Improvements in Electric Switches.
Year: 1899

page_text: Date of Application, 5th June, 1899
Complete Specification Left, 23rd Jan., 1900-Accepted, 24th Feb., 1900
PRUVDIVAAL UITICATIOA.
Improvements in Electric Switches.
We, THOMAS HERBERT MARSH and ALBERT VANDAM, both of 39, Victoria Street,
Westminster, in the County of London, Electrical Engineers, do hereby declare
the nature of this invention to be as follows:-
Our invention relates to electric switches and has for its object to improve the
construction of switches of that kind or class in which a pivoted metallic bridge
piece is caused by the operation of a lever to make connection between two fixed
terminals. In switches of this general character it has hitherto been the custom
to provide for insulating the bridge piece from the operating lever, which latter
is commonly made of metal, by mounting said bridge piece upon a bar of insulat-
ing material such as vulcanized fibre, ebonite or the like material, and it has not
been found practicable to use porcelain or earthenware for said bar owing to the
fact that its small size and the fragility of the material prevent the metallic parts
being secured thereto by screws or similar means such as are employed for securing
said parts to vulcanized fibre.
It is desirable, however, for reasons which will be readily appreciated by persons
skilled in the art that all the insulating parts of the switches including the bar
above mentioned should be formed of porcelain, and our invention has for its
object to provide an improved construction of switch of the type above mentioned,
in which the metallic bridge piece is secured to a porcelain or earthenware bar
with which the operating lever engages.
According to our invention we accomplish this in the manner following:-
The metallic part of the bridge piece is made in the form of a shoe, one end of
which is provided with a recess in which the end of the porcelain bar engages;
the other end of the shoe is furnished with side flanges by means of which the
bridge piece is pivoted to uprights secured to or forming part of the base of the
switch. The pivoted pin passes through holes formed in said flanges, and in
order to maintain the insulating bar in position in the shoe may also pass through
an orifice in said bar, or may be seated in a notch or nick formed in the end of
said bar. The upper portion of the bar is preferably provided with a groove or
channel in which the end of the operating lever moves, as is usual in switches
of this type.
It will be seen that by our improved construction the insulating bar can be
made of very simple form, and that no screw holes need be provided therein for
the securing of the metallic parts, said parts are, however, held very firmly to the
insulating portions. It is obvious that our improved construction is not restricted
to switches in which the insulating parts are made of porcelain, although it was
designed with a view to the employment of this substance, said parts may, how-
ever, be made of vulcanized fibre or any other suitable insulating material.
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page_text: We, THOMAS HERBERT MARSH and ALBERT VANDAM, both of 39, Victoria Street,
Westminster, in the County of London, Electrical Engineers, 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 invention relates to electric switches and has for its object to improve the
construction of switches of that kind or class in which a pivoted metallic bridge
piece is caused by the operation of a lever to make connection between two fixed
terminals. In switches of this general character it has hitherto been the custom
to provide for insulating the bridge piece from the operating lever, which latter
is commonly made of metal, by mounting said bridge piece upon a bar of insulat-
ing material such as vulcanised fibre, ebonite or the like material, and it has not
been found practicable to use porcelain or earthenware for said bar owing to the
fact that its small size and the fragility of the material prevent the metallic
parts being secured thereto by screws or similar means such as are employed for
securing said parts to vulcanised fibre.
It is desirable, however, for reasons which will be readily appreciated by persons
skilled in the art that all the insulating parts of the switches including the bar
above mentioned should be formed of porcelain, and our invention has for its
object to provide an improved construction of switch of the type above mentioned,
in which the metallic bridge piece is secured to a porcelain or earthenware bar
with which the operating lever engages.
We will now proceed to describe our invention with reference to the accom-
panying drawings, in which the same reference figures refer to the same parts
in the various figures.
Figure 1 is a part sectional front elevation of the switch in its on" position,
the cover being removed.
Figure is a side elevation of the same.
Figure 3 is a plan of the same.
Figure 4 is a transverse section of the switch in its "off" position the cover
being removed.
Figure 5 is a detail view of the metallic bridge-piece and insulating block.
The base of the switch is provided with two uprights 2, 3 formed integral
with or securely attached to said base, and is also provided with the two terminal
blocks 5, 6, to which the two leads, inserted through two holes in the base, are
connected. The bridge piece 7 pivoted on the pin 13 between the two uprights 2,
3 is adapted, on the switch being operated, to make connection between the two
terminal blocks 5, 6, and is returned to its original position when the switch is
turned off by means of the spring as seen in Figure 4. The switch is operated
by means of the switch lever 4 pivoted to a cap fixed on the ends of the up-
rights 2, 3, said switch lever 4 actuating the pivoted bridge piece 7 through the
insulating block 9 carried by the bridge piece. The metallic bridge piece
made in the form of a shoe preferably by bending sheet copper or other suitable
metal into the required shape, one end of which is provided with a recess, clip
or hook in which the end 8 of the porcelain or earthenware insulating block
engages. The other end of the shoe is provided with side flanges 12 by means
of which the bridge piece is pivoted to the uprights. In order that the block 9,
insulating the switch lever from the bridge piece, may be kept in position on
said bridge piece, it is convenient to arrange the pivot pin 13 to pass through an
orifice 11, in said block, as shewn clearly in Figure 4, or a notch or nick may
is

page_text: be formed in the end of said block. The upper portion of the block is prefer-
ably provided with a groove or channel 10 in which the end of the operating
switch lever moves, as is usual in switches of this type.
It will be seen that by our improved construction the insulating bar can be
made of very simple form, and that no screw holes need be provided therein for
the securing of the metallic parts, said parts are, however, held very firmly to
the insulating portions. It is obvious that our improved construction is not
restricted to switches in which the insulating parts are made of porcelain, although
it was designed with a view to the employment of this substance, said parts may,
however, be made of vulcanized fibre or any other suitable insulating material.
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:-
1. In an electric switch of the kind described a metallic bridge piece in the
form of a shoe adapted to support a block of porcelain or other insulating
material with which the operating lever engages, substantially as described.
2. An electric switch constructed substantially as described with reference to
the accompanying drawings,
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham