Improvements in Means for Providing for the Free Circulation of Air in Steam Cylinders when the Pistons are Running and the Steam Cut Off.
Year: 1897

page_text: COMPLETE SPECIFICATION.
Improvements in Means for Providing for the Free Circulation of Air
in Steam Cylinders when the Pistons are Running and the Steam
Cut Off.
A communication from abroad by the RICHMOND LOCOMOTIVE & MACHINE
WORKS, of Richmond, in the State of Virginia, United States of America.
I PHILIP MIDDLETON JUSTICE, of 55 and 56, Chancery Lane, London, Chartered
Patent Agent, 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:—
The object of this invention is to provide simpler and more efficient automatic
over-pass valves for free circulation of air in the cylinder while running, when
steam is shut off, as hereinafter described reference being made to the accom-
panying drawings in which:
Fig. 1 is an end elevation of a steam cylinder and part of the saddle frume
of a locomotive, showing the application of the improved over-pass apparatus, the
steam chest being removed.
Fig. 2, is a vertical longitudinal section on line 2-2 of Fig. 1, the valve being
omitted.
Fig. 3, is a horizontal section on line 3-3 of Fig. 1.
Fig. 4, is a section on line 3-3 Fig. 1, in a modified form of some of the parts.
Fig. 5, is a section as in Fig. 3, with the valves open and with a coiled spring
between them instead of the atmospheric port for opening them.
A represents the cylinder, 6 the port face, e the steam ports and f the exhaust
port: g represents a valve case that is provided on the outside of the port case as
an integral part of the cylinder casting and preferably parallel with the cylinder,
through the middle portion of which is provided an over-pass way g' for free
circulation of air from one steam port to another when steam is shut off, by ports i,
which have communication with the steam ports e, with valves h to close said ports
when steam is admitted to the cylinder. Other ports ; in communication with
the steam chest, and with the valve case y admit steam behind the valves and
normally keep them closed on the seats k, which are intermediate of the ports i.
Between the valve seats is a small port open to the atmosphere.
l
It will be seen that when steam enters the steam chest it closes the valves h, and
they remain closed until steam is shut off. When steam is shut off and the engine
is running it creates a vacuum in the steam chest and the atmospheric pressure
through port, or a spring forces the valves back sufficient to open a passage
between the steam ports e through which the air will pass from one side of the
piston to the other forward and backward, thus relieving the piston from excessive
resistance in drifting and preventing an excessive amount of cold air from
entering the cylinder.
For more positive action of the valves which in case of not closing tightly may
possibly be equally subject to steam pressure on both sides they are provided with

page_text: counterbalancing pistons m, Fig. 4, in the middle part of the case g, between the
valve seats, whereby there will always be preponderating pressure on the other
sides for closing them. In this case a by-pass for air is provided around the pistons
consisting of the lateral passage n and ports o connecting therewith through the
side of the valve case.
The valves may have a spring or springs for opening them when steam is shut
off instead of air pressure if desired, for example a coiled spring ? placed between
them as in Fig. 5, .suitably for taking effect on both, the atmospheric port then
being omitted.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me from abroad by my foreign correspondents, I declare that what I claim is:-
1. The combination with the steam cylinder, of the valve case having the over-
pass between the steam ports, the automatic valves in said case normally subject
to pressure from the cylinder steam chest for closing said overpass, and means for
opening said valves when steam is shut off substantially as described.
2. The combination with the steam cylinder, of the valve case having the over-
pass between the steam ports, the automatic valves in said case normally subject
to pressure from the cylinder, steam chest for closing said over-pass, and the
atmospheric port intermediate of the valves substantially as described.
3. The combination with the steam cylinder, of the valve case having the over-
pass between the steam ports, the automatic, independent and reversely acting
valves in said case normally subject to pressure from the cylinder steam chest,
for closing said over-pass, and means for opening said valves when steam is shut
off substantially as described.
4. The combination with the steam cylinder, of the valve case having the over-
pass between the steam ports, the valves in said case normally subject to pressure
from the steam chest for closing said over-pass, counterbalancing pistons
intermediate of the valves, by-pass around said pistons, and means for opening
said valves when steam is shut off substantially as described.
5. The combination with the steam cylinder, of the valve case having the
over-pass between the steam ports, the valves in said case normally subject to
pressure from the steam chest for closing said over-pass; counterbalancing pistons
intermediate of the valves, by-pass around said pistons and the atmospheric port
intermediate of the pistons substantially as described..
:
6. The combination with the steam cylinder, of the integral valve case, having
the over-pass between the steam ports, the valves in said case normally subject
to pressure from the cylinder steam chest for closing said over-pass, and means for
epening said valves when steam is shut off substantially as described.
Dated 3rd August. 1897.