A New Kind of Coupling for Shafts and the like.
Year: 1891

page_text: Date of Application, 18th Nov., 1891
Complete Specification Left, 18th Aug., 1892-Accepted, 24th Sept., 1892
PROVISIONAL SPECIFICATION.
A New Kind of Coupling for Shafts and the like.
I WILLIAM HORATIO HARFIELD, of Mansion House Buildings, in the City
of London. Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to a new kind of coupling designed to prevent the
fracture of shafts or the like in case the same are subjected to sudden torsional
strain.
In carrying out my invention I advantageously arrange upon the adjacent parts
to be connected dises (or other suitably formed plates) having in them holes
or slots adapted to receive the ends of a spring bar or series of spring bars
or plates.
In practice I prefer to build up a bar of a number of flat spring plates lying
one against the other the two ends of this spring bar being inserted into apertures
in the discs so that the said spring bar is in axial alignment with the two parts
which it connects. I may however arrange a series of independent bars in different
parts of the discs with their axes parallel to the axis of the shaft.
When dealing with heavy strains I prefer to hold the ends of the said spring
bars to prevent them from turning in their holes while allowing them lateral
movement, but when slight strains are to be dealt with 1 leave the ends free.
My improved coupling is very advantageously used in connection with the
propeller shafts of steam ships in order to relieve the great and sudden torsional
strains to which such shafts are subjected. It is also very advantageously used in
connection with a ship's rudder for relieving the strain to which the latter is
subjected when struck by a wave.
Dated the 18th day of November 1891.
G. F. REDFERN & Co.,
4,,South Street, Finsbury, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
A New Kind of Coupling for Shafts and the like.
WILLIAM HORATIO HARFIELD, of Mansion House Buildings, in the City
of London, 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 :-
My invention relates to a new kind of coupling designed to prevent the fracture
of shafts or the like in case the same are subjected to sudden torsional strain.
In carrying out my invention I advantageously arrange upon the adjacent parts
to be connected discs (or other suitably formed plates) having in them holes
or slots adapted to receive the ends of a spring bar or series of spring, bars
or plates.
In practice I prefer to build up a bar of a number of flat spring plates lying
one against the other the two ends of this spring bar being inserted into apertures
in the discs so that the said spring bar is in axial alignment with the two parts
which it connects. I may however arrange a series of independent bars in different
parts of the discs with their axes parallel to the axis of the shaft.
When dealing with heavy strains I prefer to hold the ends of the said spring
bars to prevent them from turning in their holes while allowing them lateral
movement, but when slight strains are to be dealt with I leave the ends free.

page_text: To enable my invention to be fully understood I will describe how it can be
carried out in practice by reference to the accompanying drawing, in which :-
-
Figure 1 is a plan of the abutting ends of two shafts provided with a coupling
constructed according to my invention the parts being in the position they occupy
when there is no strain upon the shaft.
Figure 2 is an elevation of Figure 1, and
Figure 3 is a horizontal section on the line A B, showing the position of the
parts when the shaft is subjected to a strain.
a and indicate the adjacent ends of the two shafts through which motion is to
be transmitted; a and are the discs fixed on the ends a and b respectively of the
shafts; c, c are the holes or slots in the discs corresponding with each other,
and d, d are the series of spring bars which I place in the holes or slots c, e such
bars being made up of plates laid parallel with one another so as to fill the smaller
ends of the holes or slots which are enlarged towards the inner faces of the discs as
shewn in Figures 1 and 3.
The spring bars d, d so long as there is no torsional strain upon the shafts, are in
axial alignment with the two ends of the shafts and are only held by their ends
in the smaller portion of the holes or slots c, e as shewn in Figure 1, but upon being
subjected to a strain they bear more or less upon the wider part of the holes,
thereby gradually reducing or shortening the flexible portion of the bars and
increasing the resistance to the strain in an inverse ratio as will be readily under-
stood by reference to Figure 3 in which the arrows indicate the direction of the
strain. As the strain is augmented the bars or plates bend or yield with a
gradually increasing resistance until they bear upon the whole length of the
sides of the holes when any further strain will be resisted by the shearing strength
of the spring bars.
My improved coupling is applicable to all kinds of shafting and the like which
are subject to sudden strains such as forge and rolling mill driving shafts and it is
very advantageously used in connection with the propeller shafts of steam ships in
order to relieve the great and sudden torsional strains to which such shafts
are subjected. It is also very advantageously used in connection with a ship's
rudder for relieving the strain to which the latter is subjected when struck by
a wave.
In applying my invention directly to the rudder shaft of a ship a slight modifi-
cation is required, that is to say, one of the discs is keyed upon the shaft and the
other is allowed to turn loosely on the shaft and forms the boss of the rudder
crosshead or boss of the tiller or steering quadrant.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what
claim is
1. A new kind of coupling for shafts and the like comprising discs or plates
arranged upon the adjacent parts to be connected and spring bars or plates laid
parallel with the axis of the shafts or the like and held in the said discs or plates,
substantially as and for the purpose hereinbefore described.
.
2. In a coupling for shafts and the like discs or plates having holes or slots
therein made of larger size at one end than the other and adapted to carry
spring bars or plates operating under the influence of a torsional strain upon
the shaft or the like substantially in the manner and for the purpose herein before
described.
3. The improved coupling for shafts hereinbefore described and illustrated in the
accompanying drawing.
2
1009
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.