IMPROVEMENTS IN DRIVING SCREW PROPELLERS
Year: 1880

page_text: LETTERS PATENT to Charles Maw, of 18, Hyde Park Terrace, in the County
of Middlesex, for an Invention of "IMPROVEMENTS IN DRIVING SCREW
PROPELLERS,"
PROVISIONAL SPECIFICATION left by the said Charles Maw at the Office
of the Commissioners. of Patents on the 24th November 1880.
CHARLES MAW, of 18, Hyde Park Terrace, in the County of Middlesex.
"IMPROVEMENTS IN DRIVING SCREW PROPELLERS."
At the present time the total loss of vessels fitted with screw propellers is from
time to time occasioned by the breaking of the propeller shaft. In some cases the
skin of the vessel is torn by the broken shaft, and so injured as to occasion the
vessel's loss. In other cases the screw propeller and the end of the shaft attached
to it drops out, and in this manner leaves an opening into the vessel. Even when
the safety of the vessel is not endangered in these ways the vessel is frequently in
danger from the loss of its propelling power; or if the broken parts of the shaft
are after a time coupled together and the screw again used, yet it can only be
driven slowly, and in any case there is great loss of time.
The object of my Invention is to remedy these evils.
For this purpose I enclose the screw propeller shaft, which for my purpose may
be made in any way, either solid, built in sections, or tubular, or of any other form
considered most desirable, within a tube which I attach at its outer end securely
to the screw propeller. In case of breakage of the screw propeller shaft the two
parts of the shaft would be held together by the tube surrounding them, and would
be so prevented from injuring the skin of the vessel; the screw propeller would
also be securely retained by the tube, and prevented from dropping off. At the
inner end of the tube next the driving engines I make provision for coupling the
tube to the engine shaft, so that in case of the breakage of the screw propeller
shaft the tube may be at once coupled up with the engine shaft, and the screw
propeller driven by means of the tube.
The tube may be attached to the engine so as to give extra security at all times,
but I prefer it to be detached from the engine until its use is necessitated by an
accident to the shaft.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Maw in the Great Seal Patent Office on the 24th May
1881.
CHARLES MAW, of 18, Hyde Park Terrace, in the County of Middlesex.
"IMPROVEMENTS IN DRIVING SCREW PROPELLERS."
At the present time the total loss of vessels fitted with screw propellers is from
time to time occasioned by the breaking of the propeller shaft. In some cases the
skin of the vessel is torn by the broken shaft, and so injured as to occasion the
vessel's loss. In other cases the screw propeller and the end of the shaft attached
Even when
to it drops out, and in this manner leaves an opening into the vessel.
the safety of the vessel is not endangered in these ways the vessel is frequently in
danger from the loss of its propelling power; or if the broken parts of the shaft
are after a time coupled together and the screw again used, yet it can only be
driven slowly, and in any case there is great loss of time.
The object of my Invention is to remedy these evils.
For this purpose I enclose the screw propeller shaft, which for my purpose may
be made in any way, either solid, built in sections, or tubular, or of any other form
considered most desirable, within a tube, which I attach at its outer end securely to
the screw propeller. In case of breakage of the screw propeller shaft the two
parts of the shaft would be held together by the tube surrounding them, and would
be so prevented from injuring the skin of the vessel; the screw propeller would
also be securely retained by the tube, and prevented from dropping off. At the
inner end of the tube next the driving engines I make provision for coupling the
tube to the engine shaft, so that in case of the breakage of the screw propeller
shaft the tube may be at once coupled up with the engine shaft, and the screw
propeller driven by means of the tube.
The tube may be attached to the engine so as to give extra security at all times,
but I prefer it to be detached from the engine until its use is necessitated by an
accident to the shaft.
In order that my Invention may be fully understood, and readily carried into
effect, I will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a longitudinal vertical section of the propeller shaft with its
surrounding tube or casing and other parts; Figure 2 is a plan of part of the said
tube or casing of the propeller shaft; Figure 3 is a transverse section of the tube;
and Figure 4 is a section of one of the blocks and bearing carrying the propeller
shaft.
a, a, is the ordinary propeller shaft; b, b, a tube or casing surrounding this shaft.
The tube or casing b is in convenient lengths, and excepting the length contained
within the stern tube c, it is divided longitudinally so that it may be put on over
the collars of the shaft a.
The halves or parts are bolted together, as is indicated in Figures 2 and 3. The
aft length of the tube or casing b is screwed or otherwise fixed into the boss of the
propeller d. By preference the tube or casing b is not coupled with the engines
except by its connection with the propeller, which however causes it to rotate with
the shaft, and to revolve in the bearings e. e¹ is the thrust bearing.
In case of breakage of the shaft a no displacement of the parts will occur, these
being contained within the tube b, b, and thus injury to the ship is prevented.
After such a breakage has occurred the propeller. can again be brought into use

page_text: to an extent sufficient for the control and safety of the vessel by coupling the tube
with the shaft at the point f.
Having thus described the nature of my said Invention, and the manner of
performing the same, I would have it understood that I claim as my improvements
in driving screw propellers is the employment of a tube or casing surrounding the
propeller shaft, which tube or casing serves, if breakage takes place, both to retain
in place the pieces of the shaft, and to recouple the propeller with the engines,
substantially as described.
In witness whereof, I, the said Charles Maw, have hereunto set my hand
and seal, this Twenty first day of May, in the year of our Lord One
thousand eight hundred and eighty one.