Improvements in Electrical Switches.
Year: 1892

page_text: Date of Application, 3rd Sept., 1892-Accepted, 8th Oct., 1892
Improvements in Electrical Switches.
I, CLAUDE WILLIAM ATKINSON of 17 Victoria Street, in the City of
Westminster, Civil Engineer, do hereby declare the nature of my invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
My invention relates to electrical switches and has for its object the construction
and arrangement of the contact piece with the arm or other part that operates it,
so that the contact piece is not carried rigidly thereby, but on the contrary can
move through some distance in certain directions independent of the operating
mechanism, and also the forming of the contact piece in a flexible form, with the
object that the construction of the switch may be much simpler and cheaper than
at present, and that the contact will be much more perfect, and will not be effected
by any irregularity in the construction of the mechanism of the switch.. In
electrical switches having one set of contacts in one plane superposed above the
other set of contacts in another plane and a movable connecting piece adapted to
move between these sets of contacts, it is found that in order to effect good contact
by ensuring the path of movement of the movable piece being in a plane coincident
with or parallel to those of the contacts, the cost of construction is very consider-
able as the various parts of the switch require machining to an accurate gauge
before they are put together, as any want of truth in the working of the parts
detracts from the efficiency of the switch.
My invention consists firstly in the mounting of the movable connecting piece of
the switch upon the operating mechanism that it is in a sense not influenced as to
its position on the contacts except in the direction desired and therefore forms what
I term a floating contact and secondly in the specific construction of a switch in a
cheap and efficient form.
.
In order that my invention may be the better understood I will now proceed to
describe the same in relation to the drawings hereunto annexed reference being had
to the letters and figures marked thereon. Like letters refer to like parts in the
various figures.
Figure 1 is a sectional elevation of a switch constructed according to my
invention for use on a motor.
Figure 2 is a plan of the same.
Figures 3, 4 and 5 are detail views of the floating contact piece.
Figure 6 is a diagrammatic view of the contacts showing the connections between
the switch and a motor.
I carry out my invention as follows:-
:
Within a suitable framework casing A, a spindle B is pivotably mounted,
having arranged upon it a handle C and a block of insulating material D such as
fibre. Upon the bottom of the framework A I arrange three or more legs E or
equivalent supports upon which the lugs F of the resistance frame G rest. Upon
these said lugs Fa fibre foundation ring H is mounted; the screw f passing through
the ring H and one of the lugs F into one of the legs E, the whole being further
kept firm by a steady pin e in one of the other legs E, engaging with one of the
other lugs F.
The upper contacts I and lower contacts J are secured to the fibre base H by
means of screws i and j respectively.
The block D has two recesses K arranged one on each side opposite to one
another in which the contact making pieces L are disposed. Each contact piece
D

page_text: is formed of a series of thin flexible metal strips M bent around one another as
shown in Figures 1, 4 and 5 which lie with their flat faces against the contacts I, J.
These strips M are fastened to a cage N bent into the form of a nearly closed
rectangle as shown in Figure 3, the means of attachment shewn being a rivet n.
The cage N is disposed in the space between the bent parts of the strips M and
contains a spiral spring O which tends to force the upper and lower parts of the
contact piece L away from one another, against the contacts I and J respectively.
The edges of the outside strip M are turned over so as to facilitate the entrance of
the contact piece L between the contacts I and J.
The cage N has a hole non each side into which loosely engages a pin d carried
by the operating piece D on each side of the recesses K. These pins d only
loosely control the contact piece L and are only intended to prevent the contact
piece from travelling out end wise from its recess K.
It will be obvious that by this arrangement of contact piece loosely controlled by
the operating arm the axis of the spindle need not be accurately placed as to
rotate the block D in a plane parallel to the planes of the contacts I J, as the
loosely mounted flexible contact pieces accommodate themselves to the said
contacts their whole surface being in contact, which would not be the case if they
had to cant with the spindle should the latter not be placed truly in position.
For the reasons as above stated it is very obvious the cost of manufacture may
be much reduced inasmuch as very careful and accurate fitting together of parts
is not necessary, as it is in the case of a contact piece carried rigidly by the
operating mechanism.
The particular form of switch I show is one having a series of resistances which
are short circuited one by one gradually as the increase of the current to the
motor is desired; there is also a connection with the field magnets at the end for
the "stop" position of the switch, which short circuits the field magnets just before
the main circuit to the brushes is broken thus preventing excessive sparking at the
switch due to the induction of the field magnets.
There is no novelty in this arrangement of contacts to effect the purpose
desired, the only point of novelty in the switch besides the floating contact is the
general arrangement and construction of parts as shown in the drawing. I show
in Figure 6 a diagrammatic view of the connection between the switch and the
motor L'L being the main cables B' B2 being the connections to the brushes
and M M the connections to the field magnets. The four terminals and
alternative circuits shown on the motor are only for the purpose of effecting a
reversal of direction of motion of the motor, the four cable connectors being made
uniform in order to effect the connections at either end simultaneously.
In Figure 2 the upper contact I is divided into a number of separate con-
tacts i¹,,,,,,, which are connected up at various points in the resistance
coils g of the frame G. The last contact is and the contact opposite to it are
connected to the field magnets of the motor and the space between and the next
contact is such that the connecting piece L is rather wider than the same so that
the field magnets are short circuited before the main circuit is broken.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1st. In an electrical switch having the contact surfaces disposed opposite to one
another a flexible contact piece loosely controlled by the operating mechanism
consisting of plates adapted to spring against the contacts and to make connection
therewith with their facial surfaces, substantially as described.
2nd. In such a switch, a floating contact piece formed of laminated strips of
conducting material pressed out against the contacts by spring pressure in
combination with a cage loosely connected to an operating device, substantially
as and for the purposes described.

page_text: 3rd. The construction and arrangement of a non-sparking switch, substantially
as described and shewn in the drawings.
Dated this 3rd day of September 1892.
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.