IMPROVEMENTS IN SCREW- PROPELLERS
Year: 1882

page_text: LETTERS PATENT to James Carr, of Heaton, near Newcastle on Tyne, in the
County of Northumberland, for an Invention of "IMPROVEMENTS IN SCREW-
PROPELLERS
"
PROVISIONAL SPECIFICATION left by the said James Carr at the Office
of the Commissioners of Patents on the 29th June 1882.
JAMES CARR of Heaton, near Newcastle on Tyne, in the County of
Northumberland "IMPROVEMENTS IN SCREW-PROPELLERS
"
I form a screw-propeller of separate blades so arranged as to be fitted together to
form a propeller of two, three, four or more blades as desired. The centre hole
through the boss of each blade may be cylindrical, with a key-bed slotted out, to
receive a sunk key inserted in the propeller shaft, or the said hole may be square,
hexagonal or octagonal. In the latter case the end of the shaft which receives the
said blades is made of similar form to the holes in the bosses of the blades, and is
provided with a collar so that the whole of the parts of the propeller, when slipped
on the shaft are secured and held firmly in position against the said collar by
means of a screw nut on the end of the said shaft, thus entirely dispensing with
the use of keys. The angle of the blades can be made to suit any pitch of screw
so as to suit speed or power. The blades are so constructed to suit the three-blade
or four-blade propeller and so that each blade stands at direct angles to the base of
the figure of the eye or centre hole of the boss. A lug is cast upon the boss of each
blade so as to facilitate the removal of a broken blade from the shaft. The
propeller being composed of separate blades, a broken blade can be readily replaced,
even at sea.
•

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Carr in the Great Seal Patent Office on the 27th December
1882.
JAMES CARR of Heaton, near Newcastle on Tyne, in the County of
Northumberland
"IMPROVEMENTS IN SCREW-PROPELLERS
"
My invention consists in forming a screw-propeller of separate blades, so arranged
as to be fitted together to form a propeller of two, three, four or more blades as
desired. The centre hole through the boss of each blade may be cylindrical, with
a key-bed slotted out, to receive a sunk key inserted in the propeller shaft; or the
said hole may be square, kexagonal, or octagonal. In the latter case the end of the
shaft which receives the said blades is made of similar form to the holes in
the bosses of the blades, and is provided with a collar so that the whole of the parts
of the propeller, when slipped on the shaft are secured and held firmly in position
against the said collar by means of a screw nut on the end of the said shaft, thus
entirely dispensing with the use of keys. The angle of the blades can be made to
suit any pitch of screw so as to suit speed or power. The blades are so constructed
to suit the three-blade or four-blade propeller and so that each blade stands at
direct angles to the base of the figure of the eye or centre hole of the boss. A lug
is cast upon the boss of each blade so as to facilitate the removal of a broken blade
from the shaft. The propeller being composed of separate blades a broken blade
can be readily replaced even at sea.
DESCRIPTION OF THE DRAWING.
Figure 1 is a plan and Figure 2 is an end view of a propeller constructed
according to my invention.
Each blade a of the propeller is formed separately and is provided with a boss a'
having a centre hole a" by which the blade is slipped on to the shaft b. The said
blades are constructed so as to form a propeller of two, three; four or more blades.
The end of the shaft b may be square, hexagonal or of other suitable form the
hole a in the boss of the blade being of a corresponding shape. The shaft 6 is
provided with a shoulder or collar b¹. When the blades a are placed upon the
shaft b they are held securely against the said collar b² by means of the screw-nut c
on the end of the shaft; or the blades may be held in position by being keyed to
the shaft. Each blade, when fixed, stands at direct angles to the baso of the eye or
centre hole of the boss. To facilitate the removal of the blades from the shaft a
lug d is cast upon the boss of each blade and the bosses are so formed that when
the blades are placed in position on the shaft there are holes e between the bosses.
These holes are plugged with cork, but when it is desired to remove one or more of
the blades from the shaft a wedge can be driven into the said holes and the removal
of the blade or blades be thus more readily effected.
The inner blade or blades of the propeller are interlocked with the outer blades
and with each other by ears f on the bosses of the said inner blades, the said ears
taking into sockets formed in the bosses of the adjacent or outer blades.
In witness whereof I the said James Carr have hereunto set my hand
and seal this twentieth day of December in the year of our Lord one
thousand eight hundred and eighty two