Improved Differential Regulator and Stop Motion for Steam and similar Engines.
Year: 1890

page_text: Date of Application, 22nd Feb., 1890
Complete Specification Left, 22nd Nov., 1890-Accepted, 27th Dec., 1890
PROVISIONAL SPECIFICATION.
Improved Differential Regulator and Stop Motion for Steam and
similar Engines.
I GEORGE HENRY FIRTH of Pear Tree Cottage Hurdsfield Road Macclesfield in
the County of Chester Engineer do hereby declare the nature of this invention to be
as follows:-
My invention relates to apparatus for regulating the speed of steam and similar
engines and consists in an improved arrangement of differential apparatus for this
purpose. When the load on an engine fitted with an ordinary centrifugal governor is
increased its speed becomes reduced and the governor balls drop and shift the bush so
as to open the throttle valve wider and increase the pressure or increase the admission
of steam to the cylinder, and the speed increases again but not to the normal point
because the increased load requires an increased pressure and consequently enlarged
opening of the throttle valve or increased length of admission of steam, and if the
normal speed is to be regained, the connections between the governor and the throttle
valve or expansion gear have to be altered by hand. The main object of my
improvements is to effect this regulation automatically and I attain this by means of a.
differential mechanism, which may also be used independently of the governor and
also utilised for stopping the steam engine in case of accidents.
On a suitably supported stud or spindle I arrange a bevil wheel driven at a reduced
speed from the crank shaft of the engine. Facing said bevil wheel I arrange another
bevil wheel of the same size driven in the contrary direction by means of regulated
clockwork or from a motor actuated by a constant force and under a constant load,
for instance a water motor, so that the motor and the bevil wheel driven from it has a
constant speed. This speed is equal to that of the other bevil wheel when the engine
is at its normal speed. In gear with both bevils I arrange a third one having its axis
at right angles to the former and supported in bearings in the plate of a
large wheel
hereinafter called disc wheel, the arrangement of the wheels being similar to that
known as
"Jack in the box" in spinning machinery. When the engine runs at its
normal speed, the middle bevil is simply rotated by the other two without producing
any motion of the disc wheel, but when the engine speed decreases below or increases
above the normal speed the middle bevil rolls on the slower wheel in gear with it and
the disc wheel is rotated in one or the other direction. In gear with the disc wheel I
arrange a pinion on a shaft which is thereby rotated and this rotation of the shaft is
utilised to adjust the length of one of the rods connecting the governor with the
throttle valve or automatic expansion gear, so as to increase or reduce the pressure or
admission of steam. This may be effected in various ways. The said rod may be in
two parts screwed with a right and left hand thread respectively and connected by
means of a long nut tapped correspondingly, and the nut rotated by means of a worm
wheel fixed or formed on it and a worm fixed upon the shaft rotated by the disc wheel,
or bevil wheels may be used for rotating the nut, or instead thereof the ends of the
rods may be formed with racks in gear on opposite sides with a pinion fixed. to said
shaft the rotation of which shifts the racks and lengthens the rod; or any other
equivalent arrangement may be employed. The shaft is preferably formed with two
universal joints so that the end carrying the worm or wheel can follow the movement
of the rod when actuated by the governors.
The action of this apparatus is as follows:-When the engine speed varies, for
instance becomes reduced in consequence of an increase of the load, the governor balls
drop and increase the opening of the throttle valve or length of admission. - At the
same time the speed of the bevil wheel driven from the engine is reduced while that
driven by the clock or motor remains uniform, so the latter overruns the former and

page_text: rotates the disc wheel. The motion of the latter effects in the manner bereinhefore
described an alteration in the length of the connection between the governor and
throttle valve or expansion gear acting in the same sense, that is to say so as to
increase the opening of the throttle valve or length of admission of steam.
sequence of this increase the speed increases again until the engine has attained its
normal speed and the governor the corresponding position.
In con-
These changes going on simultaneously the engine will be practically maintained at
a uniform speed.
When the engine is stopped a similar opening of the throttle valve or other parts
will take place and the parts might become jammed or broken unless provision. were
made against this. This may be done by putting the pinion gearing with the disc
wheel loose upon its shaft and driving the latter by means of toothed or friction
clutches which will slip when the rotation of the shaft is arrested. By preference
however I place upon the shaft carrying said pinion or other shaft driven from the
same a worm driving a worm wheel with a peg fixed to its side which is so arranged
or adjusted that before the length of the connecting rod is so altered as to cause
jamming, the peg encounters a catch lever and by moving it removes the catch from
another lever actuated by a spring or its equivalent which on its release puts a brake
upon the bevil wheel or other part driven by the clockwork or motor. When these
are thus stopped, the engine if still in motion will drive the bevil wheel connected to
it and thus cause the disc wheel to rotate in the opposite direction and the length of
the rod to be altered in the opposite way whereby jamming is prevented.
The catch lever may be utilised for stopping the engine from any part of the mill in
case of accident.
For this purpose an electro magnet is arranged so as to attract the end of the lever
and thereby lift the catch off the spring lever when the circuit is closed. A battery
or dynamo may he arranged for supplying current and shunts placed in different parts
of the mill by means of which the circuit can be closed in case of accident and the
core of the electro magnet magnetised so as to liberate the spring lever, which puts on
the brake as hereinafter described and arrests the motion of the bevil wheel.
The engine continuing to revolve, the bevil wheel driven from it will overrun the
engine and rotate the disc wheel in such a direction that the connecting rod is altered
in length so as to close the throttle valve or stop the admission of steam by the valve
gear.
The apparatus may be used for regulating or stopping engines without another
governor. It is applicable to other elastic fluid engines besides steam engines, for
instance, to compressed air engines.
The details of the mechanism may be varied to suit different kinds and arrangements
of engines and governors and the apparatus may be used in connection with land and
marine engines.
Dated this 21st day of February 1890.
EMMOTT & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Differential Regulator_and Stop Motion for Steam and
similar Engines.
I, GEORGE HENRY FIRTH, of 93, North Road, Clayton, Manchester, in the County
of Lancaster, Engineer, 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 :-
My invention relates to apparatus for regulating the speed of steam and similar
engines and consists in an improved arrangement of differential apparatus for this
purpose. When the load on an engine fitted with an ordinary centrifugal governor is
increased, its speed becomes reduced and the governor balls drop and shift the bush

page_text: so as to open the throttle valve wider and increase the pressure or the admission of
steam to the cylinder, and the speed increases again but not to the normal point
because the increased load requires an increased pressure and consequently enlarged
opening of the throttle valve or increased length of admission of steam, and corré-
sponding different position of the governor balls, and if the normal speed is to be
regained, the connections between the governor and the throttle valve or expansion
gear have to be altered by hand or otherwise. The main object of my improvements
is to effect this regulation automatically and I attain this by means of a differential
mechanism, which may also be used independently of the governor. and also utilised
for stopping the steam engine in case of accident.
On the two sheets of drawings appended hereunto
Fig. 1 shows a front elevation of the apparatus.
Fig. 2 a plan of one of the wheels and clutch boxes of the same, sectioned along
line A. B. of Fig. 1.
Fig. 3 an end elevation of the apparatus as seen from the right hand of Fig. 1 with
the pillar partly removed.
The apparatus is mounted upon a base plate a provided with a socket a¹ for fixing
the same on a pillar or stand, or upon a similar suitable bracket or plate. The plate:a
carries bearings for the shaft b upon which the worm is fixed and gears with
the worm wheel c. The shaft is driven in any convenient way from the crankshaft
of the engine and rotates the worm wheel c at- a reduced speed. The wormwheel
revolves on a collar d' of the hollow stud d, the section of which is indicated on
Fig. 1. The stud is fixed on the base plate a by means of the nut d². The bevil
wheel e is cast with or fixed to the worm wheel c and rotates with the same. Facing
the wheel e another bevil wheel of the same size is mounted upon the stud d and
rests on a shoulder of the same. The wheel is formed with a clutch f¹ at its back,
into which the projections g' of a sliding clutch 9 enter. A shaft h passes through the
hollow stud d and is supported at the top in the cross rail i carried by the pillar
and bracket m fixed upon the base plate a. A clutch is fixed on the shaft h into
which the teeth g of clutch g enter when the latter is held up in the position shewn
on the drawings by the pins n' of the forked lever n which enter a groove g³ of the
clutch g.
The shaft receives a uniform rotation from a motor independent from the
engine to which the apparatus is applied. This motor may be a spring motor
regulated by clockwork, or a water motor actuated by a constant pressure under a
constant load or other uniformly rotating motor. The shaft h drives through the
clutches g' and g² the bevil wheely in a contrary direction to the wheel e and at a
constant speed corresponding to the speed of e when the engine is driving the crank-
shaft at its normal speed. Between the wheels f and e a third bevil disc- or
plate-wheel is placed upon the stud d. The plate of contains an opening and
bearings for the bevil wheel to run in. This wheel is in gear with both wheels e
and as shewn. When the latter are rotated in opposite directions at the same speed,
the wheel simply rotates and no movement of the wheel takes place, but when the
speed of the engine and wheel e increases, the wheel rolls on wheel and the wheel!
is turned in the same direction as wheel e, while if the speed decreases, the wheel l¹
rolls one and the wheel is turned in the same sense as f. These motions are
transmitted through the bevil pinion k running in a boss on bracket m and the
clutches to the shaft o.
•
The rotation of the shaft o is utilized to adjust the length of one of the rods
connecting the governor with the throttle valve or automatic expansion gear, so as
to increase or reduce the pressure or admission of steam. This may be effected in
various ways. The said rod may be in two parts screwed with a right and left hand
thread respectively and connected by means of a long nut tapped correspondingly,
and the nut rotated by means of a worm-wheel fixed or formed on it and a worm fixed
upon the shaft o rotated by the disc wheel, or bevil wheels may be used for rotating
the nut. Or instead thereof the ends of the rods may be formed with racks in gear on
opposite sides with a pinion fixed to said shaft, the rotation of which shifts the racks
and lengthens the rod ;. or any other equivalent arrangement may be employed. The

page_text: shaft is preferably formed with two universal joints, so that the end carrying the
worm or wheel can follow the movement of the rod when actuated by the governor.
At
The action of this apparatus is as follows: When the engine speed varies, for
instance becomes reduced in consequence of an increase of the load, the governor
balls drop and increase the opening of the throttle valve, or length of admission.
the same time the speed of the bevil wheel e driven from the engine is reduced, while
that of wheel driven by the clock or motor remains uniform, so the latter over-runs
the former and rotates the disc wheel I. The motion of the latter effects in the
*manner hereinbefore described an alteration in the length of the connections between
the governor and throttle valve or expansion gear acting in the same sense, that is to
say so as to increase the opening of the throttle valve or length of admission of steam.
In consequence of this increase the speed increases again until the engine has attained
its normal speed and the governor the corresponding position. These changes
passing simultaneously the engine will be practically maintained at a uniform speed.
When the engine is stopped a similar opening of the throttle valve or admission
gear will take place and the parts might become jammed or broken unless provision
were made against this occurring. This may be done as shewn on the drawings by
making the pinion k loose upon the shaft o and fixing a clutch k¹ upon its boss k³,
arranging the other clutch so that it can slide upon a key o' let into the shaft o,
and pressing it into gear with k¹ by means of a spring o' placed on shaft o between
the collar o and the clutch ; a collar o³ being further fixed on the shaft to keep it
in its position. When the rotation of the shaft o becomes arrested by the stoppage of
the parts actuated by it, the clutch can push back and the rotation of the
wheel can continue till the rotation of the engine is arrested and breakages are
thus avoided. Other mechanism for effecting the same purpose may be used.
The apparatus may be utilised for stopping the engine from any part of the
premises in case of accident. For this purpose I arrange by preference an electro
magnet p carried by a bracket p¹ attached to bracket m. Above the same a wrought
iron bell crank lever is arranged mounted upon the pin in lugs m¹ on the
bracket m. The upright arm of this lever carries a stud under which the end of
the lever n catches. This lever is fulcrumed on pin n' in the stud fixed to the
cross-rail i, and holds the sliding clutch g in gear with the clutch as hereinbefore
described. The lever n is formed with an eye to pass round the clutch and bent
downwards at the end and provided with a projection or clatch n³. A springs fixed
to cross-rail i presses upon the top of catch n. A battery or dynamo is used for
supplying a current, and switches are placed in different parts of the mill or works by
means of which the circuit can be closed in case of accident and the core of the electro
magnet p magnetised. This will then attract the end of the lever whereby the pin,
is moved off the end of the lever n and the latter liberated. The springs then
depresses the end n³ and the latter drops into one of the recesses of the clutch fon
wheel and thereby arrests its rotation, while the pins n' at the same time draw the
teeth of the clutch g' out of the clutch 1. The rotation of wheelf being stopped
while that of wheel e continues, the wheel and consequently the shaft o are rotated
in such a direction that the connecting rod between the governor and the throttle
valve or valve gear is altered in length in the manner hereinbefore described so as to
close the throttle valve or stop the admission of steam by the valve gear.
Instead of using an electro magnet to operate the lever r, the latter may be
moved directly from different parts of the works by means of rods or wire pulls.
The apparatus hereinbefore described may also be used for regulating the speed or
stopping engines directly without being combined with another governor, the rotary
movement of the shaft o which occurs at every change of the speed being made use of
to actuate the throttle valve or cut-off gear. For instance, lever on said shaft o
may be connected directly to the throttle valve spindle by a link where a rapid regu-
lation is desired, or a pinion or worm on the shaft may be driving a wheel or
worm wheel on a second shaft, a lever on which is connected to the throttle valve
spindle. The apparatus is applicable to other elastic fluid pressure engines besides
steam engines, for instance to compressed air engines. Obviously the details of the

page_text: arrangement, such as the fixings or bearings of the different rotating parts may be
varied to suit different kinds and arrangements of engines and governors, and the
apparatns may be used with land and marine engines.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
Firstly. A combination with an engine governor of a differential regulating
apparatus constructed substantially as herein before described and illustrated by the
drawings and with or without the arrangement for stopping the engine hereinbefore
described.
Secondly. The arrangement or construction of a differential apparatus for regu-
lating the speed of engines in such a manner that the difference in the rotary speed
of one wheel driven from the engine crank-shaft and another wheel driven by an
independent uniformly rotating motor causes the rotation of a shaft acting by means
of mechanisms upon the rods connecting the engine governor to the throttle valve or
cut-off regulating parts in such a way, that the rotation of said shaft produces an
increase or decrease in the length of said connecting rods according to the direction
in which the shaft is turned, substantially as hereinbefore described and illustrated
by the drawings.
Thirdly. Differential apparatus constructed substantially as hereinbefore described
with reference to the drawings in combination with levers and links or equivalent
mechanisms for transmitting the motion of the shaft o resulting from the differential
rotation of the wheels e and to the throttle valve or cut-off regulating parts of the
engine.
Fourthly. In combination with apparatus for regulating the speed of engines,
operated by the differential speed of a wheel driven from the crank shaft and another
wheel driven by an independent motor, the arrangement of a clutch for driving said
other wheel held in gear by means of a lever and a catch for the same which can be
released from a distance and thereby disengages the lever, a spring or its equivalent
actuating said lever so as to disengage the clutch and disconnect the wheel and motor,
und a stop on the lever for arresting the wheel after its disengagement, substantially
as hereinbefore described and illustrated by the drawings and for the purpose of
stopping the engine from a distance.
Dated this 19th day of November 1890.
EMMOTT & Co.,
Agents for the Applicant.