Improvements in Screw Propellers.
Year: 1896

page_text: Date of Application, 25th Mar., 1896
Complete Specification Left, 25th Jan., 1897-Accepted, 25th June, 1897
MARTIN ROSE RUBLE, Mechanical Engineer, No. 3 Cursitor Street, Chancery
Lane E.C. do hereby declare the nature of this invention to be as follows:-
The object of this invention is to provide a propeller simple and durable in
construction and whereby its efficiency is increased and other advantages are
possessed as will be stated.
On the propeller shaft are secured two collars arrainged opposite to each other
to which are secured the cones or ends of a hollow shaft or hub which latter is
provided with a series of spiral blades or screw-threads forming a true screw which
constitutes the propelling medium. Said collars are provided with inwardly
extending shoulders parallel with the axial line of the shaft to receive a casing tube
around propeller shaft to prevent the water from going into hollow chamber formed
by the cones and hollow shaft or hub. The diameter of hub must be the
diameter of the outer circle of blades. The blades must be so arranged on the
screw shaft that the radial lines shall at every point be at right angles with the axial
line of the shaft.
Dated this 24th day of March 1896
MARTIN ROSE RUBLE.
Improvements in Screw Propellers.
I, MARTIN ROSE RUBLE, of 3 Cursitor Street, Chancery Lane, London,
Mechanical Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
This invention relates to screw propellers and has for its object a durable
propeller of simple construction and possessing high efficiency and other advantages
as hereinafter set forth.
The blades of my improved propeller are mounted on a hollow cylinder which is
either attached to the hub or boss by conical end plates, or is constructed and
arranged to rotate between fore and aft stationary conical plates attached to the
bull of the ship and to the stern frame. In some instances the cone at the rear
end may rotate with the cylinder while that at the forward end is stationary.
In the accompanying drawings,
Figure 1 is a perspective view, and
Figure 2 is a longitudinal central section of one form of my improved propeller.
Figure 3 is a similar section of a modified construction of my propeller adapted
to a stern frame in which there is not room for both ends of the propeller to be
coned outwardly.

page_text: Figure 4 is a side elevation illustrating a further modification hereinafter
described, and
Figure 5 is a longitudinal section of my improved propeller as applied to a twin
screw steamer.
Like letters denote corresponding parts in the several figures.
Referring to Figures 1 and 2 A is the propeller shaft; B, B are bosses or collars
secured on the shaft by keying or otherwise; C, C are conical ends bolted or
riveted to the bosses or collars B, B; D is the hollow cylinder on which the
propeller blades F, F are mounted and which is connected to the larger ends of
the cones C, C. E is a tube surrounding the propeller shaft and connecting the
bosses B, B, being secured thereto by screwing or otherwise. The said tube serves
to prevent the admission of water to the hollow cylinder and so preserves the
buoyancy of the propeller.
The propeller blades F, F are preferably secured to the cylinder D by means of
angle irons G to which the roots of the blades are riveted. Each blade is so
constructed that the pitch of every part of it is uniform.
I do not confine myself to the number of blades shewn in the drawing, nor to
the relative length of the cylinder D, nor to the relative length or inclination of
the conical ends C as these may be varied according to the construction of the
vessel without departing from the nature of my invention. I prefer however that
the diameter of the cylinder D be about five-eighths that of the periphery of the
blades, and I find it advantageous to make the pitch of the blades at the root equal
to the circumference of the cylinder D.
The cones C act as deflectors to direct the water from the cylinder D and to
prevent churning or back pressure; owing to the shape of the blades the water is
not thrown off radially by them but is directed backwards in a line parallel to the
propeller shaft and thus the possibility of churning the water and loss of power by
centrifugal action are avoided.
In some instances when the cones C cannot both be external to the cylinder by
reason of want of space in the stern frame, one of them viz. the rear one can be
made re-entrant as shown in Figure 3. In this case the hub or boss B is made in
one casting, and the tube E is dispensed with. In some instances directing conical
plates are fixed to the hull of the vessel to guide the water to the blades. Such a
construction is shown in Figure 4, H being the conical plate fixed to the near side
of the hull. A similar plate is fixed to the other side, the two plates forming
together a cone the large end of which has the same diameter as the cylinder D.
Similar conical plates J are also fixed to the stern frame K behind the propeller.
The small ends of the plates J are separated a sufficient distance to allow the
rudder to move as required between them."
In Figure 5 I have shown a propeller adapted to a twin screw steamer the
propeller shaft being supported by a bracket M in the usual manner. I attach
fixed cones H to the bracket at the forward end of the propeller, and at the rear
overhanging end of the propeller I apply a cone J which is fixed to and rotates
with the propeller.
The blades afford a large propelling surface and ensure high propelling power.
My improved propeller is sufficiently buoyant to support its own weight and by
reason of its shape it does not cause vibration in the vessel. It is moreover as
efficient when turning in the backward as when turning in the forward direction,
and its efficiency is not reduced to the same extent as that of an ordinary screw
propeller when only partially submerged; moreover the full benefit is obtained
of all power required to revolve it.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. A propeller comprising a hollow cylinder having conical ends and furnished
with blades forming portions of true screws. substantially as described.

page_text: 2. The combination with the hollow cylinder of a tube surrounding the propeller
shaft and secured to the end bosses of the propeller, substantially as described,
and for the purpose specified.
3. The combination with my improved propeller of fixed conical plates applied
to the hull and to the stern frame, substantially as described.
4. A propeller constructed substantially as described with reference to one or
other of the forms or modifications illustrated in the accompanying drawings,
for the purpose specified.
Dated this 25th day of January 1897
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.