IMPROVEMENTS IN GOVERNING APPARATUS FOR SCREW-PROPELLER ENGINES
Year: 1883

page_text: LETTERS PATENT to David John Dunlop, of Port Glasgow, in the County of
Renfrew, North Britain, Engineer and Shipbuilder, for an Invention of
IMPROVEMENTS IN GOVERNING APPARATUS FOR SCREW-PROPELLER ENGINES.
PROVISIONAL SPECIFICATION left by the said David John Dunlop at
the Office of the Commissioners of Patents on the 2nd October 1883.
DAVID JOHN DUNLOP, of Port Glasgow, in the County of Renfrew, North
Britain, Engineer and Shipbuilder, "IMPROVEMENTS IN GOVERNING APPARATUS
FOR SCREW-PROPELLER ENGINES
"
"
0
This Invention relates to governing apparatus of the kind described in the
Specification of Letters Patent obtained by the present applicant; and dated
30 March 1871 (N° 852), and its object is to render such apparatus suitable for
controlling engines of comparatively large size without the apparatus itself being
made of inconveniently large dimensions. In the governing apparatus referred to,
a varying pressure caused in apparatus at the stern of the ship by the varying
immersion of the stern is transmitted to the engine room and there made to
operate on the throttle valve of the engines. When arranged to act directly on
the throttle valve of the main engines the governing apparatus has to be
proportioned to suit the power required to move the throttle valve; and when the
engines are large or the throttle or regulating valve of a kind requiring extra
power the apparatus becomes cumbersome. By the present Invention the primary
governing apparatus may be kept comparatively small whatever may be the power
required to move the throttle valve, as the primary apparatus is arranged to act
on the valve of a small relay cylinder which may be worked by steam or water
under pressure, and it is the piston of this cylinder which moves the throttle or
regulating valve of the large engines, through a rocking shaft to which the piston
rod is connected.
The parts of the primary governing apparatus and of the relay cylinder and its
valve details are combined in a peculiar manner, so that the relay apparatus is
made to act to an extent corresponding precisely to the extent of movement of the

page_text: primary apparatus. The rod of the primary apparatus by which the governing
movement is transmitted to the valve of the relay cylinder is connected to one end
of a lever which is jointed at about its middle to the valve rod whilst the other
end of the lever is connected by a link to a short lever on the rocking shaft
moved by the piston of the relay cylinder. The direction of action of the rocking
shaft on the valve lever is always opposite to that of the primary apparatus so
that when the primary apparatus causes the valve of the relay cylinder to uncover
either of the ports (or to keep it uncovered) to an extent corresponding to a certain
length of stroke, the valve will, through the action of the rocking shaft and valve
lever, cover the port and stop further action precisely when the extent of stroke
has been accomplished.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said David John Dunlop in the Patent Office on the 31st March 1884.
DAVID JOHN DUNLOP, of Port Glasgow, in the County of Renfrew, North
Britain, Engineer and Shipbuilder "IMPROVEMENTS IN GOVERNING APPARATUS FOR
SCREW-PROPELLER ENGINES
"
.
My said Invention relates to governing apparatus of the kind described in the
Specification of Letters' Patent obtained by me, and dated 30 March 1871
(N° 852) and its object is to render such apparatus suitable for controlling engines
of comparatively large size without the apparatus itself being made of incon-
veniently large dimensions. In the governing apparatus referred to, a varying
pressure caused in apparatus at the stern of the ship by the varying immersion of
the stern, is transmitted to the engine room and there made to operate on the
throttle valve of the engines. When arranged to act directly on the throttle valve
of the main engines the governing apparatus has to be proportioned to suit the
power required to move the throttle valve; and when the engines are large or the
throttle or regulating valve of a kind requiring extra power the apparatus becomes
cumbersome. By my present Invention the primary governing apparatus may be
kept comparatively small whatever may be the power required to move the
throttle valve, as the primary apparatus is arranged to act on the valve of a small
relay cylinder which may be worked by steam or water under pressure, or by
atmospheric pressure against a vacuum and it is the piston of this cylinder which
moves the throttle or regulating valve of the large engines, through a rocking shaft
to which the piston rod is connected.
The parts of the primary governing apparatus and of the relay cylinder and its
valve details are combined in a peculiar manner, so that the relay apparatus is
made to act to an extent corresponding precisely to the extent of movement of the
primary apparatus. The movement produced by the primary apparatus is greater
or less according to the greater or less change taking place at any time in the
immersion of the ship's stern, and when such movement takes place it causes the
valve to uncover a port of the relay cylinder, but the port is closed again by the
action of the piston as soon as it moves to an extent corresponding to the extent of

page_text: movement of the primary apparatus. In apparatus made without the peculiar
combination referred to, the piston of the relay cylinder makes a complete stroke in
either direction whenever one of the. ports is uncovered the result being that the
throttle valve is either completely closed or fully opened, and that unnecessarily
great changes in the action of the engines are suddenly produced and great
inconvenience and risk of breakage are incurred. With my improved apparatus,
however, the changes produced in the action of the engines are such as to precisely
correspond in degree as well as in kind to the actions at the stern which make
those changes desirable.
And in order that my said Invention and the manner of performing the same
may be properly understood I hereunto append a sheet of explanatory drawings to
be hereinafter referred to and representing my improved apparatus.
Figure, 1, on the accompanying sheet of drawings is a plan of the part of the
apparatus which is in the engine room, and figure, 2, is a vertical section of the
same part. Figures 3 and 4, are a plan and a vertical section of the part of
the apparatus which is at the ship's stern, figure, 5, being a section of the sea cock,
as at right angles to figure, 4. In these drawings the same (reference numerals
are used to mark the same or like parts wherever they are repeated.
An air vessel, 6, fitted at the stern of the ship has its bottom end put in
communication with the external sea or water by a passage, 7, and a sea cock, 8,
and when this cock is opened to the sea the air within the vessel becomes
compressed to an extent corresponding to the depth at which the sea-cock inlet
is below the level of the external water. When the sea cock, 8, is turned to close
the inlet from the sea, and is in the position in which it is shown in figure, 5, it
puts the interior of the air vessel, 6, in communication with ports, 9, through
which any water in the vessel, 6, is drained off and replaced by air; and by this
means it can at any time be made sure that the air vessel contains the proper
quantity of air.
The top of the air vessel, 6, communicates by a small pipe, 10, with the
apparatus in the engine room, and in this apparatus the pipe, 10, (see bottom of
figure, 2) communicates with the bottom of a dish-shaped chamber, 11, and the
air acts upon the under side of a flexible diaphragm, 12, which has its outer
edge fixed in the joint by which the vessel 11 is attached to a casing, 13. The
middle, 5, of the flexible diaphragm, 12, is fixed to a rod, 14, by being gripped
between a washer, 15, secured by a nut screwed on the rod, and the bottom of
a cup, 16, screwed on the rod, this cup serving to guide the rod, 14, by working
easily through a contracted opening in the casing, 13, and to contain the lower
end of a helical spring, 17, which resists the upward pressure on the flexible
diaphragm, 12. The upper end of the spring, 17, abuts against a disk or washer, 18,
which can be adjusted by means of a gland or tube, 19, screwed through a cover, 20,
fitted to the casing, 13, The rod, 14, passes through the gland, 19, and is
connected by a link, 21, to one end of a lever, 22, which at its middle is jointed
to a pair of links, 23, which have their other ends jointed to a crosshead, 24, on
the valve rod, 25, of a cylinder, 26, which is hereinbefore termed the relay
cylinder. The valve shown is of the piston class but may be of any suitable
kind. The piston rod, 27, of the cylinder, 26, has fixed to it a crosshead, 28, to
which are jointed links, 29, having their other ends jointed to levers, 30, on a
rocking shaft, 31; and this rocking shaft has also fixed on it a slotted lever, 32,
to which there is adjustably connected a link or rod, 33, for transmitting the
movements to the throttle or regulating valve of the main engines. The rocking
shaft, 31, has also fast on it a lever, 34, which is connected by a link, 35, to the
lever, 22, through which the movements of the diaphragm, 12, are by the rod, 14;.
transmitted to the valve rod, 25; and whenever the piston of the cylinder, 26,
moves in obedience to a movement of the valve the consequent movement of the
rocking shaft, 31, acting through the levers, 34, and 22, causes the valve to
return to its middle or. neutral position and thereby stops further action of the
piston. The valve of the relay cylinder, 26, is moved a greater or less distance

page_text: accordingly as the movement of the diaphragm is greater or less, that is accordingly
as the change in the immersion at the ship's stern is greater or less; and the
piston has to move a correspondingly greater or less distance before the valve is
returned to its closed or neutral position through the action of the rocking
shaft, 31, and the levers, 34 and 22.
Having thus particularly described my said Invention and the manner of
performing the same I have to state that I do not restrict myself to the precise
details herein described or delineated but that what I believe to be novel and
original and claim as the Invention secured to me by and in terms of the
herein before in part recited Letters Patent is :-
The combination in governing apparatus for screw-propeller engines, of a
diaphragm acted on by the varying pressure of air communicating from an air
vessel at the stern of a ship through a pipe, with the valve of a relay cylinder,
and with parts connecting the piston of such cylinder to the valve substantially
in the manner and for the purposes hereinbefore described.
In Witness whereof I, the said David John Dunlop, have hereunto set my
hand and seal this twenty-eighth day of March in the year of our Lord One
thousand eight hundred and eighty-four.
Witness.
EDMUND HUNT.
Patent' Agent.
Glasgow.
D. J. DUNLOP. (L.S.)