AN IMPROVED SCREW PROPELLER
Year: 1868

page_text: LETTERS PATENT to Henry Oliver Robinson, of London and Glasgow,
but at present residing at Glasgow, in the County of Lanark, North
Britain, for the Invention of "AN IMPROVED SCREW PROPELLER."
Sealed the 17th October 1868, and dated the 17th April 1868.
PROVISIONAL SPECIFICATION left by the said Henry Oliver Robinson
at the Office of the Commissioners. of Patents,, with his Petition,
on the 17th April 1868.
I, HENRY OLIVER ROBINSON, of London and Glasgow, but at present
residing at Glasgow, in the County of Lanark, North Britain, do hereby
declare the nature of the said Invention of "AN IMPROVED SCREW
PROPELLER,' to be as follows, that is to say :-
This Invention, which relates to an improved screw. propeller, has for-
its object the constructing and arranging of the propeller in such way.
that whilst the vessel is under steam its full efficiency is employed in
propelling, and whilst under sail it affords a minimum of impediment to.
the vessel's progress. The screw may he composed of any desired.
number of blades, each one of which is attached to a division of the
central boss, and one of which blades only is fixed to the propeller
shaft, whilst the other blade or blades are arranged in such a way upon.

page_text: it that when the vessel is "under steam" they fall into their proper
position, dividing equally the circle. When the vessel is "under sail"
the blades are all by simply reversing the engine thrown together
or folded upon each other, and the engine stopped when they are in
the line of the stern post pointing upwards, in which position the
impediment to the vessel when sailing is reduced to a minimum. When
desired to "go astern" the blades will consequently remain in this
latter position on the shaft, but that will not prevent the screw propeller
from acting effectually for the purpose of "backing" the vessel. To
prevent the propellers from moving out of their folded or reefed position
ivhen the vessel is "under sail," stops or retaining blocks are lowered
from the deck through an opening in the counter, as is already
practised.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Oliver Robinson in the Great Seal Patent
Office on the 17th October 1868.
ΤΟ
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY.
OLIVER ROBINSON, of London and Glasgow, but at present residing at
Glasgow, in the County of Lanark, North Britain, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventeenth day of April, in the year of
our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Henry Oliver Robinson, Her special license
that I, the said Henry Oliver Robinson, my executors, administrators,
and assigns, or such others as I, the said Henry Oliver Robinson, my
executors, administrators, or 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 "AN IMPROVED
SCREW PROPELLER," upon the condition (amongst others) that I, the said
Henry Oliver Robinson, 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

page_text: 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 Henry Oliver Robinson, 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 accompanying
Drawings, and to the letters and figures marked thereon, that is to
say:―
My said Invention, which relates to an improved screw propeller,
has for its object the constructing and arranging of the propeller in
such way that whilst the vessel is "under steam" its full efficiency is
employed in propelling, and whilst "under sail" it affords a minimum
of impediment to the vessel's progress. The screw may be composed
of any desired number of blades, each one of which is attached to a
division of the central boss, and one of which blades only is fixed to
the propeller shaft; whilst the other blade or blades are arranged in
such a way upon it that when the vessel is "under steam" they fall
into their proper position, dividing equally the circle. When the vessel
is "under sail" the blades are all by simply reversing the engine
thrown together or folded upon each other, and the engine stopped when
they are in the line of the stern post pointing upwards, in which
position the impediment to the vessel when sailing is reduced to a
minimum. When desired to "go astern" the blades will consequently
remain in this latter position on the shaft, but that will not prevent the
screw propeller from acting effectually for the purpose of backing the
vessel. To prevent the propellers from moving out of their folded
or reefed position when the vessel is "under sail," stops or retaining
blocks are lowered from the deck through an opening in the counter, as
is already practised.
And in order that my said Invention may be properly understood I
now proceed more particularly to set forth the system, mode, or manner
in or under which the same is or may be used or practically carried
into effect, reference being had, for the sake of more complete elucidation,
to the letters and figures upon the explanatory Sheet of Drawings
which I have hereunto appended, that is to say:
Figure 1 is an elevation of the stern of an iron vessel fitted with a
two-bladed screw propeller, showing the position of the two blades A, B,

page_text: .
when the vessel is going ahead under steam; Figure 2 is a side elevation
of the stern part of a vessel, showing the blades A, B, reefed, or in tho
position which they occupy while the vessel is under canvass and not
being propelled by the screw; Figure 3 is an end elevation of the same;
and Figures 4, 5, and 6 are detailed views of the central boss and part
of the blades, as shown- in their respective positions on Figures 1, 2,
and 3; on all the views from Figure 1 to Figure 6 similar parts are
indicated by corresponding letters of reference.
The central boss is formed in two parts or divisions C, D, to which the
blades A, B, of the screw are attached, as shown on Figures 2 and 5.
The forward division D is keyed to the shaft E, and the aft or stern
division O is hung loose, and may be prevented moving longitudinally
on the shaft E by a collar or by other suitable means or mechanism not
shown on the Drawings. The inner face of each division of the boss is
checked out to a sufficient depth over three-fourths of the surface, thus
leaving one-fourth projecting on each face, as shown at F, on the forward
:division D, Figure 5, and indicated by the firm hatched lines on Figures
4 and 6, and on the aft division C, as indicated at G by the dotted red
lines, so that the total projecting surface on the two divisions of the
boss of a two-bladed screw is equal to one-half the surface of the face
of the boss. When the vessel is going ahead under steam the projecting
part F, on the forward division of the boss acts against the projecting
part G on the aft division C of the boss to which the blade A is attached,
and causes it to revolve in the position shown in Figure 4. When the
vessel is under canvass, and the screw is not being used, it is reefed or
folded as shown in Figures 2, 3, 5, and 6, so as to reduce to a minimum
the impeding surface which the blades of the screw present to the
vessel's progress. This is effected by reversing the engine, when the
blade B will turn backwards until the projecting parts F and G on the
two divisions C, D, of the boss come into the position shown at Figure 6
so as to fold the blades A and B upon each other, the engine being
stopped when the folded blades are in the line of the stern post pointing
upwards, as shown on Figures 2 and 3. To prevent the blades from
moving out of their reefed or folded position a stop or retaining block H
may be lowered from the deck through an opening in the counter, as is
already practised. The position of the blades when going astern or
backing the vessel is the same as shown on Figures 2 and 3, in which
position they will act effectually in backing the vessel.

page_text: Figure 7 is an elevation of the stern of a composite ship fitted with a
four-bladed screw propeller, showing the relative positions of the blades
when the vessel is steaming ahead.
In Figures 8 and 9 the propeller is shown having the blades folded
together or reefed.
Figures 10, 11, and 12 are detailed views of the central boss and part
of the blades, as shown in their respective positions on Figures 7, 8,
and 9. In this case two blades A, B, are attached to the forward
division C of the boss and two blades D, E, to the aft division F of the
boss. The inner face of each division of the boss is checked out to
the extent of five-eighths, leaving on each face a projecting surface of
three-eighths, as shown at G and H, or a total surface on both faces of
three-quarters, leaving one quarter open space between the projections,
being the space through which the blades A, B, on the keyed division C
of the boss must turn back to bring the blades into the reefed or folded
position shown on Figures 8 and 9. The action of the propeller when
steaming ahead is the same as herein-before described in reference to
the two-bladed screw shown at Figure 1, the projecting part G on the
division O which is keyed on the shaft I acting against the projecting
part H on the division F, which is hung loose on the shaft I. When the
vessel is under sail the blades may be reefed or folded so as to assume
the position shown on Figures 8 and 9, and prevented from moving out
of their folded position by the stop K. The position of the blades of the
propeller when going astern is the same as shown on Figures 8 and 9, in
which position they will act effectually in backing the vessel.
It is to be understood that although this Invention shown in the
accompanying Sheet of Drawings as applied to two and four bladed
screw propellers only, it may also be applied to propellers having three
or six blades by forming the central boss in three divisions, one of which
is keyed to the shaft, and the other two are hung loose.
Having now described the nature of my said Invention, and the
manner in or under which the same is or may be used or practically
carried into effect, I would observe in conclusion that what I consider
novel and original, and therefore claim as the Invention secured to me
by the herein-before in part recited Letters Patent is,-
First. The construction of screw propellers, in which the blade or
blades attached to each division of the boss is or are arranged to fold
behind each other in the line of the stern post when the propeller is not

page_text: in action, or when backing, as herein-before described and shown on the
accompanying Sheet of Drawings.
Second. The construction of the boss in separate divisions, so that
when the engines are driven "ahead" the propeller blades are thrown or
fall into the positions requisite for propelling, and when reversed they
are folded behind each other, as herein-before described and shown on
the accompanying Sheet of Drawings.
In witness whereof, I, the said Henry Oliver Robinson, have here-
unto set my hand and seal, this Fifteenth day of October, One
thousand eight hundred and sixty-eight.
HENRY OLIVER ROBINSON. (L.S.)