IMPROVEMENTS IN STEAM-VALVES OR CUTT-OFF GEAR
Year: 1880

page_text: LETTERS PATENT to Charles Stuart, of Bletchley Iron Works, Fenny
Stratford, in the County of Bucks, Mechanical Engineer, for an Invention
of " "IMPROVEMENTS IN STEAM-VALVES OR CUTT-OFF GEAR."
PROVISIONAL SPECIFICATION left by the said Charles Stuart at the Office
of the Commissioners of Patents on the 17th November 1880.
CHARLES STUART, of Bletchley Iron Works, Fenny Stratford, in the County of
Bucks, Mechanical Engineer. IMPROVEMENTS IN STEAM VALVES OR CUT-OFF
GEAR."
"
This Invention relates to a novel method of actuating the valves for the
admission and emission of steam to & from the cylinders of steam engines, and
the particular construction and arrangement of such valves, by which a simple &
efficient automatic cut-off is produced without the very great friction and consequent
wear and tear of the common form of slide-valve hitherto used. I do not confine
myself to one precise method of arranging the particular parts, as these may be
variously arranged or modified without in any way departing from the main
principles of my Invention, but what I claim is, the application of circular or
other valves having concentric areas acted upon by steam or other fluids for the
purpose of supplying and discharging steam to & from steam cylinders.
For this purpose I use four valves, two for admission and two for emission of
steam, which I place in chambers in the jacket of steam cylinder. A tube or
lining bush passes between the valves having openings or passages in it for the
steam to pass through to or from the valve chambers. In this tube I place the
expansion cylinder or moveable tube with the theoretical curve of expansion marked
upon it. On starting the engine motion is given to the expansion cylinder by a
rod through any convenient method of communicating a reciprocating, semi-rotary,
or other like movement. The expansion cylinder during its movement passes
round and opens and closes the valve passages alternately as required; and then,
when the passage is thus opened, more steam escapes from the larger area or top
of valve than that which is admitted through the small opening below, and
consequently the action of the steam on the underside of the valve raises it, and
steam is admitted into the steam cylinder,

page_text: If, then, the rod attached to the expansion cylinder is connected with a steam
engine governor, by which it receives a reciprocating and also a longitudinal motion
in the direction of its axis, various times will elapse between opening and closing
the before-mentioned passages proportionate to the particular part of the theoretical
curve described on the expansion cylinder. The steam having now performed its
duty on one side of the piston, and the expansion cylinder having rotated back-
wards the corresponding passage is opened to the next valve, and the pressure
being removed, the steam passes through the exhaust valve to the jacket of the
steam cylinder and thence into the condenser or the atmosphere, the same process
being then repeated alternately at each stroke of the engine.
An exhaust cylinder might also be employed between the expansion cylinder
and the lining bush, so that the exhaust valves may be kept longer open or shut,
as required. This motion may be also applied to steam-pumps, &c.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Stuart in the Great Seal Patent Office on the 16th May
1881.
CHARLES STUART, of Bletchley Iron Works, Fenny Stratford, in the County of
Bucks, Mechanical Engineer. "IMPROVEMENTS IN STEAM VALVES OR CUT-OFF
GEAR."
This Invention relates to a novel method of actuating the valves for the
admission and emission of steam to and from the cylinders of steam-engines, and
the particular construction and arrangement of such valves, by which a simple and
efficient automatic cut-off is produced without the very great friction and consequent
wear and tear of the common form of slide valve hitherto used. I do not confine
myself to one precise method of arranging the particular parts, as these may be
variously arranged or modified without in any way departing from the main
principles of my Invention, but what I do claim is, the application of circular or
other valves having concentric areas acted upon by steam or other fluids for the
purpose of supplying and discharging steam to and from steam cylinders. For
this purpose I use four valves, two for admission and two for emission of steam,
which I place in chambers in the jacket of a steam cylinder. A tube or lining
bush passes between the valves, having openings or passages in it for the steam to
pass through to or from the valve chambers. In this tube I place the expansion
cylinder or moveable tube, with the theoretical curve of expansion formed upon it.
On starting the engine motion is given to the expansion cylinder by a rod through
any convenient method of communicating a reciprocating motiorotary or other like
movement. The expansion cylinder during its movement passes round and opens
and closes the valve passages alternately as required, and then, when the passage is
thus opened, more steam escapes from the larger area or top of valve than that
which is admitted through the small opening below, and consequently the action of
the steam on the under side of the valve raises it, and steam is admitted into the
cylinder. If, then, the rod attached to the expansion cylinder is connected with a
steam-governor, by which it receives a. reciprocating and also a longitudinal motion
in the direction of its axis, various times will elapse between opening and closing
the before-mentioned passages proportionate to the particular part of the theoretical
curve described on the expansion cylinder. The steam having now performed its
duty on one side of the piston, and the expansion cylinder having rotated back-.
wards, the corresponding passage is opened to the next valve, and, the pressure
being removed, the steam passes through the exhaust valve to the jacket of the
steam cylinder, and thence into the condenser or the atmosphere, the same process
being then repeated alternately at each stroke of the engine. An exhaust cylinder
might also be employed between the expansion cylinder and the lining bush, so
that the exhaust valves may be kept longer open or shut, as required.
In further explanation of my Invention I annex a Sheet of Drawings, in
which
Fig. 1 is an end sectional elevation of steam cylinder and jacket, with one
admission and one emission valve within valve box or chamber.
Fig. 2 is a longitudinal sectional elevation of valve chest, showing one admission
and one emission valve, with end section of expansion cylinder.
Fig. 3 is a sectional plan showing general arrangement of the four valves, together
with longitudinal section of expansion cylinder C, lining bush E, and exhaust
cylinder D between.
Fig. 4 is an end section of valve chest cover showing arrangement for admitting
steam from boiler to valves, and the spring used to form a cushion for emission
valves.

page_text: Figs. 5 and 6 are cross sections, and Fig. 7, elevation of expansion cylinder
showing the curve of expansion.
Figs. 8, 9, 10, 11, are sections of exhaust cylinder.
Having now set forth the nature of my Invention, I wish it to be understood
that I claim,―
The application of circular or other valves having concentric areas acted upon
by steam or other fluids, for the purpose of admitting and discharging steam to and
from steam cylinders.
In witness whereof, I, the said Charles Stuart, have hereunto set my hand
and seal, this Thirteenth day of May, in the year of our Lord One thousand
eight hundred and eighty-one.
CHARLES STUART. (L.S.)