IMPROVEMENTS IN ELECTRICAL SWITCHES
Year: 1886

page_text: Date of Application, 20th Mar., 1886
Complete Left, 20th Dec., 1886.
Complete Accepted, 11th Mar., 1887.
ROBERT MAJOR BAILY Junr Engineer & ALFRED GRUNDY Electrician Amberley
Works Amberley Road Paddington Middlesex do hereby declare the nature of our
invention for IMPROVEMENTS IN ELECTRICAL SWITCHES to be as follows
The switch consists of two concentric, circular parts, one of which is fixed & the
other free to revolve either through a complete revolution or partially. Upon the
stationary circular part are two terminals or contact pieces connected by binding
screws to the wire carrying the current. A contact piece of suitable form is attached
to or forms part of the revolving portion of the switch, so formed and adjusted that
the opposite ends of it leave the stationary contact pieces at exactly the same instant.
The electrical contact between these movable parts & the fixed contact points is
secured by a spring or springs.
The whole of the above parts are mounted upon a suitable base and contained in a
circular casing which may be either stationary or may revolve carrying the contact
piece with it.
R. M. BAILY, JNR.
A. GRUNDY.

page_text: Improvements in Electrical Switches.
ROBERT MAJOR BAILY Junr. Engineer and ALFRED GRUNDY Electrician Amberley
Works, Amberley Road, Paddington W. do hereby declare the nature of our invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The objects of this Invention may be enumerated as follows. First:-The con-
struction of an electrical switch which will ensure the electrical surfaces when switched
on being maintained in close electrical contact. Second :-That the pressure keeping
them in contact is an uniform balanced pressure which will reduce the wear of the
frictional surfaces to a minimum. Third:-That the medium employed for keeping
the contact pieces in close connection forms a conductor of a very large section in
proportion to the current:-and Finally :-That the circuit is broken simultaneously
at two points so reducing sparking.
The improvements may be described as follows:-The switch consists of two
concentric parts, one of which is fixed and the other free to revolve through a complete
or part revolution only.
Upon the stationary circular part are two terminals or contact pieces connected by
suitable attachments to the wires or other conductors conveying the current.
A contact piece of suitable form is attached to, or forms part of the circular
revolving part of the switch so formed and adjusted that the opposite ends of it leave
the stationary contact pieces at exactly the same instant. Good electrical contact
between the revolving and stationary parts is ensured by a spring or springs,
preferably of the type known as a spring ring, similar to that in use in steam engine
pistons, or by means of a circular elastic hoop carrying the contact pieces and which
surrounds or is surrounded by the fixed circular part of the switch, this hoop which
must be of a good conducting material, being elongated or compressed as the case may
be to give the required pressure between the contacts when the switch is on.
In order that our Invention may be more readily understood and explained in
detail we have hereunto annexed three sheets of Drawings on which letters of reference
are marked on corresponding parts on all the Figs. alike.
DESCRIPTION OF DRAWINGS.
Fig. 1. represents a plan; and
Fig. 2 a vertical section of a plain make and break switch constructed according to
our Invention. In these Figs. a is the circular stationary portion of the switch, and
b, b are the terminals thereon, c is the moveable circular portion of the switch, placed
in a concentric position relative to the fixed circular part a and forming the key
which turns the elastic hoop d carrying the contact pieces e, e. The hoop d is
stretched from its normal shape to allow the contact pieces e, e, to slip over the circular
stationary part a see Fig. 1, by which means a steady and balanced pressure is

page_text: maintained between them thereby ensuring excellent contact. The pieces e, e, are so
adjusted that they both make and break contact with bb, at the same instant of time
thus lessening the risk of sparking.
Figs. 1 and 2 represent respectively a plan and vertical section of a similar switch
to that last mentioned; but with the fixed circular part a of the switch encircling the
movable circular part.c, instead of being encircled by it as in the former example,
according to this arrangement, the spring hoop d has the contact pieces e, e mounted
on its outside surfaces, instead of on its interior surface as in Figs. 1 and 2.
Fusible cut out wires are shewn at f. f. to prevent damage from excess of current.
For switches to carry heavy currents two or more spring hoops d may be mounted
symmetrically so as to turn about the same axis, and each carrying its own contact
pieces or all supporting contact pieces in common as may be most suitable.
Figs. 3. and 4 shew a distributing switch constructed in accordance with our
Invention.
Figs. 5 and 6 shew a combination of two switches constructed in accordance with
this Invention and applied in combination with our improvements in electrical switches
patented December 1st 1885 and numbered 14742.
Having now particularly described, and ascertained the nature of our said Invention,
and in what manner the same is to be performed, we declare that what we claim is
--
1st. The combination in an improved electrical switch of two concentric parts, one
of which is movable, and carries two contact pieces, which are forced into contact with
their respective terminals by a hoop spring in the manner as described herein and
shewn in the drawings annexed.
2. The use in revolving or sliding electrical switches, of the hoop spring or springs
marked d described and illustrated in the drawings annexed.
3. The combination of the improvements described herein, with our improvements,
patented on the 1st day of December 1885 and numbered 14742.