Improvements in Apparatus to be used in connection with Electrically Driven Machines.
Year: 1892

page_text: Date of Application, 19th Feb., 1892
Complete Specification Left, 21st Nov., 1892-Accepted, 21st Jan., 1893
PROVISIONAL SPECIFICATION.
Improvements in Apparatus to be used in connection with
Electrically Driven Machines.
We, WILLIAM STEPNEY RAWSON of 88 Queen Victoria Street, E.C. Elec-
trician, CHARLES SCOTT SNELL of Culver Park, Saltasb, Cornwall, Engineer,
and WOODHOUSE AND RAWSON UNITED LIMITED of 88 Queen Victoria
Street, E.C. Electrical Engineers and Contractors, do hereby declare the nature
of this invention to be as follows:-
:-
Our invention relates to apparatus for employment in connection with electrically
driven machines in which it is necessary that the power developed should be arrested
at a definite point and ready means be provided for enabling the work to be
continued automatically or by hand either in the same direction of rotation, or the
reverse.
For this purpose we employ what is known as a magnetic cut-out by which a
current is broken as soon as it has reached a predetermined point.
We may combine with this cut-out an arrangement by which the action of the
moving part of the cut-out breaks the main circuit and makes another circuit.
This latter circuit may be so arranged as to constitute a high resistance in circuit
with the motor.
This is conveniently effected by permanently attaching a high resistance shunt
to the terminals of the cut-out, or it may be arranged to energise a magnetic brake
acting upon any suitable portion of the moving machinery which it is desired to
bring to rest.
With the above described apparatus we may combine a switch so arranged that
on turning the handle in one direction from zero the motor is caused to rotate in
one direction and by cutting out suitable resistances the power developed is
increased, while by turning it in the opposite direction from zero, a similar effect is
produced, but with the direction of rotation reversed.
We may arrange that in the passage of the switch handle from one side to the
other a suitably arranged contact is made causing a current to energise a magnet so
arranged with regard to the cut-out, that it restores the moveable portion of the
instrument to the original position in which it was before the excess current caused
it to move.
The general arrangement and action of the apparatus
therefore as follows:-
The magnetic cut-out may be fixed in any suitable position with regard to the
machine which is being electrically operated, the switch is suitably disposed near or
on the machine, so that the operator by the turning of the switch handle starts the
motor and by cutting out resistances causes it to exert gradually increasing power:
as soon as this reaches a certain predetermined point, the circuit is broken by the
cut-out, and further movement of the motor prevented, either by the interposition
of a high resistance in circuit, or by the action of the magnetic brake. On the
return of the switch handle to zero the moveable portion of the cut-out is restored
to its original position by magnetic action, and the apparatus is ready to reverse by
the movement of the switch handle to the other side.
If desirable the motor may be so actuated and controlled, that when the current
reaches a predetermined point suitable for the special purpose, the cut-out or
equivalent device may be made to reverse the connections and cause the motor to
reverse.
We may also by the movement of the cut-out or equivalent device effect a
mechanical change of direction of rotation while the motor is always allowed to run
in the same direction

page_text: This form of apparatus would be specially applicable to tapping and drilling
machines actuated by electric motors.
Electrical connections are suitably arranged so as to employ the same or various
sources of energy for performing all the functions explained above.
Dated this 17th day of February 1892.
W. STEPNEY RAWSON.
C. SCOTT SNELL.
WOODHOUSE & RAWSON UNITED, LIMITED,
A. L. Foley, Assist. Secretary.
COMPLETE SPECIFICATION.
Improvements in Apparatus to be used in connection with
Electrically Driven Machines.
We, WILLIAM STEPNEY RAWSON of 88 Queen Victoria Street, E.C. Elec-
trician, CHARLES SCOTT SNELL of Culver Park, Saltash, Cornwall, Engineer,
and WOODHOUSE & RAWSON UNITED LD. of 88 Queen Victoria Street E.C.
Electrical Engineers & Contractors, 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 :-
Our invention relates to apparatus for employment in connection with electrically
driven machines in which it is necessary that the power developed should he
arrested at a definite point and ready means be provided for enabling the work to
he continued automatically by hand either in the same direction of rotation or the
reverse.
The better to explain our meaning, reference is made to the accompanying
drawings in which
Fig. I shows a switch and cut-out and their connections.
Figs. II and III side elevation and plan respectively of a reversing cut-out.
Figs. IV and V an electrically controlled mechanical reversing apparatus.
The coil A Fig. I is part of an electromagnetic cut-out which breaks the
motor circuit at a predetermined point such as when too much work is thrown on
the motor. This moving coil A when thrown out leaves the current passing only
through a high resistance coil B, which constitutes a high resistance in circuit with
the motor, and it may form part of the circuit of an electromagnetic brake acting
on any suitable portion of the moving machinery it may be desired to bring to
rest. In conjunction with this cut-out the switch shown below it, is used; in its
present position it will be seen that the contact C in connection with the terminal C'
of the dynamo or other source of power, is in connection with the contact E,
leading to terminal E¹ of motor. Similarly the contact D in connection with the
terminal D' of the dynamo is connected with the contact F leading through the
cut-out to terminal F' of the motor. This position was reached from zero by
passing over the small adjacent contacts in conjunction with resistances so that it
gradually reached a maximum point. If now the cut-out A. acts, the motor circuit
is practically broken or rather greatly reduced, and on rotating the switch back to
zero in the direction of the arrow," the contacts G and H are connected and
another circuit comprising the electromagnet I is completed and the armature J
throws back the coil A, breaking its own circuit which includes the cups K and L
and leaves the motor circuit intact, when the motion of the switch being continued
the brush M reaches contact C coupling it to contact F through the resistance N,
and the other pole of the switch in a like manner becomes similarly coupled. The
direction of the current however is now reversed and its power may be increased
by the continuation of the rotation of the switch.
The general arrangement and action of the apparatus is therefore as follows:-
The magnetic cut-out may be fixed in any suitable position with regard to the

page_text: machine which is being electrically operated, the switch is suitably disposed near
or on the machine, so that the operator by turning the switch handle starts the
motor, and by cutting out resistance causes it to exert gradually increasing power,
as soon as this reaches a predetermined point, the circuit is broken by the cut-out,
and further movement of the motor prevented either by the interposition of a high
resistance in circuit, or by the action of a magnetic brake. On the return of the
switch handle to zero, the moveable portion of the cut-out is restored to its original
position by magnetic action, and the apparatus is ready to reverse by the movement
of the switch handle to the other side.
If desirable the motor may be so actuated and controlled, that when the current
reaches a predetermined point suitable for the special purpose, the cut-out or
equivalent device may be made to reverse the connections and cause the motor to
reverse.
This is shown in Figs. II and III the various cups being coupled as shown in
the dotted lines, if then the right hand side is depressed as shown, the motor
terminals E, F are coupled respectively to C and D₁ of the dynamo ; an excess of
current however throws the cut-out over and the cups on the left hand side are joined
up so that C of the dynamo becomes connected to F of the motor and D' to E'
the current being therefore reversed. The current may then be totally broken by
a main switch or if desired a supplementary magnetic coil as shown in Fig. I and
marked I may be part of the connecting wire joining the cups O and P and set so
that on an excess of current again running through the motor the system shown in
Figs. I and III is again restored to the position illustrated, thus producing an
automatic reversal convenient for many purposes. We may also by the movement
of the cut-out or equivalent device effect a mechanical change of direction of
rotation while the motor is always allowed to run in the same direction. Thus in
Figs. IV and V it will be seen that if the cut-out in Fig. I has the prongs on the
left hand side so long that they only just clear the mercury in the cups K and L
when the cut-out is at rest, an excess current in the motor circuit will tend to
throw over the cut-out, but it only makes the supplementary circuit on the left
hand side, not having travel enough to break its own circuit, the supplementary
circuit as in Fig. V passes through one electro-magnet of the pair shown and pulls
the knife edge attached to the armature to the right or left as the case may be.
The knife edge T on the driving sleeve U of the main shaft V meeting the knife
edge on the armature, the whole sleeve is forcibly transferred to engage with the
other bevel wheel shown, letting go its existing hold thus reversing the direction
of rotation of the shaft at right angles. These bevel wheels of course run loose
on the main shaft and only receive the motion through the sleeve U which runs on
a feather on the shaft. This sleeve is provided with pins and springs so that when
forcibly thrown over to the opposite position it can take its full movement even if the
holes in the wheels corresponding to the pins are not at the moment in a position
to receive them. The direction being reversed and load therefore removed the
hand switch shown at W is transferred to the other contact and upon the cut-out
again acting, that is again making the supplementary circuit, it is the other coil
that receives the current and the knife edge is again changed and the direction
reversed.
Electrical connections are suitably arranged so as to employ the same or various
sources of energy for performing all the functions explained above.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
J. The combination with a magnetic cut-out of a switch and other apparatus
substantially as described whereby the power absorbed by an electric motor may
be first increased to a predetermined point then the motor brought to rest and
finally its direction of rotation reversed and a similar cycle completed, all these
actions being controlled by the movement of a single lever.

page_text: II. The combination with a motor controlling switch of a magnetic cut-out,
provided with a magnetic device for restoring the same to its original position,
substantially as described.
III. The combination with a magnetic cut-out, of mechanism so arranged as to
reverse direction of current through a motor after the current has exceeded a
predetermined point, substantially as described.
IV. The combination with a magnetic cut-out of mechanism to cause reversal
of rotation of a shaft by the action of the cut-out, substantially as described.
Dated this 19th day of November 1892
W. STEPNEY RAWSON.
C. SCOTT SNELL.
WOODHOUSE & RAWSON UNITED, LIMITED,
A. L. Foley, Secretary.