IMPROVEMENTS IN LOCOMOTIVE AND OTHER ENGINES
Year: 1858

page_text: This Invention received Provisional Irotection, out
что
application for Letters Patent was not given within the time prescribed
by the Act.)
PROVISIONAL SPECIFICATION left by Charles Patrick Stewart and David
Graham Hope at the Office of the Commissioners of Patents, with their
Petition, on the 4th March 1858.
We, CHARLES PATRICK STEWART, of the firm Sharp, Stewart, and Company,
of the City of Manchester, Engineers, and DAVID GRAHAM HOPE, of the
same Place, Civil Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN LOCOMOTIVE AND OTHER ENGINES," to be as follows:-
Firstly, our Invention relates to those engines in which the immission and
emission of the steam or other motive power is regulated by a slide valve or
by slide valves, and its principal object is to remove the excessive pressure on.
the back of the valve, forcing it against its facing; but there are other
advantages consequent.
Our Invention consists of the following arrangements :-The upper part of
the ordinary valve is extended at each end, so that the steam or other motive
power to be admitted-into the "ports" can only enter at the sides of the valve,
and flanges are formed on each side of the valve. The valve thus formed
when working is covered over by a casing which has two facings. One flange
of the valve works against an interior facing on one side, and the other flange
of the valve against an exterior facing on the other side of the casing; with
this arrangement the steam or other motive power is prevented from getting to
the back of the valve that is between the casing and the valve, as it is kept

page_text: close upon the ports by vertical pressure, and against the sides of the casing
by lateral
pressure.
The tendency which the steam or other motive power has to lift the valve is
counteracted by the external pressure acting on the edges of the flanges on the
sides of the valve, the area of which is so proportioned as to give a sufficient
surplus of pressure to keep the valve down. An excess of lateral pressure is
likewise obtained to keep the valve against its side facings on the casing by
making the side area of the flange on one side exposed to pressure in excess
of that on the other side. With this arrangement of valve a "stuffing-box
and "valve spindle "may be dispensed with, and the valve connecting rod may
be attached directly to the valve, as the interior of the casing and back of the
valve are open to the atmosphere.
This arrangement is also applicable in that system of slide valve where an
"exhaust port" is not used; but in this case the back of the valve is exposed
'to the pressure of the exhaust steam or other motive power, but this exhaust
pressure is counteracted wholly or partly by the full pressure of the motive
power acting within the valve to lift it.
Secondly, our Invention relates to those engines in which the immission and
emission of the steam or other motive power is regulated by a slide valve or
slide valves, and is particularly applicable to such engines as are worked at
high speeds.
Hitherto it has been usual to form and arrange slide valves so that when in
the central position they will cover or close the ports or passages leading to
both ends of the cylinder. Now we have discovered, and in this our Invention*
consists, that it is advantageous to form and arrange the slide valves having
"lap" on the admission side and the ports so that when the valves are in the
central position the ports or passages leading to both ends of the cylinder will'
be partly open to the exhaust. The advantages resulting from this modifica
tion of valves or ports consist in diminishing the "compression" and "back
pressure," and in the production of a more easy and uniform exhaust and
steady blast, by which an economy of motive power is obtained: