IMPROVEMENTS IN THE CONSTRUCTION AND ARRANGEMENT OF SCREW PROPELLERS
Year: 1855

page_text: PROVISIONAL SPECIFICATION left by William Major at the Office of
the Commissioners of Patents, with his Petition, on the 9th January
1855.
I, WILLIAM MAJOR, of Copenhagen, in the Kingdom of Denmark, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
CONSTRUCTION AND ARRANGEMENT OF SCREW PROPELLERS" to be as follows:-
This Invention relates to an improved mode or modes of feathering the
blades of screw propellers, and of fitting the same into the holding or carrying
boss, and consists in feathering the blades by means of a transverse nut in
the interior of the boss, and a screw spindle may be worked either through the
interior of the propeller shaft, which will in that case be made tubular, or the
spindle may be worked by keying a bevil wheel on to its outer extremity, sucli
wheel gearing into another wheel which is keyed on to a shaft or spindle pass-
ing through the boss at right angles to the propeller shaft. A slot is formed
on the end of each shank of the blades, and in each of these slots works a
slide and stud pin, connected to or formed in one piece with the traversing nut.
By turning the screw spindle the nut will be drawn back or moved forward, as
the case may be, and consequently the stud pins in the slots of the blade
shanks will cause the blades to turn the requisite distance on their axis.
Another mode of feathering the blades of screw propellers consists in forming

page_text: a spiral groove on the side of each shank; in each of these grooves works a
stud pin, attached to or made in one piece with a traversing nut, which is
actuated by a short screw spindle situated on the side of the main boss, and
placed parallel with the central or axial line of the propeller blade shanks. By
turning this screw spindle, which may be effected by a long key from the stern
of the vessel, the nuts will be elevated or depressed, and the stud pins con-
nected therewith will rise or fall in the spiral groove, and give the requisite
feather to the blades. "In order to obviate the disadvantage attendant on the
blades becoming.fixed in their sockets, an. apparatus is employed for loosening
them, and rendering them free to turn in their sockets before bringing the
feathering apparatus into action. This apparatus consists of a screw spindle,
having a collar and nut upon it, and formed with a screw thread at its
extremity. One end of this spindle is screwed into the shank of one of the
blades, or into a nut received into "such blade, and the other end is passed
through the centre or any radial line from the centre of the shank of the
opposite blade, and, may be screwed thereon by a nut keyed on to the end of
the spindle. A key or stop is fitted into each socket for the blades, and a
corresponding recess is made in the shanks, such recess, however, being rather
wider than the keys or stops, so as to allow of a slight play between the two.
When it is requisite to feather the blades, they are first loosened in their
conical sockets by turning the screw spindle with a long key from ship-board,
and this turning of the spindle causes the shanks to recede from each other or
to move outwards in their sockets until the keys or stops prevent their further
egress. The blades will now be quite loose in their sockets, and free to turn
in either direction. When they have been brought into this desired position
by the feather apparatus, they are secured firmly in such position by simply
turning the last-described screw spindle in the contrary direction, which has
the effect of drawing the blades towards each other in their conical sockets,
and consequently tightening and fixing them therein.