IMPROVEMENTS IN EXPANSION VALVE GEAR FOR STEAM AND OTHER MOTIVE POWER ENGINES
Year: 1883

page_text: LETTERS PATENT to William Edmund Rich of Whitehall Place in the City
of Westminster for an Invention of "IMPROVEMENTS IN EXPANSION VALVE
GEAR FOR STEAM AND OTHER MOTIVE POWER ENGINES
"
3
PROVISIONAL SPECIFICATION left by the said William Edmund Rich at
the Office of the Commissioners of Patents on the 18th May 1883.
WILLIAM EDMUND RICH of Whitehall Place in the City of Westminster
"IMPROVEMENTS IN EXPANSION VALVE GEAR FOR STEAM AND OTHER MOTIVE
POWER ENGINES
"
This invention has for its object improvements in expansion valve gear for
steam and other motive power engines.
A common arrangement for varying the expansion in steam engines is to work
two expansion valves or plates on the back of the main slide valve or valves and
to connect these two expansion valve plates to the spindle or spindles which work
them (in a longitudinal direction) by means of right and left hand screws in such
a way that the distance between the said plates and consequently the points at
which they cut off the admission of steam can be varied by turning the spindle.or
spindles either by hand or by the governor.
The right and left hand screws in this gear have heretofore been of equal pitch
and the chief defect in the gear has been that if the slides are set to cut off evenly
on the two sides of the piston for one grade of expansion they will cut off at
very dissimilar points on the two sides of the piston when adjusted for other
grades of expansion.
According to my invention this defect is removed by making the right and left
hand screws of dissimilar pitch so that the plates approach and recede from one
another at dissimilar rates when the grade of expansion is altered by revolving
the spindle or spindles and it thus becomes practicable by suitable proportions of
the pitches of these screws one to the other to make the cut off at each grade of
expansion nearly the same on the two sides of the piston.

page_text: :
SPECIFICATION in' pursuance of the conditions of the Letters Patent and of
an Order of the Lord Chancellor filed by the said William Edmund Rich in
the Great Seal Patent Office on the 24th November 1883.
WILLIAM EDMUND RICH of Whitehall Place in the City of Westminster
"IMPROVEMENTS IN EXPANSION VALVE GEAR FOR STEAM AND OTHER MOTIVE
POWER ENGINES".
This Invention has for its object improvements in expansion valve gear for
steam and other motive power engines.
A common arrangement for varying the expansion in steam engines is to work
two expansion valves or plates on the back of the main slide valve or valves and
to connect these two expansion valve plates to the spindle or spindles which work
them in a longitudinal direction by means of right and left hand screws in such a
way that the distance between the said plates, and consequently the points at
which they cut off the admission of steam can be varied, by turning the spindle or
spindles either by hand or by the governor.
The right and left hand screws in this gear have heretofore been of equal pitch
and the chief defect in the gear has been that if the slides are set to cut off evenly
on the two sides of the piston for one grade of expansion they will cut off at very
dissimilar points on the two sides of the piston when adjusted for other grades of
expansion.
According to my invention this defect is removed by making the right and left
hand screws of dissimilar pitch so that the plates approach, and recede from one
another at dissimilar rates when the grade of expansion is altered by revolving the
spindle or spindles and it thus becomes practicable by suitable proportions of the
pitches of these screws one to the other to make the cut off at each grade. of
expansion nearly the same on the two sides of the piston.
i
In order that my said invention may be most fully understood and readily
carried into effect, I will proceed to describe.the drawing hereunto annexed.
The drawing shows a longitudinal section of a slide valve with expansion plates
or valves upon its back, and these are controlled in accordance with my invention
by a spindle having upon it right and left hand screws of dissimilar pitch.
A is a main valve and it may receive its movement from an eccentric in the
ordinary manner.
B B, are the expansion valves or plates on the back of the main valve and serve
as they and the main valve move to and fro to open and close the steam ports
A1 A2 in the main valve.
C C, are screw nuts which are inserted in recesses in the valves B B, the nuts
are held in these recesses in such manner as to prevent them turning.
D is the spindle and D¹ D2 are screw threads formed upon it.
This spindle may be actuated by an eccentric in the usual manner or by: an
arrangement of levers and rods. The lead of the respective eccentrics in advance
of the crank in the arrangement shown may conveniently be for the main
eccentric 115 degrees and for the eccentric of the expansion valve 180 degrees.
Also in the arrangement shown the pitch of the left hand screw D¹ should be 304"
and that of the right hand screw D³ should be 25", these measurements being.in
decimals of an inch.
1.
:.
When in place of employing one main valve, two main valves are provided (the
steam port at each end of the cylinder having its separate valve) then each main
valve will carry one of the expansion valves.

page_text: Having thus described the nature of my said Invention and the manner of
performing the same, I would have it understood that I claim as my improve-
ments in expansion valve gear, a right and a left hand screw of dissimilar pitch
actuating two expansion valves or plates on the back of the main slide valve or
valves, substantially as described.
In witness whereof the said William Edmund Rich have hereunto set my
hand and seal this Eighteenth day of November in the year of our Lord One
thousand eight hundred and eighty three.
WILLIAM EDMUND RICH (L.S.)