Non-percussive Quick Break Electric Switch.
Year: 1891

page_text: Date of Application, 26th Feb., 1891-Accepted, 28th Mar., 1891
COMPLETE SPECIFICATION.
Non-percussive Quick Break Electric Switch.
We, CHARLES MARK DORMAN, of 24, Brazennose Street, Manchester, in the
County of Lancaster, Electrical Engineer, and REGINALD ARTHUR SMITH, of 24,
Brazennose Street, Manchester, in the County of Lancaster, 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 invention relates to that class of switch described in our Patents Numbers 16578,
1886, 14768-1887, 16099-1888 in which the motion of the contact arm or arms is
controlled by means of a spring embracing a spindle and acting on cams or projections.
The object of our invention is to prevent the percussive action which generally takes
place in switches of the sudden release type, when the contact arm flies off against
a rigid stop tending to derange the mechanism of the switch. Our object also is to
obtain a good elastic spring contact between the contact arm and the fixed jaws in
the shortest possible space. Referring to the drawings accompanying this Speci-
fication Fig. 2 is a plan of the switch with the cover removed and the hollow spindle
attached to the contact arms in section on the line w. w. Fig. 1 is a sectional
elevation of the switch on the line a. a. Fig. 3 is a section of the contact jaw on the
line y. y. Fig. 5 is the plan of another form of our improved contact jaw. Fig. 4
is a section of the same jaw on the line . z. a. is a hollow spindle with cams or
projections rigidly attached to the contact arms b. b. and acted on by the spring c.
The hollow spindle turns freely on the peg d. rigidly fixed in a plate attached to the
base of the switch. It will be seen that the cams on a. are so shaped that at the
moment of breaking contact the pressure of the spring causes a strong turning
couple tending to cause the contact arms to dart rapidly away from the jaw, but
that when the arms reach the position shewn in dotted lines in Fig. 2 any further
motion is opposed by the action of the spring on the cams, and the arms are brought
gradually to rest without any percussive shock. The stop e. is to prevent the
operator turning the switch in a backward direction, and making contact with the
terminals. f. is an elastic metal tongue which presses the contact arm against the
contact plate g. ensuring a good contact. It will be seen that the contact plate g.
can either be fitted with a terminal for cables as shewn in Fig. 2 and 3 or fitted
with a screw for attachment of small wires as shewn in Fig. 4 and 5. The elastic
tongue f. is turned under itself and is fixed between the contact plate g. and. the base
of the switch at a point below the point of contact of the arm with the contact plate
by a screw or screws one of which projects through the contact plate and forms a
stop for the arm of switch. In the form of jaw shewn in Fig. 4 and 5 the elastic
plate forming the tongue is also projected backwards under the contact plate and is
held in position by the screw h. The switches shewn in drawings are of the double
break type but it is obvious that our improvements are equally applicable to switches
having one only or any number of contact arms. Our improved non-percussive
action is equally applicable to forms of switches in which the arm is held in contact
with the contact plates by other methods than the top spring tongue, and our
improved contact jaw is applicable to switches in which the contact arm is actuated
by any of the methods commonly in use.
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 method of forming the projections or cams attached to the contact arm in
uch a manner that the enring eating compressively on either side of central snindle

page_text: after the contact arms have cleared the contact places tends to bring the contact
arms to rest without percussive action before they reach the rigid stop.
(2.) The improved contact jaw in which the top elastic tongue is turned under
itself and held between the contact plate and base of switch at a point below the
point of contact of the arm with the contact plate.
Dated this Twenty-fifth day of February 1891.
CHARLES MARK DURMAN,
24, Brazenose Street, Manchester.
REGINALD ARTHUR SMITH,
24, Brazenose Street, Manchester.