IMPROVEMENTS IN DIRECT-ACTING STEAM ENGINES
Year: 1876

page_text: LETTERS PATENT to James Cadoux Hudson, of Brixton, in the County of
Surrey, for the Invention of "IMPROVEMENTS IN DIRECT-ACTING STEAM
ENGINES."
Sealed the 5th December 1876, and dated the 8th June 1876.
PROVISIONAL SPECIFICATION left by the said James Cadoux Hudson at the
Office of the Commissioners of Patents on the 8th June 1876.
JAMES CADOUX HUDSON, of Brixton, in the County of Surrey.
IN DIRECT-ACTING STEAM ENGINES."
"IMPROVEMENTS
This Invention relates to the arrangements used in actuating the main slide valve
of direct-acting pumping and other engines. In this class of engine it is common
to use a main slide valve moved by a piston operated by steam admitted by the
action of an auxiliary valve which is moved directly by the main piston.
The said improvements consist in constructing the auxiliary valve on a seat
on the back of main valve, and with wings rising vertically from the auxiliary
valve, and clipping parallel plane faces formed on sides of valvo piston at about the
centre of its length. The valve piston contains ports running from each end towards
the centre of its length, and branching out at opposite sides of same through said
parallel faces. Each port is continued down through a wing of auxiliary valve, and
out at face, moving on seat on back of main valve. This seat is provided with ports
communicating with steam chamber of main cylinder, and other ports commu-
nicating with exhaust port of same cylinder, so arranged that when one port in
auxiliary valve communicating to one end of valve piston is open to a port to steam
chamber the other port in auxiliary valve communicating to opposite end of valve
piston is open to a port to exhaust port of main cylinder. The valve piston moves
in conjunction with the auxiliary valve. A determined independent movement is
allowed between valve piston with auxiliary valve and main valve sufficient to
move one port in auxiliary valve from steam port to exhaust port in seat on main
valve, the other port in auxiliary valve from exhaust port to steam port in same
seat, and vice versa, thus alternately admitting steam to and exhausting from
opposite ends of valve piston, and causing it to move alternately in opposite
directions.
The independent movement to valve piston and auxiliary valve is obtained from

page_text: main piston when nearing either end of its stroke, and the ports opened to auxiliary
valve are such as will continue the motion of valve piston, and cause it to reverse
main slide valve, which will then open ports to return the stroke of main piston.
Should the main piston move with a rapidity that would cause insufficient time
for the valve piston to reverse main valve before main piston struck the end of
its cylinder the main valve will be reversed by the mechanical movement which
moves valvo piston from main piston.
A cushion to valve piston is obtained by the exhaust ports to seat at back of
main slide valve being closed by passing over bars in main valve seat.
The valve piston may clip the auxiliary valve, the centre of valve piston being
formed as a yoke, and the wings or wing of auxiliary valve fitting against faces
formed within the yoke.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Cadoux Hudson in the Great Scal Patent Office on the
7th December 1876.
+
"8
JAMES CADOUX HUDSON, of Brixton, in the County of Surrey. IMPROVEMENTS
IN DIRECT-ACTING STEAM ENGINES."
Figure 1 is a sectional elevation of upper part of steam cylinder, showing ports,
valves, and valve piston.
Figure 2 is a cross section of upper part of steam cylinder, and thro' ports of
main and auxiliary valves and valve piston.
Figure 3 is a plan, with upper part of steam chest and cylinders of valve piston
removed.
Figure 4 is a plan of upper face of main valve.
These improvements consist in constructing the auxiliary valve on a seat on the
back of main valve, and with wings rising vertically and clipping valve piston;
also arranging certain ports in valve piston, auxiliary valve and main valve, which
by suitable combinations operate main valve, and allowing a determined indepen-
dent movement between valve piston with auxiliary valve and main valve to obtain
these combinations; also operating main valve by a mechanical movement from
main piston when valve piston would fail to act.
In the Drawing (A) is the main cylinder; (b, b₁₁) the steam ports; and (c) the
exhaust port to same; (D) is the main slide valve (the exhaust cavity is shown in
Fig. 1 in dotted lines); its upper face forms a seat for the auxiliary valve (E), from
which wings (ff¹) rise vertically and clip parallel plane faces formed on valve
piston (G); ports (h, h) in valve piston (G) run from ends towards centre, and
branch out at opposite sides thro' said parallel faces, and are continued down
wings (ff) of auxiliary valve (E) to its face on main slide valve (D). Certain
ports are arranged on the upper face of main valve (D), two of which (, ) are in
communication with steam chest (L); other ports (m, m¹) are drilled thro' to
lower face of main valve (D), and at times communicate with exhaust port (c) of
main cylinder, or pass over bars between steam and exhaust ports of saine. This
arrangement of ports admits steam to and exhausts from opposite ends of valve
piston (G), and cushions the same at proper times.
The
The auxiliary valve (E) moves in conjunction with valve piston (G), and both
receive their motion from main piston when nearing the end of its stroke.
main valve (D) is moved by certain abutments (n, n',) on valve piston (G), which
come in contact with sides of main valve (D), but the abutments (n, n¹) are apart
a distance greater than the width of main valve (D), and so when one abutment
has driven valve (D) in one direction the valve piston (G) and auxiliary valve (E)
move a distance independently of main valve (D) before the other abutinent comes
in contact with valve (D) to drive it in an opposite direction. Now suppose the
'

page_text: parts to be in positions shown in Figure No. 1, the main piston is supposed to be
now nearing the end of its stroke towards the left hand, and has moved the valve
piston (G) and auxiliary valve (E) towards the right hand a distance equal to the
play between the abutments (n, n¹,) and sides of valve (D), and has carried the
port (h) in auxiliary valve (E) communicating to left hand end of valve piston (G)
over a steam port (b) in upper face of main valve (D), and the port (h¹) communi-
cating to right hand end of valve piston (G) over exhaust port (m³) in upper face
of main valve (D) communicating now to main exhaust port (c) this will cause
valve piston (G) to continue its movement and drive main valve (D) towards the
right hand, and cause it to uncover main ports to reverse the motion of main
piston, but during the movement of main valve (D) the exhaust port (m²) covered
by the port (h) cominunicating to the right hand end of valve piston (G) will have
been closed at its end at lower face of main valve (D) by passing over a bar between
exhaust port (c) and steam port (61) in main valve face; this will cushion the
motion of valve piston, which with valve (D) and auxiliary valve (E) will arrivo
in positions to receive similar but return motions to the preceding when the main
piston nears the opposite end of its stroke.
Should the main piston move with a rapidity that would leave insufficient time
for the valve piston (G) to reverse main valve (D) before the main piston struck the
end of its cylinder the mechanical movement which moves valve piston (G) from
main piston will continue the movement of valve piston after the abutment
(n or n¹) has come in contact with side of main valve, and reverse main valve.
It is not essential that the ports (m, m¹) should be controlled by the main
exhaust port (c); they may have independent ports in main valve face communi-
cating with exhaust pipe of engine. Noither is it essential that the ports (h, h¹,)
in valve piston should branch out thro' parallel faces at opposite sides, as both
may be thro' one or both faces, the other ports being arranged to suit; also the
valve piston may clip the auxiliary valve, the centre of the valve piston being
formed as a yoke, and the wing or wings of auxiliary valve fitting against faces
formed within the yoke, and having continuous ports running from ends of valve
piston thro' faces down said wing or wings to face of auxiliary valve on seat on
main valve.
Having thus described the nature of my Invention, and the manner of performing
the same, I wish it to be understood that I claim,-
First. Constructing the auxiliary valve on a scat on the back of main valve,
which seat is provided with ports (m, m², h, k¹) and providing the auxiliary valvo
with wings (1) clipping faces formed on valve piston, and causing the auxiliary
valve to move with valve piston, and allowing a determined independent movement
between valve piston and main valve, and arranging ports (h,h',) in valve piston
and auxiliary valve, controlled by ports (m, m³, h, k,) in main valve, all constructed
and operating in the manner and for the purpose specified and illustrated.
Second. The valve piston at centre being formed as a yoke, and clipping the
auxiliary valve, the wing or wings of auxiliary valve fitting against faces formed
within the yoke, and with ports arranged as specified.
In witness whereof, I, the said James Cadoux Hudson, have hereunto set my
hand and seal, this Seventh day of December, in the year of our Lord
1970
Witness,
HENRY WRIGHT.
JAMES CADOUX HUDSON. (L.S.)