Improvements in Propellors for Boats and other Vessels.
Year: 1891

page_text: Date of Application, 20th Mar., 1891
Complete Specification Left, 21st Dec., 1591-Accepted, 30th Jan., 1892
PROVISIONAL SPECIFICATION.
Improvements in Propellors for Boats and other Vessels.
I, JOHN DRYSDALE of Saughall Massie in the County of Chester, Engineer
do hereby we
follows:-
This invention has for its object a propellor applicable not merely for small
boats and pinnaces, but for large steamers,
On a revolving, preferably square, shaft, parallel or nearly parallel with the
axis of the vessel, I place an enlarged cylinder or its equivalent in such manner
that it cannot revolve on the shaft. This cylinder is cut at an angle of 4.5° into
two parts and a large washer or disc or washer, with its central hole cut to a
similar angle, is placed on the shaft so that it shall lie flat between the two parts
of the enlarged cylinder. A blade, very similar to an ordinary screw propellor
blade, is formed with a broad flat shank, the thickness of the washer, and has a
hole in this shank filling the washer, it is placed on the shaft with the washer in
this hole as a journal, the shank lying between the two parts of the "cylinder 1
aforesaid. The blade is also extended in its axis beyond the cylinder forming a
shank, and this shank works in a circular and nearly or quite horizontal slot in the
frame work of the vessel.
"
To prevent friction in the water, the hinder part of the enlarged cylinder is
preferably made into a cone or other form of little resistance with its smaller end
astern. Beyond the cone, I prefer to put a nut on the shaft so as to tighten all
up solidly, and beyond this nut place a bearing in the stern post or bracket.
The mode of action is as follows:-
The propellor, washer and enlarged cylinder aforesaid being threaded on a
square shaft, the latter is set in motion. The propellor travels forwards with its
edge vertically against the water, the propellor lying substantially in the vertical
plane. Arriving at its full forward position, it rapidly turns till the blade is
practically perpendicular to the direction of motion, it then is very rapidly brought
backward to the full backward position ready for another stroke; the peculiar
action of the mechanism causing it rapidly to feather at this point before taking
its forward stroke.
It will be obvious that this apparatus can be placed at the bow, at the stern, at
the bottom or the sides of the ship, or in two or more of these places.
The
There can be two propellors in the bow or the stern; if, however, the propellors
be at the bow, the cone portion of the enlarged cylinder is in front.
apparatus can be driven by hand or any desired power.
One of the advantages of this apparatus is that, as wear occurs, the washer can
at any time be taken out, relined, or another substituted therefor, and thus the
whole can be tightened up afresh.
If, too, the surfaces of the oblique cut portions of the enlarged cylinder have
one or more furrows, water can freely enter the same to lubricate the blade.
Dated this 19th day of March 1891.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.

page_text: I, JOHN DRYSDALE of Saughall Massie in the County of Chester, Engineer,
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 for its object a propellor applicable not merely for small
boats and pinnaces but for large steamers.
The invention is best described by aid of the accompanying drawings, in which,
Figure 1 is a front elevation of the propellor, propellor shaft and aft part of a
vessel,
Figure 24 a horizontal section, and
Figure 2a plan;
Figure 3 an end elevation, with stern post G removed,
Figure 4a perspective view of an alternative shape for the cam for operating
the propellor, and
Figure 5a view of the propellor blade.
On revolving shafts A. A. parallel or nearly parallel with the axis of the vessel,
I place cams or cylinders Bor their equivalent in such manner that they cannot
revolve on the shafts A. Each of these cams B are cut at an angle of 45 degrees
into two parts, and a disc or washer (with its central hole cut to a similar angle
is mounted loosely on each shaft so that it shall lie flat between the two parts of
the cams R.
Blades D, very similar to an ordinary screw propellor blade are formed with flat
bosses d the same thickness as the washers and have holes in these bosses which
the washers are adapted to fill. The propellors are then placed on the shafts A,
with the washers C in their holes forming journals for the propellor blades, the
bosses d lying between the two parts of the cains B aforesaid.
The blades are also extended in their axes beyond the cams B forming shanks d¹
and these shanks work in semicircular and nearly horizontal slots in the frames E.
The cams B are keyed on the shafts A or fixed by means of screws a or in any
other suitable manner and I prefer to put muts a' on the shafts A so as to tighten
all up solidly, and beyond this nut a' locate a bearing F in the stern post or
bracket. When however the cams are keyed on the shafts A, the said nuts are not
actually necessary.
The mode of action is as follows:-
The propellor D, washer C, and cam B, being mounted on the shaft A, the latter
is set in motion. The propellor travels forward with its edge vertically against
the water, the blade lying substantially in the vertical plane. Arriving at its
full forward position it rapidly turns until the blade is practically perpendicular to
the direction of its motion. It then is very rapidly brought upward to the full
backward position ready for another stroke, the peculiar action of the mechanism
causing it rapidly to feather at this point before taking its forward stroke.
Figure 2 shows the propellor travelling forward. The position on the extreme
right shows the blade on the point of rapidly turning from a horizontal to a
vertical plane. The middle position shows the blade with its edge vertically
against the water lying in a vertical plane and the position on the extreme left
shows its full forward position after the blade has rapidly turned back into a
horizontal plane. Figure 24 shows the propellor travelling back to its full
backward position ready for another forward stroke.
It will be obvious that the apparatus can be placed at the bow at the stern at
the bottom or at the sides of the ship or in one, two or more of these places, or
that one blade only can be employed instead of two blades as shown on the
drawings.

page_text: One of the advantages of this apparatus is that, as wear occurs the washer can
at any time be taken out, re-lined, or another substituted therefor, and thus the
whole can be tightened up afresh.
If, too, the surfaces of the oblique cut portions of the enlarged cam have one
or more furrows, water can freely enter the same to lubricate the blade.
I have described this way in which the invention may be carried out, but it is
obvious that once given the general idea slight modifications may be made without
departing from the nature of the invention, for example, the frame E may be
located between the blade D and the shaft A, or instead of the rotatable ram other
equivalent guiding mechanism may be used, or the cam B may be made in the form
of a cylinder (Figure 4) with the hinder part in cone shape to prevent friction in
the water.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what 1
claim is :-
1. The improvement in propellors for vessels which consists in forming them
with a blade (very similar in shape to an ordinary propellor blade), the flat boss of
which is mounted (preferably on a washer) on the propellor shaft and held in place
by a rotatable cam, whose adjacent and opposite faces are cut at an angle of 45°
or by equivalent guiding mechanism, the said boss or blade being guided by a
horizontal or nearly horizontal slotted frame or equivalent device, whereby a
reciprocating motion is imparted to the propellor, the blade travelling forward
with its edge vertically against the water and substantially in the vertical plane
while it travels backward substantially perpendicular to the direction of motion.
2. In a propellor for vessels the combination of the blade A, the cam B cut at
an angle of 45° into two parts, and the washer or disc ( mounted on the shaft
between the two parts of the cam and filling the hole in the boss or shank of the
propellor blade, whereby a journal or bearing is formed for the blade, substantially
as described.
3. The general combined arrangement and construction of parts forming the
improved propellor for vessels, substantially as described.
Dated this 19th day of December 1891.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.