IMPROVEMENTS IN SCREW PROPELLERS
Year: 1873

page_text: LETTERS PATENT to Samuel Osborn, of the Clyde Steel and Iron
Works, Sheffield, in the County of York, and Stephen Alley,
Engineer, of Glasgow, in the County of Lanark, for the Invention
of "IMPROVEMENTS IN SCREW PROPELLERS."
PROVISIONAL SPECIFICATION left by the said Samuel Osborn and
Stephen Alley at the Office of the Commissioners of Patents, with
their Petition, on the 18th October 1873.
We, SAMUEL OSBORN, of the Clyde Steel and Iron Works, Sheffield,
in the County of York, and STEPHEN ALLEY, Engineer, of Glasgow, in
the County of Lanark, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN SCREW PROPELLERS," to be as follows, that is to
say:
This Invention relates principally to the modes and materials to be
adopted in forming and combining together the parts of screw propellers,
but at the same time screw propellers made with the improvements will

page_text: in action be accompanied by a diminished surface friction and edgeway
resistance.
By the Invention, the propeller blades are made of steel, malleable
iron, gun metal, or brass, in the form of sheets rolled or hammered, or
both rolled and hammered.
Each blade may be a single sheet of a tapering thickness, or as is
preferred it may consist of two thicknesses, either partially or to its entire
extent, such thicknesses being welded or rivetted together so as to leave
an internal space, which may be left void or be filled with any suitable
substance.
The sheets composing the blade may be shaped to form neck flanges,
whereby the blade may be bolted upon the central boss or hub; or the
blade may be secured to the boss in any of the ways herein-after
described.
The blade may be secured directly to the boss or to a root piece which
can be adjusted and fixed on the boss, as is already done in some existing
propellers..
!
The root piece may be of cast steel, cast malleable iron, cast gun
metal, or cast iron, and in one modification it may be cast with a
tapered fin for the sheet metal blade to be rivetted on, the edges of the
blade near the root being in that case by preference folded round the
edges of the fin; or the blade may be inserted in a groove in the boss
or root piece, snch groove having an inwardly increasing width, and
receiving a wedge which is placed at one side of a single sheet blade, or
between the sheets composing the blade when there are two.
The wedges may be tightened by screws or by cross wedges acting on
them, and when forced home are held in place by the propeller shaft, or
by the boss if there is a root piece.
The root piece may be made in two flanged halves, to be bolted
together with the root of the blade between them.
The boss or hub may be made in helical sectors, and be bolted together
with the roots of the blades between them, malleable iron or steel rings
being afterwards shrunk on in front and rear to bind the whole securely.
:
Each blade may be formed with a rib, bead, or dovetail on its root
edge; and be entered helically into a helical groove formed for it in a

page_text: In the case of small propellers, two or more blades may be formed in
the same sheets or pair of sheets, shaped at the middle to fit round and
over the boss, and secured thereto by rivetting or bolting, and by shrunk
rings.
SPECIFICATION in pursuance of the conditions of the Letters Patent,.
filed by the said Samuel Osborn and Stephen Alley in the Great
Seal Patent Office on the 17th April 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, SAMUEL
OSBORN, of the Clyde Steel and Iron Works, Sheffield, in the County of
York, and STEPHEN ALLEY, Engineer, of Glasgow, in the County of:
Lanark, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of October, in the
year of our Lord One thousand eight hundred and seventy-three, in
the thirty-seventh year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto us, the said Samuel Osborn and
Stephen Alley, Her special licence that we, the said Samuel Osborn
and Stephen Alley, our executors, administrators, and assigns, or
such others as we, the said Samuel Osborn and Stephen Alley,
our executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN SCREW PROPELLERS," upon the condition (amongst others)
that we, the said Samuel Osborn and Stephen Alley, our executors or
administrators, by an instrument in writing under our, or their, or one
of their hands, and seals, should particularly describe and ascertain

page_text: the nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent.
Office within six calendar months next and immediately after the date of
the said Letters Patent.
NOW KNOW YE, that we, the said Samuel Osborn and Stephen Alley, 5
do hereby declare the nature of our said Invention, and in what manner.
the same is to be performed, to be particularly described and ascertained
in and by the following statement in writing, reference being had to the
accompanying Drawings, that is to say:-
Our said Invention relates principally to the modes and materials to 1
be adopted in forming and combining together the parts of screw
propellers, but at the same time screw propellers made with our improve-
ments will in action be accompanied by a diminished surface friction and
edgeway resistance..
.
By our said Invention, the propeller blades are made of steel, malleable 1
iron, gun metal, or brass, in the form of sheets rolled or hammered, or
both rolled and hammered.
Each blade may be a single sheet of a tapering thickness, or as we
prefer, it may consist of two thicknesses, either partially or to its entire
extent, such thicknesses being welded or rivetted together so as to leave 2
an internal space, which may be left void or be filled with any suitable
substance.
Our Invention also comprises various modes of fixing the propeller
blades on the cental boss or hub.
And in order that our said Invention and the manner of performing 2
the same may be properly understood, we hereunto append a Sheet of
explanatory Drawings to be herein-after referred to, and representing
various modifications of our improved arrangements. In these Drawings
no attempt is made to accurately delineate any particular helical or other
curved configuration of the blades, as our improvements are applicable 3
with blades of any of the variety of shapes in common use.
The same
reference numerals are used to mark the same or like parts wherever they
are repeated.
Figure 1 is a section, as taken through the axis of the shaft and
through the radial centre lines of a pair of blades, and shows a modifica- 3
tion in which each blade 1 is made of two sheets 2. 3. of thin steel

page_text: welded or rivetted together- round the edges, and with a thin space
between them. A socket or deep groove is made in the boss or hub 4
to receive the root of the blade, this groove extending quite through
from the outside to the centre of the boss, except at the middle through
which the section is taken, the two sides of the groove being there
connected, as shown at 5, to strengthen the boss, whilst the root of the
blade is notched to pass in on each side. The groove in the boss is made
of a slightly increasing width inwards, and the sides of the root of the
blade are expanded to fill the groove like a dovetail by wedges 20,
entered between them from the inside, and afterwards prevented from
loosening by the shaft 6, the wedges being shaped to fit against the shaft
when this is entered into the boss. A slight rib may be formed on the
inner edges of the root of the blade to catch within the inner edges of
the sides of the socket, and so effectually prevent the withdrawal of the
blade without first taking the propeller off the shaft and loosening the
wedges.
Figure 2 is a section of a modification in which the blade 1 made of
thin steel sheets 2, 3, has these sheets formed into neck flanges 7,
whereby the blade is bolted to the boss 4.
Figure 3 is a sectional elevation of a modification in which the neck
flanges 7 are shaped spherically for bolting on a plain spherical boss 4,
and are strengthened by plates 8.
Figure 4 is a section of a modification similar to Figure 2, but with
the strengthening plates 8.
In the modification shown in section in Figure 5, the neck 9 of the
blade is shaped to fit the interior of a cylindrical flanged root piece 10,
which is fixed in a socket in the boss 4, the inner edge of the blade
neck 9 being rivetted or flanged over the inner edge of the root piece 10,
and further secured by, an inner ring 11.
The root piece 10 may be of cast steel, cast malleable iron, cast gun
metal, or cast iron.
Figure 6 is a section of a modification in which a metal fin 12 is
rivetted or otherwise held between the sides 2, 3, of the blade 1, and in
which the blade is held in a root piece made in two halves 13, 14, and
with a flanged cylindrical shape to fit in a corresponding socket in the
boss 4, the two halves of the root piece being held together by their

page_text: attachment to the socket and boss, and also by a cap 15 fixed to their
innermost parts.
In the modification shown in section, as at right angles to the shaft in
Figure 7, the boss or hub is made up of four quadrants or sectors 16, the
approaching surfaces being helically shaped to receive between them the
roots of four blades 1. These blades, shown as made of thin sheet steel,
have their roots made solid by filling pieces 12, and the quadrants 16 are
bolted together with the blade roots between them, whilst rings are
shrunk upon the parts of the boss fore and aft of the blade roots. A thin
spherical shell 17 may be applied externally to form a smooth outer
surface to the boss.
Figure 8 is a section, as taken through the axis of the shaft, of a
modification in which each blade 1 is solid or of a single thickness of
steel, malleable iron, gun metal, or brass, and is fixed like those shown
in Figure 1, excepting that the wedge 20 is in each case applied to the
back or front of the blade instead of entering inside.
Figures 9 and 10 are sections as at right angles to each other of a
modification in which the root piece 10 is cast on the root of the
blade 1, being fixed thereto by bolts, as well as by the metal being
united through a hole in the root, and by the dovetailed form of the
root.
Figures 11 and 12 are sections as at right angles to each other,
showing the mode already described with reference to Figure 7, of fixing
blades between quadrants or sectors 16 of the boss as applied to solid
blades.
The shrunk-on rings 18 are shown in Figure 12.
Figure 13 is a section of a modification in which a root piece in two
parts 13, 14, is fixed on the blade root by rings 19, shrunk on necks
formed on the inner parts.
Figure 14 is a section of a modification in which a blade is formed by ;
rivetting or otherwise fixing a comparatively thin sheet or plate 2 on a
thicker fin piece 21, the two being fixed by bolting between the two
halves 13, 14, of a root piece which is bolted to the boss 4.
Figures 15 and 16 are sections at right angles to each other of a
modification in which four blades 1 are bolted between four helical

page_text: 3. The fixing of a blade formed of double metal sheets to the boss by
means of neck flanges formed on the blade, as herein-before described.
4. The fixing of a blade formed of double metal sheets to the boss by
means of a root cast, bolted, or otherwise fixed on the blade, as herein-
before described.
5. The fixing of screw propeller blades by bolting between helical
sectors combining to form a boss, as herein-before described.
6. The fixing of a blade consisting of a single sheet or plate of steel,
malleable iron, gun metal, or brass, by inserting it in a dovetailed
socket or groove in the boss, as herein-before described.
7. The fixing of a blade consisting of a single sheet or plate of steel,
malleable iron, gun metal, or brass, by means of a root piece cast on or
bolted or otherwise fixed to it, as herein-before described.
In witness whereof, I, the said Stephen Alley, on behalf of the said
Samuel Osborn and myself, have hereunto set my hand and seal, 1
this Sixteenth day of April, in the year of our Lord One thousand
eight hundred and seventy-four.