Improvement in the Construction of Valves and Valve Gear for Steam or other Motive Power Engines.
Year: 1891

page_text: Date of Application, 31st Dec., 1891
Complete Specification Left, 30th S pt., 1892-Accepted, 31st Dec., 1892
PROVISIONAL SPECIFICATION.
Improvement in the Construction of Valves and Valve Gear for
Steam or other Motive Power Engines.
We, JOHN WILD of Falcon Iron Works Oldham in the County of Lancaster
Engineer and JOSEPH HOWARTH MARSDEN Back King Street Oldham in the
County of Lancaster Mechanic, do hereby declare the nature of this invention to
be as follows:-
:-
Our improvements have for their object the construction of slide valves and their
seats in such a manner that the surfaces of the moving parts exposed to the steam
pressure are so arranged as to put them in equilibrium or thereabouts and also in
mechanism for cutting the steam off at any part of the stroke.
In constructing a slide valve and seat according to our invention we make a
casting for the valve in such a form that each side is similar to an ordinary slide-
valve face but made taper in section and fitted into a suitably prepared recess with
the broad end towards the base of the seat and having a wedge at the bottom so
that the valve may be forced outwards towards the facing should any wear take
place.
In constructing a seat each of the ports are divided in two each division having
the same area and curved so that each division is brought opposite the other in
such a manner that equal steam is admitted and exhausted on each side of the valve
And in order to get equal
thereby placing it in equilibrium in that respect.
pressure on each edge of the valve we make a recess or groove in the broad edge
equal to the area of the narrow edge so as to admit steam between the wedge and
the valve.
In some cases it may be more convenient or advisable to make the valve parallel
in which case suitable arrangements may be adopted to compensate for wear and in
other cases it may be more convenient to have the wedge piece on the side instead
of on the bottom with suitable arrangements for securing same.
For cutting off the steam at various parts of the stroke we employ two blocks one
at each end of the valve sliding in suitable paths so that they may be moved into
such a position as to close the ports and actuated by suitable mechanism driven by
cams whose motion may be reduced or retarded by the action of a governor or other
suitable means.
It will thus be seen that steam will be cut off at various parts of
the stroke early or late according as the cams have been advanced or retarded.
JOSEPH HOWARTH MARSDEN.
COMPLETE SPECIFICATION.
Improvement in the Construction of Valves and Valve Gear for
Steam or other Motive Power Engines.
We, JOHN WILD of Falcon Iron Works Oldham in the County of Lancaster
Engineer and JOSEPH HOWARTH MARSDEN Back King Street Oldham in the
County of Lancaster Mechanic, 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:-
Our invention has for its object the construction of slide valves and their seats in
such a manner that the surfaces of the moving parts exposed to the steam pressure
are so arranged as to put them in equilibrium or thereabouts as regards steam
pressure.

page_text: In constructing a slide valve and seat according to our invention we make a
casting for the valve in such a form that each side is similar to an ordinary slide
valve face but made taper in cross section and fitted into a suitably prepared recess
with the broad end towards the base of the seat and having a wedge at the bottom
so that the valve may be forced outwards towards the facings should any wear take
place.
In constructing a seat each of the ports are divided in two each division having
the same area and curved so that each division is brought opposite the other in such
a manner that equal steam is admitted and exhausted on each side of the valve
thereby placing it in equilibrium in that respect. And in order to get equal
pressure on each edge of the valve we make a recess or groove in the broad edge
equal to the area of the narrow edge so as to admit steam between the wedge and
the valves.
In the accompanying drawing Fig. 1 is a longitudinal sectional elevation. Fig. 2
is a sectional plan through the line C D and Fig. 3 is a cross sectional elevation on
the line A. B. a is the valve bis the adjusting wedge c is the valve-seat d are the
steam ports leading into the cylinder steam ports k. e are the exhaust ports leading
into the cylinder exhaust ports m. f is the narrow edge of valve. is the groove
in base equal in area to the narrow edge f. h are the exhaust chambers in valve a.
The valve seat c may be made in one casting with the cylinder or may be made
separate and secured by means of bolts n as shewn.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is―
1st. A taper slide valve having a groove in the broad edge equal in area to the
narrow edge for the purpose described and as illustrated by the accompanying
drawings.
2nd. A wedge adjustment for slide valves for the purpose described and as
illustrated by the accompanying drawings.
September 29th 1892.
JNO. WILD.
JOSEPH HOWARTH MARSDEN.