IMPROVE- MENTS IN SCREW-PROPELLERS FOR NAVIGABLE VESSELS
Year: 1881

page_text: LETTERS PATENT to William Morrison and Christopher Norfolk, of the Town
and County of Kingston-upon-Hull, Engineers, for an Invention of "IMPROVE-
MENTS IN SCREW-PROPELLERS FOR NAVIGABLE VESSELS."
.
PROVISIONAL SPECIFICATION left by the said William Morrison and
Christopher Norfolk at the Office of the Commissioners of Patents on the
19th July 1881.
William MorrisON and CHRISTOPHER NORFOLK, of the Town and County of
Kingston-upon-Hull, Engineers. "IMPROVEMENTS IN SCREW PROPELLERS FOR
NAVIGABLE VESSELS."
The main object of our Invention is to provide screw propellers which will act
more efficiently than those heretofore in use. Other advantages are (1) the parts
are easily moulded or formed, (2) sound castings are secured, (3) the parts are easily
handled, transported, and affixed on the shaft, (4) spare parts can conveniently be
carried on board ship, and (5) in the event of one or more blades being broken
only the broken parts become useless and require renewal.
Our propellers may have blades of any ordinary uniform, variable, or other
desired or adjustable pitch.
Under one modification we cast each blade with a narrow boss and place two,
three, or more of these one-blade-one-boss parts on the shaft so that they follow
each other. The blades so fitted provide a propeller with two, three, or four
threads. To secure the parts in position relative to each other we employ bolts
and nuts or their equivalents. A flange (or studs) is formed ou cach boss so that
the bolts can be conveniently passed through the contiguous flanges or studs and
screwed up.
Under a second modification we form or cast the one-boss-one-blade propeller
with the boss and blade separate, and connect them by suitable fastenings and
secure them on the shaft one after the other as in the modifications first above
described, employing the flanges or studs if desired.
Should a blade get broken in this construction it would only become necessary
to remove the broken part and attach another blade.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Morrison and Christopher Norfolk in the Great Seal
Patent Office on the 19th January 1882.
WILLIAM MORRISON and CHRISTOPHER NORFOLK, of the Town and County of
Kingston-upon-Hull, Engineers. "IMPROVEMENTS IN SCREW PROPELLERS FOR
NAVIGABLE VESSELS."
The main object of our Invention is to provide screw propellers which will act
more efficiently than those heretofore in use. Other advantages are (1) the parts
are easily moulded or formed, (2) sound castings are secured, (3) the parts are
easily handled, transported, and affixed on the shaft, (4) spare parts can conveniently
be carried on board ship, and (5) in the event of one or more blades being broken
only the broken parts become useless and require renewal.
Our propellers may have blades of any ordinary uniform, variable, or other
desired or adjustable pitch.
Under one modification we cast each blade with a narrow boss and place two,
three, or more of these one-blade-one-boss parts on the shaft so that they follow
each other. The blades so fitted provide a propeller with two, three, or four
threads. To secure the parts in position relative to each other we employ bolts
and nuts or their equivalents. A flange (or studs) is formed on each boss so that
the bolts can be conveniently passed through the contiguous flanges or studs and
screwed up.
Under a second modification we form or cast the one-boss-one-blade propeller
with the boss and blade separate and connect them by suitable fastenings and
secure them on the shaft one after the other as in the modifications first above
described, employing the flanges or studs if desired. Should a blade get broken in
this construction it would only become necessary to remove the broken part and
attach another blade.
Figs. 1 and 2 are side elevations at right angles to each other of a screw propeller
constructed. in accordance with our Invention; a are the propeller blades, each cast
The blades
with a narrow boss b and placed following each other on the shaft c.
and bosses are secured together by the bolts d passing through the flanges e;
f, tightening nuts. The bosses are secured to the shaft by keys or feathers, or in
any usual or desired manner, and an end nut g to prevent longitudinal motion is
provided. To avoid lengthening the propeller shaft the outermost boss overhangs
the shaft and is made with an aperture through which the nut g is placed in
position and screwed home.
Figs. 3 and 4 are views at right angles of a second modification of screw propeller
under our Invention; here the blades a are cast separate from the bosses b and are
connected thereto by bolts and nuts i, or in any well known or suitable manner.
The bosses are secured to each other by the bolts and nuts d and projecting
pieces e, and to the shaft by keying, or in any usual or desired manner, and the
nut g.
If desired the shaft passes through all the bosses instead of part only, as above
shown, and lugs may be used instead of flanges: Cement is placed around the
bosses so as to cover the flanges or lugs, and bolts, and nuts, and present a smooth
surface to the water.
It will be obvious that the shapes of the bosses and blades may be varied, and

page_text: that any well known devices may be used for connecting the bosses together and
to the shaft.
Having now described and illustrated 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 two, three, or more one-blade-one-boss
parts secured to the shaft and relatively to each other, substantially as hercin set
forth.
Second. Screw propellers constructed with separable bosses and blades when
two, three, or more bosses are connected together and to the shaft, substantially as
herein set forth.
In witness whereof, we, the said William Morrison and Christopher Norfolk,
have hereunto set our hands and seals, this Eighteenth day of January,
in the year of our Lord One thousand eight hundred and eighty-two.