IMPROVED CUT-OFF GEARS FOR STEAM ENGINES
Year: 1869

page_text: LETTERS PATENT to John Turnbull, of Glasgow, in the County of
Lanark, North Britain, for the Invention of "IMPROVED CUT-OFF GEARS
FOR STEAM ENGINES."
Sealed the 29th April 1870, and dated the 5th November 1869.
PROVISIONAL SPECIFICATION left by the said John Turnbull at the
Office of the Commissioners of Patents, with his Petition, on the
5th November 1869.
I, JOHN TURNBULL, of Glasgow, in the County of Lanark, North
Britain, do hereby declare the nature of the said Invention of "IMPROVED
CUT-OFF GEARS POR STEAM ENGINES," to be as follows, that is to say :-
This Invention, which relates to so employing the governors of steam
engines that they may act upon the slide valves for the purpose of
cutting off the steam at any instant as rapidly as possible, in order to
maintain the engine at a constant speed without altering the length of

page_text: travel of the slide valve, consists in using in connection with the governor
an epicyclic train, composed either of spur or bevil gearing (according
to the arrangement of the engine), and the Invention is applicable to
those engines wherein double or covered slide valves are employed,
that is to say, valves which have a sliding plate or a hinged plate
working over ports in the back of the valvo proper. The pinion of the
epicyclic train is carried in one arm of a lever, which lever is centred
on the axis of the driving wheel of the train. The pinion carries a
striking pin or tappet, which during a portion of its revolution acts
upon a lift plate, this being in connection with rods attached by levers
to the spindles of the covers of the slide valves. The other part of the
lever which carries the pinion of the epicyclic train is coupled by rods
and levers to the governor, and is raised and lowered by its action, this
having the effect of varying the position of the lever and pinion of the
train, so that these are thrown to a small angle relatively with their
normal position. Accordingly then with the variation of the angle the
circle in which the striking pin or tappet revolves is slightly moved, so
that the tappet or striking pin acts upon a different part of the curve of
the lifting plate, which has the effect by the intervention of the lifting
plate and lever herein-before referred to of altering the position of the
covering plates of the slide valves relatively with the ports over which
they act without altering the length of their travel or lift according as
the plates slide or are hinged, so that the steam is cut off sooner or later
as may be required.
This Invention also consists in regulating the cut-off valves from the
engine governor by using ordinary differential cams to slide on a driving
shaft; the cams are controlled or moved to vary the cut-off by using a
small hydraulic cylinder and piston worked by a small pump driven from
the engine. On the hydraulic cylinder nozzles are placed for admitting
the fluid used to either side of the piston as required to impel it in either
direction, horizontally, or upwards or downwards vertically. The slide
valve or three-way cock for admitting the fluid is controlled by the
governor, which when the speed of engine alters either rises or falls and
moves the valve or cock, and causes the piston to travel and move the
cut-off cams until the engine comes to its proper speed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Turnbull in the Great Seal Patent Office
on the 5th May 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
TURNBULL, of Glasgow, in the County of Lanark, North Britain, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of November, in the year of
our Lord One thousand eight hundred and sixty-nine, in the 33rd year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said John Turnbull, Her special license that I, the said
John Turnbull, my executors, administrators, and assigns, or such others
as I, the said John Turnbull, my executors, administrators, or assigns,
should at any time agree with, and no others, from time to time and at
all times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "AN IMPROVED CUT-OFF GEAR FOR STEAM ENGINES," upon the
condition (amongst others) that I, the said John Turnbull, by an
instrument in writing under my hand and seal, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Turnbull, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings,
and to the letters and figures marked thereon, that is to say:-
My said Invention, which relates to so employing the governors of
steam engines that they may act upon the slide valves for the purpose
of cutting off the steam at any instant as rapidily as possible, in order
to maintain the engine at a constant speed without altering the length
of travel of the slide valve, consists in using in connection with the
governor an epicyclic train composed either of spur or bevil gearing
(according to the arrangement of the engine), and the Ivention is

page_text: applicable to those engines wherein double or covered slide valves are
employed, that is to say, valves which have a sliding plate or a hinged
plate working over ports in the back of the valve proper. The pinion of
the epicyclic train is carried in one arm of a lever, which lever is centred
on the axis of the driving wheel of the train. The pinion carries a
striking pin or tappet, which during a portion of its revolution acts upon
a lift plate, this being in connection with rods attached by levers to the
spindles of the covers of the slide valves. The other part of the lever
which carries the pinion of the epicyclic train is coupled by rods and
levers to the governor and is raised and lowered by its action, this having
the effect of varying the position of the lever and pinion of the train, so
that these are thrown to a small angle relatively with their normal
position. Accordingly then with the variation of the angle the circle
in which the striking pin or tappet revolves is slightly moved, so that
the tappet or striking pin acts upon a different part of the curve of
the lifting plate, which has the effect by the intervention of the lifting
plate and lever herein-before referred to of altering the position of the
covering plates of the slide valves relatively with the ports over which
they act without altering the length of their travel or lift according as
the plates slide or are hinged so that the steam is cut off sooner or later
as may be required.
This Invention also consists in regulating the cut-off valves from the
engine governor by using ordinary differential cams to slide on a driving
shaft. The cams are controlled or moved to vary the "cut-off" by using
a small hydraulic cylinder and piston worked by a small pump driven
from the engine. On the hydraulic cylinders nozzles are placed for
admitting the fuid used to either side of the piston as required to impel
it in either direction horizontally or upwards or downwards vertically.
The slide valve or three-way cock for admitting the fluid is controlled by
the governor, which when the speed of the engine alters either rises
or falls and moves the valve or cock and causes the piston to travel
and move the "cut-off" cams until the engine comes to its proper speed.
And in order that my said Invention may be properly understood I
now proceed more particularly to set forth the system, mode, or manner
in or under which the same is or may be used or practically carried into
effect, that is to say :-
On Sheet 1 of the annexed Drawings, Figure 1 is a side elevation,
and Figure 2 a transverse section of the two cylinders of a compound

page_text: hozisontal engine showing my improved "cut-off"
under one modification applied thereto.
gear as constructed
A, A, are the two cylinders; B, the valve chest of the high pressure
cylinder; C, an ordinary slide valve with two covering plates or gridiron
valves x on the back thereof, which gridiron valves are actuated by the
spindles and buckles D, as shown more particularly at Figure 2. The
spindles D are connected to upright rods F by the levers E and bell
cranks G. These rods F are provided at their lower extremities with
lift plates. H, seen more particularly at Figure 2, which plates are
adjustable by means of the jamb nuts a. The pinion I of the epicyclic
train is carried in brackets J, which brackets are centered on the axis
of the driving wheel K of the train, and are connected to the engine
governor by means of the adjustable rod M fixed to the other end of
the bracket J, as shown at Figure 2. On the boss of the pinion I
striking pins or tappets e are placed, which pins or tappets during a
portion of the revolution of the pinion aet on the lift plates H, and
thereby actuate the covering plates or gridiron valves through the
intervention of the rods F, cranks G, levers E, and spindles D, as herein-
before described. The brackets J being attached to the governor by
the rod M are raised and lowered by its action; this has the effect of
varying the position of the brackets J and pinion I carried therein so.
that they are thrown to a small angle relatively with their normal
position, consequently with the variation of the angle the circles in
which the striking pins or tappets e revolve are slightly moved, so that
the striking pins or tappets e aet on different parts of the curved faces
of the lifting plates H, which has the effect through the intervention.
of the mechanism herein-before described of altering the position of
the covering plates or gridiron valves x on the top of the slide valve C
relatively with the parts over which they act without altering the length
of their travel, so that the steam is cut off sooner or later as may be
required.
At Figure 3 is shown a side elevation, and at Figure 4 a plan of a
horizontal steam engine showing my improved gear for cutting off the
steam as constructed according to the second modification of my In-
vention applied thereto. Figure 5 is a transverse section of the
cylinder on the line a, a, Figure 4, showing the "cut-off" valve. On
these several Figures corresponding parts are indicated by the same
letters of reference.

page_text: The mechanism consists of an epicyclic train of wheels actuated from
the crank shaft A through the intervention of the bevil gearing B,
and which epicyclic train is used in conjunction with the engine
governor C to cut off the steam at any instant as rapidly as possible
in order to maintain the engine at any required speed, that is to say,
the train is so arranged as to vary the amount and time of "cut-off"
according to the power required from the engine. This train of wheels
may either consist of bevil or spur gearing (according to the arrange-
ment of the engine), and on the Drawings now being referred to a
train composed of spur wheels is shown applied, namely, a wheel D
and pinion D', which are employed to reduce the speed of the train.
On the same boss or centre as the wheel D another wheel E is fitted,
and these wheels D and E run loosely on a cam or tappet shaft F, on
which shaft a pinion J is also placed, as shown at Figure 4 and firmly
keyed to the shaft. On the same shaft Fa lever G provided with two
arms, as shown at Figure 4, is centered, on which arms the pinion H
and wheel I are carried, as shown. The pinion E is rotated by the
wheel E and communicates motion to the wheel I through the inter-
vention of the shaft x, the wheel I in its turn actuating the pinion J
keyed on the cam or tappet shaft F, as herein-before set forth. These
wheels D, D, E, H, I, and J, which compose the epicyclic train are
so constructed and arranged as to cause the shaft F to revolve with
the same number of revolutions as the crank shaft A. The lever G
is connected to the governor C by an ordinary adjustable rod, which
rod is attached to the lever G by a pin or stud at the point marked e.
The lever G being free to move on the shaft F the rising and falling of
the governor balls regulates (by the motion thereby given to the
epicyclic train) the time of cutting off the steam to be altered to any
part of the stroke, as herein-before more particularly set forth. The
equilibrium valves O are actuated by means of the levers b, b, fixed on
the shaft F¹, as shown more particularly at Figure 5, which levers are
actuated by the striking pins or tappets a on the shaft F. The valves O
are situated at one end of the slide valves N as shown more particu-
larly in horizontal section at Figure 4. The slide valves N are placed
at each end of the cylinder, and are constructed as shown at Figure 4
in order to shorten the steam passages of the cylinder or cylinders. On
the balls d of the governer C being raised or lowered their action has
the effect of varying the position of the lever G, pinion H, and wheel I
of the train, so that these are thrown to a small angle relatively with

page_text: their normal position. Accordingly with the variation of the angle the
levers b, b, act differently on the T-headed spindles X of the equilibrium
valves O, which spindles work through stuffing boxes c on the under
side of the valve box Q, so that the steam is sooner or later cut off as
required. In lieu of employing striking pins or tappets to actuate
the cut-off valves O as herein-before set forth ordinary cams may be
placed on the shaft F and so employed. In order to regulate the speed
of the governor a small cylinder marked L is provided, which cylinder is
shown at Figure 5 and is herein-after more particularly described. The
slide valves N are of the usual box construction and are set so as to
admit steam and exhaust in the usual manner. The equilibrium
valves O, O, are arranged so as to cut off the steam at any required
part of the stroke by being acted upon by the striking pins or tappets
a, a, through the intervention of the levers b, b, and spindles X, as
herein-before described.
On Sheet 2 Figure 1 is a horizontal section, and Figure 2 a transverse
section of another modification of my improved cut-off valves as applied
to ordinary valve faces.
In this instance two cut-off or equilibrium valves O, O, are employed
to cut off the steam at any part of the stroke, these two valves being
arranged on either side of the slide valve N, as shown particularly at
Figure 1. In this case as at Figures 3, 4, and 5 of the preceding Sheet
of Drawings the valves are actuated from the under side of the steam
chest, but in lieu of a single strike pin or tappet being employed as
herein-before described the T-headed spindles of the valves O are acted
upon by a double lever R, as shown at Figure 2, which lever is caused
to actuate the valves alternately by the epicyclic train through the inter-
vention of a crank or eccentric in communication with the rod S. The
connecting rod S is formed with a slot or groove at that part by which
it is connected to the double lever R so as to allow the valve to stand
full open during a portion of the stroke of the piston. By increasing
the lengths of the stroke and slot the "cut-off" valve may be made to
close in a shorter space of time.
At Figures 3 and 4 are shown two views of a slide valve having two
gridiron valves T, T, on the back, which valves are situated so as to
admit steam to each end of the cylinder, and they may be actuated
either from the top or bottom of the valve boxes of horizontal cylinders
or through the side of the steam chests of vertical cylinders, the motion

page_text: being imparted to the valves from the epicyclic train by rods and other
mechanism, as herein-before described.
Figures 5 and 6 are detailed views of the epicyclic train, connected
to which is shown an hydraulic cylinder N and ram M.
To the top or
upper part of the ram M a lever W is attached, which lever acts on
the lever Fattached to the double bracket herein-before described in
reference to Figures 1 and 2 of the preceding Sheet of Drawings, the
object of which brackets are to keep the engine at an uniform rate of
speed by the action of the governor. The hydraulic cylinder N is shown
provided with a slide valve V for admitting and discharging the oil or
other fluid used to actuate the ram M. The valve V is actuated by the
governor through the levers U, which levers either open or shut the
valve and raise or lower the ram M, and thereby regulate the expansion
of the steam in the steam cylinder. The cylinder and ram may be made
double-acting, and when the engine is at its mean speed the valve will
remain closed as shown at Figure 5. A small force pump (not shown
on the Drawings) is connected with the hydraulic cylinder and is driven
from any convenient part of the engine. In lieu of employing a slide
valve to admit the oil or other liquid to the cylinder D a four-way
cock. may be used. In lieu of employing a hydraulio cylinder as
herein-before deseribed to regulate the "cut-off," the same end may
be attained by having on the moveable "sleeve "on the governor spindle
two disc plates with a pulley and shaft to be acted upon by the discs
when the speed of the engine changes, this shaft driving a worm gearing
into a quadrant or frame which support the train of wheels, which
train of wheels will change its position and cause the steam to be cut
off sooner or later and thereby keep the engine at one uniform speed.
The epicyclic gearing and "cut-off" valves herein-before described and
shown on the appended Sheets of Drawings may be used in conjunction
with or applied to any kind of steam engine and in any position. When
the equilibrium or "cut-off" valves cannot drop of themselves on their
spindles being released from contact with the strike pin, tappet, or cam
they may be closed by springs provided for that purpose, as shown at
Figure 2 (Sheet 2), or by any other suitable mechanism.
Having now described the nature of my said Invention, and the
system, mode, or manner in or under which the same is or may be
used or practically carried in effect, I would observe in conclusion that
what I consider novel and original, and therefore claim as the Invention

page_text: secured to me by the herein-before in part recited Letters Patent
is,--
(1.) The employment of an epicyclic train of wheels arranged to
impart motion to cams, levers, or lifters acting upon equilibrium or
other valves fitted in two or three ported slide valves, the said epicyclic
train being in connection with the governor, substantially as herein-
before described.
(2.) The use and application of a fluid or liquid pressure cylinder and
piston acting as herein-before described.
(3.) The method of fitting double beat equilibrium valves into slide
valves, and also the manner of actuating these equilibrium valves,
substantially as herein-before set forth.
In witness whereof, I, the said John Turnbull, have hereunto set
my hand and seal, this Third day of May One thousand eight
hundred and seventy.