IMPROVEMENTS IN SCREW PROPELLERS
Year: 1860

page_text: LETTERS PATENT to Hermann Hirsch, of Berlin, in the Kingdom of.
Prussia, and of Bridge Road, Lambeth, in the County of Surrey, Civil.
Engineer, for the Invention of "IMPROVEMENTS IN SCREW PROPELLERS."
Sealed the 18th January 1861, and dated the 24th July 1860.
PROVISIONAL SPECIFICATION left by the said Hermann Hirsch at the
Office of the Commissioners of Patents, with his Petition, on the
24th July 1860.
I, HERMANN HIRSCH, of Berlin, in the Kingdom of Prussia, and of Bridge
Road, Lambeth, in the County of Surrey, Civil Engineer, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN SCREW PROPELLERS,"
to be as follows:-
This Invention relates to a new mode of constructing the boss and blades of
propellers in such a manner that the pitch of the blades may be varied when
required. The boss, which is fitted to the shaft of the propeller, has a portion
of its outer surface turned truly conoidal or spheroidal round an axis at right,
angles to that of the shaft. Each of the two blades of the propeller is formed
with a semi-conoidal or hemi-spheroidal boss, which is faced and bored out so
as to fit on to half of the boss on the shaft. The two blades being placed on.
this boss (so that their faces meet) are secured to the boss and to one another
by bolts passing on either side of the shaft through holes which are widened

page_text: in one direction, so that the blades can be turned partly round upon the boss,
and thus the pitch or angle which the surface of the blade makes with the axis
may be varied.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Hermann Hirsch in the Great Seal Patent Office on the 24th
January 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HERMANN
HIRSCH, of Berlin, in the Kingdom of Prussia, and of Bridge Road, Lambeth,
in the County of Surrey, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of July, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Hermann Hirsch, Her special licence that I, the said Hermann Hirsch,
my executors, administrators, and assigns, or such others as I, the said Her-
mann Hirsch, 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
SCREW PROPELLERS," upon the condition (amongst others) that I, the said
Hermann Hirsch, 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.
NOW KNOW YE, that I, the said Hermann Hirsch, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, that is to say :-
My improvements apply to a mode of constructing the boss and blades of
propellers in such a manner that the pitch of the blades may be varied
when required.
Fig. 1 of the accompanying Drawings represents a section through the
middle of a propeller, supposed to be made by a plane at right angles to the

page_text: axis, a portion only of each blade being shewn thereon, as it may be made of
any suitable forin, provided the root or part next the boss be curved so as to
admit of the arrangements which constitute the subject of my Invention;
Fig. 2 is a sectional plan through the middle of the boss on the line marked
A, A, on Fig. 1; and Fig. 3 is a sectional plan on the line marked B, B, on
Fig. 1; and Figs. 4 and 5 represent portions of the details, to which reference
will be made hereafter by the Figures and letters marked thereon.
a is an inner boss, which may either be bored, as represented on the
Drawing, to receive the shaft of the propeller, or may form a portion of the
shaft; each side of this boss a is made conical, or it may be spheroidal round
an axis at right angles to the axis of the propeller, so as to be of greatest
diameter at its middle, and to taper in either direction from the middle;
6', b, are portions of two blades, each blade terminating in a hemi-spheroidal,
or it may be semi-conoidal boss, which is hollowed out, so as to fit accurately
on the tapering portion of the inner boss a, so that when the two blades are
placed upon this inner boss at 6 they can be firmly tightened on its tapering
surfaces. Two bolts c', c, are made to pass through both bosses, recesses
being formed at each side of the inner boss a to let them clear it, each of
these recesses being wider than the bolt, so as to allow of its passing a little
on either side of the central line; the head of each bolt is fitted into a recess
formed in each blade, and is shaped off to the form of the blade boss, and the
point of each bolt is screwed and fitted with a washer d', d², and a nut e, e².
A recess is formed in each blade to admit the nut and washer, and to afford
sufficient room round the nut for admitting a socket wrench to tighten or
slacken the nut when required. And each of these recesses is elongated in
one direction to permit of the bolt and nut occupying a position a little on
either side of the central line. Each of the bolts is made of such a length
that the nut stands somewhat above it when fully tightened, and a wedge-
shaped piece ff, is placed in each recess, so as to lie upon the surface of the
nut, and over this is fitted another wedge-shaped piece g', 92, the outer surface
of which is shaped off to the curvature of the blade when it is driven tightly
into the recess, and each of those pieces is secured in its place by a screw h', h²,
entering into it from the back surface of the blade. When it is desired to
alter the pitch of the blades, or to change the angle which any portion of their
surfaces makes with the axis of the propeller, the screws h¹, h, are removed,
the pieces g', g, and f³, f, are removed from the recesses, a socket wrench is
introduced into the recesses so as to slacken the nuts, and the blades are turned
partly round upon the tapering surfaces of the inner boss a to the required
position; the nuts are again tightened, and the pieces f', fs, and 91, 9, and

page_text: their screws h', h³, are again inserted. When it is considered desirable to fix
the blades at a particular pitch, and to provide additional security against their
shifting during work, the washers d', d', are made to fit the recesses in which.
they lie, and several spare washers are provided with bolt holes through them
bored more or less out of the centre line, as represented on Figs. 4 and 5.
When one of these washers having the bolt hole in its suitable position for the
required pitch is introduced into each recess the bolt and blade are retained
in the same relative position to one another, even if the nut be slackened.
Having now described the nature of my said Invention, and the manner of
performing the same, I would have it understood that I do not confine myself
to the details; but I claim as my Invention. the mode of constructing a
propeller of two blades with hollow bosses made to fit tightly on the tapering
surfaces of an inner boss fixed to the shaft, and secured thereon by means of
bolts passing through portions of both blades clear of the inner boss, so as to
permit such alteration of position as may be required for shifting the pitch of
the blades.
And I also claim the mode of forming recesses in the blades for receiving
the nuts and washers, and of fitting such recesses with wedge pieces bearing
on the nuts, so as to provide security against the nuts becoming slackened,
and at the same time to fill the apertures of the recesses flush with the
surfaces of the blades.
And I also claim the use of washers fitted into the recesses with bolt holes
in various positions to suit various pitches of blades, so as to form an additional
security against a change of pitch during the working of the propeller.
And, lastly, I claim the combination of parts herein described as applied to
propellers.
In witness whereof, I, the said Hermann Hirsch, bave hereunto set my
hand and seal, this Twenty-third day of January, in the year of our
Lord One thousand eight hundred and sixty-one.
HERMANN HIRSCH. (L.s.)
Witness,
ALEX. PRINCE,
Agent for Patents,
4, Trafalgar Square, Charing Cross.