IMPROVEMENTS IN SCREW PROPELLERS FOR PROPELLING VESSELS
Year: 1868

page_text: LETTERS PATENT to George Alder, of Newcastle-on-Tyne, in the
County of Northumberland, Engineer, for the Invention of
"IMPROVEMENTS IN SCREW PROPELLERS FOR PROPELLING VESSELS."
Sealed the 22nd December 1868, and dated the 30th June 1868.
PROVISIONAL SPECIFICATION left by the said George Alder at the
Office of the Commissioners of Patents, with his Petition, on the
30th June 1868.
I, GEORGE ALDER, of Newcastle-on-Tyne, in the County of
Northumberland, Engineer, do hereby declare the nature of the said:
Invention for "IMPROVEMENTS IN SCREW PROPELLERS FOR PROPELLING
VESSELS," to be as follows:-
My Invention of improvements in propelling vessels relates to that
class of propeller called a screw propeller, which is usually mounted on
a longitudinal shaft, to which rotary motion is imparted by means of any
convenient arrangement of gearing.
My Invention consists in imparting to the screw propeller a compound
motion consisting of a rotary motion with the shaft on which it is

page_text: mounted, and also a rocking or sculling motion produced by continually
changing the angle of the propeller blades with the axis of the longi-
tudinal shaft. To this end the boss of the propeller, instead of being
keyed firmly and immoveably on the shaft is connected therewith by
a cross pin, on which it is capable of being made to rock while the
shaft rotates. The rocking motion of the boss on its cross pin is
effected by means of a crank or excentric motion derived from the main.
driving shaft and imparted to the boss or sleeve shaft, which is made to
slide to and fro on the propeller shaft and is connected by a pair of
rods to the boss or arms of the propeller.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said George Alder in the Great Seal Patent Office
on the 30th December 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
ALDER, of Newcastle-on-Tyne, in the County of Northumberland,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirtieth day of June, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said George Alder, Her special licence
that I, the said George Alder, my executors, administrators, and assigns,
or such others as I, the said George Alder, my 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 PROPELLING VESSELS," upon
the condition (amongst others) that I, the said George Alder, my
executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain 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.

page_text: NOW KNOW YE, that I, the said George Alder, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawing hereunto
annexed, and to the letters and figures marked thereon (that is to
say) :-
My Invention of "Improvements in Propelling Vessels" relates to
that class of propeller called a screw propeller, which is usually mounted
on a longitudinal shaft, to which rotary motion is imparted by means of
any convenient arrangement of gearing.
My Invention consists in imparting to the screw propeller a compound
motion consisting of a rotary motion with the shaft on which it is
mounted, and also a rocking or sculling motion produced by continually
changing the angle of the propeller blades with the axis of the longi-
tudinal shaft. To this end the boss of the propeller, instead of being
keyed firmly and immoveably on the shaft, is connected therewith by a
cross pin, on which it is capable of being made to rock while the shaft
rotates. The rocking motion of the boss on its cross pin is effected by
means of a crank or excentric motion derived from the main driving
shaft and imparted to the boss or sleeve shaft, which is made to slide to
and fro on the propeller shaft, and is connected by a pair of rods to the
boss or arms of the propeller.
In the accompanying Drawing Fig. 1 represents a longitudinal
section of part of a screw vessel fitted with a stern propeller constructed
according to my Invention; Fig. 2 is a plan view of the propelling
gear.
a is the propeller shaft provided at its inner end with two cranks a¹, a','
which are connected by the rods b, b, to the piston rods of two steam
cylinders c, c, above; rotary motion is by this means communicated to
the propeller shaft a in the usual manner. The propeller blades d, d,
instead of being fixed in a boss which is keyed firmly to the propeller
shaft a are fixed in a boss which is capable of vibrating or moving on
a pin or stud e, which passes through the propeller shaft. This rocking
or vibrating motion of the blades is effected by connecting them by
means of a rod f to a reciprocating block g, which is capable of
being moved to and fro on the propeller shaft, as indicated by the
red lines. The block g works on that part of the shaft a which is
outside the vessel and is immersed in the water, and it is connected by

page_text: means of the rods h, h, with a similar sliding block g', which works on
the propeller shaft inside the vessel. The propeller shaft a, and also
the rods h, h, work through stuffing boxes in the usual manner for the
purpose of keeping the external water from entering the vessel. The
required reciprocating motion is communicated to the blocks g, g', and
their appendages by means of a bell crank lever j, which is connected
at one end by means of the long rods i, i, to the inner sliding block g',
and by its opposite end by means of a short link to the crosshead k at
the end of one of the piston rods. It will now be understood that as
the pistons reciprocate in their cylinders c, c, they will not only impart
rotary motion to the propeller shaft through the cranks a', a', but will
through the bell-crank lever j, rods i, i, and blocks g and g' cause the
blades of the propeller to rock on the centre pin e, and thus produce the
compound motion above mentioned.
Fig. 3 is a plan view of a somewhat different arrangement of
propelling gear to that shewn at Figures 1 and 2, but precisely the
same effect is produced. a is the propeller shaft, on which is keyed
the bevil wheel l, which gears into a similar wheel m on the end of
a short cross crank shaft n, the crank g of which is connected.by
the rod to the inner sliding block g', which is connected to the
blades of the propeller in the same manner as is shewn in Figures 1
and 2.
Having now described my Invention of " Improvements in Propelling
Vessels," and having explained the manner of carrying the same into
effect, I claim, as the Invention secured to me by Letters Patent as
aforesaid, communicating to screw or stern propellers a compound motion
by combining a rotary with a sculling motion, as herein set forth.
In witness whereof, I, the said George Alder, have hereunto
set my hand and seal, the Twenty-eighth day of December, in the
year of our Lord One thousand eight hundred and sixty-eight.
ARADAN
GEORGE ALDER. (..)