REW PROPELLER
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by the said Samuel Wilkinson Snowden
at the Office of the Commissioners of Patents on the 16th April 1883.
SAMUEL WILKINSON SNOWDEN Engineer, "West Hartlepool"
IN "SCREW PROPELLERS"
"IMPROVEMENTS
This invention has for its object improvements in screw propellers.
I form the boss in one piece and secure it on to the screw shaft in the ordinary
manner, Each screw blade I form with a cylindrical shank to be received into a
hole formed for it in the boss.
Through the shank end of each blade a key or feather is passed and made to
project from both sides of it or the projections may be solid with the shank.―
within the boss a slot is formed around each hole formed in it-this slot is for
the projecting ends of the key or feather to enter and thereby lock the blade to
the boss. To permit of the shank of the propeller blade being inserted into the
hole in the boss slots are formed along opposite sides of it for the projecting ends
of the key or feather to pass along whilst the shank is being passed into the hole.
When the shank has been passed into the hole a partial turn is given to the blade
and then the projecting ends of the key or feather enter the slot which is formed
around the hole and so lock the blade to the boss. The end of the shank may be
made either to abut against the shaft or the end of the shank may be pointed and
enter a shoe or slipper which is capable of sliding endwise along a recess in the
shaft in this case the recess in the shaft should be oblong and length wise of the
shaft to allow of the propeller boss being shifted somewhat end wise of the shaft
should it be necessary to do so. Exterior of the boss the shank of each blade has
upon it a worm wheel.
A worm at right angles to the shaft and carried by the boss is made to gear with
this worm wheel-one or both ends of the axis of the worm are formed to receive
a key or spanner by means of which the worm may be turned. By turning the
מ.

page_text: worm the screw blade may be turned in order to lock it to the boss as above
explained and the blade can be set at any angle to the shaft according to the pitch
required and to feather the blade.
The spanner or key used for turning the worm can be worked from the deck.
To allow of a blade being shipped the screw shaft is turned to a certain position
indicated by a pointer or indicator on the shaft to bring one of the holes in the
propeller boss uppermost. A frame constructed of angle iron or steel is passed
down from the deck to the screw shaft the lower end of the frame is forked so
that it may embrace the screw shaft at each end of the propeller boss whilst the
upper end of the frame is fixed to the deck rail. The frame may be made in
sections for convenience of stowage and portability. A blade is lifted from the
deck by a portable davit and is by the rope tackle lowered into the guide frame
and down the frame until the shank of the blade enters the hole in the boss.
guide frame is then removed and a partial turn is given to the screw shaft to bring
the worm which is to lock this blade into a vertical position. The end of the worm
when in this position comes opposite a key or spanner.
The
The spanner is made to engage with the worm and to turn it-the spanner itself
is worked from the deck-by turning the worm the screw blade is locked to the
boss in the manner above explained. An indicator is fitted to the spanner to
adjust the blade to the pitch required.
In a similar manner to that above described a broken screw blade may be released
from the boss and allowed to drop away into the sea when the shaft is afterwards
turned so as to bring the blade downwards.
It will be seen that by the means above described propeller blades may be shipped
or unshipped without the necessity of docking the vessel or altering her trim or of
employing a diver to assist in replacing a broken blade.
In place of forming a worm wheel around the shank of each blade as above
described and each blade having its separate worm wheel the shank of each blade
may have bevil teeth around it to gear into a bevil toothed wheel which can
revolve around the boss or the thimble or ferrule part of the nut that secures the
propeller on to the screw shaft. A worm or worms may be made to gear with
teeth formed around the edge of the bevil wheel-if more than one worm is used
the several worms must be geared together so as to be all revolved simultaneously.
The worms can be carried by brackets projecting from the propeller boss and all
the working gear can be protected by a casing. If only one blade is required to
be taken out of the boss the rest of the blades are kept in place by plates and
screws whilst the one blade is being removed.
a
Where I do not use a propeller blade toothed on its edge or periphery I have
quadrant worm wheel having a recess in it at the top part to receive the key in
shank of propeller blade. The "quadrant" part of above has a worm pinion
geared into it where each blade is acted upon separately and where all the blades
are acted upon simultaneously-the above "quadrant" wheel has ordinary teeth
and then the toothed and worm wheel before described (working on propeller nut)
is used to work the blades.
The object of this arrangement is to have all the working parts inside the boss-
the "quadrant" wheels are passed through to the inside either by the block holes
or at the end of boss.
Or in place of employing worms to lock the blades a variable block dovetailed
at the ends may at one end be made to butt against a collar on the blade and against
a solid stop on the propeller boss at the other end. The block may be held in
place by tapped screws or studs and by a plate and studs at the side of the
variable block.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Samuel Wilkinson Snowden in the Great Seal Patent Office on
the 16th October 1883.
SAMUEL WILKINSON SNOWDEN Engineer West Hartlepool
SCREW PROPELLORS"
"IMPROVEMENTS IN
This Invention has for its object improvements in screw propellors.
I form the boss in one piece and secure it on to the screw shaft in the ordinary
manner. Each screw blade I form with a cylindrical shank to be received into a
hole formed for it in the boss.
Through the shank end of each blade a key or feather is passed and made to
project from both sides of it or the projections may be solid with the shank.
Within the boss a slot or recess is formed around each hole formed in it. This
slot is for the projecting ends of the key or feather to enter and thereby lock the
blade to the boss. To permit of the shank of the propellor blade being inserted
into the hole in the boss slots are formed along opposite sides of it for the
projecting ends of the key or feather to pass along whilst the shank is being passed
into the hole. When the shank has been passed into the hole a partial turn is
given to the blade and then the projecting ends of the key or feather enter the
slot which is formed around the hole and so lock the blade to the boss. The end
of the shank may be made either to abut against the shaft or the end of the shank
may be pointed and enter a shoe or slipper which is capable of sliding end wise
along a recess in the shaft. In this case the recess in the shaft should be oblong
and lengthwise of the shaft to allow of the propellor boss being shifted somewhat
end wise of the shaft should it be necessary to do so. Exterior of the boss the
shank of each blade has upon it a worm wheel. A worm at right angles to the
shaft and carried by the boss is made to gear with this worm wheel. One or both
ends of the axis of the worm are formed to receive a key or spanner by means of
which the worm may be turned By turning the worm the screw blade may
be turned in order to lock it to the boss as above explained and the blade can be
set at any angle to the shaft according to the pitch required and to feather the
blade.
A propellor arranged as above described is shown on sheet 1 of the annexed
Drawings.
Figure 1 is a plan partly in section. Figure 2 is an elevation of the same and
shows the arrangement of worm and worm rim formed on the flange of one of
the blades. Figure 3 is an end elevation (looking forward) and shows the
arrangement of the four worms. Figure 4 is a section of the propellor boss taken
on the line A. A. in Figure 1. Figure 5 is a cross section taken through a
propellor boss somewhat differently arranged, the shaft not being grooved to
receive the centre pins.
I prefer to coat the shanks of the blades with white metal to prevent them
setting fast in the recesses into which they are received. I also coat the worm
spindles
The spanner or key used for turning the worm can be worked from the deck.
To allow of a blade being shipped the screw shaft is turned to a certain position
indicated by a pointer or indicator on the shaft to bring one of the holes in the
propellor boss uppermost. A frame constructed of angle iron or steel is passed
down from the deck to the screw shaft the lower end of the frame is forked so
that it may embrace the screw shaft at each end of the propellor boss whilst the

page_text: upper en UL ще паше 18 Пхеа TO the deck rail, or waterways or side of the
vessel
These arrangements are illustrated by sheet 2 of the Drawings, Figure 6 is a
side elevation and Figure 7 is a rear elevation of the stern of a ship with the guide
frame in position for shipping a screw blade.
The frame may be made in sections for convenience of stowage and portability
A blade is lifted from the deck by a portable davit and is by the rope tackle
lowered into the guide frame and down the frame until the shank of the blade
enters the hole in the boss. The guide frame is then removed and a partial turn
is given to the screw shaft to bring the worm which is to lock this blade into a
vertical position. The end of the worm when in this position comes opposite a
key or spanner.
The spanner is make to engage with the worm and to turn it-the spanner
itself is worked from the deck-by turning the worm the screw blade is locked to
the boss in the manner above explained. An indicator is fitted to the spanner to
adjust the blade to the pitch required. and to feather the blade-A locking
collar may be arranged on the worm spindles to prevent their turning when the
propeller is at work
In a similar manner to that above described a broken screw blade may be
released from the boss and allowed to drop away into the sea when the shaft is
afterwards turned so as to bring the blade downwards.
It will be seen that by the means above described propeller blades may be
shipped or unshipped without the necessity of docking the vessel or altering her
trim or of employing a diver to assist in replacing a broken blade.
In place of forming a worm wheel around the shank of each blade as above
described and each blade having its separate worm wheel, the shank of each blade
may have bevil teeth around it to gear into a bevil toothed wheel which can
revolve around the boss or the thimble or ferrule part of the nut that secures the
propellor on to the screw shaft. A worm or worms may be made to gear with
teeth formed around the edge of the bevil wheel-if more than one worm is used
the several worms must be geared together so as to be all revolved simultaneously.
The worms can be carried by brackets projecting from the propellor boss and all
the working gear can be protected by a casing.
The Drawings on Sheet 3 show a screw propeller thus constructed. Figure 8 is
a plan partly in section, Figure 9 is an elevation, in this figure the vertical
blades are omitted. Figure 10 is a section on the line B B in Figure 8.
Figure 10 is a similar section showing the arrangement where the shanks of the
screw blades are made to terminate within the boss. Figure 11 is a' rear
elevation.
If only one blade is required to be taken out of the boss the rest of the
blades are kept in place by plates and screws whilst the one blade is being
removed.
Where I do not use a propellor blade toothed on its edge or periphery I have a
"quadrant" worm wheel, having a recess in it at the top part to receive the key
or shank of propellor blade. The "quadrant" part of above has a worm pinion s
geared into it where each blade is acted upon. separately and where all the blades
are acted upon simultaneously the above "quadrant" wheel has ordinary teeth and
the toothed and worm wheel before described (working on propellor Dut) is used
to work the blades.
The object of this arrangement is to have all the working parts inside the
"boss." The quadrant wheels are passed through to the inside either by the blade
holes or at the end of "boss."
Or in place of employing worms to lock the blades a variable block dovetailed
at the ends may at one end be made to butt against a collar on the blade and
against a solid stop on the propellor boss at the other end. The block may be t
held in place by tapped. screws or studs and by a plate and studs at the side of
the variable block,

page_text: Having thus described the nature of my said invention and the manner of
performing the same I would have it understood that I claim :-
First The construction and arrangement of screw propellors substantially as
described.
Second-The arrangements herein described in connection with screw propellors
which render it possible to remove and replace the blades without docking the
vessel or altering her trim and without the aid of divers.
In witness whereof I the said Samuel Wilkinson Snowden have hereunto set
my hand and seal this fifteenth day of October in the year of our Lord One
thousand eight hundred and eighty three.
SAMUEL WILKINSON SNOWDEN. (L.S.)