Improvements in Switches for Electrical Purposes.
Year: 1891

page_text: ate of Application, 8th Dec., 1891-Accepted, 9th Jan., 1892
COMPLETE SPECIFICATION.
Improvements in Switches for Electrical Purposes.
I, FRANK GEERE HOWARD of 13 Berners Street, London, W. 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:
The object of my invention is to remedy a defect in the well known tumbler
switch. That apparatus is apt to jam when the bar is in position to make contact.
In such case, if the spring becomes weakened or for any other reason cannot cause
the contact bar to rise when the handle is turned so as to release the bar and allow
it to rise if the spring worked effectively for the purpose for which it is
intended, the bar remains in the position of making contact, and contact cannot be .
broken.
In apparatus constructed according to my invention the handle part A has a
slot D cut in it in that part of the handle part which is nearest the contact bar B
and of the shape shown in the drawings. This slot D works on a pin C fixed to
the bar B as shown in Figs. II and III. There may (preferably) be a pin on
either side of the bar, and the end of the handle part is then forked so as to pass
over the bar; a slot cut in each side of the fork working on its pin as shown
in Fig. III.
Alternatively the slot may be made to work in connection with a staple C¹, the
ends of which are rigidly fastened to the sides of the bar B, passing over the top
of the bar the part of the staple C' which is over the bar being arranged to pass
through the slot D as shown in Figs. IV and V.
A roller round the pin C or the cross bar of the staple C¹ is of material
advantage in reducing friction in the working of the apparatus.
The advantage derived by the use of either of the forms of my invention is
that when contact has been made by turning the handle part, on the pivot F, so
that the bar B is forced down and makes contact by touching the contacts H, it
can with certainty be withdrawn again and contact broken, whether the spring S
works or not, as the handle controls the bar B by means of the pins or staple
respectively working in the slot and forcing the bar to rise and break contact when
the handle is turned in the opposite direction.
In the accompanying drawings, in which like letters indicate like parts, I have
shown. how my invention may be carried into practice.
Fig. I is a section of the handle part A. with the slot D.
Fig. II is a side elevation of the whole apparatus, with the slot D working on a
pin Caffixed to the side of the contact bar B. This bar B works on a pivot or
hinge G. The thread of a screw shown round the arm in which is the pivot F
(on which the handle part A turns) is intended to hold a cover to protect the
working parts.
Fig. III is a front elevation of a forked handle part working on pins C, C, on
either side of the bar B.
Fig. IV is a side elevation, and Fig. V a front elevation of the handle part A.
when connected to the bar by means of a staple C¹ working in the slot D.
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:
(I.) The use of a slotted handle part working on a pin or staple which is rigidly

page_text: fixed to the contact bar of a tumbler switch for electrical purposes substantially as
above described and with reference to the drawings.
(II.) The construction of a switch for electrical purposes substantially as above
described.
Dated this Eighth dox of December 1801