Safety Yielding Connection of Pulleys, Wheels, or the like to their Shafts.
Year: 1892

page_text: Date of Application, 30th Sept., 1892
Complete Specification Left, 6th June, 1893-Accepted, 8th July, 1893
PROVISIONAL SPECIFICATION.
A Safety Yielding Connection of Pulleys, Wheels, or the like to
their Shafts.
1, CARL SCHLICKEYSEN, of 17 & 18 Wassergasse, Berlin, Germany, Engineer,
do hereby declare the nature of this invention to be as follows:-
In machinery of all kinds it may happen that a greater strain is suddenly imposed
than the various parts can bear.
This invention relates to means of providing against fracture resulting from
excessive strain, by connecting the driving pulley, wheel, crank or other revolving
part to the driven shaft in such a way that the connection will break or give way
under a strain less than that which would cause fracture of any part of the driven
machine.
This connection may be made in various ways, the pulley or wheel that is to
operate as the driver being loose on the shaft, while an arm fixed on the shaft is
linked to it by the safety connection.
it
be
This
may
be a wire coiled several times round the connected parts, or
may
a loop or link or several of these side by side with eyes engaging pins on the con-
nected parts, the number of the coils of wire or of the combined loops or links, or
the transverse sections of these connections being adapted to the strains under
which they are intended to give way.
Another form of safety connection may be a bolt or pin of such section that it
will be broken or shorn transversely by a predetermined strain, or it may be a pin
held engaged in a V shaped recess by a spring or otherwise, so that when an
excessive strain is imposed upon it, the spring or other holder yields, allowing the
pin to slide along the sloping side of the recess and so to become disengaged.
Dated this 30th day of September 1892.
ABEL & IMRAT,
Agents for the Applicant.
COMPLETE SPECIFICATION.
A Safety Yielding Connection of Pulleys, Wheels, or the like to
their Shafts.
I, CARL SCHLICKEYSEN, of 17 & 18 Wassergasse, Berlin, Germany, 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:-
In machinery of all kinds it may happen that a greater strain is suddenly imposed
than the various parts can bear.
This invention relates to means of providing against fracture resulting from
excessive strain, by connecting the driving pulley, wheel, crank or other revolving
part to the driven shaft in such a way that the connection will break or give way
under a strain less than that which would cause fracture of any part of the driven
machine.
This connection may be made in various ways, the pulley or wheel that is to
operate as the driver being loose on the shaft, while an arm fixed on the shaft is
linked to it by the safety connection.
This may be a wire coiled several times round the connected parts, or it may be a
loop or link or several of these side by side with eyes engaging pins on the con-
nected parts, the number of the coils of wire or of the combined loops or links, or

page_text: the transverse sections of these connections being adapted to the strains under
which they are intended to give way.
Another form of safety connection may be a bolt or pin of such section that
it will be broken or shorn transversely by a predetermined strain, or it may
be a pin held engaged in a V shaped recess by a spring or otherwise, so that
when an excessive strain is imposed upon it, the spring or other holder yields,
allowing the pin to slide along the sloping side of the recess and so to become
disengaged.
On the accompanying drawing are shewn various arrangements for carrying out
my said invention.
In Fig. 1 the main shaft a of any machine carries two loose pulleys b and c.
Next to the pulley can arm d is fixed on the shaft, which arm is connected to the
pulley by means of a suitably formed coupling device by means of which on the
rotation of the pulley in the direction of the arrow the arm d and consequently also
the shaft a will be carried round in the same direction.
The coupling device is consequently subject to a
tearing strain, its resistance to
rupture being proportionate to its sectional area, and the nature of the material of
which it is made. It can be readily proportioned in strength to the strain due to
the maximum power which it is required to transmit to the shaft. If this strain
should be exceeded at any time owing to the occurrence of some unusual resistance
in the machine to be driven, the coupling will tear and the arm d and shaft a being
no longer dragged round by the pulley, the machine will come to a standstill, and
thus he destruction of any other part of the machine is prevented.
The coupling can consist of a loop made of coiled metal wire or band metal, e
with either a single or several windings, as shewn at Fig. 1 in two examples. The
wire or band can be wound on the one hand round a part of the pulley, for
example directly round one of its arms c', and on the other hand round a pin d¹ on
the arm d fixed to the shaft a, the ends of the wire or band being twisted together
or otherwise secured. The number of windings of the loop will determine the
maximum power which is to be transmitted to the machine.
Fig. 2 shews a coupling in the form of a closed loop or chain link e¹ which
engages on the one hand with a pin c² on one of the arms of the pulley and on the
other hand with a pin d² on the arm d fixed on the shaft a. In place of such a
loop or link, a two-eyed link e² such as is shewn in front and edge views at Fig. 3
may be used.
This can be made of a single plate or piece of sheet metal of a definite sectional
area as shewn or it may be of several thin plates placed side by side as at Fig. 4.
The latter arrangement has the advantage that the coupling may, at will, be made
weaker or stronger by removing or adding one or more of the links, thus propor-
tioning the link exactly to a decreased or an increased power which the machine is
required to receive. In this example, Fig. 4, the arm dis replaced by a disc f
fixed on the shaft a, which affords greater security against accident than the arm d
revolving with the shaft.
Fig. 5 shews a coupling consisting of a pin or bolte which connects the pulley c
with the arm don shaft a; such bolt being subject to a shearing strain, which
will cause it to break as soon as the maximum power to be transmitted is exceeded
to a certain extent. The maximum strain to be transmitted is determined by the
sectional area of the pin between the two coupled parts, and this can consequently
be determined with great accuracy by turning a circular groove to a certain depth
on the pin at that point. As soon as the maximum strain is exceeded, the pin or
bolt breaks or is sheared at such groove and the machine comes to a standstill
without breaking or damaging any vital part thereof.
Fig. 6 shews a similar arrangement of grooved pin e fixed to the arm d on the
shaft a, the free end of which pin is simply made to bear against the arm c¹ of the
pulley for transmitting the power.
The coupling can also be so arranged that the connecting part, instead of being
broken or torn, is merely detached from its connecting point.

page_text: Thus for example, as shewn at Fig. 7, a bolt or pin e' can be made to bear with
a pointed or rounded end against a correspondingly recessed part of a stud g fixed
to the driving loose pulley c, the stud being pressed against the stud with sufficient
force to enable the required lateral strain to be transmitted through the pin e* to
the arm & without causing the stud to slip out of the recess, while when the maximum
strain is exceeded, the device that holds the stud will yield and this will slip out of
the recess. The means for holding the stud as described may be variously arranged,
thus for instance the stud or bolt may be fixed to the arm d and be made to project
such a length therefrom in proportion to its thickness, that when the maximum
strain is exceeded, it will bend and thus be disengaged from the recess of the
stud g. Or, as shewn at Figs. 7 and 8, in two modifications, the bolt or pin can be
held engaged with the recess of the stud by the pressure of a plate h Fig. 7 or a
spring Fig. 8, which will be bent backwards by the bolt e in sliding out of the
recess of g when the maximum strain is exceeded.
In the arrangement at Fig. 8 the bolt e may have a spring pawl k, which, when
the bolt has been forced back a certain distance through the arm d, will spring
outwards as shewn in dotted lines, and will thus prevent the bolt from being pushed
inwards again by the spring i, so that no re-engagement thereof with the pulley
can take place during the continuance of the rotation of the latter.
It will be obvious that the above described arrangements can be reversed, that
is to say, the bolt or pin e be carried by the pulley arm and the recessed stud g by
the arm
also, that the transmission of power may in all the above described cases
take place from the shaft to the pulley instead of as described. The said coupling
may also be employed to connect the pulley of the driving machinery with any
other revolving part of driven or operative mechanism, such as a toothed wheel,
fly wheel, shaft coupling &c., fixed on the main shaft of such machinery, or it may
be employed for connecting the main driving shaft to a pulley on a transmission
shaft instead of to the driven machine itself.
The pulley Figs. 1, 2, 5, 6, 7 acts in all cases as loose pulley for throwing the
operating machine out of gear in the usual manner, so long as the pulley c remains
coupled with the driving shaft.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
A safety coupling for transmitting power from a driving pulley to a shaft or
other mechanism to be driven, or the converse, consisting of a coupling device,
such as e e e e e e e so arranged that when a predetermined maximum strain to be
transmitted is exceeded the said device will break tear, become sheared or be
disengaged in order to prevent the further transmission of power substantially as
described.
1 1
T1002
ABEL & IMRAY,
Agents for the Applicant.