Improvements in the Construction of Propeller Shafts for Steamers, and in the Method of and Means for Securing the Propeller Blades in Position.
Year: 1889

page_text: Date of Application, 25th July, 1889
Complete Specification Left, 25th Apr., 1890-Accepted, 7th June, 1850
BRAXT
Improvements in the Construction of Propeller Shafts for Steamers,
and in the Method of and Means for Securing the Propeller
Blades in Position.
I, JAMES TAYLOR, of 3, Westminster Chambers, Westminster, Shipowner, do hereby.
declare the nature of this invention to be as follows:-
My Invention relates to the construction of the shafts of screw propellers, and to
the method of and means for securing the propeller blades in position upon the
shaft.
The solid forged shafts at present in use are liable to fail under lower strains than
is due to their diameter or sectional area owing to internal unsoundness which can
only be discovered when fracture actually occurs. I am aware that hollow propeller
shafts have also been used, which consist of cast steel of great thickness, and are
therefore unreliable for the same reasons which apply to solid forged shafts.
The object of my invention is to construct screw propeller shafts in the form of
hollow tubes, the plates of each tube being of such moderate thickness as to be
incapable of concealing internal unsoundness, and which can therefore be relied on to
bear the strains to which the shaft will be subjected, and which are provided for by its
diameter and sectional area.
A further object of my invention is to secure each blade to the shaft separately, so
that any one blade can be detached and other substituted without disturbing the
remainder, and to provide means for effecting this operation during the immersion of
the propeller.
In carrying my invention into effect I make up the propeller shaft in lengths of
tubes of the needful diameter and sectional area, and formed from plates of such
suitable thickness as is insufficient to conceal internal unsoundness; these separate
lengths are coupled together by flanges, collars, coupling dises rivetted or bolted
together, or by other efficient means; the shaft so made up is furnished in the usual
way with thrust collars and pillow blocks.
These hollow shafts in some cases are of uniform dimensions throughout their entire
lengths, in which case the screw propeller is secured to the tail end thereof.in the
manner in ordinary use with solid shafts. In other cases in order that the blades of
the propeller may be separately detached from the propeller shaft and others secured
thereto while the vessel is afloat, I enlarge the dimensions of the tail end of the shaft.
sufficiently to enable a man to work inside, access to which is through a manhole
provided at some position within the vessel.
Each blade is provided or terminates at its inner end with a tenon which fits into a
slot of corresponding dimensions in the shaft, into which it extends a sufficient distance.
to receive a key or be otherwise securely held in position; between this tenon and the.
root of the blade is provided what may be termed the seat of the blade, which for.
structural compactness and equal distribution of strains preferably takes the form of.a,
section or part of the propeller boss, that is, the seats of all the blades combined.
together fit in between each other and make up the boss.
In order to detach any one blade from the propeller and substitute another therefor
without lifting the propeller out of the water, I provide a well or trunkway leading
through the ships' deck to the screw port, the screw frame being enlarged at the
upper part to correspond with the said well or trunkway, through which the propeller
blade is let down by a frame or cradle to its position on the shaft, its exact position
being adjusted by upper and lower guides which slide up and down between the stern.
posts. The guides are grooved, tongued, or otherwise fitted between the stern posta
so as to be restricted to a vertical motion only.

page_text: The operation for detaching a blade from the screw is as follows: turn the shaft to
the position in which the blade extends vertically downwards, withdraw the key or
other securing device from the inside and the blade when released falls into the water.
In order to insert another blade in its place, turn the shaft half round so as to bring
the slot to the top of the circle, lower the blade through the well or trunkway by
of the frame tackle and guides into position, and then secure it from the inside
by a key or other device. In order to prevent water from entering the shaft when
the tenon is withdrawn from the slot, I provide an inside cover proferably recessed
deep enough to receive the full length of the tenon and which must be secured firmly
in position, and I insert a short sliding rod in this cover to be actuated say by a small
hydraulic ram so as to force the tenon out of the slot if needful.
means
July 24th 1889
COMPLETE SPECIFICATION.
Improvements in the Construction of Propeller Shafts for Steamers,
and in the Method of and Means for Securing the Propeller
Blades in Position.
I, JAMES TAYLOR, of 3, Westminster Chambers, Westminster, Shipowner, 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:-
-
My Invention relates to the construction of the shafts of screw propellers, and to
the method of and means for securing the propeller blades in position upon the
shaft.
The solid forged shafts at present in use are liable to fail under lower strains than
is due to their diameter or sectional area owing to internal unsoundness which can
only be discovered when fracture actually occurs.
I am aware that hollow propeller shafts have also been used, which consist of cast
steel of great thickness, and are therefore unreliable for the same reasons which apply
to solid forged shafts.
One object of my invention to construct screw propeller shafts in the form of
hollow tubes, the plates of each tube being of such moderate thickness as to be
incapable of concealing internal unsoundness, and which can therefore be relied on to
bear the strains to which the shaft will be subjected and which are provided for by its
diameter and sectional area.
A further object of my invention is to secure each blade to the shaft separately so
that any one blade can be detached and another substituted therefor without disturbing
the remainder, and to provide means for effecting this operation during the immersion
of the propeller.
if
"
In carrying the first part of my invention into effect I make up the propeller shaft
in lengths formed from plates of iron or steel of such suitable and moderate thickness
as to be incapable of concealing internal unsoundness, these plates I arrange in layers
necessary and unite them together by any efficient means to form hollow tubes of
convenient lengths and of the requisite sectional area, which separate lengths are
coupled together by flanges, collars, coupling discs rivetted or bolted together, or by
other efficient means; the shaft so made up is furnished in the usual way with thrust
collars and pillow blocks. These hollow shafts in some cases are of uniform dimen-
sions throughout their entire lengths, that is, are not enlarged at their tail ends in
the manner hereinafter described, when constructed to be used only in combination
with screw propellers of the ordinary construction which are secured to the tail end
thereof from the outside of the ship in the manner in ordinary use with solid
shafts.
In other cases in order to carry out the further object of my invention by which
the blades of the propeller may be separately detached from my improved propeller
shafts and others secured thereto while the vessel is afloat and the propeller

page_text: consequently immersed in water, I enlarge the dimensions of the tail end of the shaft
sufficiently to enable a man to work inside, access to which is through a manhole
provided at some position within the vessel.
I will now refer to the accompanying drawings which illustrate in part sectional
view the enlarged tail end of the propeller shaft and the mode of securing the pro-
peller thereto together with such parts of a ships' stern as are modified to adapt them
to my invention or enable the said invention to be more clearly understood; those
details of construction which are not essential for this purpose being generally
left out.
The invention is not limited to any precise means or details of construction for
carrying out the objects specified, but convenient means for effecting these objects are
shown in the drawings in which the same letters of reference indicate corresponding
parts in all the figures. Figure 1 illustrates in position in the stern of a vessel a part
sectional view of the tail end of a propeller shaft with the propeller attached thereto
and Figures 2 and 3 aro sectional views taken on lines V V and X X respectively of
Figure 1. Figure 4 illustrates more particularly a view of the screw propeller
mounted in position on the propeller shaft which is taken in section on line YY
of Figure 1. Figure 5 is a similar view to Figure 1 but illustrates the means
employed for lowering a propeller blade into position on the propeller shaft from
the deck above; Figure 6 being a sectional view taken on line ZZ of Figure 5.
In the drawings a is the enlarged tail end of the propeller shaft, which enlarged
part extends from the extreme or aft end of the shaft to any required distance
within the vessel, which for structural purposes will generally be to the aftermost
bulkhead, from which the shaft is continuod to its connection with the ships' engines
in suitable lengths and of a diameter reduced to correspond with the intended
sectional area and strength of the shaft. The shaft is furnished with a stern tube
and packing of the usual or suitable arrangement.
Referring more particularly to Figures 1 and 4 which illustrate in corresponding
sectional views the tail end of the propeller shaft with propeller blades b secured
thereto; it will be observed that each blade is separately secured to the shaft by
a tenon c which accurately fits into a slot c¹ through which it extends a sufficient
distance to receive a key or to be otherwise secured from the inside of the shaft ;
extending from the root of the blade in the manner shown more particularly in
Figure 4, I provide the seat d, which for structural compactness and equal distribu-
tion of strains preferably takes the form of a section or part of the propeller boss,
which instead of being cast in one piece as hitherto, is made up in equal sections
of the seats of all the blades combined together and fitting in between each
other.
In order to detach any one blade from the propeller and to substitute another
therefor without lifting the propeller out of the water, I provide a well or trunk-
way e leading through the ships' deck to the screw port, the screw frame being
enlarged or otherwise modified at the upper part to correspond with the said well
or trunkway e, through which the propeller blade is let down by a frame or cradle
and suitable tackle to its position on the shaft.
It is requisite that the blade should be so accurately guided into its position
that the tenon c does not foul the slot c¹ endwise, to effect which various con-
trivances may be devised such for instance as the guides illustrated in Figures 5
and 6, in which upper guides fare furnished at the ends of a cross bar slung from
the lifting tackle which is drawn up from the reach of the propeller blades when not
in use, lower guides are formed by extending the blade seat d end wise to embrace
each stern post until the tenon c has entered the slot c¹, the distance between the
stern posts increases at the proper part to clear the guides of the blade seat. The
guides are grooved, tongued, or otherwise fitted between the stern posts so as to be
restricted to a vertical motion only.
The operation for detaching a blade from the screw is as follows:-Turn the shaft a
to the position in which the blade 6 extends vertically downwards, withdraw the key
or other securing device from the inside, access to which is from the manhole and

page_text: the blade when released falls into the water. In order to insert another blade in its
place, turn the shaft a half round so as to bring the slot c¹ to the top of the circle,
lower the blade & through the well or trunkway e by means of the frame and tackle
and guides into. position and then securo it from the inside by a key or other
device.
In order to prevent water from entering the shaft a when the tenon c is withdrawn.
from the slot, I provide an inside cover preferably recessed deep enough to receive
the full length of the tenon c,, which must be secured firmly in position; and I insert
a short sliding ròd in this cover / to be actuated say by a small hydraulic ram so as to
force the tenon c out of the slot c' if needful.
my said
Having now particularly described and ascertained the nature of
invention, and in what manner the same is to be performed, I declare that
what I claim is :-
Firstly
Improvements in the construction of screw propeller shafts consisting in
the use of metal plates of such moderate thickness as to be incapable of concealing
internal unsoundness, arranged in layers if necessary and united together to form
hollow tubes of convenient lengths and of the requisite sectional area, substantially as
herein before described.
Secondly The means employed for securing each blade to the propeller shaft
separately and in such a manner that any one blade can be detached and another
substituted therefor during immersion of the propeller for which purpose the tail end
of the propeller shaft is made internally accessible and each blade is secured thereto
from the inside and detached therefrom, substantially as described, with reference to
the accompanying drawings.
Thirdly: The combination of parts as a whole, constructed, arranged and fitted
together for effecting the operations and purposes, substantially as hereinbefore.
described with reference to the accompanying drawings.
Date HS
day of ap
G. J. CLARKSON,
Stockton-on-Tees, Agent for the Applicant.
G. J. CLARKSON,
Stockton-on-Tees, Agent for the Applicant.