Improvements in and connected with Electrically Driven Screw Propellers.
Year: 1893

page_text: Date of Application, 6th Feb., 1893
Complete Specification Left, 6th Nov., 1893-Accepted, 6th-Feb., 1894
PROVISIONAL SPECIFICATION.
Improvements in and connected with Electrically Driven Screw
Propellers.
I, HARRY THEODORE BARNETT, M.I.E.E. of 14 Narcissus Road West
Hampstead, London do hereby declare the nature of this invention to be as
follows:-
This invention relates to that class of propeller for whatever purpose used which
consists of a pair of screws, the two screws of such pair being mounted one before
the other directly in the line of propulsion, & revolving in opposite directions but
having their blades vanes or arms so set that the principal motion produced by each
upon the propelled substance is approximately or entirely similar in direction. I
arrange that this double acting screw be driven by a double acting electro motor,
the said motor consisting of two opposed mutually reacting sectionally wound
commutation electro magnets with their commutators, brushes bearings or axles,
frames &c. each of the said commutation magnets driving one of the pair of
screws.
A simple form of such a motor may be constructed as follows:-Two gramme
rings of the flattened or disc type are arranged with their faces opposed their
commutators turned toward the outside & their brushes so placed that when the
electric current is passing thro' the windings on the said rings their magnetic polar
positions shall not be immediately opposite. When the current is passing each ring
tends to turn as from the position of its own poles toward the direction of the
others reverse polarity.
I may cause the motor to operate the propeller by some device of pulleys &
belts, friction gear, chain gear or other motion transmitting device but I prefer to
arrange the said mutually reacting portions of the motor each directly upon the
same shaft or spindle which carries one of the pair of revolving screw propellers.
In the case of boat propellers or other device necessitating that the motor be at
some distance from the screws I prefer to arrange the inner screw & commutation
magnet upon a hollow shaft & the end or outer screw & commutation magnet upon
a shaft passing thro' the said hollow shaft.
Where the screws revolve in a fluid I prefer to keep the same from contact with
the motor not by the usual device of stuffing boxes but by causing the said motor
to be situated above the highest point which the fluid may reach, the screw shafts
passing downwards thro' a tube or channel in which the fluid finds its natural
level.
In the case of aerial propellers, fans, or the like arranged with their commutation
magnets upon the same shafts which carry the fans I prefer to mount each fan & its
actuating commutation magnet co-axial the blades of the former being preferably
mounted, either directly or with some suitable substance interposed, upon the
periphery of the latter. Where an outer casing or frame is not necessary to the
proper working of this form of apparatus, as for instance in a propeller arranged
for vertical up or down thrust, I prefer to support the brush holders upon a spindle
passing thro' the centre of the said commutation magnet & fan combinations
forming a bearing for hollow cylindrical shafts upon which the said combinations
are mounted.
Where there is any tendency to unequal working & it is desired that the two.
screws shall move at an equal or proportionally regular speed I provide a suitable

page_text: gearing surface in connection with either the motor or propeller axes & intergear
therewith a suitable wheel revolving upon a fixed axis or bearing.
Dated this Fourth day of February 1893.
Improvements in and connected with Electrically Driven Screw
Propellers.
I, HARRY THEODORE BARNETT M.I.E.E. of 14 Narcissus Road West
Hampstead London N.W. do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
This invention relates to that class of propeller for whatsoever purpose used
which consists of a pair or pairs of screws, the two screws of each pair revolving in
opposite directions but having their blades, vanes, or arms so set that the principal
motion produced by each upon the propelled substance is approximately or entirely
similar in direction. The said screws are oue before the other as regards the
stream of material to be propelled, and are situated upon the same axial line, there-
fore as their direction of rotation is reverse one to the other one must be left and
the other right hand threaded or set.
I arrange that this double-acting screw be driven by a double-acting electro-
motor of the form described in my Specification No. 23,460 of 1892, the said motor
consisting of two opposed mutually re-acting sectionally wound commutation
electro magnets with their commutators, brushes, bearings, or axles, frames, etc.
Two gramme rings of the flattened or disc type, their faces opposed and in close
proximity, the commutators turned towards the outside, and the brushes so arranged
that when the electric current is passing through the conductor upon the said rings
(their polar position should not be immediately opposite) would constitute a simple
form of such a motor, each ring tending to turn toward the direction of the others
reverse polarity.
A better form of this motor in that there is no magnetic thrust or pull to be
taken by the bearings or to spring the commutation magnets out of truth, consists
of the same number and relation of parts as in the motor previously described but
the sectionally wound commutation electro magnets instead of being of the flattened
or disc type of gramme ring are of the cylindrical type, and are arranged one
contained within the other, there being a clearance between them to allow of their
revolving in contrary directions. The motor is very fully described in my Patent
No. 23460 dated 20th December 1892.
I may cause the motor to operate the screws by means of pulleys and belts,
friction gear, chain gear, cog wheels or other motion transmitting device, but I
prefer to arrange the said mutually re-acting portions of the motor each directly
upon the same shaft or spindle which carries one of the pair of screw propellers.
In the case of boat propellers or the like, I prefer to arrange the inner or nearer
screw and commutation magnet upon a hollow shaft and the end or outer screw and
commutation magnet upon a shaft passing through the said hollow shaft.
In the accompanying drawings
Figure 1 is a plan of a pair of screw propellers P P¹ mounted on two co-axial
shafts QQ each of which carries one of the two commutation magnets R R¹.
Figure 2 is a right hand end view of the same.
In the case of aerial propellers, fans, or the like arranged upon the same shafts
as the commutation magnets, I prefer to mount each fan and its actuating
commutation magnet co-axial; the blades of the former being mounted preferably
upon the periphery of the latter—they may be attached to and secured by rings of

page_text: fibre, wood, ebonite or other suitable substance connected by cement or wedges or
otherwise attached to the iron core, or to the conductor winding of the commutation
magnets.
A convenient form of this preferred air propelling arrangement, is fully shown in
Figures 3 and 4-it will be noticed that the commutation magnets T. T¹ are of
the first mentioned type, solidly constructed, and provided with a ball thrust
bearing between them to take the magnetic pull, each commutation magnet being
mounted on a sleeve axle U. U through both of which passes a fixed spindle V.
which also serves to carry the brush holders. In conclusion I wish to remark that
the drawings are intended as examples for the arrangement of parts constituting
my invention and not as models of ordinary mechanical details or construction.
Having now particularly ascertained and described the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
Claim I. The combination of a duplex electro motor consisting of two opposed
mutually re-acting sectionally wound commutation magnets (so called armatures)
with their commutators, brushes, bearings or axles frames, etc. with a pair of screw
propellers adapted to operate together while revolving in opposite directions, each
propeller being connected with one of the commutution inagnets either directly
through the propeller shaft, or through intermediate driving mechanism
substantially as described.
Claim . The combination of a duplex electro motor consisting of two opposed
mutually re-acting sectionally wound commutation magnets (so called armatures)
with their commutators, brushes, bearings or axles frames etc., with a pair of
bydraulic screw propellers adapted to co-operate by turning in opposite directions,
and a pair of concentric propeller shafts, the inner shaft carrying one of the
commutation magnets of the said motor and the outer or further screw propeller,
while the tubular outer shaft carries the other commutation magnet, and the inner
or nearer screw propeller, substantially as described.
Claim III. The combination of a duplex electro motor consisting of two opposed
mutually re-acting sectionally wound commutation magnets (so called armatures)
with their commutators, brushes, bearings or axles frames, etc., with a pair of aerial
screw propellers or fans adapted to co-operate by turning in opposite directions
each fan or propeller being directly mounted on one of the commutation magnets of
the motor substantially as described.
Dated this 24th October 1893.
HARRY THEODORE BARNETT.