An Improvement in Single Acting Compound Steam Engines.
Year: 1898

page_text: Date of Application, 5th May, 1898
Complete Specification Left, 1st Feb., 1899-Accepted, 4th Mar., 1899
PROVISIONAL SPECIFICATION.
An Improvement in Single Acting Compound Steam Engines.
We, WILLIAM HOPE WILSON, Engineer, and ROBERT BRYSON MITCHELL, Secretary
of the Mirrlees Watson & Yaryan Company Limited, both of 45, Scotland Street,
Glasgow, in the County of the City of Glasgow, do hereby declare the nature of
this invention to be as follows:-
-
In our Specification No. 8580 of 1897 we described an arrangement of single
acting compound steam engine having two parallel cylinders with a valve chest
between them occupied by a pair of double piston slide valves on one rod. As
the lower slide valve and ports are there arranged the under part of the low pres-
sure cylinder beneath its piston is always in communication with the exhaust
chamber E. This is objectionable especially in condensing engines because the low
pressure cylinder is thus to a certain extent subject to the comparatively low
temperature existing in the condenser.
Our present invention relates to a modification whereby the low pressure cylinder
has its lower part cut off from the exhaust chamber except when its piston is
descending.
For this purpose as shewn in the accompanying drawing which is a vertical
section of the cylinders and slide valves we enclose a space E, at the part marked E
in the drawing annexed to our previous specification, the space so enclosed being
in communication with the exhaust passage which is shewn by a dotted circle, and
we also elongate
we make a port B opening into this space E from the valve chest ;
the lower piston 2 of the lower slide valve so as to cover the port B when the slide.
valve is up. When the low pressure piston is descending the slide valve being
down, the port Q2 is in communication through the annular passage with the
new port B and the partitioned off space E with the exhaust; but when the low
pressure piston is ascending, the slide valve being then up, this communication
is cut off, and the ports Q1 Q2 being in communication through the annular
space 1, the lower part of the low pressure cylinder receives steam from the upper
port.

page_text: Glasgow, in the County of the City of Glasgow, 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:-
In our Specification No. 8580 of 1897 we described an arrangement of single
acting compound steam engine having two parallel cylinders with a valve chest
between them occupied by a pair of double piston slide valves on one rod. As
the lower slide valve and ports are there arranged the under part of the low pres-
sure cylinder beneath its piston is always in communication with the exhaust
chamber E. This is objectionable especially in condensing engines because the low
pressure cylinder is thus to a certain extent subject to the comparatively low
temperature existing in the condenser.
Our present invention relates to a modification whereby the low pressure cylinder
has its lower part cut off from the exhaust chamber except when its piston is
descending.
For this purpose as shewn in the drawing accompanying our Provisional
Specification which is a vertical section of the cylinders and slide valves we enclose
a space E at the part marked E in the drawing annexed to our previous specifica-
tion, the space so enclosed being in communication with the exhaust passage
which is shewn by a dotted circle, and we make a port B opening into the space E
from the valve chest; we also elongate the lower piston of the lower slide valve
so as to cover the port B when tlie slide valve is up. When the low pressure
piston is descending the slide valve being down, the port Q2 is in communication
through the annular passage with the new port B and the partitioned off space E
with the exhaust, but when the low pressure piston is ascending, the slide valve
being then up, this communication is cut off and the ports Q1 Q3 being in com-
munication through the annular space the lower part of the low pressure cylinder
receives steam from the upper port.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that what we
claim is:-
The modification of the valves and cylinders described in the Specification
No. 8580 of 1897 whereby the lower side of the low pressure cylinder is cut off
from direct communication with the condenser, substantially as and for the pur-
pose set forth.
Dotod this 1st da
1000