IMPROVEMENTS IN COUPLINGS FOR BROKEN SHAFTS."
Year: 1881

page_text: LETTERS PATENT to Archibald Thomson, of Southampton, in the County of
Southampton, Engineer, for an Invention of "IMPROVEMENTS IN COUPLINGS
FOR BROKEN SHAFTS."
PROVISIONAL SPECIFICATION left by the said Archibald Thomson at
the Office of the Commissioners of Patents on the 13th September 1881.
ARCHIBALD THOMSON, of Southampton, in the County of Southampton,
Engineer. "IMPROVEMENTS IN COUPLINGS FOR BROKEN SHAFTS."
This Invention has for its object to provide improved couplings for use when a
shaft becomes fractured in circumstances in which it is important or desirable that
the shaft should be put into a working condition with the least possible delay, with
the least possible disturbance of the machinery or other parts connected with the
shaft, and without removing the shaft. The fracture of a screw-propeller shaft at
sea is one of the cases for which the improved couplings may be provided, and in
which their use will be of very great service.
A complete coupling as made with the improvements consists of three metal
segments, such as would be obtained by dividing a tubular piece by three planes
extending outwards from the axis and making equal angles with each other. The
ends of each segment are formed with concave surfaces to fit the shaft for which
the coupling is provided; whilst the part between the ends is enlarged and made
with an internal cavity capable of enclosing either the coupling ends originally
forged on the shaft lengths, or any rough projecting or distorted parts occurring at
the fracture. Strengthening ribs or feathers are formed on the segments if
considered necessary; and at the longitudinal edges of the fitting parts at the ends,
flanges are formed by which the segments are bolted together when placed on the
shaft. The seginents are made so that the joint surfaces do not quite touch each
other when the concave surfaces bear on the shaft, and in consequence the screwing
up of the bolts causes a very powerful gripping action to be exerted on the shaft,
the segments being each drawn towards the axis, and the gripping strain being
equally distributed on the shaft. It is also not an unimportant advantage of the
improved couplings that the segments can be very conveniently stowed on
shipboard, whilst they can be got into position when they are required, without
much space being needed about the shaft for their introduction.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Archibald Thomson in the Great Seal Patent Office on the
8th March 1882.
ARCHIBALD THOMSON, of Southampton, in the County of Southampton, Engineer.
"IMPROVEMENTS IN COUPLINGS FOR BROKEN SHAFTS."
My said Invention has for its object to provide improved couplings for use when
a shaft becomes fractured, in circumstances in which it is important or desirable
that the shaft should be put into a working condition with the least possible delay,
with the least possible disturbance of the machinery or other parts connected with
the shaft, and without removing the shaft. The fracture of a screw propeller shaft
at sea is one of the cases for which my improved couplings may be provided, and
in which their use will be of very great service.
A complete coupling as made with my improvements consists of three metal
segments, such as would be obtained by dividing a tubular piece by three planes
extending outwards from the axis, and making equal angles with each other. The
ends of each segment are formed with concave surfaces to fit the shaft for which
the coupling is provided, whilst the part between the ends is enlarged and made
with an internal cavity capable of enclosing either the coupling ends originally
forged on the shaft lengths, or any rough projecting or distorted parts occuring at
the fracture.
And in order that my said Invention and the manner of performing the same
may be properly understood, I hereunto append a Sheet of explanatory Drawings
to be hereinafter referred to and representing one of my improved couplings.
Figure 1 on the accompanying Sheet of Drawings is a side elevation, and Figure 2
is an end elevation showing the complete coupling, and Figure 3 is a sectional
elevation showing the coupling as applied to a fractured shaft. In these Drawings
the same reference numerals are used to mark the same or like parts wherever they
are repeated.
The complete coupling consists of three metal segments 4, 5, 6, which when
united, as shown, form a tubular-piece-having-parts-7-at-the-ends-shaped-internally
to fit or nearly fit upon the shaft 8 for which the coupling is provided, whilst the
middle part is enlarged and made with a cavity. 9 capable of enclosing either the
coupling ends 10 of the shaft 8, or any rough projecting or distorted parts
occurring at the fracture. Strengthening ribs or feathers 11 are formed on the
segments if considered necessary; and at the longitudinal edges of the fitting
parts 7 flanges 12 are formed by which the segments are bolted together, as shown,
when when placed on the shaft 8. The segments 4, 5, 6, are made so that the joint
surfaces do not quite touch each other when the concave fitting surfaces 7 bear
on the shaft 8, and in consequence of this the screwing up of the bolts causes
a very powerful gripping action to be exerted on the shaft, the segments being each
drawn towards the axis, and the gripping strain being equally distributed on the
shaft. It is also a not unimportant advantage of my improved couplings that the
segments can be very conveniently stowed on shipboard, whilst they can be got
into position when they are required without much space being needed about
the shaft for their introduction. The enlarged middle part is made externally
cylindrical, and without any greater projection than is necessary to go over the
shaft coupling ends 10; and in cases in which support is considered necessary a
bearing of wood or other suitable material may be placed under the middle part.
Having thus particularly described my said Invention and the manner of
performing the same, I have to state that I do not restrict myself to the precise

page_text: details herein described or delineated, but that what I believe to be novel and
original, and claim as the Invention secured to me by and in terms of the
herein before in part recited Letters Patent is,-
The construction of couplings for broken shafts in three segments and otherwise,
substantially as hereinbefore described.
In witness whereof, I, the said Archibald Thomson, have hereunto set my
hand and seal, this Sixth day of March, in the year of our Lord One
thousand eight hundred and eighty-two.
ARCH. THOMSON. (L.S.)