A Improvements in or relating to Switches for Starting Resistance for Electric Motors and other cases where Resistances are required.
Year: 1897

page_text: Date of Application, 3rd June, 1897
Complete Specification Left, 4th Feb., 1898-Accepted, 19th Mar., 1898
A
Improvements in or relating to Switches for Starting Resistance for
Electric Motors and other cases where Resistances are required.
I, JOHN WALTER GIBBS, of 72, 74 and 76, Duke Street, Liverpool, in the
County of Lancaster, Engineer, do hereby declare the nature of this invention to
be as follows:-
:-
This invention has for its object a safety switch which shall prevent the current
being suddenly turned on to electric motor or other electrical device until such
motor or electrical device is capable of bearing it, thus if the current be suddenly
turned on to the motor with its full strength while the motor is running slowly the
coils will be fused. If however a high resistance be placed in the circuit first then
the motor can be turned. on and the resistance gradually reduces as the speed
increases.
Now by my invention I make is impossible to turn on the current until the
resistance has been put in circuit.
In carrying out my invention I use a double pole quick break switch of the
usual type but form it with a projection or interlocking gear which comes in
contact with the circular disc of the resistance switch. when that switch is in any
other position than that in which the full resistance is in circuit. At this point
it passes through a slot in the disc or passes the end of the segmental disc as the
case may be. The current being on the switch can be turned so as to knock off
one resistance after another the discs sliding over the projection on the pole quick
break switch. When all the resistances are off a stop on the switch handle or
disc or segmental disc comes in contact with the projection on the double pole
quick break switch and thus prevents further motion. It can however be stopped
in any other convenient manner. In order to stop the machine the full resistance
must again be put on when the projection on the double pole quick break switch
can again pass through the disc or pass its end. At this point the switch prefer-
ably comes against a stop which prevents its further movement. It will thus be
seen that when once the current is put on the resistance can be varied indefinitely
from full to zero, but it is only when the full resistance is on that the current
can be put off and on.
Dated the 2nd day of Tuna 1007
Improvements in or relating to Switches for Starting Resistance for
Electric Motors and other cases where Resistances are required.
"
I, JOHN WALTER GIBBS, of 72, 74 and 76, Duke Street, Liverpool, in the
County of Lancaster, Engineer, do hereby declare the nature of this invention and
[Price 8d.]

page_text: in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
This invention has for its object a safety switch which shall prevent the current
being suddenly turned on to electric motor or other electrical device until such
motor or electrical device is capable of bearing it, thus if the current be
suddenly turned on to the motor with its full strength while the motor is running
slowly the coils will be fused. If however a high resistance, be placed in the
circuit first, then the motor can be turned on and the resistance gradually reduced
as the speed increases...
Now by my invention I make it impossible to turn on the current until the resis-
tance has been put in circuit or while the resistance is out of circuit.
=
Referring to the accompanying drawings:
Figure 1 is a plan view of an apparatus constructed according to my invention,
Figure 2 a cross section through liner and
Figure 3 an end view with the casing in section.
In these, A is the casing, B a slate foundation and C a double pole quick break
switch of the usual type mounted thereon. D is a tongue or projection carried
by the double pole switch and moving therewith and forming part of an inter-
locking gear, the other part consisting of a rotatable shield or disc E of the resis-
tance switch F. This shield or disc E is formed with a recess or slot G which,
when in one position, that is when the full resistance is in circuit as shown in
Figures 1 and 2 allows of the movement of the tongue D by means of the handle H
when putting on or taking off the current, but when the disc is rotated by means
of the resistance switch handle, the tongue D when the current is on is prevented
from rising or in other words is locked by the overhanging portion E¹ of the
disc E. Jis the resistance contact or switch arm and K a series of contact studs,
K being the highest resistance contact the others being gradually reduced down
to K2 which is the lowest resistance. L is an ordinary hour and minute gear to
control the speed at which the resistance contacts are cut out, this being more
convenient and compact than screw gear, and M M¹ are stops to limit the travel
of the switch arm J. N are the cut out terminals and springs which are
common to all double pole quick break switches of this type. P is a strip of brass
or other suitable substance moving with the handle H so as to close the slot or
opening Qin the cover or casing A when the current is on and R is a catch with
which the strip P engages as shown in Figure 3 thereby locking the cover down
so that it cannot be removed while the current is turned on and rendering it
necessary to turn off the current before removing the casing for examination or
repairs, thus minimising the risk of accident, S is a bridge covering the contact
studs K.
-
The mode of operation is as follows:-
To turn on the current the handle H of the double pole switch C is moved in the
direction of the arrow Figure 2 but this is possible only when the recess or slot G
of the interlocking shield E is opposite the tongue D of the double pole switch C,
and the resistance switch or contact arm J is in the position shown in Figure 1
that is in contact with the highest resistance stud K¹. The current being on,
the contact arm J can be turned by means of the handle J¹ so as to knock off one
resistance after another until it reaches the lowest resistance K2 when it comes
against the stop M. During this movement of the contact arm J, the tongue or
projection D is held locked by the overhanging portion E' of the shield or disc E
which slides over it so that the current cannot be taken off until the contact arm J
has been returned to the highest resistance contact K¹ and the recess or slot G
brought opposite the tongue D as shown in Figure 1, it will thus be seen that
when once the current is put on, the resistance can be varied indefinitely from
full to zero but it is only when the full resistance is on that the current can be
put on or taken off.

page_text: 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 I
claim is:
1. The improvement in switches for starting electric motors or dynamos con-
sisting in an interlocking gear so arranged either,
(a) That it is impossible to turn on the current until the requisite resistance
for safety has been placed in the circuit, and yet that when the current
is turned on the resistance can be altered at pleasure, or
(b) That it is impossible to turn off the current till (or nearly) the maximum
resistance is again placed in circuit, or
(c) Both these.
2. The special mechanism for obtaining the effects described in Claim 1 substan-
tially as described and illustrated.
WM. P. THOMPSON & Co.,
Patent Agents, of Liverpool, Manchester, Birmingham, and London.