Improved Screw Propellers.
Year: 1893

page_text: PROVISIONAL SPECIFICATION.
Improved Screw Propellers.
We, HENRY SHIELD, Engineer, and DAVID JAMES HOWELLS, Engineer,
both of 17, York Street, Liverpool, in the County of Lancaster, do hereby declare
the nature of this invention to be as follows:-
This invention has reference to screw propellers for propelling navigable vessels,
and consists of a certain construction by which an efficient propelling effect is
obtained combined with great strength.
According to this invention the tips of each two adjacent blades are coupled
together by a strip or plate lying in the plane of direction of movement of the ship;
that is, the connecting or coupling plates lie with their leading and back edges
directed forward and aft, so that they have in themselves no propelling action.
These plates or parts in cast propellers are cast in one with the blades, that is, two
blades are cast together and constitute duplex blades; and at the blade tip the
blades may be rounded or bent where they run into the coupling plates or strips.
In the case of propellers having blades in pairs, the said blades will in most cases
be arranged in two planes one behind the other, and the tips of the blades forming
a couple or pair are formed or cast in one, that is, coupled by a plate or strip at
their tips. In some cases the blades forming the couples in two separate planes
are in advance of one another, say the rear one in advance of the forward one;
while in other cases the two may be directly one behind the other.
These duplex blades may be cast on the boss of the propeller or connected to it
in any known suitable way.
Dated this 17th day of March 1892
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicants' Patent Agents.
Improved Screw Propellers.
We, HENRY SHIELD, Engineer, and DAVID JAMES HOWELLS, Engineer,
both of 17, York Street, Liverpool, in the County of Lancaster, 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 has reference to screw propellers for propelling navigable vessels
and consists of a certain construction by which an efficient propelling effect is
obtained, combined with great strength.
According to this invention the tips of each two adjacent blades are coupled
together by a strip or plate lying in the plane of direction of movement of the ship,

page_text: that is, the connecting or coupling plates lie with their leading and back edges
directed forward and aft, so that they have in themselves no propelling action.
These plates or parts in cast propellers are cast in one with the blades, or bolted,
riveted or otherwise secured to the blades, that is, two blades are cast together on
the boss, or bolted on the boss and constitute duplex blades; and at the blade tip the
blades may be rounded or bent where they run into the coupling plates or strips.
The blades will in most cases be arranged in two planes one behind the other, and
the tips of the blades forming a couple or pair are formed or cast in one, that is,
coupled by a plate or strip at their tips. In some cases the blades forming the
couples in two separate planes are in advance of one another, say the rear one in
advance of the forward one; while in other cases the two may be directly one
behind the other.
These duplex blades may be cast on the boss of the propeller or connected to it
in any known suitable way.
Drawings illustrative of the invention, the nature of which is above described,
are annexed hereto. These illustrate three examples of propellers under the
invention. The first example, shewn in end elevation looking forward in Figure 1,
in plan in Figure 2. and in side view partly in section in Figure 3, is a propeller in
which two sets of blades are arranged in two planes one forward of the other, the
blades forming each pair or couple being in advance of each other circumferentially.
The second example, of which Figure 4 is a forward elevation, Figure 5 a plan,
and Figure 6 a side elevation partly in section, is one in which the blades are
arranged in two planes, and lie directly in couples one behind the other. The
example shewn in elevation in Figure 7 and in plan in Figure 8, is a modification
of the propeller shewn in Figures 1 to 3, having two pairs of duplex blades and
two ordinary blades arranged between them.
The same letters of reference are used throughout the different views of the
drawings to denote the same or like parts wherever they occur.
Referring now to these drawings (and more particularly to Figures 1 to 3)
BF are the blades of the propeller which lie in the forward plane thereof; and
BA are the blades which lie in the aft plane of the propeller. Each pair of
forward and aft blades, adjacent to each other, are connected together at their tips
by the strip or plate P; and the aft blade BA is in advance of the forward
blade B F, circumferentially, as shewn. The strip P forms at the periphery of the
propeller a segmental connecting piece to each pair of blades and has negative
effect so far as the propelling efficiency or quality of the propeller is concerned.
In case of a six bladed propeller, shewn in these Figures 1 to 3 (and also
Figures 4 to 6), the construction produces a propeller having three duplex
blades.
In the propeller shewn in Figures 4 to 6, as stated, the blades of the two
different sets, that is, those arranged in the forward plane, and those in the aft
plane are disposed directly one behind the other, and each couple is connected by a
plate P as shewn, possessing the same characteristics and purposes as that or those
set forth with reference to Figures 1 to 3.
In the modification shewn in Figures 7 and 8, a six bladed propeller is shewn,
but in this case four only of the blades, namely two blades B F and two B A, of
the kind above set forth, are provided; the other two, designated O, being
arranged as and of the ordinary kind. These blades B F and B A are connected
together by plates P, exactly as those specified with reference to Figures 1 to 3 are
connected.
Some of the qualities of propellers constructed as herein described are, that great
strength is afforded; vibration is prevented or diminished in a vessel to which they
may be fitted; and greater relative efficiency is produced by them.
Various numbers of blades, or sets of blades in pairs, may be used in a propeller
according to this invention; as for instance, it may have for convenience two pairs
or three pairs as shewn, or more pairs. Also although in the drawings cast metal
propellers are shewn, the blades may be connected together by plates P of wrought

page_text: iron, steel, or brass, or other suitable metal, bolted, riveted, or otherwise secured,
suitably to the tips of the blades; and they may be cast in pairs separately of cast
iron, steel, manganese bronze, or other suitable metal.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. The herein described improvement in screw propellers, consisting in having or
constructing the blades connected together in pairs by plates, as P, whose planes
are parallel to the axis of the propeller; for the purposes specified.
2. A screw propeller having two sets of blades arranged in different planes, one
behind the other, the blades of one set being in advance of the other circum-
ferentially, and the tips of the adjacent blades forming pairs being connected
together by a plate, as P, whose plane is parallel to the axis of the propeller at
their tips; substantially as and for the purposes set forth.
3. A screw propeller having two sets of blades arranged in different planes, one
behind the other, each pair of the forward set and aft set being disposed directly
one behind the other, and connected together at their tips by a plate, as P, whose
plane is parallel to the axis of the propeller; substantially as and for the purposes
set forth.
4. The respective propellers constructed particularly as set forth with reference
to and shewn in the different sets of drawings hereto annexed.
Dated this 16th day of December 1892
CHEESBROUGH & ROYSTON, Fels. Chart. Inst. P.A.,
15, Water Street, Liverpool, Applicants' Patent Agents.