AN IMPROVEMENT IN CONNECTING AND DISCONNECTING SCREW PROPELLER AND OTHER SHAFTS
Year: 1855

page_text: LETTERS PATENT to Thomas Trapp. of Mile End, in the County of
Middlesex, Ship Owner, for the Invention of "AN IMPROVEMENT IN
CONNECTING AND DISCONNECTING SCREW PROPELLER AND OTHER SHAFTS."-A
communication.
Sealed the 28th December 1855, and dated the 18th July 1855.
PROVISIONAL SPECIFICATION left by the said Thomas Trapp at the
Office of the Commissioners of Patents, with his Petition, on the 18th
July 1855.
I, THOMAS TRAPP, of Mile End, in the County of Middlesex, Ship Owner,
do hereby declare the nature of the said Invention for "AN IMPROVEMENT IN
CONNECTING AND DISCONNECTING SCREW PROPELLER AND OTHER SHAFTS" (communi-
cated to me by a foreigner residing abroad) to be as follows:-
My Invention consists in a certain disconnecting apparatus, which I will
briefly describe, as fitted to a screw propeller shaft. That part of the shaft
connected to the engine carries close to the outer extremity thereof a disc with
arms or cross head. That part of the shaft on which the screw is fitted carries
on its inner end a disc, and between the cross head and disc is a ring or collar,
formed at that side which faces the cross head, with two grooves or receivers
for the two arms of the cross head; it has also cast on or permanently con-
nected to it a flange or rin, to prevent the dise on the screw part of the shaft

page_text: passing through the collar. On the screw side of the collar it is so formed
as to receive the disc on the shaft, and to allow it to revolve loosely therein.
After the disc has been inserted in the collar, it is prevented from being drawn
out therefrom by means of flanges screwed on to the face of the collar.
Four or more grooves or slots are cut out on the inside of the collar, and in
each of them are placed first a clip, which falls on the top and slightly over-
laps the disc on the screw end of the shaft, and a wedge. The end of the two
shafts, or the end of one of them, protrudes slightly beyond the cross head or
disc, so that the ends of the shaft come close together. In order to connect
the two shafts, these wedges are driven in, which tighten up the space between
the disc and collar, and to disconnect them it is only necessary to drive out or
loosen the wedges, whereby the disc will revolve loosely in the collar. The
operation being so simple, the connecting and disconnecting can be effected
most speedily at any portion of the stroke of the engine, and whether the
vessel be in dock or afloat, and whether in a rough or calm sea.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Trapp in the Great Seal Patent Office on the
18th January 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
TRAPP, of Mile End, in the County of Middlesex, Ship Owner, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of July, in the year of our Lord One
thousand eight hundred and fifty-five, in the nineteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said Thomas Trapp, Her special licence that I, the said Thomas Trapp, my
executors, administrators, and assigns, or such others as I, the said Thomas
Trapp, my executors, administrators, 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 "AN IMPROVEMENT IN CONNECTING
AND DISCONNECTING SCREW PROPELLER AND OTHER SHAFTS," (communicated to me
by a foreigner residing abroad,) upon the condition (amongst others) that I,
the said Thomas Trapp, by an instrument in writing under my hand and
seal, should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause the same

page_text: 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 Thomas Trapp, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, reference being had to the Drawings hereunto annexed,
that is to say:-
The Invention consists in fitting to the ends of two shafts which it may
be required to connect and disconnect, discs, a collar or ring, and keys or
wedges, and in causing the connection and disconnection of the shafts by
tightening or loosening the keys or wedges at any portion of the revolution of
either shaft.
In the annexed Drawings I exemplify the manner in which I carry the
Invention into effect. Figure 1 is an elevation of one side of the connecting
and disconnecting apparatus, with a shaft (leading from a steam engine), in
section; Figure 2 is an elevation of the reverse side of the apparatus, with
a shaft (fitted with a screw propeller, paddle wheel, or other appliance), in
section; and Figure 3 is a side elevation of the apparatus and shafts. The
same letters denote similar parts in all the Figures. A is the driving shaft;
B is a disc, with arms or cross heads keyed or otherwise fixed thereon, and
within a very short distance from the outer end thereof; C is a ring or collar,
formed with channels D, D, for receiving the ends of the cross head B. The
inside rim of this ring is also hollowed out for receiving keys or wedges a, a, a', a'.
The position of these wedges is alternately reversed; the bases of the wedges
a, a, presenting themselves in the side view, Figure 2, while the bases of the
wedges a¹, a', present themselves in the view of the opposite side of the appa-
ratus, Figure 1. E, E, are flanges, forming part with or affixed to the ring C,
for preventing the disc on the shaft, hereafter described, passing through and
out of the ring. The revolution of the shaft A carries with it the ring C and
keys a, a, a, a'. F, Figure 2, is the shaft, which I shall describe as the pro-
peller shaft; it has fixed on it and close to the end thereof a plain disc or
wheel G, which is to be made of such a diameter that it will just revolve
within the ring C without touching it. b, b, b, b, are clips, which lie upon the
periphery of the disc G, and slightly overlap it on both sides; they are placed
under the wedges a, a, a', a', and, like them, revolve with the collar C. The
propeller shaft F is placed on the same axial line as the driving shaft A, and
is brought up close to the end thereof, as shewn by the dotted lines, Figure 3,
which also brings the disc G within the collar C; and in order to prevent it
being drawn out of the collar in a direction from the driving shaft, the flanges

page_text: or guards H, H, are screwed on to the back face of the collar, as shown at
Figure 2. The shafts and apparatus being in the position shewn at Figure 3,
will revolve independently of each other, but by driving the wedges a¹, a',
towards, and the wedges a, a, from, the propeller shaft, the disc G will become
locked in the collar C, and will consequently revolve with it; by simply revers-
ing the wedges, that is, driving them respectively in a contrary direction, the
disc will be free to revolve loosely in the collar, consequently the driving and
propeller shafts will be disconnected. The appliances to the shafts may be
reversed, that is to say, the cross head and collar may be fitted on the propeller
shaft, and the disc to the driving shaft, and the number of keys and clips may
be increased or diminished, and the apparatus may be fitted to the end of
any two shafts in order to effect connection and disconnection between them.
When this disconnecting apparatus is fixed upon the ends of shafts between a
steam engine and screw propeller or paddle wheel, it will afford the means
of almost instantaneous connection or disconnection between them, whether
the vessel provided with it be in dock, in harbour, or at sea, and at any
portion of the revolution of either shaft.
And having now described the nature of the said Invention, and in what
manner the same is to be performed, I declare that I claim, as the improve-
ment in connecting and disconnecting screw propeller and other shafts, the
fixing of a dise on one end of a shaft, and causing it to revolve with a ring or
collar on the end of another shaft, or causing or allowing the disc and collar
with their respective shafts to revolve independently of each other, by driving
in or out one or more wedges or keys to effect the connection and disconnection,
as lierein-before described.
In witness whereof, I, the said Thomas Trapp, have hereunto set my
hand and seal, this Twelfth day of January, One thousand eight
hundred and fifty-six.