IMPROVEMENTS IN AND IN CONNECTION WITH SCREW PROPELLERS
Year: 1880

page_text: LETTERS PATENT to William Cooke and Daniel Mylchreest, of Liverpool,
in the County of Lancaster, Consulting Engineers, Naval Architects, and
Co-partners, for an Invention of "IMPROVEMENTS IN AND IN CONNECTION
WITH SCREW PROPELLERS."
PROVISIONAL SPECIFICATION left by the said William Cooke and Daniel
Mylchreest at the Office of the Commissioners of Patents on the 7th December
1880.
WILLIAM COOKE and DANIEL MYLCHREEST, of Liverpool, in the County of
Lancaster, Consulting Engineers, Naval Architects, and Co-partners. "IMPROVE-
MENTS IN AND IN CONNECTION WITH SCREW PROPELLERS."
Heretofore screw propellers for steam ships have been so made that great
difficulty has been experienced in removing them from their shafts. The con-
struction has almost invariably been such that in order to place them on or take
them off their shafts it has been necessary to draw the said shafts within ship.
The ends of such shafts too being tapered, it was very difficult to get an accurate
fit between a new boss and an old shaft without removing the shaft from the
ship.
Now the main objects of our Invention are to provide screw propellers so
constructed that they may be easily removed from and attached to their shafts,
and may be easily fitted to the said shafts when such shafts are in position for use.
For that purpose we construct, that is, arrange and combine the parts of screw
propeller bosses in two or more pieces, that is, two or more pieces in their length,
length meaning the direction with the axis of the shaft, and we connect the said
pieces together by bolts and nuts or equivalent fastenings. The blades of the said
propellers are cast with or secured to the said pieces of the boss in any convenient
or desired manner.
When it is desired to remove a propeller constructed under our Invention from
its shaft, all that is necessary to be done is, to undo or unfasten the bolts and

page_text: nuts or holding pieces and remove the pieces from the shaft. In attaching our
said propellers to their shafts the pieces are placed in position round the said
shafts, and are bolted or connected together and keyed or otherwise secured, if
desired.
For the purpose of firmly securing a screw boss under our Invention to its shaft,
we form the end of the shaft with one or more collars or projections, and the
interior of the screw boss with corresponding recesses and collars, so that when
screwed up in position the parts are locked, and when desired made watertight.
Advantages resulting from our Invention are:-(1) Indrawing of propeller
shafts is avoided; (2) removal or application of propellers rendered easy without
docking; (3) economy in cost; (4) any practical sized propellor can be sent by
rail on ordinary trucks; (5) soundness of casting ensured; (6) damage of bosses
avoided by the hitherto indispensable forcing on and off.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Cooke and David Mylchreest in the Great Seal Patent
Office on the 4th June 1881.
WILLIAM COOKE and DANIEL MYLCHREEST, of Liverpool, in the County of
Lancaster, Engineers, Naval Architects, and Co-partners. "IMPROVEMENTS IN
AND IN CONNECTION WITH SCREW PROPELLERS."
Heretofore screw propellers for steam ships have been so made that great
difficulty has been experienced in removing them from their shafts. The con-
struction has almost invariably been such that in order to place them on or take
them off their shafts it has been necessary to draw the said shafts within ship.
The ends of such shafts too generally being tapered, it was very difficult to get an
accurate fit between a new boss and an old shaft without removing the shaft from
the ship.
Now the main objects of our Invention are to provide screw propellers so
constructed that they may be easily removed from and attached to their shafts,
and may be easily fitted to the said shafts when such shafts are in position
for use.
For that purpose we construct, that is, arrange and combine the parts of screw
propeller bosses in two or more pieces, that is, two or more pieces in their length,
length meaning the direction with the axis of the shaft, and we connect the said
pieces together by bolts and nuts or equivalent fastenings. The blades of the
said propellers are cast with or are secured to the said pieces of the boss in any
convenient or desired manner.
When it is desired to remove a propeller constructed under our Invention from
its shaft, all that is necessary to be done is to undo or unfasten the bolts and nuts
or holding devices, and remove the pieces from the shaft. In attaching our said
propellers to their shafts the pieces are placed in position round the said shafts,
and are bolted or connected together and keyed or otherwise secured, if desired.
For the purpose of firmly securing a screw boss under our Invention to its
shaft, we form the end of the shaft with one or more collars or projections, and the
interior of the screw boss with corresponding recesses and collars, so that when
screwed up in position the parts are locked, and when desired made watertight.
Advantages resulting from our Invention are:-(1) Indrawing of propeller
shafts is avoided; (2) removal or application of propellers rendered easy without
docking; (3) economy in cost; (4) any practical sized propeller can be sent by
rail on ordinary trucks; (5) soundness of casting ensured; (6) damage of bosses
avoided by the hitherto indispensable forcing on and off.

page_text: Fig. 6 is a view of a modified construction of split screw, boss, and shaft; here
the end of the shaft projects beyond the boss, and a single recess and collar fis
used.
Fig. 7 is a view showing a method of attaching split screw propeller bosses, in
which provision is made for holding one half on the shaft whilst the other half is
removed. For that purpose a collar h formed on the shaft has two bolts i which
pass through holes in the halves of the bosses; j are nuts screwed on the said
bolts for retaining either half in position whilst the other half is removed.
We
We are aware that previous to our Invention propeller bosses have been made in
more than one piece, but such propeller bosses have not been divided longitudinally.
Having now described and ascertained the nature of our said Invention in such
manner that others will be enabled to carry our improvements into effect, we
claim,―
First. Constructing screw propellers with bosses divided longitudinally into two
or more parts, and connected together by bolts and nuts or equivalent devices.
Second. The combination of the parts a, b, c, c¹, d, and e, for the purposes set
forth.
Third. The combination of the parts a, b, c, c¹, d, e, and f, for the purposes set
forth.
Fourth. The combination of the parts a, b, c, c¹, d, d¹, h, and i, for the purposes
set forth.
In witness whereof, I, the said Daniel Mylchreest, have hereunto set my
hand and seal, this Third day of June, in the year of our Lord One
thousand eight hundred and eighty one.
J. JOHNSON,
Patent Office,
4, Clayton Square,
Liverpool.
Witness.
D. MYLCHREEST. (L.S.)