IMPROVEMENTS IN MOTIVE-POWER ENGINES AND IN APPARATUS CONNECTED THEREWITH
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the
Office of the Commissioners of Patents, with his Petition, on the
1st November 1875.-A communication from abroad by Christopher
Columbus Wolcott, of Washington, District of Columbia, United
States of America.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN MOTIVE-POWER ENGINES AND IN APPARATUS
CONNECTED THEREWITH," a communication to me from abroad by Christopher
Columbus Wolcott, of Washington, District of Columbia, United States
of America, to be as follows:-
This Invention relates to the governors and cut-off mechanism of
motive-power engines, and it has for its main object the constructing a
sensitive marine engine governor by causing the establishing and
breaking of an electric current due to the motion of the vessel to
control the force exerted for operating the throttle valve of the engine,
but it is also applicable to the operation of the cut-off valves of engines
generally.

page_text: In carrying out this Invention as applied to a marine engine governor,
the throttle valve spindle or a countershaft connected therewith is
provided with an arm connected to the outer end of a piston rod, the
piston of which is contained within a small cylinder, and is operated by
steam, air, or other motive fluid. The valve chest of this cylinder
contains a valve which admits of different constructions, but a balanced
or other valve demanding the least exertion to operate is preferred.
The valve spindle is connected to an arm which is secured to a shaft
hung to any fixed object, to which arm there is attached an armature
secured to a double electro-magnet.
A small covered glass or earthenware receptacle containing a supply
of mercury is provided. Near one cud of the cover of this receptacle
there is fitted a set screw, the lower end of the stem of which is
constantly immersed in the mercury, whilst near the opposite end of the
cover of the receptacle there is fitted another screw, the stem of which
is never in contact with the mercury excepting under the circumstances
explained hereafter. A wire extends from the magnet to one pole of a
battery, another wire extends from the other pole of the battery to the
first mentioned screw, and a third wire is conducted from the screw
secondly mentioned to the magnet.
"
It will be seen that there can be no electric circuit until the mercury
is in contact with the stem of the second screw, and this never takes
place excepting when the motion or position of the vessel is such as to
induce the engines to "race as the running of the engines at a
dangerous speed is technically termed, the receptacle being arranged in
the most advantageous position for insuring the prompt action of the
mercury in accordance with the motion of the vessel, and the said screw
being so adjusted that the mercury cannot come in contact with it
unless an increased speed of the engines demands the formation of an
electric circuit. As long as no electric circuit exists the small engine
remains quiescent, the throttle valve of the engine being open, and the
piston at the rear end of the cylinder, but the moment an electric
circuit is formed the armature will be brought into instant contact with
the magnets, and the valve will be so operated that steam (when steam
is the motive fluid employed) will be admitted to the rear of the piston,
and the arm of the throttle valve spindle will consequently be so
operated as to close the throttle valve to an extent sufficient to prevent
the racing of the engine, and this closing or partial closing of the throttle

page_text: valve will be continued as long as the eletric circuit is continued, and
consequently as long as the position of the vessel induces the engine to
race.
The moment the circuit is broken, however, by the receding of the
mercury from the point of the set screw secondly mentioned, the arm
carrying the armature will be released and drawn back by a spring to
its original position, the piston of the engine will be moved rearward, and
the throttle valve will be opened.
It will be seen that the governing of the engine is dependent upon
the making and breaking of a current of electricity due to the motion
of the vessel and in obedience to the requirements of the engine. This
making and breaking of the current of electricity may be accomplished
by means other than those described, for instance, the mercurial
receptacle may be entirely dispensed with, & the wires referred to as
connected to the screws be carried over the stern of the vessel, and
both immersed in the sea (by preference just over the screw propeller),
the wires being adjustable so that they can be arranged to suit the
degree of pitching. The salt water in this case makes the connection,
and while the arm of the engine valve spindle is held up to the magnets
the throttle valve is open. The instant the stern rises out of the sea the
wires leave the water, the circuit is broken, the arm is released and
drawn back by the spring, the piston is moved, and the throttle valve
closed, and remains closed until the stern sinks back again. into the sea
and the wires are again immersed, when the circuit is made, the arm
drawn up, and the throttle valve is opened.
A pendulum may also be used for making or breaking the circuit
in obedience to the position of the vessel and requirements of the
engine.
The small engine may be operated by compressed air, or the engine
may be dispensed with, and the force exerted to move the throttle valve
may be derived from the main engine of the vessel and controlled by
the making and breaking of an electric circuit due to the motion of the
vessel. In this case an arm is hung loosely to the spindle of the
throttle valve, and is vibrated at a comparatively rapid speed from the
main engine of the vessel through the medium of such connections as
circumstances may suggest. To this arm there is loosely hung a lever
having two projections, one on each side of the fulcrum, one arm of the

page_text: lever being extended outwards and connected by a link to a lever which
is controlled by the magnet. To the valve spindle there is secured
another arm provided at the top with a projection, with which is
brought in contact the one or the other of the projections of the lever
during the vibrating movement of the arm carrying it, according as the
circuit is broken or restored, whereby the valve is opened or closed as
the case may be.
When this Invention has to be employed as a simple cut off without
any regard to the movement of the vessel, the following device which
takes the place of the mercury receptacle and its adjuncts is employed.
In this case a shaft having two projections arranged opposite to cach
other is caused to revolve in unison with the crank shaft of the engine.
An arm is hung loosely to any suitable fixed object, and to this arm
is connected one of the electric wires, while the other electric wire is
connected to the shaft with the projections before mentioned. As this
shaft revolves the electric circuit will be broken whenever the pro-
jections are free from the suspended arm, and will be restored when the
latter is in contact with either projection. These projections may be
so formed that the valve shall cut off the steam at the desired points in
the stroke of the engine.