Improvements in Electrical Switches.
Year: 1895

page_text: Improvements in Electrical Switches.
We, CHARLES MARK DORMAN, of Ordsal Electrical Works Salford, in the
County of Lancashire, Electrical Engineer, and REGINALD ARTHUR SMITH of
Ordsal Electrical Works, Salford, in the County of Lancashire, 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 :-
Our improvements relate to the various types of switches described in this
Specification.
Our improvements consist in the combination of the type of controlling spring
described in our Specification, 13410-1894' with the various types of switch
described in this Specification.
Referring to the drawings
Figs. 1. 2. 3. 4 and 5 are diagrammatic views of several types of switches in
combination with the controlling spring described in our Specification 13410-
1894.
'
Figs. 6. 7. 8. 9. 10. 11. 12. and 13 shew some suitable forms of the controlling
spring.
It will be seen that in all the types of switches shewn electrical contact is made
or broken by means of a contact arm or arms A 1. A 2 which turn on a pivot B
and complete the circuit between the terminal pieces C 1. C 2. D is the spring of
a bowed or U or V form the arms of which have a permanent tendency to open
outwards. The two ends of the spring E 1. E 2. form or are provided with bearings
or pivots round which they can turn in the same plane or in a plane parallel to that
in which the arm or arms A 1. A 2. move. One end E 1. of the spring is pivoted'
either on one of the arms A 1. A 2. or on a piece rigidly connected thereto, except
in the arrangement shewn in Figs. 4 and 5 which will be described further on.
The other end E2 of the spring is pivoted to a fixed point at the same side of the
centre pivot B as E 1 but preferably for convenience a little further from it. The
part of the spring from which the arms radiate is unconstrained except by
the pivoted ends, and when the switch is moved travels in a circular path round
the fixed point E 2. It will be seen that when the contact arm is moved into such
a position that the pivot E 1 lies on a line drawn between the pivot B and the
pivot E2 owing to the outward pressure of the arms of the spring the contact arm
is in a state of unstable equilibrium. If the contact arm is moved so that the
pivot E1 is slightly on either side of the same line, the spring at once exerts a
pressure tending to carry the pivot E1 and with it the contact arm further in the
same angular direction round the pivot B. The best position for the pivots E1
and E 2 is such that at the moment when the contact arm is leaving, the terminal
pieces, the pivot El is well over to one side of the line joining B and E2 in such
a manner that the spring tends to produce a very quick break, but when the
contact arm is right home in or on the terminal pieces the pivot E 1. is slightly
over on the opposite side of the line so that the spring has a tendency to hold the
contact arm in or on the terminal pieces.
It is obvious that any of the types of switch shewn in Figs. 1. 2. and 3. can if
desired be fitted with a handle which can turn through a certain angle determined
by stops without moving the switch, and as soon as the contact arm is clear of the
terminals allows it to dart rapidly away under the influence of the spring however
lowly the handle is turned as described in Holmes' Specification 3256-1884.

page_text: Any of the types of switch shewn in Figs. 1. 2. and 3 can also if desired be fitted
with the arrangement shewn in Figs. 4 and 5, in this case the contact arm or
arms A 1. A 2, the handle F., and the intermediate piece G. shewn in the figure of
a star shape, all turn independently on the pivot B, the angular movement between
the handle F. and the intermediate piece G. being limited by stop pegs, wards or
projections, shewn at H. H. and the angular movement between the intermediate
piece G and the contact arms A 1. A 2. being limited by stop pegs, wards, or pro-
jections shewn at E 1. E 1. K. K. The pivoted ends of the spring or springs E 1. E 1.
instead of being pivoted direct in the contact arms, or a piece rigidly connected
thereto, are pivoted in the intermediate piece G at E 1. E 1. The result of this
arrangement is that the pivot E1 can be pushed across the line joining B and E2
in advance of the movement of the contact arm and the contact arm will be free to
fly under the influence of the spring either in the "on or "off" direction,
according to the motion of the handle, through an are the length of which will be
regulated by the position of the wards or projections.
"
The types of switch shewn may be fitted with any kind of contacts generally in
use; either with rigid contact arms and spring contact jaws, or with rigid contact
blocks and spring contact arms of the laminated-bridge or other type.
The type of switch shewn in Fig. 1 may be fitted as shewn with the contact
arms A 1. A 2. entering the contact blocks C 1. C 2. simultaneously or it may be
arranged as a two way switch with the two arms and two contact blocks in such
relative positions that only one arm is in or on its own contact block at once and
the position of the pivot E1 so arranged that the spring holds either arm firmly in
or on its own contact block.
The type of switch shewn in Fig. 2. may be fitted as shewn with a single contact
arm making contact on two contact pieces or with one contact piece only, or it may
be fitted with a branched contact arm, or with two or more contact arms one behind
the other in the figure, with separate contact pieces to each arm.
The type of switch shewn in Figs. 3. 4. and 5 may be fitted as shewn with two
contact arms or it may be fitted with one contact arm only, or with four contact
arms as a double pole switch.
It will be seen from the figures that in any of the types of switch shewn one or
more springs may be used on each switch, as may be found desirable, either in
different parallel planes, or at different points in the same plane; thus in the types
of switch shewn in Figs. 1. and 2 it may be desirable to use two or more springs in
parallel planes one behind the other in the figures, or in the type of switch shewn
in Figs. 3. 4 and 5. two springs may advantageously be used in the same plane at
opposite sides of the centre pivot B as shown.
Any kind of spring is suitable for our purpose either formed from one piece of
metal or built up of several parts providing that when looked at in the same
direction as in Figs. 1. 2. 3. 4. 5. 6. 8. 10 and 12. it is of a bowed or U or V form,
and that the pivoted ends have a tendency to fly apart. If desired one or both of
the arms can be formed in duplicate if necessary with duplicate bearings as shewn
in Figs. 8. 9. 12 and 13.
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.
1. The combination of the bowed spring having pivoted arins as described in our
Specification 13410-1894 and in this Specification with the several types of switch
described in this Specification substantially as described and shewn.
Dated this 8th day of January 1895.
CHARLES MARK DORMAN.
REGINALD ARTHUR SMITH.