IMPROVEMENTS IN COUPLINGS FOR SHAFTING
Year: 1876

page_text: LETTERS PATENT to Archibald Thomson, of the Town and County of South-
ampton, Engineer, for the Invention of "IMPROVEMENTS IN COUPLINGS FOR
SHAFTING."
Sealed the 4th July 1876, and dated the 8th January 1876.
"
PROVISIONAL SPECIFICATION left by the said Archibald Thomson at the
Office of the Commissioners of Patents on the 8th January 1876.
ARCHIBALD THOMSON, of the Town and County of Southampton, Engineer.
IMPROVEMENTS IN COUPLINGS FOR SHAFTING."
My Invention relates to couplings for shafting of every descripton, and is
intended more particularly for temporary use in the case of a fracture of the shaft
occurring, but it is also applicable as a permanent or fixed coupling for connecting
together the different lengths composing a shaft.
One special object of the Invention is the production of a coupling of an
economical construction, capable of being applied with facility and rapidity to any
part of a shaft at which fracture may occur. In order to effect this object I con-
struct the coupling in the form of a tube made in two or more pieces or segments in
cross section, by preference in two pieces, that is to say, two semi-tubes which are
fitted round the shaft so as to surround or enclose the same and are secured together
by screw bolts. The semi-tubes or segments are made of a bulged or enlarged form in
the centre of their length or otherwise shaped so as to provide a recess or chamber
in the interior of the tube when the pieces or segments are fitted together, whereby
facility is afforded for the adaptation of the coupling to any portion of the shaft, the
recess or chamber being capable of receiving the ordinary coupling, or the thrust
portion or any other enlarged portion of the shaft to which it may be required to
apply it. This coupling is applicable among other purposes to screw shafts on
board steam vessels, as it may be fitted to any part from the stern gland to the
engine framing.
The enlarged cylindrical part of the coupling is turned perfectly true, and when
the semi-tubes or segments are bolted together forms a journal which can be used
as such by fixing a temporary bearing for it to run upon. When the shaft breaks
in a journal the coupling can be used to form a journal by removing the plummer
block and running the coupling on a temporary bearing.
The coupling bolted in the manner before mentioned may be further secured to
the shaft by means of keys, cottars, or set screws if deemed necessary.

page_text: When a shaft breaks, if broken completely asunder, it usually becomes somewhat
bent and out of truth, and the edges of the fractured part projects outwards. This
coupling is made so as to receive the fractured part within the recess or chamber,
thereby being easily applied without the labour of straightening or fitting the shaft
as in ordinary couplings.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Archibald Thomson in the Great Seal Patent Office on the 6th July
1876.
ARCHIBALD THOMSON, of the Town and County of Southampton, Engineer.
"IMPROVEMENTS IN COUPLINGS FOR SHAFTING."
My said Invention relates to couplings for temporary use in the case of a fracture
of the screw shaft of a steam vessel at sea, and it has for its special object the pro-
duction of a coupling of an economical construction capable of being applied with
facility and rapidity to any part of the shaft (from the stern gland to the engine
framing) at which fracture may occur.
And in order that my said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawings, the same letters of
reference indicating corresponding parts in all the Figures.
Figure 1 of my Drawings represents a half longitudinal section and half side
elevation of a coupling constructed according to my Invention in order to effect the
above objects, and Figure 2 is an end view of the same.
Figure 3 represents a side elevation drawn to a reduced scale of a portion of a
screw shaft with the coupling (shewn in section) fitted at various parts thereof, in
order to indicate the general applicability of the said coupling.
In carrying out my Invention I construct the coupling in the form of a tube
made in two or more pieces or segments in cross section, by preference in two pieces,
that is to say, two semi-tubes, as shewn in the Drawing and marked A, A', which
are fitted round the shaft B (Figure 3) so as to surround or enclose the same, and
are secured together by screw bolts and nuts a, a, having threads of a fine pitch.
The semi-tubes or segments A, A¹, are made of a bulged or enlarged form in the
centre of their length or otherwise shaped, so as to provide a recess or chamber C in
the interior of the tube when the pieces or segments A, A¹, are fitted together,
whereby facility is afforded for the adaptation of the coupling to any portion of the
shaft (from the stern gland to the engine framing), the recess or chamber C being
capable of receiving the ordinary coupling, or the thrust portion, or any other
enlarged portion of the shaft to which it may be required to apply it; b, c, d, e,
(Figure 3), represent fractures at which points the coupling is shewn applied by
way of example illustrating the applicability of the coupling to any portion of the
shaft, the fractures b, e, being represented as occurring at enlarged portions which the
recess or chamber is nevertheless capable of receiving.
The enlarged portion of the semi-tubes or segments A, A¹, is made cylindrical on
its exterior and turned perfectly true, so that when the semi-tubes or segments are
bolted together such enlarged portion forms a journal which can be temporarily
utilized as such in the event of the shaft breaking in a journal by removing the
plummer block, and running the coupling on a temporary bearing, as shown at f
(Figure 3).
The coupling bolted in the manner before mentioned may be further secured to the
shaft by means of keys, cottars, or set screws if deemed necessary.
When a fracture of a shaft occurs if the shaft is broken completely as under, it
usually becomes somewhat bent and out of truth and the edges of the fractured part
project outwards. This coupling is constructed so as to receive the fractured part
within the recess chamber, whereby it may be applied with facility, the labour

page_text: of straightening or fitting the shaft as in ordinary couplings being entirely
obviated.
Having now described and particularly ascertained the nature of my said
Invention and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the herein-before in part
recited Letters Patent is, constructing temporary couplings in such a manner that
they shall be capable of being readily applied to or receiving any portion of the
screw shaft of a steam vessel from the stern gland to the engines wherever fracture
may occur, and also of being utilized as temporary journals when the shaft breaks
at a journal, substantially as herein-before described.
In witness whereof, I, the said Archibald Thomson, have to this my Speci-
fication set my hand and seal, this Thirtieth day of June, One thousand
eight hundred and seventy-six.
ARCHIBALD THOMSON. (L.S.)