An Improved Spring Jack for Telephonic and other Electrical Purposes in which it is Desired to Change or Switch a Current from one Conductor to another.
Year: 1887

page_text: NEJ
Date of Application, 19th Nov., 1887
Complete Specification Left, 18th Aug., 1888
Complete Specification Accepted, 19th Oct., 1888
An Improved Spring Jack for Telephonic and other Electrical
Purposes in which it is Desired to Change or Switch a Current
from one Conductor to another.
We, ALFRED COLEMAN, of Dûlas, Stanmore Road, Edgbaston in the County of
Warwick, telegraph engineer, HUBERT FEILDEN JACKSON, of Ashurst, Sydenham in
the County of Surrey, Gentleman, and ERNEST LEONARD DUDLEY, of 110 Eversley
Road, Small Heath in the County of Warwick, mechanic, do hereby declare the
nature of this invention to be as follows:-
A spring jack for telephonic purposes, but which may of course be used for other
analogous electrical purposes in which it is desired to change or switch an electrical
current from one conductor to another, as usually constructed, consists of a spring and
of a slipper of which the spring is bent downwards at its forward end to bear upon
the slipper and give the necessary electrical contact for the passage of the current from
the spring to the slipper; and the forward end of the spring is curved up to allow
of the ready insertion of a plug when it is desired to switch the current through a line
otherwise than the one passing from the slipper. It is found, however, that as there is
practically no rubbing contact between the spring and slipper, but simply a bearing
contact, there is a liability of the spring not bearing sufficiently upon the slipper to
give the necessary electrical contact, owing to the fact that the absence of a rubbing
contact prevents the spring from rubbing itself to a proper bearing upon the slipper
each time it comes in contact therewith on the withdrawal of the plug; and this liability
is aggravated by the tendency there is of corrosion taking place, or grit accumulating,
between the bearing surfaces, in cases in which the insertion of the plug takes place
at very infrequent intervals; and this liability may also be aggravated to some extent
even in cases where the insertion of the plug is of very frequent occurrence,
owing to a tendency which the spring has to become strained.
Now, the object of this invention is to provide means for ensuring proper electrical
connection between the spring and slipper, upon the removal of the plug, even
though the spring may fail to bear properly upon the slipper.

page_text: This object is effected, according to this invention, by fitting the spring jack with a
secondary spring which is fixed at its forward end permanently in contact with the
slipper and, when the plug is not inserted within the jack, bears up at its hinder end
against the underside of the main spring. As the plug is inserted within the jack it.
not only raises the front end of the main spring, but bears also upon the secondary
spring and depresses its unconnected end, and thus breaks the contact between the
two springs. It will be seen that the two springs being fixed at their opposite ends in
relation to one another, the effect of their vibration as the plug is inserted into and
withdrawn from the jack causes a rubbing contact between the unconnected end of
the secondary spring and the underside of the main spring, and thus there is always
a complete electrical connection between the main spring and the slipper through
the secondary spring.
"
The secondary spring may, if desired, be formed in one piece with the slipper.
This invention is specially useful for employment with a test board in which spring
jacks are employed for cutting the line wires out of their ordinary circuit, such as in the
test board described in the provisional specification filed by the said Alfred Coleman
and Hubert Feilden Jackson on the 14th day of October 1887, No. 13960, with an
application for a patent in respect of their invention of "A novel combination of
spring-jack and lightning arrester for use in or with a test board for telephone wires,
"and means of carrying and a method of arranging any required number of sets or
"apparatus formed of such combination; such invention being applicable, also, for
"the purpose of a telephone switch board, and for other analogous electrical purposes,"
because when used with a test board it is comparatively seldom that the plug has to
be inserted within the jack and therefore there is special liability to corrosion taking
place between the spring and slipper, and to the accumulation of dirt.
Dated this 18th day of November 1887.
STEPHEN WATKINS,
Wolverhampton and Walsall,
Agent for the Applicants.

page_text: An Improved Spring Jack for Telephonic and other Electrical
Purposes in which it is Desired to Change or Switch a Current
from one Conductor to another.
We, ALFRED COLEMAN, of Dûlas, Stanmore Road, Edgbaston in the County of
Warwick, telegraph engineer, HUBERT FEILDEN JACKSON, of Ashurst, Sydenham
in the County of Surrey, Gentleman, and ERNEST LEONARD DUDLEY, of 29, Bordesley
Green Road, Small Heath, late of 110, Eversley Road, Small Heath, in the County of
Warwick, mechanic, 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 :—
A spring jack for telephonic purposes, but which may of course be used for other
analogous electrical purposes in which it is desired to change or switch an electrical
current from one conductor to another, as usually constructed, consists of a spring and
of a slipper of which the spring is bent downwards at its forward end to bear upon the
slipper and give the necessary electrical contact for the passage of the current from
the spring to the slipper; and the forward end of the spring is curved up to allow of
the ready insertion of a plug when it is desired to switch the current through a line
otherwise than the one passing from the slipper. It is found, however, that as there
is practically no rubbing contact between the spring and slipper, but simply a bearing
contact, there is a liability of the spring not bearing sufficiently upon the slipper to
give the necessary electrical contact owing to the fact that the absence of a rubbing
contact prevents the spring from rubbing itself to a proper bearing upon the slipper
each time it comes in contact therewith on the withdrawal of the plug; and this
liability is aggravated by the tendency there is of corrosion taking place, or grit
accumulating, between the bearing surfaces, in cases in which the insertion of the
plug takes place at very infrequent intervals; and this liability may also be
aggravated to some extent even in cases where the insertion of the plug is of
very frequent occurence, owing to a tendency which the spring has to become
strained.
Now the object of this invention is to provide means for ensuring proper electrical
connection between the spring and slipper, upon the removal of the plug, even
though the spring may fail to bear properly upon the slipper.
In order that the invention may be readily understood we will proceed to describe
it with reference to the accompanying drawing; of which Figure 1. is a full size
view of the apparatus hereinafter described. Figure 2. is a front view of the same.
Figure 3. shows the operation of the plug on the springs of the spring jacks. a is the
slipper, is the main spring a & b together forming the spring jack, c is the
secondary spring. With the object of ensuring a good electrical connection between
the slipper a and the spring b in any ordinary or special form of spring jacks a
secondary spring c is provided, which is fixed at its forward end permanently in
contact with the slipper a and, when the plug is not inserted within the jack, bears up

page_text: at its hinder end c¹ against the underside of the main spring b. As the plug A
Figure 3 is inserted within the jack, it not only raises the front end of the main
spring but bears also upon the secondary spring c and depresses its unconnected
end and thus breaks the contact between the two springs. It will be seen that the
two springs being fixed at their opposite ends in relation to one another, the effect of
their vibration as the plug is inserted into and withdrawn from the jack causes a
rubbing contact between the unconnected end of the secondary spring and the under-
side of the main spring, and thus there is always a complete electrical connection
between the main spring and the slipper through the secondary spring.
The secondary spring may, if desired, be formed in one piece with the slipper.
This invention is specially useful for employment with a test board in which spring
jacks are employed for cutting the line wires out of their ordinary circuit, such as in
the test board described in the provisional specification filed by the said Alfred Coleman
and Hubert Feilden Jackson on the 14th day of October 1887 No. 13960 with an
application for a patent in respect of their invention of "A novel combination of
spring jack and lightning arrester for use in or with a test board for telephone wires,
"and means of carrying and a method of arranging any required number of sets or
apparatus formed of such combination; such invention being applicable, also, for
"the purpose of a telephone switch board, and for other analogous electrical purposes,"
because when used with a test board it is comparatively seldom that the plug has to
be inserted within the jack and therefore there special liability to corrosion taking
place between the spring and the slipper, and to the accumulation of dirt.
"
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 means of ensuring proper electrical connection between the spring and
slipper of any ordinary or special form of spring jack, by the provision of a secondary
spring, either in the form shown in the drawings or in any other form answering
the same purpose, substantially as described.