An Improved "Bar" or Bridge "Electric Light Switch.
Year: 1888

page_text: Date of Application, 9th Nov., 1888
Complete Specification Left, 9th Sept., 1889-Accepted, 19th Oct., 1889
PROVISIONAL SPECIFICATION.
66
An Improved "Bar" or Bridge "Electric Light Switch.
I, ANDREAS PETER LUNDBERG, of 1A Bowling Green Lane Buildings, Farringdon
Road, in the County of Middlesex, "Scientific Instrument Manufacturer" do hereby
declare the nature of this invention to be as follows:-
My invention relates to that class of electric light switches known as "Bar" or
Bridge" switches; the improvement consists of an improved method of applying
the throw off springs.
The springs being applied in such a manner as to cause the two ends of the contact
bar or bridge to be pulled or pressed down on to the contact or pole pins, by the
pressure of the two springs, each acting at equal distances from the centre of the bar
or bridge so as to remain equal pressure on both sides of the centre of the bridge,
and thereby securing a good rubbing contact, while the bridge is in motion, and
a firm decided contact when the bar or bridge is in the "on position.
,,
I construct my Invention with an insulating base which may be of any material,
but preferably of some refractory material, such as porcelain or slate, and mount upon
it, two contact or pole pieces of metal placed opposite each other fixed to the base by
screws, with a cross bar or bridge which is fixed to the aforesaid base by screws.
Upon this fixed bridge is pivotted on a screw, the moveable contact bar or bridge, and
the handle which may be of any suitable material. On the under side of the bar or
bridge two pins are fixed carrying rollers, the shape of which resembles a musliroom
turned upside down.
Fixed in a recess in the base are two steel springs of a spiral pattern, these springs
by their ends fixed to screws set in such a position that both ends of each spring are
below the surface of the rollers, and one end of each spring placed a little lower down
than the other end of the same spring.
These springs pass across the recess and round the outside of the rollers and
through the ends of the springs being placed lower than the rollers on which they
rest, they will exert a pressure on the moveable bridge according to the tension of the
springs.
The action of the switch is as follows When the switch is in the " on" position
the springs are here stretched, and the rollers are movod round towards the lowest ends
of the springs, thereby causing the springs to exert a downward pressure on the
moveable bridge in proportion to the tension of the springs, and after the bridge
having passed the turn in right angles to the turn of the spring in the "on" position,
until moved by force. The downward pressure of the springs is due to the tendency
of the springs to straighten themselves which the flange or head of the roller prevents.
The pressure being transmitted by the springs through the flanges or heads of
the rollers, and from the rollers to the headed pius, and from the pins to the
moveable bridge or bar.
When the switch is in the "off" position the springs are lying nearly parallel
and only slightly stretched sufficiently to keep in the off" position. The springs
here do little more than keep the moveable bridge in the "off" position, and
having very little pressing down action in this position, owing to the rollers
being at the highest ends of the springs, and through being constructed in this
way it has a particularly smooth feel when moving it from the "on" to the "off"
position.
n
1000
J. P. BAYLY,
18, Fulham Place, W., Agent for the Applicant.

page_text: Figure 2 denotes an elevation,
To this end, I take an insulating base A which may be of any material but preferably
of some refractory material as porcelain or slate, and mount upon it two contact
or pole pieces of metal B, B, placed opposite each other as in figure 1, fixed to the
base by means of screws.
D) is a cross-bar or bridge which is fixed to the base A by means of screws C, C.
Upon this fixed bridge D is pivotted on a screw at E the moveable contact bar
or bridge F and the handle G which may be of any suitable material.
On the under side of F two pins G, G, are fixed carrying rollers H, H, the shape
of which resembles a mushroom turned upside down. Fixed in a recess I in the
base are two springs J, J, which are preferably of the spiral pattern as shewn made
of any springy metal; these springs by their ends fixed to the screws C, C, in
such a position that both ends of each spring aro below the surface of the
rollers H, H, and one end of each spring placed a little lower than the other end of
the same spring. These springs pass across the recess I and round the outside of
the rollers H, H, and through the ends of the springs being placed lower than the
rollers on which they rest they will exert a pressure on the moveable bridge according
to the tension of the springs.
The action of the switch is as follows:-
In the position shewn in figure 1 the switch is in the ON position the springs are
here stretched and the rollers are moved round towards the lowest ends of the
springs thereby causing the springs to exert a downward pressure on the moveable
bridge D in proportion to the tension of the springs, and after the bridge having
passed the line K, K, in right angle to the line of the two springs is kept in the ON
position until moved by force.
The downward pressure of the springs is due to the tendency of the springs to
straighten themselves which the flange or head of the roller prevents the pressure
being transmitted by the springs through the flanges or heads of the rollers, and
from the rollers to the headed pins G, G, and from the pins G, G, to the moveable
bridge or bar F.
When the switch is in the OFF, position the springs are lying nearly parallel and
only slightly stretched sufficiently to keep the switch in the off position, the
springs J, J, here do little more than to keep the moveable bridge in the off position
and having very little pressing down action in this position owing to the rollers
being at the highest ends of the springs J, J, and through being constructed in
this way it has a particularly smooth feel when moving it from the ON to the OFF
position.

page_text: 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 :-
The application of the throw off springs in such a manner as to press the
contact surfaces into contact as well as throwing the bar into the ON or Off
position, substantially as herein described and according to the accompanying
drawings.
Dated this 9th day of Santamshon 1884
J. P. BAYLY,
18, Fulbam Place, W., Agent for the Applicant.