Improvements in Slide Valves.
Year: 1890

page_text: Date of Application, 10th Mar., 1890
Complete Specification Left, 25th Nov., 1890-Accepted, 7th Mar., 1891
PROVISIONAL SPECIFICATION.
Improvements in Slide Valves.
I, JOHN THOMAS JAMESON, of 25, Azalea Terrace South, Sunderland,
Engineer, do hereby declare the nature of this invention to be as follows:-
An important object of this invention is to diminish the pressure, friction and
power to work slide valves exposed to high pressure steam especially in engines
having two or more cylinders, the steam expanding from one into the other.
I construct the slide valve of the ordinary hollow form but with a bar arranged
in the middle of the hollow part so as to form a port at each end of the bar,
such ports being of the same size as a central steam admission port on the
cylinder face. This central port takes the place of the ordinary wide exhaust port
but serves to admit fresh steam to interior of the slide valve, whence it is distributed
to a port at each end of the cylinder face and leading to each end of the cylinder.
The exhaust steam is released directly past the end of the valve into the chest or
box in which the slide valve works. In order to counteract the tendency of the
valve to lift when the steam is first admitted I provide a plate which by a spring or
springs is made to bear on the back of the slide valve, or I may provide the latter
with a balancing ring or rings working steam tight against a face.
As applied to triple or quadruple cylinder expansion engines the slide valves for
the first and the second cylinder would be in the same chamber, the usual division
being omitted thus admitting of the valves being brought closer together or working
back to back, the first cylinder valve rod would be exposed to a pressure materially
below the boiler pressure, where the No. 1. and No. 2. cranks are directly opposite
to each other, the valves for No. 1. and No. 2. cylinders are by preference on one
spindle, thus doing away with one set of valve gearing, the No. 1. valve being of the
construction and arrangement described, taking its steam inside, while the No. 2.
valve would be of the ordinary construction and arrangement admitting the steam
at each end. In the case of a quadruple cylinder expansion engine with four cranks
the No. 3. and No. 4. cylinders having their slide valves arranged as just described
there would only be two sets of valve gearing instead of four thus effecting a saving
in the cost and length space of the engine.
A collateral advantage is that my improved slide valve takes up less space in
length as compared with the ordinary slide valve of same stroke for the same
cylinder and having the same lap and lead.
Dated this 10th day of March 1890.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Slide Valves.
I, JOHN THOMAS JAMESON, of 25, Azalea Terrace South, Sunderland,
Engineer, do hereby declare the nature of this invention, and in what manner. the
Bame is to be performed, to be particularly described and ascertained in and by the
following statement :-
:-
An important object of this invention is to diminish the pressure, friction and
power to work slide valves exposed to high pressure steam especially in engines
having two or more cylinders the steam expanding from one into the other.
I construct the slide valve of the ordinary hollow form as shewn in the longi-
tudinal section Figure 1 but with a bar A arranged in the middle of the hollow
part so as to form a port B and B' at each end of the bar A, such ports being of or
[Prins 677

page_text: about the same size as a central steam admission port C or ports on the cylinder
face, this central port or ports taking the place of the ordinary wide exhaust port,
and in my construction serving to admit fresh steam to the interior of the slide valve
whence it is distributed to a port D and D' at each end of the cylinder face and
leading to each end of the cylinder. The exhaust steam is released directly past
the ends E and E' of the valve into the chest or box F in which the slide valve
works. In order to counteract the tendency of the valve to lift when the steam is
first admitted to the interior thereof by the port C, I provide a plate G which by
a spring H or springs is made to bear on the back of the slide valve, or I may
provide the latter with a balancing ring or rings of any suitable or well known
construction working steam tight against a face.
As applied to triple or quadruple cylinder expansion engines the slide valves for
the first and the second cylinder would be in the same chamber, the usual division
being omitted thus allowing the valves to be brought closer together or even back
to back..
The first cylinder valve rod would be exposed to a pressure materially below the
boiler pressure.
Where the No. 1 and No. 2 cranks are directly opposite to each other the valves
for No. 1 and No. 2 cylinders are by preference on one spindle I as shewn in
Figure 2 thus doing away with one set of valve gearing, the No. 1 valve being of
the construction and arrangement described taking its steam inside from the port C
while the No. 2 valve K would be of the ordinary construction and arrangement
admitting the steam at each end from the chamber F.
In the case of a quadruple cylinder expansion engine with four cranks the No. 3
and No. 4 cylinders having their slide valves arranged as just described there would
only be two sets of valve gearing instead of four thus effecting a saving in the
cost and length space of the engine besides diminishing friction and loss by radiation
of heat, condensation of steam and leakage at stuffing boxes.
By my construction of valve I reduce the pressure on the bearing surfaces-of
same very considerably.
A. collateral advantage of my improved slide valve when used with one central
steam port Con cylinder face is that it takes up less space in length as
compared with the ordinary slide valve of same stroke for the same cylinder and
having the same lap and lead.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
First. A slide valve of D form provided with a central bar in the hollow and
ports at each end of said bar and working in a chamber which receives the exhaust
fluid in combination with a central steam admission port or ports on the cylinder face
substantially as and for the purposes set forth.
Second. The application of the slide valve firstly claimed to triple and quadruple
cylinder expansion engines substantially in the manner and for the purposes set
forth.
.
Third. The slide valve constructions shewn on the drawings.
31 onl
JENSEN & SON,
77, 'Chancery Lane, London, W.C., Patent Agents.