Improvements in Contact Fingers 1or Electric Controners.
Year: 1897

page_text: Date of Application (in United Kingdom), 21st May, 1897
Complete Specification Left, 21st May, 1897-Accepted, '26th June, 1897
Improvements in Contact Fingers 1or Electric Controners.
I, EUGENE CHILTON PARHAM, of Johnstown, Cambria County, and State
of Pennsylvania, United States of America, Electrical 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 electric controllers of the type used on electric railways"
and bas for an object the provision of an improved form of spring pressed finger
therefor, the contact portions of which, when delivering current to the drum of
the controller, are in a strong magnetic field, so that any are formed by the
breaking of the circuit may be surely and quickly broken.
My invention comprises, broadly, the use of a separate electromagnetic
arc-interrupter for each contact-finger; and it consists in the simple and novel
construction, combination and arrangement of parts, as will be pointed out
hereinafter.
Referring to the drawings,
Fig. 1 is a top view of portions of a controller, showing the features of my
invention and having certain of the upper parts of the controller removed to
better show the contact-rings, etc.
Fig. 2 is a side view of the inside of a controller with the upper and lower
portions broken away.
Figs. 3 and 4 are views similar, respectively, to Figs. 1 and 2, but illustrating a
modified form of my invention.
A is the finger board and is made of wood or other suitable material.
EE and GG are respectively contact-rings and insulating-disks of any approved
form and adapted to be secured about the shaft of the drum (not here shown) by
any preferred method.
B B are helical springs secured near their outer ends to A, as by screws a a, and
having at said ends means, such as the eyes ee and binding-posts ff, for connecting
The inner end of each
the springs with any desired part of the electric circuit.
spring is connected to a member C, which is composed of magnetizable material
and carries a contact D, adapted to engage the contacts upon E. If D is in contact
with the drum, whatever current may be passing takes its course through B to C,
to D, to E, and so on, or vice versa. The spring B, surrounding as it does, a portion
of the member C, becomes the field coil of an electromagnet, C becoming the core
thereof, and c 1 and c 2 becoming the poles of the magnet.

page_text: In Figs. 1 and 2, C is shown with its poles c1 and c2 carrying the contact D
between them. In this case D should be made of substantially non-magnetic
material if it is desired to effectively blow out the arc which tends to form as the
drum rotates.
In Figs. 3 and 4, C is shown with only one pole near the contact portions of the
finger, magnetic conducting members, as a 1, J. H and E, being used to provide a
path for the magnetic lines of force, as shown by the dotted line. The provision of
this path is not essential, but is preferable as conserving energy. It is evident that
this arrangement is magnetically the equivalent of that shown in Figs. 1 and 2.
By the provision of the conducting path for the magnetic lines of force I place the
contact portion of the finger between the poles of the electromagnet, for this
conducting-path is equivalent to making that portion of the drum opposite the
finger one pole of the electromagnet.
D in the modification of my device last described is preferably made of copper
or brass because of the electrical functions it is designed to perform, but as far as
the magnetic properties of the invention are concerned c1 may itself be used as the
contact. It is therefore understood that where refer in the claims to the finger
members as carrying contacts I do not limit myself to the use of the separate
member D, except where the combination requires such limitation to adapt it for
operation.
F is a stop made of wood or other suitable material and is designed to prevent
too much inward movement of D.
It will be seen that when the circuit between D and E is broken by the rotation
of the drum, as at a, the magnetic field between c1 and c 2 will interrupt the arc
which tends to form.
A valuable feature of my invention is that the strength of the magnetic field
varies substantially in proportion to the volume of the current passing through the
contact-finger, so that the greater the size of the arc to be broken the stronger will
be the field with which to break it. On the other hand if there is no current
passing through the contact-finger, ncne will be wasted in the field-coil to energize
a magnet that is not needed.
Another advantage of my invention is that I am not required to use any more
parts or more complicated parts to obtain the magnetic field than are necessarily
used for other ordinary forms of contact-fingers which have not the advantage of
an arc-interrupting attachment.
A further advantage of my improvement is obtained by the use of the separate
electro-magnets for each finger, for if one is damaged in any manner, such damage
is only local and may readily be repaired.
I do not limit myself to the exact form of my invention as herein shown and
described nor to its use with any particular form of controller.
Many modifications of my invention will readily suggest themselves to those
skilled in the art, such as other methods of providing a path for the magnetic lines
of force and different methods of energizing the member C.
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. In a contact finger for electric controllers, in combination, a magnetizable
finger member, means for magnetizing said member, and a contact carried by said
member and carried between the poles thereof.
2. In an electric controller, in combination, a rotatable drum carrying suitable
contacts, a plurality of fixed fingers contiguous thereto, said fingers each comprising
a magnetizable finger member, a contact carried thereby, and an energizing coil
about, and electrically in series with, said finger member.
3. In a contact finger for electric controllers, a spring constituting the field-coil
of an electromagnetic arc-interrupter and adapted to press the contact portions of
the finger against the contact portions of the controller drum.

page_text: 4. In combination with a contact-finger for electric controllers, a spring
electrically connecting a desired part of the cutside circuit with the contact fingers
and constituting the field coil of an electromagnetic arc-interrupter, said spring-
being also adapted to press the contact portions of the said finger against the
contact portions of the controller-drum.
5. A contact finger for electric controllers comprising, in combination, a.
magnetizable finger member, a contact carried thereby, and a spring adapted to
press said contact toward the controller drum and to constitute an energizing coil.
for said magnetizable member.
6. In an electric controller, in combination, the finger board of the controller,
a plurality of magnetizable finger members, and an energizing coil for each of said
members constituting means for securing it to the finger-board.
7. In a contact-finger for electric controllers, in combination, a helical spring
constituting the energizing-coil of an electromagnet, and a contact carrying finger
constituting the core of the electro magnet.
plurality
of fixed contact-fingers contiguous thereto, each of said fingers comprising a
magnetizable contact carrying member and a spring adapted to hold said member
in a yielding contact relation with the drum and adapted to magnetize said
member.
8. In an electric controller, in combination, a rotatable drum and
9. In a contact finger for electric controllers, in combination, a member composed
of magnetizable material and carrying a contact, a field coil adapted to maguetize
and secure in position said member, said contact being magnetically between the
poles of said member.
10. In a contact finger for electric controllers, a fork made of magnetic
conducting material, with two prongs which are adapted to become opposite
magnetic poles when energized by a suitable field coil surrounding a part of said
fork, and a contact piece carried between the prongs and near the free ends.
thereof.
11. In a contact finger for electric controllers, in combination, a magnetizable
fork carrying a contact between its prongs and means for magnetizing said
fork.
12. In a contact finger for electric controllers, in combination, a magnetizable
member carrying a contact, means adapted to hold said member in a desired
position and magnetize it, said contact being magnetically between the poles of
said member.
13. In a contact finger for electric controllers, in combination, a fork carrying
a contact between its prongs, said prongs constituting the poles of an electro-
magnet and a suitable field coil about a part of said fork and in series therewith.
14. In a contact-finger for electric controllers, a helical spring secured at its
outer end to the finger board of the controller and connected electrically to a
suitable part of the circuit, and having its inner end connected to a magnetizable
finger and in circuit with the contact carried thereby.
15. In a contact finger for electric controllers, in combination, a magnetizable
fork, a contact between the prongs of said fork, a helical spring adapted to
energize said fork and deliver current thereto, said spring being adapted to secure-
the fork in its proper position.
EUGENE CHILTON PARHAM.
Haseltine, Lake & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.