IMPROVEMENTS IN PROPELLING VESSELS
Year: 1853

page_text: LETTERS PATENT to, Robert Griffiths, of Great Ormond Street, in
the County of Middlesex, for the Invention of "IMPROVEMENTS IN
PROPELLING VESSELS."
PROVISIONAL SPECIFICATION left by the said Robert Griffiths
at the Office of the Commissioners of Patents, with his Petition,
on the 26th February 1853.
I, ROBERT GRIFFITHS, of Great Ormond Street, in the County of
Middlesex, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN PROPELLING VESSELS" to be as follows:-
This Invention has for its object the improvements in my former
Patent, where a spherical boss was employed to the propeller; and my
present improvements consist of applying screws within such spherical
boss to set the propeller blades at the desired angle with the keel, or.
fore and aft; also in filling such sphere with fatty matters, to keep,
out the sea and other water; and also in forming cast projections on
to the shanks of the propeller blade, in order to affix the shanks more
securely, and to secure them within the sphere.
m

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Griffiths, in the Great Seal Patent Office,
on the 26th August 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I
ROBERT GRIFFITHS, of Great Ormond Street, in the County of Mid-
dlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-sixth day of February, in
the year of our Lord One thousand eight hundred and fifty-three,
in the sixteenth year of Her Reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Robert Griffiths, Her
special licence that I, the said Robert Griffiths, my executors, adminis-
trators, and assigns, or such others as I, the said Robert Griffiths, 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 Robert Griffiths, by an instrument in writing
under my hand and seal, 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.
NOW KNOW YE, that I, the said Robert Griffiths, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof (that is to say):
This Invention has for its object improvements in my former Patent,
where a spherical boss was employed to the propeller; and my present
improvements consist of applying screws within such spherical boss to
set the propeller blades at the desired angle with the keel, or fore and
aft; also in filling such sphere with fatty matters, to keep out the sea

page_text: and other water; and also in forming cast projections on to the shanks of
the propeller blades, in order to affix the shanks more securely, and to
secure them within the sphere.
Firstly, in constructing propellers that are made for varying the pitch
or propelling angle of the blades, so that when in combination with
tapered blades and large central boss the angle is altered by machinery
contained within the propeller itself, acted upon by a shifting spanner
or key inserted from the vessel.
Secondly, in constructing screw propellers with loose, blades, secured
to the centre boss when it is not desired to vary the angle or pitch when
working.
And, in order that my Invention may be understood and readily
carried into effect, I will proceed to describe the means pursued by me.
DESCRIPTION OF DRAWINGS.
"
Sheet A, Figure 1, is a longitudinal section of a left-handed screw;
Figure 2, is, a sectional plan; Figure 3, is a transverse section of a
screw, with the tapered blades and shifting gear applied.
A, is the blade, tapered on its leading side more than on the trailing
side; and B, the boss which fits upon the engine shaft. The blade A, is
secured to the boss B, by means of the shank C, of the blade fitting
into the socket D, which is part of the boss. The blade is secured in
the socket by means of the lugs E, E, fitting into the lower part of the
socket, which is enlarged; and the lugs E, E, being of greater diameter
than the upper part of the socket D, are unable to pass through in any
place except along the two slots f, and 9, through which they are
entered when the blade is put into its place. These lugs do not prevent
the rotation of the blade for altering the angle, as the chambered part
extends the whole circumference of the socket at the lower part.
The blade, when placed in the socket, is retained in its proper posi-
tion, and at the same time made adjustable to any required pitch, by
means of the bevil segment H, (which is formed on the blade,) fitting
into the double-segment bevil wheel I, which revolves upon the boss.
The segment bevil wheel I, is capable of adjustment by means of the
screw K, which is secured to the disc L: the screw moves the nut M:

page_text: which has an internal check flange, which flange fits into a corre-
sponding groove on the boss B. The ring P, is put into its place in
two parts, and the ring Q, is then shrunk over it, and secured by the
bolts R, R.
The whole of the pitching gear is enclosed in the shell, through
which a hole is made to insert the long key or spanner from the vessel
to turn the screw K.
Figure 4, is a plan.
"
33
5, a half section.
6, a half front view.
When the key is removed from the socket of the screw, the screw
is prevented from moving. On the bottom of the bracket is formed a
series of notches, arranged in an annular form round the screw; and
through the screw itself is formed a slot, through which the cotter 1,
is passed; this cotter being pressed upwards by an india-rubber pack-
ing beneath, so that it has a continued tendency to enter the notches
when it is necessary to shift the screw. The key Figure 7, (which is
pointed at the end,) is inserted into the socket, and the long point of it
passes down a hole in the centre of the screw, and depresses the cotter,
when the screw is easily turned to vary the pitch: the key having been
removed, the cotter immediately rises and enters one of the notches,
thereby effectually securing the screw in the position required.
Figures 7, and 9, clevation and plan of key.
Sheet B, Figure 1, a transverse section.
39
2,,, horizontal do. of a screw adapted with another
kind of shifting gear.
In this case the screw as formed in a precisely similar manner to the
screw shewn in Sheet A, as regards the blade, &c.; but the shifting gear
is in this case formed by wormed segments A, A, cast upon the blades,
which are moved by the screws B, B, and which screws are moved by
the worm wheel C, and screw D.
Figure 3, is a transverse section.
"
4, „ horizontal section of a screw arranged in the same manner

page_text: as the one on Sheet A, but with a worm and segment of a worn
wheel for altering the pitch of the blades, instead of the nut slides and
lever, as in Sheet' A.
Figure 5, is a screw, arranged in the same manner as Figures 3
and 4, but with a bevil segment fitted to the shank of the blade, and
passed through a slot in the socket, instead of being cast to the blade
self, as in Drawing, Sheet A.
Sheet C, Figure 1, a longitudinal section.
"
2,,, plan, ditto.
وو
3,,, transverse ditto of a screw formed in parts, with-
out any apparatus for shifting the pitch. The blade, in this case, having
been placed in the required position, is fixed by means of rivets bolts or
other convenient fastenings.
Sheet D, Figure 1, a transverse section.
"
2,,, longitudinal ditto of a screw formed in parts,
but with the blade fixed in such a manner that it may be loosened, and
then shifted to any pitch, and again fixed. In this case the socket A,
is formed in two parts, one part b, being cast on the boss, and the other
half c', cast a slip separately. The blade is put into the fixed half
of the socket; the other half is bolted on; and the socket, being turned
rather small, pinches the shank of the blade, and prevents it from
turning. By this arrangement spare blades are easily inserted in case
of fracture.
Having now described the nature of my Invention, and the manner
in which the same is to be performed, I would have it understood that
I do not confine myself to the precise details herein described, provided
the peculiar character of my Invention be retained. And I would
have it understood that I am aware that it has before been proposed to
alter the angle or pitch of the blades; but such has been done with
a sliding collar connected to the screw, worked by cranks or levers
always attached, and consequently working and wearing, and has been
applied to screw-propellers formed with the blades wider at the outside
extremities. I am also aware that the blades have been feathered
(with a spanner) from one fixed propelling angle to fore and aft. I
do not therefore claim this as my Invention; but what I do claim is―

page_text: Firstly, in the arrangement of pitching apparatus for altering the
propelling angle, contained within the propeller, to be acted upon by a
spanner or key applied from the vessel in combination with blades
made narrower or taper towards their outside extremities.
Secondly, the constructing the blades of screw-propellers separately
from the boss or centre, so that the same may be fixed or replaced at
pleasure, in combination with the taper blades and large centre boss, as
patented by me, Thirteenth of September, One thousand eight hundred
and forty-nine.
In witness whereof, I, the said Robert Griffiths, have hereunto
set my hand and seal, this Twenty-fifth day of August, in
the year of our Lord One thousand eight hundred and
fifty thro
ROBT GRIFFITHS. (L.S.)
Witness, JNo. Cooк, 12, Cursitor Street.