IMPROVEMENTS IN TWIN SCREW PROPELLING APPARATUS
Year: 1868

page_text: LETTERS PATENT to John George Kincaid, of Greenock, in the
County of Renfrew, North Britain, Engineer, for the Invention of
"IMPROVEMENTS IN TWIN SCREW PROPELLING APPARATUS
33
Sealed the 28th August 1868, and dated the 4th March 1868.
PROVISIONAL SPECIFICATION left by the said John George Kincaid
at the Office of the Commissioners of Patents, with his Petition,,
on the 4th March 1868.
I, JOHN GEORGE KINCAID, of Greenock, in the County of Renfrew,
North Britain, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN TWIN SCREW PROPELLING APPARATUS," to
be as follows, that is to say :-
This Invention has for its object the constructing or arranging of
twin screw propelling apparatus so that the propellers can be con-
veniently adjusted at various depths. If a vessel fitted with the
apparatus navigates shallow waters at one time and deep waters at
another, she can in the first case have her propellers adjusted high
enough to avoid all risk of their touching the bottom; whilst on
passing into deep water she can have them adjusted at the depth at

page_text: which they will produce the best effect, it being well understood that
it is desirable for screw propellers to act in comparatively undisturbed
water and at a good depth. Also if the vessel is proceeding under
sail alone it will be very advantageous for her to have the propellers
raised completely out of the water so as not to retard her progress..
The Invention consists in fixing the propellers on shafts. connected
to the shafts which pass through the stern pipes by universal joints just
outside the stern pipes, and in carrying these outside shafts in bearings
in the opposite ends of a crosshead, the middle of which is fitted to
slide on a frame curved concentrically with the universal joints. A
segmental toothed rack is fixed to the crosshead and passing upwards
through the vessel's stern has a pinion applied in gear with it, whereby
the crosshead can be raised or lowered and with it the propellers..
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John George Kincaid in the Great Seal Patent
Office on the 3rd September 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
GEORGE KINCAID, of Greenock, in the County of Renfrew, North
Britain, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourth day of March, in the year of our
Lord One thousand eight hundred and sixty-eight, in the thirty-first
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said John George Kincaid, Her special licence that I,
the said John George Kincaid, my executors, administrators, and assigns,
or such others as I, the said John George Kincaid, my executors, admi-
nistrators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN TWIN
SCREW PROPELLING APPARATUS," upon the condition (amongst others)
that I, the said John George Kincaid, my executors or adminis
trators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly describe and ascertain

page_text: the nature of the said Invention, and in what manner the same was
to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said John George Kincaid, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement in writing, reference being had to the
accompanying Drawings, that is to say :-
My said Invention has for its object the constructing or arranging
of twin screw propelling apparatus so that the propellers can be con-
veniently adjusted at various depths. My improved apparatus is
designed for steamers navigating shallow rivers, canals, and other shallow
waters at one time, and the sea or other deep waters at another; and
it is also suitable for sailing vessels fitted with auxiliary steam power
to enable them to cross calm belts and steam against light head winds
and thus save valuable time ordinarily lost in East India, China, and
similar voyages, as when a vessel is under sail alone her propellers can
be raised completely out of the water so as not to retard her progress.
My improved apparatus may also be applied with advantage to the
gun boats and steam launches of the royal navy.
And in order that my said Invention and the manner of performing
the same may be properly understood, I have hereunto appended two
Sheets of explanatory Drawings to be herein-after referred to, and
representing by way of example some of the various modifications of
which my improved arrangements are susceptible.
Figure 1, Sheet 1, is a sectional side elevation of the stern of a twin
screw steamer, and Figure 3, Sheet 2, is a corresponding back end
elevation. Figure 2, Sheet 1, is a sectional side elevation showing a
different modification of the lifting gear. The same reference numerals
are used to mark the same or like parts in all the Figures.
My Invention consists in having the end shaft lengths 1, on which
the screw propellers 2 are fixed, connected by universal joints 3 to the
next inner shaft lengths 4, which pass through the stern pipes 5 into
the interior of the vessel, such universal joints 3 being just, outside
of the stern pipes 5, whilst the other ends of the shafts 1 are carried
by a crosshead 6, which can be raised or lowered by suitable gearing
of any convenient kind. In the modification shown in Figures 1 and 3

page_text: the keel 7 of the vessel, which is an iron one, is extended aft beyond
the sternpost 8 and under the rudder 9, and has its outer end welded
or otherwise united to the bottom end of a segmental frame 10 curved
concentrically with the transverse horizontal line passing through the
centres of the two universal joints 3. The upper end of the segmental
frame 10 is fixed by means of a pair of plates 11, one on each side,
to the head of the stern post, and the rudder shaft 12 passes down between
these two plates. The segmental frame 10 serves as a guide and support
for the crosshead 6, and this crosshead, of which the form is best scen
in Figure 3, has fixed to or formed in one with it a segmental rack 13,
which fits and when being adjusted works upon the segmental frame 10.
"The crosshead 6 is held against the frame 10 by means of a roller held
by lugs on the crosshead and bearing against the inner or front edgo
of the frame 10%; and the crosshead 6 has its ends fitted with bearings
and strap caps to fit journals formed with collars on the propeller
shafts 1, these shafts by means of the collars on their journals thus acting
as longitudinal stays in steadying the ends of the crosshead. The
crosshead rack 13 is acted upon by a pinion 14 fast on the same shaft
as a worm wheel 15, in gear with which there is a worm 16 on a vertical
spindle 17, having hand levers at its upper end to turn it by, and the
pressure of the pinion 14 is met by an antifriction roller 18 against
which the inside of the crosshead rack 13 bears. With these arrange-
ments the position as to height of the propellers 2 can at any time be
easily adjusted; thus when the ship is in shallow waters the propellers
may be set in the middle position, shown in full lines, or even a little
higher, so as to avoid all risk of their touching the bottom; whilst on
passing into deep water the propellers can be set to project down
below the keel in the lowest position indicated by dotted lines so as to
obtain a better propelling effect by operating in water that is less
disturbed than that nearer the surface. Again if the ship is proceeding
under canvas alone the propellers may be raised up out of the water
into the highest position indicated by dotted lines, just under the
counter, when they will be quite out of the water so as not to retard
her progress.
Instead of the segmental frame 10 with the crosshead
6 and its rack 13 being astern of the rudder 9, as herein-before de-
scribed, they may be arranged in front of the sternpost 8, as indicated
by dotted lines at 19 in Figure 1, a slot or opening being formed
through the ship's run with a narrow well centrally at the upper part
for the rack 13 to pass up into.

page_text: Another modification is shown in Figure 2, Sheet 1, in which the
guide frame 10 abaft the rudder 9 is made vertical, and the cross-
head 6 is fitted to slide vertically upon it, being held against it by
rollers carried by lugs 20 and bearing against its front edge; whilst
for raising and lowering it a vertical screw shaft 16 is placed against
the frame 10 with a footstep bearing in a prolongation of the keel at the
bottom of that frame, and passing up through a stuffing box in the
counter. This screw shaft 16 works in a nut fixed to the crosshead 6 and
shifts the crosshead up or down on being turned. The propellers 2
still move in arcs concentric with their universal joints 3, but their
shafts 1 are made without collars, so that they can move to the required
extent in bearings which are formed for them in the ends of a transverse
horizontal shaft 21 carried in bearings on the crosshead 6, and capable
of turning therein so as to accommodate itself to the different inclinations
assumed by the shafts 1.
The system of adopting twin screws with my improved lifting and
adjusting gear has the advantages herein-after indicated, namely,-
1. A very simple and easily arranged plan is thereby offered for
applying small auxiliary power to sailing vessels for use in calms or
light contrary winds, and one requiring little space for boiler and
engines which when not steaming can be used for pumping, hoisting
sails, lifting anchors, and the like, and the boiler for distilling water.
The plan has also the advantage of not altering the shape of the vessel;
whilst when under sail alone there is nothing but the bare shafts to
act as a drag, the propellers themselves being then quite out of the
water.
2. For cargo steamers requiring to navigate deep and shallow waters
alternately, it prevents risk of breaking the propellers in shallow water,
as they can be lifted even as much as half out of the water and still
continue at work at a reduced speed, whilst on regaining deep water they
can be lowered deeply enough to develop the full power of the engines
by working in comparatively undisturbed water.
3. The system is admirably adapted for the transport service as applied
to boats or launches for landing troops or war material; also for war
purposes as applied to floating batteries, gunboats, and launches for
manoeuvring at sea and for entering shallow rivers and approaching
shores. In the case of war ships the propellers can be lowered so as
to be more than ordinarily out of reach of the enemy's shot; whilst

page_text: when the ship is on a foreign station where fuel is expensive the
propellers can be lifted out of the water so that the most may be made
of fair winds.
4. One advantage of great importance in all applications of the
system, whether to sailing vessels, merchant steamers, or war ships,
consists in being able to examine the propellers or even to replace a
broken one without having to go into dock as on lifting the propeller to
the top whatever is required can be done, even at sea if calm.
5. Another advantage is that the propellers can be raised or lowered
to suit different depths of water without stopping the engines.
Having thus particularly described my said Invention, and the
manner in which the same is to be performed, I have to state that
I do not restrict myself to the precise details herein described or
delineated, but that what I believe to be novel and original, and claim
as the Invention secured to me by the herein-before in part recited
Letters Patent is, the providing of twin screw propellers with apparatus
for raising and lowering them, substantially such as is herein-before
described.
In witness whereof, I, the said John George Kincaid, have here-
unto set my hand and seal, this Twenty-fourth day of July, in
the year of our Lord One thousand eight hundred and sixty-eight.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
JOHN G. KINCAID. (L.S.)