Improvements in High Speed Steam Engines.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in High Speed Steam Engines.
I, ALLAN COATS, Jr., of Hayfield, Paisley, in the County of Renfrew, Draughts-
man, do hereby declare the nature of this invention to be as follows:-
This invention, which relates to high speed steam engines, has for its object
to provide such an engine of the single acting type wherein the steam distribu-
tion and valve arrangements are simplified and improved and wherein special
provision is made for cushioning the high pressure piston.
In a single cylinder engine steam is admitted to the under side of the piston
through a port or passage from a valve casing wherein is fitted a piston or
other valve operated to uncover the port for admission of steam, to cut off at any
part of the stroke and to open the port to exhaust. The upper end of the cylinder
above the piston is closed and boiler steam is admitted thereto through a non-
return reducing valve, for the purpose of cushioning the piston, or taking up
the inertia of the reciprocating parts. The engine is in general of the vertical
type (but may be horizontal or inclined) and the upper end of the piston means the
end furthest removed from crank shaft. A two way valve is provided so that
the steam may be exhausted from the upper end of cylinder to the atmosphere
while the boiler steam is shut off from the reducing valve, and to close the outlet
to the atmosphere when the boiler steam is admitted to the reducing valve.
In lieu of the boiler steam air or steam and air may be admitted to the upper
end of the piston.
In multiple cylinder engines two cylinders and pistons are arranged tandemwise
with the high pressure cylinder on top and low pressure cylinder below. The steam
for operating the engine is admitted as in a single cylinder engine through a
port in the lower end of the high pressure cylinder; it is exhausted therefrom to
the top of the low pressure cylinder and it passes thence to the lower end of
the low pressure cylinder wherein after expansion it exhausts to the atmosphere.
Two valves only are provided and fitted on the same spindle, one serving for
the high pressure cylinder and the other to cover and uncover a port at the
lower end of the low pressure cylinder, steam being admitted to the lower
side of the piston in the high pressure cylinder whilst the steam from the upper
end of the low pressure cylinder is admitted to the lower end of the latter, and the
high pressure cylinder exhausting to the top of the low pressure cylinder whilst
the latter exhausts from the lower side of the piston to the atmosphere. The
reciprocating parts are cushioned as in the single cylinder engine by means of
steam or air or steam and air on the top of the high pressure piston and by
compression in the space above the upper end of the low pressure piston after
the valve of the low pressure cylinder cuts off. The engine so constructed and
operated is a triple expansion engine but by adding a third cylinder in line it may
be made a quintuple expansion engine.
In single cylinder side by side engines the cylinders and valves are arranged
and the steam admitted as above described but the steam exhausting from the

page_text: bottom of the high pressure cylinders would pass to the bottom of the low
pressure cylinders, and each cylinder may be cushioned as in the single cylinder
arrangement.
Sets of side by side tandem cylinders may be used the steam distribution and
valves being as in the single tandem arrangement described.
Dated this 17th day of June 1898.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
Saint Vincent Street, Glasgow, Agent for the Applicant
I, ALLAN COATS, Jr., of Hayfield, Paisley, in the County of Renfrew, Draughts-
man, 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:-
This invention, which relates to high speed steam engines, has for its object
to provide such an engine of the single acting type wherein the steam distribu-
tion and valve arrangements, are simplified and improved and wherein special
provision is made for cushioning the reciprocating parts of the engine.
The invention is illustrated by the accompanying drawings, Figs. 1 and 2 being
vertical sections of slightly modified forms of a single cylinder engine as con-
structed under my invention. Fig. 3 is a section of a detail, and Fig. 4 a vertical
section of a multiple cylinder engine.
In a single cylinder engine steam is admitted within the cylinder A to the under
side of the piston A through a port or passage B from a valve casing C wherein
is fitted a piston valve D or other valve operated to uncover the port B for
admission of steam, to cut off at any part of the stroke and to open the port B to
exhaust. The upper end of the cylinder A above the piston A¹ is closed and
boiler steam is admitted thereto preferably through a non-return reducing
valve E, such as shown in detail at Fig. 3, or through a bye-pass G, covered
alternately by an extension of the piston and an extension of the valve, as shown
at Fig. 2, for the purpose of cushioning the piston A', or taking up the inertia
of the reciprocating parts. On Fig. 2, at H, an alternative plan of bye-pass non-
return valve is shown, whereby the cushioning steam instead of being at boiler
pressure is admitted to the upper side of the piston from the under side thereof at
a predetermined part of the stroke. The engine is in general of the vertical
type (but may be horizontal or inclined) and the upper end of the piston means
the end furthest removed from crank shaft. A two way valve E is provided in
conjunction with or forming part of the reducing valve E, so that the steam may
be exhausted from the upper end of cylinder A to the atmosphere while the
boiler steam is shut off from the reducing valve E and to close the outlet to the
atmosphere when the boiler steam is admitted to the reducing valve E, or it
may be closed to both steam and atmosphere. In lieu of the boiler steam, air or
steam and air may be admitted to the upper end of the piston.
In multiple cylinder engines two cylinders A2, A3, and pistons A, A³, are
arranged tandemwise, as shown at Fig. 4, with the high pressure cylinder A³ on
top and low pressure cylinder A3 below. The steam for operating the engine
is admitted as in a single cylinder engine through a port B in the lower side

page_text: of the high pressure piston A², it is exhausted therefrom to the top of the low
pressure piston A³ expanding meanwhile, and it passes thence by way of a port F
to the lower side of the low pressure piston A wherein after exansion it exhausts
to the atmosphere. Two valves 1), D³, only are provided and fitted on the same
spindle D3, one serving for the high pressure cylinder and the other to cover and
uncover the port at the lower end of the low pressure cylinder A³, steam being
admitted to the lower side of the piston A4 in the high pressure cylinder A² whilst
the steam from the upper end of the low pressure cylinder A3 is admitted to the
lower end of the latter, and the high pressure cylinder A2 exhausting to the top
of the low pressure cylinder A3 whilst the latter exhausts from the lower side of
the piston A5 to the atmosphere. The reciprocating parts are cushioned as in the
single cylinder engine by means of steam or air or steam and air on the top of
the high pressure piston A4 and by compression in the space above the upper
end of the low pressure piston A5 after the valve of the low pressure cylinder cuts
off. The engine so constructed and operated is a triple expansion engine but
by adding a third cylinder in line it may be made a quintuple expansion engine.
In single cylinder side by side engines the cylinders and valves are arranged
and the steam admitted as above described but the steam exhausting from the
bottom of the high pressure cylinders would pass to the bottom of the low
pressure cylinders, and each cylinder may be cushioned as in the single cylinder
arrangement.
Sets of side by side tandem cylinders may be used the steam distribution and
valves being as in the single tandem arrangement described.
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:―
1. A high speed steam engine the several parts of which are constructed and
arranged to operate substantially as described.
2. A single cylinder high speed engine in which the steam is admitted,
expanded and exhausted below the piston and a steam or air buffer formed above
the piston substantially as described.
3. A high speed steam engine wherein the steam is admitted to the under side
of the piston of a high pressure cylinder, is exhausted therefrom and expanded
above the piston of a low pressure cylinder and thence passes to and is expanded
in the lower end of said cylinder and finally exhausted therefrom, substantially
as described.
4. A single acting high speed engine operated as described in the preceding
claim in combination with a steam or air buffer or cushion formed above the
piston of the high pressure cylinder substantially as described.
5. The modification of high speed engine referred to in Claims 3 and 4 in
which a third cylinder is added wherein the steam is expanded above and below
the piston, substantially as described.
Dated th: 1011.
el 1000
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
62, Saint Vincent Street, Glasgow. Agent for the Applicant.