An Improved Arrangement and Apparatus for Casting Bronze Slide Valves.
Year: 1892

page_text: Date of Application, 28th Apr., 1892
Complete Specification Left, 27th Jan., 1893-Accepted, 22nd Apr., 1893
PROVISIONAL SPECIFICATION.
An Improved Arrangement and Apparatus for Casting Bronze Slide
Valves.
I, JOHN DEWRANCE of 158 Great Dover Street, London S.E. Engineer, do
hereby declare the nature of this invention to be as follows:—
The slide valve of a steam engine generally has a thick rectangular flange,
one face of which works upon the cylinder.
The cavity in the centre of this flange that forms the passage for the exhaust
is enclosed by what may be called the crown of the slide valve to distinguish it
from the flange. The outside of the crown fits into the buckle of the valve
spindle. The crown is of a much thinner substance of metal than the flange
and when cast in a sand mould in the usual way solidifies first, the flange solidifies
more slowly and the metal of this part has time to crystallize into large crystals
so that it is not so homogeneous as is desirable.
In work a slide valve is subject to great variations of temperature due to the
heat of steam and to friction, and the less homogeneous the metal is the more
it is liable to crack. I cast the face of the flange that forms the working surface
of the slide valve on a slab of iron or steel. A sand core is secured to the slab
in any suitable way to form the inside of the crown or exhaust passage and a
sand half mould is laid upon the iron slab so as to form a complete mould.
I coat the iron or steel with some refractory powder cemented by a suitable
material to cause it to adhere to the slab while the metal is poured into the
mould.
By casting the slide valve in this way the metal of the thick flange is chilled
and solidifies more rapidly than if cast in the usual way, the crystals are much
smaller, the metal more homogeneous, and the slide valve is not so liable to crack
or break when in use.
Dated this 27th day of April 1892.
JOHN DEWRANCE.
COMPLETE SPECIFICATION.
An Improved Arrangement and Apparatus for Casting Bronze Slide
Valves.
I JOHN DEWRANCE of 158 Great Dover Street, London S.E. 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:-
The slide valve of a steam engine generally has a thick rectangular flange, one
face of which works upon the cylinder.
The cavity in the centre of this flange that forms the passage for the exhaust is
enclosed by what may be called the crown of the slide valve to distinguish it from
the flange. The outside of the crown fits into the buckle of the valve spindle.
The crown is of a much thinner substance of metal than the flange and when cast
in a sand mould in the usual way solidifies first.
The flange solidifies more slowly and the metal of this part has time to crystallize
into large crystals so that it is not so homogeneous as is desirable.
In work a slide valve is subject to great variations of temperature due to the
heat of steam and to friction and the less homogeneous the metal is the more it is
liable to crack.

page_text: I cast the face of the flange that forms the working surface of the slide valve on
a slab of iron or steel.
A sand core is secured to the slab in any suitable way to form the inside of the
crown or exhaust passage and a sand half mould is laid upon the iron slab so as to
form a complete mould.
I coat the iron or steel with some refractory powder cemented by a suitable
material to cause it to adhere to the slab while the metal is poured into the
mould.
By casting the slide valve in this way the metal of the thick flange is chilled and
solidifies more rapidly than if cast in the usual way, the crystals are much smaller,
the metal more homogeneous, and the slide valve is not so liable to crack or break
when in use.
On the accompanying sheet of drawings
JOHN DEWRANCE.