Improvements in and connected with Propellers.
Year: 1899

page_text: Date of Application, 8th Dec., 1899-Accepted, 17th Feb.,
1900
COMPLETE SPECIFICATION.
Improvements in and connected with Propellers.
I, ALEXANDER BENJAMIN KOKERNOT, of 1521, South Liberty Street, in the City
f New Orleans, Parish of Orleans, and State of Louisiana, United States of
America, Accountant, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
ained in and by the following statement:-
This invention relates to screw propellers, and the objects of the invention are
to reduce the slipping action of the propeller to a minimum, to render a small
cross sectional area of the blades or flukes effective, to permit a slowly driven pro-
peller to be more effective in operation, to economise in the motive power, to
increase the power and efficiency of the wheel, and attain the maximum pro-
pelling power of a wheel of a given area or size.
The device contemplated in this invention is auxiliary to a propeller wheel
of ordinary construction, and consists of a cushion so constructed and connected
with a reflex bellows as to impart more responsive and greater resistance pro-
perties to the auxiliary device, approaching as nearly as possible a perfect re-
action. The improvement is also designed with special reference to any accident
which would cause injury to the auxiliary device, in which case the normal
efficiency of the propeller will not be impaired or affected. The above objects
are attained by simple means, easily applied, and reliable in operation, as
hereinafter more fully explained and illustrated in the drawings.
The invention consists in a screw propeller embodying novel features and
details of construction and arrangement of parts, as hereinafter fully described,
illustrated in the drawings, and incorporated in the claims.
In the accompanying drawings:-
Figure 1 is a face view of a screw propeller equipped with the auxiliary device
forming the subject matter of this invention, looking toward the active side of
the blades or flukes, and showing the manner of securing the cushion clasps or
binding frames upon the blades, and also the cushions or tires.
Figure 2 is a detail view of one of the clasps or frames detached and thrown
partially open.
Figure 3 is a detached perspective view of one of the cushions or tires.
Figure 4 is a similar view with the attaching studs omitted, the said view
being partially broken away to show the interiorly arranged suspension springs.
Figure 5 is a similar view of a cushion, showing the exteriorly arranged
5 springs.
0
Figure 6 is a detail view of one of the springs.
Figure 7 is a plan view of one of the flexible blade coverings, looking toward
the side which carries the cushion.
Figure 8 is a reverse plan view of the same.
Figure 9 is an enlarged perspective view of a section of the driving shaft.
Figure 10 is an enlarged longitudinal section through one of the reflex

page_text: Figure 1 is a plan view of one of the clips or rings by means of which the
bellows are mounted on the driving shaft.
Figure 12 is a plan view of the rear end portion of one of the pipes leading
from the bellows to the cushions, showing the manner of branching the pipe
so as to communicate with the opposite ends of its respective cushion.
Figure 13 is a similar view showing the manner of crossing the adjacent pipes
within the propeller hub, so that the said pipes will not interfere with each
other.
Figure 14 is an enlarged diagrammatic view illustrating the principle of
Figure 13.
Similar numerals of reference designate corresponding parts in all the figures
of the drawings.
I have illustrated in the drawings a propeller of the ordinary type, com-
prising a hub 1 and blades or flukes 2, which may be of any desired shape, size,
or configuration, and number, as this invention has nothing to do with the
general construction of the propeller, being applicable to all kinds of screw
propellers. One of the essential features of the present invention consists in the
application to the blade or fluke of a screw propeller, of a peripheral cushion
or tire, shown at 3, which extends around and bounds the outer edge of the
blade, and is disposed on the rear or active surface thereof. One of such cushions
is employed for each blade, and consists of a hollow inflatable sack which is com-
posed of flexible material which will yield to the resistance offered by the water
under the rapid rotation of the propeller. The material of the cushion may
consist of rubber or of textile material, or of a combination of both, the essential
idea being that the cushion or tire be flexible throughout. The cushion is also
of the greatest cross sectional area at its central portion, and it tapers therefrom
to the opposite extremities which are contracted or reduced, as shown at 4, the
said extremities being provided with metal sleeves 5, which, if desired, may be
equipped with other sleeves or couplings 6, adapting the terminal portions of the
cushion 'to be connected with pipes leading to reflex bellows in the manner
hereinafter set forth.
Several methods of attaching the cushions or tires to their respective blades
may be employed. A practical and efficient means for accomplishing this pur-
pose consists of a cushion clasp or binding frame 7 constructed of metal, and
comprising twin sections 8 hinged together at the point 9, so that they may be
opened or moved apart in applying the clasp or frame to the propeller blade or
fluke. The clasp or frame conforms exactly to the shape of the peripheral edge
of the propeller blade, and in cross section resembles the letter U, in that it
embraces oppositely located portions or flanges 10 designed to bear respectively
upon the front and rear surfaces of the propeller blade, and to hug closely and
fit snugly thereto. The hinged sections of the clasp or frame are securely retained
in their applied positions on the blade by means of straps or stays 11, which are
preferably of metal, each of said straps being connected at one extremity to
one of the hinged sections 8, and having means at its other extremity for engag-
ing the remaining section, the said means consisting preferably in providing
the free end of the strap with an opening at the point 12 to receive a stud or
button 13 on the other section. The straps 11 pass across the rear or inactive
surface of the blade, and do not, therefore, interfere with the operation of the
same. The frame or clasp 7 is provided along its inner edge, and in that flange
which is located on the active side of the blade, with a continuous groove 14,
forming a seat for the cushion or tire 3, said cushion being cemented or otherwise
secured within the groove, and being thus retained in proper working shape.
At the same time the cushion bears against and finds its support upon the active
surface of the blade, where it may act with full effect upon the water.
Another means for securing the cushion or tire to the blade is illustrated in
Figures 7 and 8, wherein the fastening means is shown as consisting of a flexible
blade cover 15 of any suitable material, having the cushion 3 firmly united to

page_text: he outer surface thereof, or that surface which is disposed away from anu
ontact with the blade. The cover 15 is provided with a hollow extension or
ap 16 in which the outer extreme portion of the blade is received, and the inner
edge of said cap is provided with lace holes or perforations 17. The blade
over 15 is also provided with oppositely extending lateral flaps 18, extending
nward as far as the propeller hub 1, and having their outer edges curved in
gee shape. The flaps are provided along their outer and top edges with eyelet
holes or perforations 20 and 21, respectively, and securing laces are passed
alternately through the holes 17 and 21 to secure the flaps along their top edges
to the cap 16, and also through the holes 20 in the side edges of both flaps, so as
to draw the same tightly across the back of the blade. In this manner, the
cover is stretched tightly across the active side of the blade, leaving a smooth
surface which will offer no obstruction to the water.
If desired, the cushion 3 may be provided along that side which comes in
contact with the blade, with a metal strip 22 extending longitudinally throughout
the length of the cushion and provided with laterally projecting threaded studs 23
The studs 23 may be passed through correspondingly
to receive securing nuts.
located openings near the periphery of the blade, thus securing the cushion
directly to the blade without the interposition of the clasp or frame 7, or the
cover 15, or said studs may be inserted through openings in the cover 15 for
of the means above described may be
securing the cushion thereto. Any
employed for securely attaching the cushions or tires to their respective blades
In order to impart the desired stiffness and power of resistance to the cushions,
I employ in connection with each cushion a plurality of springs 24, which are
substantially in the form of resilient split rings of metal, the terminals of which
are rounded, as shown at 25, to prevent puncturing the material of which the
cushion is formed. These springs are preferably covered with some textile
material to prevent abrasion of the cushion, and they may be located either
within the cushion, as shown in Figure 4, or upon the exterior of the cushion,
as shown in Figure 5, the springs in the latter instance being secured along
their lengths to the outer surface of the cushion, so as to properly support the
latter.
The driving shaft 26 upon which the propeller is mounted, is grooved longi-
tudinally upon its outer surface to provide seats 27 for a plurality of pipes 29
which may thereby be located within the circumferential surface of the shaft,
and flush with its outer surface. These pipes 29 may extend any required
distance along the shaft, and are held in place by retaining collars 28 at suitable
intervals. The propeller is fastened in any usual manner upon the end of the
driving shaft, and the propeller hub is of hollow construction so as to form a
space or chamber in which the opposite ends of the pipes 29 are received. Each
pipe 29 is bifurcated, or provided with branches 30 within the hollow hub of the
propeller, the said branches leading to opposite ends of the respective cushion
supplied by that pipe. Each pipe 29 passes through a pair of heads or disk-
shaped plates 31 secured to the front and rear ends of the hollow propeller hub,
5 the pipe 29 being supported within the hub in this manner, and the heads 31
In order to prevent adjacent
being secured to the hub in any preferred way.
pipes from interfering with each other within the hollow propeller hub, one of
said pipes may be formed as shown in Figure 12, while the adjacent pipe is
provided with an arch or bridge 32 spanning one of the branches 30, or the
50 first named pipe may be provided with a single lateral extension or branch 33,
passing under the arch or bridge 32, and having a T-extension 34 terminating
in nipples 35. It will be understood that each pipe 29 terminates in a pair of
nipples 35 which are connected by means of the couplings 6 hereinabove described
to the opposite ends of the respective cushion or tire 3, and in this manner, and
55 by means of the plurality of pipes above described, an independent air supply
is communicated to each cushion.
Each pipe 29 is connected at its opposite end to an independent pair of

page_text: bellows 36, the construction of which is best illustrated in section in Figure 10.
Each pair of bellows consists of an outer shell 37 which is preferably cylindrical,
and having both ends closed by heads 38 and 39. The head 38 is provided with
a central opening 40 for the reception of the end of one of the pipes 29. The
opposite head 39 has inserted therethrough and permanently mounted therein,
a guide tube 41, the same projecting both upon the outside and inside of the
head 39 to form an elongated bearing for a sliding stem or indicator 42 carrying
a knob or button 43 at its outer end. Upon the inner end of the stem 42 is
mounted a piston comprising a disk-shaped head 44, extending rearwardly
from which is a cylindrical shell 45 which slides in contact with the inner
surface of the outer shell 37. The head 38 of the outer shell 37 and the
head 44 of the piston are connected by a pair of bellows 46 tightly joined to
both heads so as to prevent the escape of air passing in and out from the pipe 29.
Springs 47 are arranged within the shell 37 so as to exert a pressure on the
piston, and these springs may be arranged either between the piston and the
head 38, or between the piston and the head 39, according to preference, the
said springs serving to preserve the proper equilibrium of the piston, while the
stem 42 indicates the extent of the pressure exerted upon the cushions or tires
on the propeller blades. The shell 37 is exteriorly threaded, as shown, and the
threaded portion terminates in a circumferential Hange or shoulder 48.
Surrounding the shaft 26 is a clip or collar 49, provided with a superimposed
eye or ring 50 which is internally threaded to receive the shell 37. The shell 37
is screwed into the ring 50, until the flange 48 bears against the adjacent side
of the ring 50, and the flange 48 and the ring 50 are provided with registering
holes 51 and 52, to receive screws, bolts, or rivets whereby the outer shell of the
bellows is securely connected to the collar 49 and supported thereby upon the
shaft 26. In order to avoid interference between the several pairs of bellows,
they are preferably arranged one in the rear of the others, as illustrated in
Figure 9. However, where only a few pairs of bellows are employed, they
may be arranged in a circumferential series upon the shaft, in which event the
collar 49 may be provided with a number of eyes or rings 50, corresponding
to the number of bellows employed. Each bellows has a vent 54.
In order to primarily inflate the cushions and compress air within the cushions
and bellows, the several pipes 29 are individually equipped with inflating
valves 53 adapted to receive a suitable air pump in a manner that will be readily
understood.
The propeller hereinabove described when attached to a vessel may be en-
closed within a crate or cage of wire or other suitable material in order to pre-
vent injury thereto. Except under extraordinary conditions, however, such crate
or cage will be unnecessary. Should the cushion or other parts of the apparatus
for any reason get out of order, or the operation thereof become impaired, this
will in no wise interfere with the normal efficacy of the propeller itself. The
cushions will be made of some light, tough, flexible material, impervious to
water and air.
I have illustrated some variations in the form of the means for attaching the
cushions to their respective blades or flukes, and it will be obvious that the
buoyant attachment may also be greatly varied in shape, figure or form, and
number and position on the flukes. I therefore do not desire to limit myself to
the specific applications and attaching means herein-above described, but reserve
to myself the right to change, modify, or vary the construction within the scope
of this invention.
By means of the construction set forth, the tendency of the blade to slip
uselessly through the water is reduced and greater efficiency is obtained from a
propeller of a given area. It will, of course, be understood that any compression
of a portion or all of any particular cushion or tire will result in a similar action
upon the piston of the bellows, and the latter will operate with a reflex action
to resist the yielding action of the cushion and restore the active portion of

page_text: e cushion to its normal position. The cushion thus acts with a yierar
on the water and does away with the rigidity of the ordinary propeller, which
many cases is caused to operate upon and lift a dead weight of water without
In the event that one of the cushions or tires
y beneficial or driving effect.
otherwise injured or destroyed, the
ould burst or become punctured, or
dicator stem will give visual notice thereof.
Having now particularly described and ascertained the nature of my said
vention and in what manner the same is to be performed, I declare that what
claim is:-
1. A propeller having a yielding cushioned surface, substantially as described.
2. A propeller having a portion of its surface composed of a yielding cushion,
ubstantially as described.
3. A propeller having a yielding cushion along its outer edge, substantially
s described.
4. A propeller having a yielding cushion applied to its active surface, sub-
tantially as described.
5. A propeller blade having a yielding cushion along its edge, substantially
As described.
6. A propeller having an inflated cushion on its active surface, substantially
as described.
7. A propeller having an inflated cushion on its active surface, in combination
with a reflex air device in communication therewith, substantially as described.
8. A propeller having an inflated cushion on its active surface, in combination
with a pair of reflex bellows, communicating therewith, substantially as described.
9. The combination with the blades of a propeller of cushions on the active
faces thereof, and an independent reflex bellows for each cushion, substantially
as described.
10. The combination with the blades of a propeller, of air cushions thereon, a
driving shaft on which the propeller is mounted, and reflex bellows mounted
on said shaft, and communicating with the cushions, substantially as described.
11. The combination with the blades of a propeller, of air cushions thereon, a
driving shaft, independent pipes for the respective cushions, extending along the
said shaft, and inflating valves connected with said pipes, substantially as
described.
12. A propeller and a yielding cushion on the active side thereof, in combina-
tion with attaching means for securing the cushion to the propeller, substantially
us described.
13. A propeller and a yielding cushion on the active side thereof, in com-
bination with a device for binding the cushion against the propeller and holding
it thereon, substantially as described.
14. A propeller and a yielding cushion on the active side thereof, in com-
bination with a driving shaft, and a series of pipes located in longitudinal re-
cesses in the shaft and communicating with the cushions, and having inflating
means, substantially as described.
5 15. A propeller and a yielding air cushion on the active side thereof, in com-
bination with a driving shaft, pipes leading to said cushions and arranged in
grooved seats extending along the shaft, and retaining means surrounding the
shaft and engaging the pipes, substantially as described.
16. A propeller and a yielding air cushion on the active side thereof, in com
50 bination with a driving shaft, a pipe leading to the cushion and arranged in
a grooved longitudinal seat in the shaft, a retaining collar encircling the shaf
and engaging the said pipe, and a pair of reflex bellows mounted on the shaf
and communicating with said pipe, substantially as described.
17. A propeller and a yielding cushion on the active side thereof, in combina
65 tion with a driving shaft, a pipe leading to the cushion and extending along th
shaft, a pair of bellows mounted on the shaft and communicating with said pipe

page_text: and an indicator attached to and actuated by the bellows, substantially as
described.
18. A propeller having a hollow hub, and a yielding cushion on the active
side thereof, in combination with a driving shaft, a pipe extending along the
shaft, a reflex air device connected thereto, and a coupling within the hollow
hub of the propeller connecting the pipe and cushion, substantially as described.
19. The combination with a propeller blade, of a flexible air cushion thereon,
means for inflating said cushion, and springs for expanding the cushion, sub-
stantially as described.
20. The combination with a propeller blade, of a flexible air cusliion mounted
thereon, and circular springs for stiffening or expanding the cushion, substan-
tially as described.
21. The combination with a propeller blade, of a cushion extending around the
edge thereof and having its extremities arranged adjacent to the propeller
hub, and an inflating pipe extending into the hub, where it is branched and
connected to the terminal portions of the cushion, substantially as described.
22. The combination with a propeller blade, and a flexible air cushion thereon,
of a driving shaft, a collar thereon having an internally threaded eye, an
exteriorly threaded pair of reflex bellows screwed into said eye, a flange on said
bellows adapted to be fastened to the eye, and a pipe leading from the bellows
to the cushion, substantially as described.
For the Applicant,
J. G. LORRAIN, M.I.E.E., M.I.Mech. E.,
Norfolk House, Norfolk Street, London, W.C.,
Chartered Patent Agent.