IMPROVEMENTS IN SLIDE VALVES AND VALVE CHESTS FOR STEAM ENGINES
Year: 1884

page_text: I, EUSTACE FITZMAURICE PIERS, Baronet, of N° 5 Westminster Chambers,
Westminster in the County of Middlesex do hereby declare the nature of my
invention for "IMPROVEMENTS IN SLIDE VALVES AND VALVE CHESTS FOR STEAM
ENGINES" to be as follows:-
My invention relates to an improved construction of slide valves and valve
chests for steam engines whereby the valves are more or less relieved of pressure
so as to lessen the wear and tear thereof.
For this purpose, the slide valve which has a central exhaust. opening right
through it, and operates in a similar manner to an ordinary D slido, is divided
longitudinally into two separate parts. The part working on the cylinder ports
bas near each end a projecting piece fitting into a correspondingly shaped opening
in the other part, which works against the steam chest cover, and this part has
a flange projecting round its central opening which fits into the central opening of
the first named part. The projections or the openings on either part are formed
with grooves packed with soft metal, or metal which expands more at a certain
temperature than the metal of which the valve is made, or other suitable material
may be used as a packing, so as to enable the parts to work steam tight upon each
other. The steam from the steam chest entering between the meeting surfaces of
the two parts of the slide valve surrounding the above mentioned projections,
presses them apart so as to cause the one to bear against the port face and the
other against the steam chest cover, the degree of such pressure being in proportion
to the area of the said meeting surfaces. Small passages are made right through
the projections on the part working against the ports, and on the inner face of the
steam chest cover arc formed shallow recesses corresponding in configuration to
that of the steam and exhaust ports, so that whatever degree of pressure or
exhaust exists in the cylinder ports covered by the valve, precisely the same
pressure will be transmitted through the said passages and through the central
opening to the corresponding recesses in the steam chest cover, and consequently
whatever pressure or exhaust the valve is subjected to on its working face such
pressure is always balanced by the pressure exerted over a corresponding area by
the steam or exhaust in the recesses of the valve cover.

page_text: Thus, the only pressure exerted upon the valve to cause it to work steam tight
over the ports is that exerted between the meeting faces of the two parts of the
valve, the area of which is regulated so as to obtain the exact pressure required.
In the case of two slide valves working in a steam chest common to two
cylinders, I provide a partition in the steam chest against each side of which the
one valve works, and on both faces of such partition I form the shallow recesses
corresponding to the ports, as above described.
In some cases, instead of allowing the metal of the above described slide valve
to work directly upon the port face and steam, chest cover, I provide them with
removeable facings or slippers that can be renewed when worn.
ABEL & IMRAY,
Agents for the Applicant,
28, Southampton Buildings,
London, W.C.

page_text: COMPLETE SPECIFICATION.
I, EUSTACE FITZMAURICE PIERS, Baronet, of No: 5 Westminster Chambers,
Westminster in the county of Middlesex, do hereby declare the nature of my
invention for "IMPROVEMENTS IN SLIDE VALVES AND VALVE CHESTS FOR STEAM
ENGINES and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
"
My invention relates to an improved construction of slide valves and valve chests
for steam engines whereby the valves are more or less relieved of pressure so as to
lessen the wear and tear thereof.
For this purposo, the slide valve which has a central exhaust opening right
through it and operates in a similar manner to an ordinary D slide, is divided'
longitudinally into two separate parts. The part working on the cylinder ports
has near each end a projecting piece fitting into a correspondingly-shaped opening
in the other part, which works against the steam chest cover and this part has a
flange projecting round its central opening which fits into the contral opening of
the first named part. The projections or the openings on either part are formed
with grooves packed with soft metal or metal which expands more at a certain
temperature than the metal of which the valve is made or other suitable material
may be used as a packing so as to enable the parts to work steam tight upon each
other or the meeting surfaces may be merely tooled so as to produce a steam tight
fit. The steam from the steam chest entering between the meeting surfaces of
the two parts of the slide valve surrounding the above mentioned projections
presses them apart so as to cause the one to bear against the port face and the
other against the steam chest cover the degree of such pressure being in proportion
to the area of the said meeting surfaces. Small passages are made right through
the projections on the part working against the ports, and on the inner face of the
steam chest cover are formed shallow recesses corresponding in configuration to
that of the steam and exhaust ports, so that whatever degree of pressure or
exhaust exists in the cylinder ports covered by the valve, precisely the same
pressure will be transmitted through the said passages and through the central
opening to the corresponding recesses in the steam chest cover and consequently
whatever pressure or exhaust the valve is subjected to on its working face such
pressure is always balanced by the pressure exerted over a corresponding area by
the steam or exhaust in the recesses of the valve cover.
Thus, the only pressure exerted upon the valve to cause it to work steam tight
over the ports is that exorted between the meeting faces of the two parts of the
valve the area of which is regulated so as to obtain the exact pressure required.
In the case of two slide valves working in a steam chest common to two
cylinders, I provide a partition in the steam chest against each side of which the
one valve works and on both faces of such partition I form the shallow recessos
corresponding to the ports as above described:
In some cases, instead of allowing the metal of the above described slide valve
to work directly upon the port face and steam chest cover, I provide them with
removeable facings or slippers that can be renewed when worn.

page_text: Fig. 1 of the accompanying drawing shews a longitudinal section of a steam
cylinder with slide valve and, valve chest constructed according to my before
described invention. Figs. 2 and 3 show respectively a side elevation and plan of
the part A detached and Figs. 4 and 5 shew respectively a side elevation and plan
of the part B detached. The slide valve consists of the two separate parts A and B
of which A works upon the cylinder ports C while B works against the valve chest
cover D. The part A has firstly a central exhaust opening a into which fits steam
tight the projecting part 6 of B; secondly the part A has, projecting parts a¹ a'
that fit steam tight into the openings 6¹¹ of B. The part B has an opening b²
formed right through it, and the part A has passages a³ as formed through the
projections a¹ a¹. The parts a and b, a' and b¹ are made to fit into each other in a
steam tight manner either merely by having their surfaces accurately tooled, or by
the introduction of packing in grooves formed therein as above described.
The steam from the steam chest entering between the meeting surfaces at 2, x,
will cause the part A to be pressed against the cylinder face and the part B to be
pressed against the cover face with a degree of pressure dependent upon the extent
of the surfaces at c. The valve chest cover being provided with rocesses d, d', d',
corresponding in form and position to those of the ports c, c¹, c' it will be seen
that by means of-the-opening-6-and-passages.ala², the slide valve will always be
subjected to the same pressure on its-upper-surfaco-as that to which it is subjected
on its under surface.
Having now particularly described and ascertained the nature of my invention
and in what manner the same is to be performed, I declare that what I claim is
Constructing slide valves and valve-chests. -for-steam engines, substautially_as
herein described.