IMPROVEMENTS IN CONNECTION WITH THE SCREW OR OTHER SIMILAR PROPULSION OF VESSELS
Year: 1879

page_text: LETTERS PATENT to William Dawes, of Kingston Grove, Leeds, in the County
of York, Engineer, for the Invention of "IMPROVEMENTS IN CONNECTION WITH
THE SCREW OR OTHER SIMILAR PROPULSION OF VESSELS."
Sealed the 14th October 1879, and dated the 18th April 1879.
PROVISIONAL SPECIFICATION left by the said William Dawes at the Office
of the Commissioners of Patents on the 18th April 1879.
WILLIAM DAWES, of Kingston Grove, Leeds, in the County of York, Engineer.
"IMPROVEMENTS IN CONNECTION WITH THE SCREW OR OTHER SIMILAR PROPULSION
OF VESSELS."
The object of this Invention is to provide a more efficient and certain automatic
or self-acting mechanical means of preventing the "racing" or greatly increased
speed of the engines and screw, when through the "pitching" of the vessel or the
roughness of the sea the screw becomes either partially or entirely exposed, or not
sufficiently submerged to prevent this sudden and objectionable increase of speed,
and the consequent strain and danger of damage or breakage when the screw as
suddenly again becomes submerged, and both it and the shaft are subjected at this
great speed to the full power of the engines.
In carrying this Invention into effect I first construct and fix upon the screw
shaft or other convenient part of the machinery or engines a break or breaks, or
other suitable equivalent retarding power; and to cause this to act automatically
in such a manner as to be always quiescent or inoperative when the screw is sub-
merged, and in action or efficiently operative when it is not submerged; I employ
generally a pendulum of sufficient size and power to actuate the break or breaks by
direct action or connection; the said pendulum being guarded or guided on its two
sides so as to be capable of a longitudinal action only, and this also being confined
by a banking stop or a check-strap or chain to the forward half or part of its
travel, and consequently to the forward motion or pitching only of the vessel.
In those cases where it may not be convenient to employ the before-described
direct-acting pendulum, I substitute a small cylinder and piston, and power either
of steam or water from the engine boilers; the valve of this cylinder and piston
being actuated in a similar automatic manner, either by a smaller pendulum of

page_text: like construction and action to the one described, or by floats, buoys, water-
cylinders and pistons, or other convenient means.
In those cases where from the light draught of the vessel or other peculiarities
the screw may be liable to exposure in a rough or "chopping" sea, otherwise than
from the extensive forward pitching of the vessel I prefer to employ the floats,
buoys, or water cylinders and pistons (either with or without the steam or water
boiler power), and to construct and place these in such a manner that whenever
from any cause the screw may be exposed either partially or entirely, the retarding
breaks or other power shall be brought into action, and this in proportion to the
extent of the exposure of the screw, and thus compensation and comparative
uniformity of speed of engines and screw and freedom from danger are obtained.
As a means of further increasing the completeness and efficiency of my Invention,
I also prefer generally to employ a relieved or equilibriated valve in the steam
pipes between the boilers and the engines, and I connect this valve with any
convenient part of the before-described mechanical parts or details, so that it shall
also partake of a simultaneous and therefore automatic action, and cause a less
powerful break or retarding effect to suffice; or even in some cases this latter may
be omitted, and the valve with any of the before-described automatic actions be
retained.

page_text: pursuance of the conditions of the Letters ratent med by
the said William Dawes in the Great Seal Patent Office on the 18th October
1879.
WILLIAM DAWES, of Kingston Grove, Leeds, in the County of York, Engineer.
"IMPROVEMENTS IN CONNECTION WITH THE SCREW OB OTHER SIMILAR PROPULSION
OF VESSELS."
The object of this Invention is to provide a more efficient and certain automatic
or self-acting mechanical means of preventing the "racing" or greatly increased
speed of the engines and screw, when through the pitching of the vessel or the
roughness of the sea the screw becomes either partially or entirely exposed, or not
sufficiently submerged to prevent this sudden and objectionable increase of speed,
and the consequent strain and danger of damage or breakage when the screw as
suddenly again becomes submerged, and both it and the shaft are subjected at this
great speed to the full power of the engines.
"
In carrying this Invention into effect I first construct and fix upon the screw
shaft or other convenient part of the machinery or engines a "break or breaks, or
other similar or suitable equivalent retarding power; and to cause this to act
automatically in such a manner as to be always quiescent or inoperative when the
screw is submerged and in action, or efficiently operative when it is not submerged,
I employ generally a pendulum of sufficient size and power to actuate the break or
breaks by direct action or connection; the said pendulum being guided or guarded
on its two sides so as to be capable of a longitudinal action only, and this also
being confined by a banking stop or a check strap or chain to the forward half or
part of its travel, and consequently to the forward motion or pitching only of the
vessel. In some cases where it may not be convenient to employ the before-
described direct-acting pendulum, I substitute cylinders and pistons (one of each to
each break), and the pressure as power of either the steam or water from the engine
boilers, the valves of these cylinders being actuated in a similar automatic manner,
either by a smaller pendulum of similar construction and action to the one described,
or by floats, buoys, water cylinders and pistons, or other convenient means.
In those cases where from the light draught of the vessel or other pecularities
the screw may be liable to exposure in a rough or "chopping" sea, otherwise than
from the extensive forward pitching of the vessel, I prefer to employ the "floats,
buoys, or water cylinders and pistons," either with or without the boiler pressure
and power, and to construct and place these in such a manner that whenever from
any cause the screw may be exposed either partially or entirely, the breaks or
other retarding power shall by them be brought into action, and this in proportion
to the extent of the exposure of the screw, and thus compensation and comparative
uniformity of speed of engines and screw and freedom from danger are obtained.
As a means of further increasing the completeness and efficiency of my Invention
I also sometimes employ relieved or equilibriated "throttle valve" in the steam
pipes between the boilers and the engines, and by any convenient connection
I cause this also to work automatically and simultaneously with the herein before-
described retarding mechanical arrangements or details. The object of this com-
bined action is to enable smaller breaks to suffice. It may be well to explain that
I generally encase the before-described breaks with galvanized iron or other
suitable metal or material.
In the accompanying illustrations Figure 1 is a side elevation of one break and
pendulum, and Figure 2 is a side elevation of the breaks with cylinders and pistons
actuated by one pendulum in rotation according to the extent of the exposure of
the screw, showing also the manner in which the additional throttle or governing
valve may be attached or coupled thereto.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into

page_text: effect, I wish it to be understood that I do not confine or restrict myself to the
precise details or arrangements which I have described or referred to, as many
modifications and variations may be made therefrom without deviating from the
principles or main features of the said Invention, but what I consider to be novel
and original, and therefore claim as the Invention secured to me by the herein-
before in part recited Letters Patent is,-
"
The application, use, and automatic action and effect of a break or breaks, or
other similar retarding power, and cylinders and pistons in connection with the
same, and actuated by the boiler pressure with or without "throttle or governing
valves; and these actuated automatically by pendulum, water pistons, floats, or
buoys, and so constructed and employed as to prevent the dangerous increase in
speed of the screw and engines, when the screw from the pitching of the vessel or
other course is not sufficiently submerged to prevent this increase of speed, virtually
as or after the manner of the foregoing description.
In witness whereof, I, the said William Dawes, have hereunto set my hand
and seal, this Seventeenth day of October, in the year of our Lord One
thousand eight hundred and seventy-nine.
Witness,
FREDERIC BAPTY,
Park Square,
Leeds.
WILLIAM DAWES. (L.S.)