IMPROVEMENTS IN THE CONSTRUCTION OF Valve Gear FOR STEAM AND OTHER ENGINES
Year: 1880

page_text: LETTERS PATENT to John Crighton, Robert Crighton, and Peter Chell, all of
Manchester, in the County of Lancaster, for an Invention of "IMPROVEMENTS
IN THE CONSTRUCTION OF Valve Gear FOR STEAM AND OTHER ENGINES."
PROVISIONAL SPECIFICATION left by the said John Crighton, Robert
Crighton, and Peter Chell at the Office of the Commissioners of Patents on the
29th October 1880.
JOHN CRIGHTON, ROBERT CRIGHTON, and PETER CHELL, all of Manchester, in
the County of Lancaster. " IMPROVEMENTS IN THE CONSTRUCTION OF VALVE
GEAR FOR STEAM AND OTHER ENGINES."
The Invention relates to the valve gear of engines wherein the valve is opened
by the excentric and is closed by means of a spring to effect the "cut-off," the
time of opening and closing the "cut off" valve being regulated by the action of the
"governor.
According to our Invention the excentric rod is connected to a sliding plate
(which, for the sake of illustration, we will call the "excentric-plate"), whilst
the valve rod is connected to a second sliding plate (which we will call the "valve
plate").
The valve plate" rests upon the upper side of the "excentric plate," and is
provided with a vertical slide capable of rising and falling in a slot made for that
purpose through the "valve-plate." The top of the "excentric-plate" and the
bottom of the vertical slide are provided with slightly projecting surfaces (which we
will call "catch-plates"), and these are so arranged that when the vertical slide is
in its lowest position the edges of these "catch-plates" come into contact, and the
movement of the excentric rod is communicated to the valve rod, but when the
vertical slide is raised the "catch plates" are released, and the spring with which
the valve rod is connected immediately closes the valve.
The rising or falling of the vertical slide (with its "catch-plate") is effected as
follows:-
The upper part of the vertical slide is formed with a hollow chamber, in which
works the lower end of a slotted lever made in the form of a double cam working

page_text: beneath two lips in the slide in such a manner that as the lever is rocked upon its
fulcrum by the horizontal movement of the "excentric plate" in opening the valve
it lifts the vertical slide at the right moment and raises the catch plate so as to
release the valve rod and allow the spring to close the valve. On the return
movement of the excentric rod the reverse action takes place.
"
The exact time of the "cut-off" being effected is regulated in the following
manner The fulcrum of the slotted lever consists of a pin attached to the
governor-rod," the said pin working in a slide moving vertically in a fixed
standard and passing through a similar slide working in the slot of the lever. Thus
it will be evident that the fulcrum of the slotted lever will be lowered or raised by
the action of the governor, and the cam on its lower end will then act sooner or
later as may be required according as the rate at which the engine revolves increases
or decreases in velocity.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Crighton, Robert Crighton, and Peter Chell in the Great
Seal Patent Office on the 28th April 1881.
JOHN CRIGHTON, ROBERT CRIGHTON, and PETER CHELL, all of Manchester, in
the County of Lancaster. "IMPROVEMENTS IN THE CONSTRUCTION OF VALVE
GEAR FOR STEAM AND OTHER ENGINES."
This Invention relates to the valve gear of engines wherein the valve is opened
by the excentric and is closed by means of a spring to effect the "cut off," the
time of opening and closing the "cut off" valve being regulated by the action of the
governor.
Such being the nature and object of our said Invention, we will now proceed to
describe in detail the manner in which the same is to be or may be performed or
carried into practical effect, and in order that the same may be clearly understood
we have annexed hereunto a Sheet of Drawings illustrative thereof, and have
marked the same with figures and letters of reference corresponding with those in
the following explanation thereof.
Figs. 1 to 9 in the annexed Drawing illustrate the application of our Invention
to the gear of flat or slide valves wherein the valve rods are in the horizontal
position, and Figs. 10 to 15 illustrate the application of the same to "Stamper,"
Cornish," or "double-beat" valves, wherein the valve rods work vertically.
85
Fig. 1 is a sectional elevation of the apparatus, Fig. 2 a plan view, and Fig. 3 an
end view of the same.
a, a, is the rud leading from the excentric; b, b, the rod leading to the valve; and
c, c, the rod leading from the governor; d, d, is the spring box.
According to our Invention the excentric rod a, a, is connected to a sliding
plate e, e, (which for the sake of illustration we will call the "excentric plate"),
whilst the valve rod b, b, is connected to a second sliding plate f, f, (which we will
call the "valve plate ").
The valve plate f, f, rests upon the upper side of the excentric plate e, e, and is
provided with a vertical slide or die g, g, capable of rising and falling in a slot
or open box h, h, made for that purpose in the valve plate (see enlarged views,
Figs. 4, 5, 6, and 7).
The top of the excentric plate e, e, and the bottom of the vertical slide or die g, g,
are provided with slightly projecting steel plates i, ix, (which we will call "catch
plates "), and these are so arranged that when the vertical slide or die g, g, is in its
lowest position (as shown at Figs. 1 and 4) the edges of these catch plates come
into contact, and the movement of the excentric rod a, a, is communicated to the
valve rod b, b, but when the vertical slide or die g, g, is raised, the catch
plates i, i, are released, and the spring with which the valve rod b, b, is connected
immediately closes the valve.
The rising or falling of the vertical slide or die g, g, (with its catch plate i*) is
effected as follows:-
The upper part of the vertical slide or die g, g, is formed with a hollow chamber,
in which works the lower end of a slotted lever k, k, having at its lower end a
double cam l, l, which may be either separate from the lever, as shown enlarged at
Fig. 8, or made in one piece, as shown at Fig. 9. This cam Ɩ, l, works beneath the
top of the slide g, g, in such a manner that as the lever k, k, is rocked upon its
fulcrum by the horizontal movement of the excentric plate e, e, in opening the
valve it lifts the vertical slide or die g, g, at the right moment and raises the catch
plate i* so as to release the valve rod b, b, and allow the spring in the box d, d, to
close the valve.

page_text: On the return movement of the excentric rod a, a, the reverse action takes
place.
The exact time of the "cut off" being effected is regulated in the following
manner:
The fulcrum of the slotted lever h, k, consists of a pin m (see Figs. 1 and 3)
attached to the governor rod c, c, the said pin m working in a slide moving
vertically in a fixed standard n, n, and passing through a similar slide working in
the slot of the lever k, k. Thus it will be evident that the fulcrum w of the slotted
lever k, k, will be lowered or raised by the action of the governor, and the cam 1,
on its lower end will act sooner or later as may be required according as the rate at
which the engine revolves increases or decreases in velocity.
In adapting our Invention to the working of "Stamper," "Cornish," or "double
beat" valves, in which the valve rods works vertically, some slight modifications are
required, as will be readily seen on reference to Figs. 10 to 15, in which (so far as
practicable) the same letters are used as in the preceding Figs. to indicate the parts
which have similar functions.
-
Instead of using the excentric plate e, c, the upper part of the tappet rod a, a, is
made in the form of a square socket e, e, (see Fig. 14) to which is attached the slot
or open box h, h, and instead of the valve plate f, f, the lower part of the valve
rod b, b, is made square (us at f. f) to work in the socket e, e.
The slotted lever k, k, and double cam l, l, are dispensed with, and a plain lever
and single cam, Fig. 15, are substituted therefor; a spring o, o, is also fixed on the
back of the slide or die g, g, to ensure its being forced into the required position at
the right moment.
In the modification illustrated by Figs. 12 and 13 the "cut off" apparatus is
shown as applied direct to the valve spindle p, P.
Having now described the nature and object of the said Invention, together with
the manner in which the same is to be or may be performed or carried into practical
effect, we wish it to be understood that we claim as our Invention, the general
construction and arrangement of the "cut off" apparatus, as herein before described
and illustrated by the Drawings annexed, and especially we claim the combination
of the catch plates with the sliding block or dic actuated by the cam and lever
connected to and controlled by the governor of the engine.
In witness whereof, I, the said Robert Crighton (on behalf of myself and the
said John Crighton and Peter Chell), have hereunto set my hand and seal,
this Twenty seventh day of April, in the year of our Lord One thousand
eight hundred and eighty one.
ADTAMAN