted on to the back of the valves by means
of wedges H. To adjust the relief devices D in this case up to or onto the inclined
back of the valves A the wedges H are driven in between the metal of the valve
case and the end plates of the devices D, which in this case are provided with
projecting portions d', by which such devices and wedges are held together. The
result is that the two devices approach each other until they bear upon the valve,
when the bolts E are tightened up, and the operation is complete.
It will be evident, at any time when the devices require re-adjustment onto the
back of the valve, all that is required to do is to slack the bolts E and move the
devices again up and onto the inclined surfaces of the back of the valve, in the manner
above described, and then tighten up the bolts again.
It will be understood that as it is required to relieve the valve or valves from
pressure more or less, so are the devices D constructed to cover more or less of the
surface of the back of the valve or valves; and it will also now be plainly seen that
the invention may be applied to various kinds of steam and other fluid pressure
engines and machines employing slide valves.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed, I wish to say that it is not
intended to limit this invention to the precise angle of inclination of the valve and
relief devices, or the precise construction or form of such devices hut what I do claim
in respect of the herein described invention is :-
1. The combination of slide valve (A) having inclined back, and relief plates or
devices (D) applied, and adapted to operate, substantially as in the manner set
forth for the purposes specified.
2. In valves having relief devices such as described, the arrangement and combina
tion substantially as described of two of such valves (A) and relief devices (B).
3. The combination with the devices D, of the wedges H, substantially as and for
the purposes described.
4. The construction of slide valves and relief devices, and means of adjustment
substantially as set forth respectively with reference to Figures 1, 2 and 3; Figure 4;
and Figures 5, 6, 7 and 8 of the drawings.
Dated this 20th day of January 1890.
WITTTAM TOT I D
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