Year: 1885

page_text: I, ROBERT MATTHEWS, of Green Bank, Hyde in the County of Chester, Engineer,
do hereby declare the nature of this invention to be as follows:-
The slide of a steam engine which is usually pressed against the facing of the
cylinder, is capable of being forced away by excess of pressure from within, such
as may result from the presence of water in the cylinder at or near the end of a
stroke; and thus the slide by its yielding operates as a relief valve. When,
however, the valve employed is in the form of a piston working in a cylindrical
slide case, there can be no such yielding to excess of internal pressure, and, con-
sequently, unless special relief valves be provided, excessive strain and damage may
result from the presence of water in, the cylinder. My invention relates to a
construction of piston valve combined with a relief valve, whereby while the
piston valve, itself accurately fitting its cylindrical case, is covering a port,
provision is made for escape of water from the covered port. For this purpose,
I form in the piston part of the slide a cavity with lateral holes opening outwards
at the periphery, and with an annular opening and valve seating on that side of
the piston which is presented towards the exhaust passage. To this seating I fit
an annular valve which is pressed by a helical spring surrounding the valve rod,
the strength of this spring being, like that of an ordinary relief valve, adjusted to
load the valve somewhat above the maximum steam pressure. When the piston
part of the slide is covering the port, any water under pressure that may be
present in the port can pass through the lateral apertures into the cavity and
escape thence into the exhaust compartment of the slide case by opening the valve
in opposition to the spring. In cases where the exhaust compartment of the slide
case is in the middle, between two slide pistons, one spring embracing the slide rod
may serve for the relief valves of both of these pistons, each of these valves
opening towards the exhaust. In cases where a relief valve of the kind above
described cannot conveniently open to the exhaust, I provide in the slide case a
special cavity to which it can open, this cavity being connected by a pipe or passage
with the exhaust.

page_text: I, ROBERT MATTHEWS of Green Bank Hyde in the County of Chester, 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 which is usually pressed against the facing of
the cylinder, is capable of being forced away by excess of pressure from within,
such as may result from the presence of water in the cylinder at or near the end
of a stroke; and thus the slide by its yielding operates as a relief valve. When,
however, the valve employed is in the form of a piston working in a cylindrical
slide case, there can be no such yielding to excess of internal pressure, and
consequently, unless special relief valves be provided, excessive strain and damage
"may result from the presence of water in the cylinder. 'My invention relates to a
construction of piston valve combined with a relief valve, whereby, while the
piston valve itself accurately fitting its cylindrical case is covering a port, provision
is made for escape of water from the covered port. For this purpose, I construct
the combined slide and relief valve as shewn in the accompanying drawing which
represents a longitudinal section. I form in the piston part of the slide a cavity A
with lateral holes opening outwards at the periphery, and with an annular opening
and valve seating on that side of the piston which is presented towards the exhaust
passage C or G. To this seating I fit an annular valve B which is pressed by a
helical spring D surrounding the valve rod, the strength of this spring being, like
that of an ordinary relief valve, adjusted to load the valve somewhat above the
maximum steam pressure. When the piston part of the slide is covering the port E
or F, any water under pressure that may be present in the port can pass through
the lateral apertures into the cavity A and escape thence into the exhaust com-
partment of the slide case by opening the valve in opposition to the spring. In
cases where the exhaust compartment of the slide case is in the middle, between
two slide pistons, one spring embracing the slide rod may serve for the relief
valves of both of these pistons, each of these valves opening towards the exhaust.
In cases where a relief valve of the kind above described cannot conveniently open
to the exhaust, I provide in the slide case a special cavity to which it can open as
shown at H this cavity being connected by a pipe or passage with the exhaust.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is: :-
In combination with the piston of a piston valve for a steam engine, an annular
relief valve, substantially as and for the purpose herein set forth.
Dated this 8th day of July 1886.
ABEL & IMRAY,
.Agents for the Applicant.