Improvements in and connected with Slide-valves for Steam or other Fluid-pressure Engines.
Year: 1889

page_text: Date of Application, 14h Jan., 1889
Complete Specification Left. 13th Nov.. 1889-Accepted, 14th Dec., 1889
PROVISIONAL SPECIFICATION.
Improvements in and connected with Slide-valves for Steam or
other Fluid-pressure Engines.
I JAMES MARSHALL of the firm of Marshall Sons & Company Limited of Britannia
Iron Works Gainsborough in the County of Lincoln Engineers do hereby declare
the nature of this Invention which has been communicated to me from abroad by
Henry Hanna of Indianopolis Indiana in the United States of America Engineer to
bo as follows:-
This Invention has for its object to provide a slide valve and adjuncts for steam
and other fluid pressure engines which valve will work with a minimum amount of
friction and which offers hy reduction of two small surfaces a ready means of
compensating for wear of the surfaces subject to wear-The Invention has for a
further object to relieve the motor cylinder of excessive pressure due to motive fluid
compression or water of condensation.
According to this Invention the valve is made with its working and opposite faces
parallel and with its ends at right angles thereto whilst the two opposite sides of the
valve are inclined inwardly from the working face towards the top or opposite face
leaving however a flat face at top. The ends of the valve are recessed or made
hollow and a passage is made through the centre of the valve extending from the
working face to the top thereof. The valve slides in a hood or cover bolted down or
secured to the port face of the chest and corresponding in internal shape with the
external shape of the valve. In the said hood or cover channels or passages are
formed corresponding to the inlet and exhaust ports in the port face so that as the
valve in its travel uncovers the ports the motive fluid enters these channels and equili-
briates the pressure the exhaust passing through the central passage in the valve to
the exhaust outlet and it does not interfere with the equilibrium-The outside depth
of these channels corresponds with the depth of the ports on the cylinder face and the
valve is made considerably narrower so that these channels act also as supplementary
motive fluid passages giving a rapid admission of motive fluid to each ond of the
cylinder with a comparatively small travel of the valve. In order to relieve the
cylinder from excessive pressure and water of condensation the aforesaid hood or
cover is provided with passages situated over the inlet ports in the cylinder. These
passages are provided with valves which open to allow of the relief of excessive
pressure and the escape of water of condensation.
The form of the valve and hood or cover as described causes wear of the rubbing
surfaces to be readily and effectually taken up.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in and connected with Slide-valves for Steam or
other Fluid-pressure Engines.
I JAMES MARSHALL of the firm of Marshall Sons and Company Limited of
Britannia Iron Works Gainsborough in the County of Lincoln Engineers do hereby
declare the nature of this Invention which has been communicated to me from abroad
by Henry Hanna of Indianapolis Indiana in the United States of America Engineer
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 for its object to provide an improved arrangement of Slide valve
and adjuncts for Steam and other fluid pressure Engines which Valve will work with

page_text: a minimum amount of friction and offers by reduction of two small surfaces a ready
means of compensating for wear of the surfaces subject to wear. The Invention has
for a further object, to relieve the motor cylinder of excessive pressure, due to motive
fiuid compression or water of condensation. I will describe the Invention with
reference to the accompanying drawings, Figures 1 and 2 of which represent the
valvular arrangements in sections at right angles to each other. Figure 3 is an
underside plan of the hood covering the valve, and Figure 4 shews a plan and side
and end views of the valve proper.
are
According to this Invention, the valve proper A is made with its working face a
and opposite face a² parallel to each other and with its ends a³ ³ at right angles
thereto, whilst the two opposite sides of the valve at a are each of them inclined
inwardly, from the working face towards the top or opposite face, leaving however
the flat face a² at top.-The ends of the valve are recessed or made hollow at b, and
a passage is made through the centre of the valve, extending from the working
face to the top thereof. The valve slides in a hood or cover C, bolted down or secured
to the port face of the chest and corresponding in internal shape with the external
shape of the valve A. In the said hood or cover channels or passages c. c,
formed corresponding to the inlet ports and exhaust port e, in the port face F so
that as the valve A in its travel uncovers the ports, the motive fluid enters these
channels and equilibriates the pressure on the valve, the exhaust passing through the
central passage in the valve to the exhaust outlet and it does not interfere with the
equilibrium. The width of the channels in the hood corresponds with the width of
the ports on the cylinder face and the valve is made considerably narrower so that
these channels act also as supplementary motive fluid passages giving a rapid
admission of motive fluid to each end of the cylinder with a comparatively small
travel of the valve. In order to relieve the cylinder from excessive pressure and
water of condensation, the aforesaid hood or cover is secured by bolts g which bottom
in their holes and leave a clearance between their heads and the upper surface of the
parts of the hood through which they pass. This allows the hood to lift or open to
allow of the relief of excessive pressure and the escape of water of condensation.
To ensure the re-seating of the hood, a spring (or springs) presses the said hood down
as shewn at h, or instead of this, there may be coiled springs under the heads of the
bolts.
The form of the valve and hood or cover, as described, enables wear of the rubbing
surfaces to be readily and effectually taken up.
To prevent wear due to the weight of the valve, shallow recesses are made in the
surfaces to be protected from wear, these recesses being connected with the motive
fluid spaces by means of holes j.-The area of these recesses will be proportioned to
the weight of the valve and the normal pressure of the motive fluid. In an Engine
with a motive fluid chest at top, the recesses should be in the bars between the ports
in the valve sent as shewn in the drawing and when the valve is on the side of the
cylinder, they should be in the bars of the hood (as shewn at 2 Figures 2 and 3,)
upon which the lower edge of the valve slides. The motive fluid entering the recesses
through the holes tends to buoy up the valve, which floating on the cushion of motive
fluid is prevented or in part prevented from having wearing contact with the seat or
hood.
Having now particularly described and ascertained the nature of any said Inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The improvements in and connected with slide valves for Steam engines or other
fluid pressure Engines consisting in the combination of parts substantially as herein-
before decorihad