Improvements in Plugs for Telephone Switchboards.
Year: 1899

page_text: Date of Application, 10th Aug., 1899
Complete Specification Left, 9th May, 1900-Accepted, 7th July, 1900
I, ERNEST DOUGLAS PEARMAIN, 12, Houblon Road, Richmond, Surrey, Engineer,
de hereby declare the nature of this invention to be as follows:-
The object of this invention is to provide a better way of holding the cord
in the plug. The disadvantage with the present method is that the cord easily
becomes defective owing to the fabric composing the outer covering to the con-
ductors not being held securely and also by it becoming torn and frayed at the
point where it enters the plug.
According to my invention the end of the plug which is bored to receive the
cord is slightly bevelled and through it three or more saw kerfs or slits are cut
longitudinally. A metal ring is then slipped over the body of the plug from the
opposite end. In placing the fibre cover in position by means of the nut in the
usual way this metal ring is forced over the bevel to a shoulder thus closing the
saw cuts or slits and reducing the diameter of the bore at the cord end, thereby
compressing the cord and causing a firm grip to be obtained on the fabric.
Dated 9th day of August 1809
E. DOUGLAS PEARMAIN.
Improvements in Plugs for Telephone Switchboards.
I, ERNEST DOUGLAS PEARMAIN, Engineer; 2, Station Road, Hampton, Middlesex,
formerly of 12, Houblon Road, Richmond, Surrey, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particu-
larly described and ascertained in and by the following statement:―
The object of this invention is to provide a better way of holding the cord
in the plug. The disadvantage with the present methods is that the cord easily
becomes defective owing to the fabric composing the outer covering to the con-
ductors not being held securely and also by it becoming torn and frayed at the
point where it enters the plug.
According to my invention the end of the plug which is bored to receive the
cord is slightly bevelled, and through it three or more saw kerfs or slits are cut
longitudinally, a metal ring is then slipped over the plug from the opposite end,
the fibre cover is slipped on resting on the metal ring, a nut is screwed on the
threaded portion of the plug forcing the fibre cover, and consequently the metal
ring over the bottom of the plug thereby closing the saw kerfs or slits, and thus
compressing and causing a firm grip to be obtained on the fabric.

page_text: My invention is illustrated by the accompanying drawing, in which like parts
are indicated by similar letters of reference in the different figures.
Fig. I illustrates the plug in elevation with metal ring, fibre cover, and nuts
in position.
Fig. II is a similar view with metal ring, fibre cover, and nuts removed.
Fig. III is a plan of bottom of plug shewing saw kerfs or slits.
Fig. IV is an elevation of metal ring.
Fig. V is a plan of top of metal ring.
Fig. VI is an elevation of fibre cover of plug.
a represents fibre cover, 6 metal ring, c saw kerfs or slits in body of plug, the
latter being bevelled as shewn, d a projection on body of plug, e a pin projecting
from top of ring b, f a slot cut on inside of metal ring & fitting over projection d,
ga slot cut in fibre cover a, into which fits pin e of metal ring b, h, h', nuts for
screwing and locking fibre cover a in position. In practice my invention is
carried out in the following manner: -the cord is passed through hole in the
bottom of plug, and the ends attached to the plug conductors in the usual way,
the metal ring 6 is now slipped over the top of plug, so that slot f fits over pro-
pection thus preventing ring from turning cover a is also slipped over top of
plug in such a manner that slot g fits over pin c of ring b, nut is now screwed
on to thread cut on body of plug, thereby forcing fibre cover a, and with
it metal ring b over bottom of plug causing saw kerfs or slits e to close thus
gripping the cord passing through the bottom of plug, finally lock nut ¹ is
screwed on locking nut .
Having now particularly described, and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what
I claim is
1. The combination with a switchboard plug having saw kerfs or slits in the
bottom, of a metal ring, fibre, cover and fixing nuts substantially as and for
the purpose above specified.
T 01.
1000
ERNEST DOUGLAS PEARMAIN.