Improvements in Insulators for the Overhead Conductors of Electric Tramways.
Year: 1899

page_text: Date of Application, 11th July, 1899
Complete Specification Left, 9th Apr., 1900-Accepted, 12th May, 1900
Improvements in Insulators for the Overhead Conductors of Electric
Tramways.
A communication from abroad from THE ACTIEN-GESELLSCHAFT ELEKTRICITÄTS-
WERKE vormals 0. L. KUMMER & Co., of Dresden and Niedersedlitz, Germany.
I, WILLIAM LLOYD WISE, of 46, Lincoln's Inn Fields, in the County of London,
Consulting Engineer and Chartered Patent Agent, do hereby declare the nature
of this invention to be as follows:-
The suspension of the insulators of the overhead conductors of electric tramways
by span wires on curves is not very practical, as there is a tendency for the insula-
tor to be displaced on account of the tensile strain of the conductor tending to
draw the insulator to the centre of the curve, whereby the brush of the trolley pole
may be prevented from passing smoothly along, and may be caused to leave the
overhead conductor.
Now this invention relates to means for obviating these inconveniences while
at the same time providing an insulator of neat exterior appearance.
For this purpose an overhead wire insulator for curve-lines, suspended on a
cross wire, is so constructed that the pull exerted by the overhead wire on the
insulator proper in a direction towards the centre of curvature of such overhead
wire, is compensated by giving the insulator a corresponding moment of rotation
in an opposite direction by suitably arranging the points of attachment of the
cross wire to the insulator.
In one arrangement according to this invention the two points of attachment
for the span wires to the insulator are on lateral arms or projections of the insula-
tor, one of the arms or projections being approximately horizontal and the other
bent upwards in such a manner that, by means of the pull of the two parts of the
span wire, a moment of rotation will be produced opposite in direction to the strain
on the lower downwardly extending portion of the insulator, i.e. the insulator
proper, due to the pull of the curved portion of the overhead conductor. It can
easily be arranged that for a certain strain, the insulator proper shall retain its
vertical direction.
In another arrangement according to this invention there are several points of
attachment for the span wire on the upwardly bent lateral arm. or projection of the
insulator. According as the span wire is fastened to a higher or lower point of
attachment on the said upwardly bent arm or projection, the moment of rotation
caused by the pull of the span wire, will be increased or diminished. An insulator
such as described can be used for curves of greatly varying radii and tensions..
According to a third mode of construction the insulator is adapted to be readily
fastened to a span wire already spanned. For this purpose the points of attach-
ment are provided with hooks (which are turned downwards on the horizontal arm
or projection and upwards on the upwardly extending arm or projection. The
insulator also carries a projection provided with a thread and slot the slot being

page_text: of sufficient size to allow of the insertion of the span wire which may be secured
therein by suitable means such as a nut screw. The hooks on the lateral arms
or projections are respectively set over and under the span wire.
It will be understood that by this third mode. of construction the tension of the
span wire also produces a moment of rotation opposed to the strain due to the
curve of the overhead conductor.
Data
1111 1
1000
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.
Improvements in Insulators for the Overhead Conductors of Electric
Tramways.
A communication from abroad from THE ACTIENGESELLSCHAFT ELEKTRICITÄTS-
WERKE (vorm. O. L. KUMMER & Co.,) of Dresden and Neidersedlitz, Germany.
I, WILLIAM LLOYD WISE, of 46, Lincoln's Inn Fields, in the County of London,
Consulting Engineer and Chartered Patent Agent, 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; —
When ordinary trolley-wire insulators suspended by cross-wires are on curves,
the tension of the wire, the resultant of which acts towards the centre of curvature
of the wire, throws the insulator out of its vertical position and thereby
causes it to form an obstruction to the motion of the trolley and also to present an
unsatisfactory appearance.
Now this invention has for object to remedy these disadvantages. According
thereto such an insulator is so constructed as to furnish means of attachment for
the cross wire or wires such that the insulator can be thereby given a turning
moment to compensate for the pull towards the centre of curvature exerted by the
trolley or overhead wire upon the insulator clip.
The accompanying drawings represent three examples of insulators according
to this invention carrying curved conductors suspended by their cross wires. In
each case the insulator-clip a is pulled by the trolley wire in the direction indicated
by the arrow P.
In the example shown in Fig. 1 the points of attachment b and c for the cross
wires are arranged on two lateral arms of the insulator-one of which is approxi
mately horizontal whilst the other is bent upwards-in such a manner that the
turning moment exerted by the cross-wires and acting in the direction indicated
by the arrow pl is equal and opposite to the turning moment in the direction
indicated by the arrow and resulting from the curve.
points of attachment b and c can easily be arranged for a given trolley wire pull
The positions of the
so as to retain the insulator in its vertical position.
In the example shown in Fig. 2 there are several points e for the attachment of
the cross-wires to the upwardly bent arm. According as the cross-wire is fastened
to a higher or a lower point the turning moment resulting from the tension of the
cross-wires will be increased or diminished. An insulator of this kind may there-
fore be used for curves of different radii and tensions.
Fig. shows an example adapted to be fastened to a cross-wire already stretched
and fixed. For this purpose at the points band where the cross-wires are
attached there are provided hooks, that at the point on the horizontal being

page_text: turned downwards and those at c on the upwardly extending arm being turned
upwards. The insulator also carries a projection d provided with a thread and a
slot. The cross-wire is inserted into this slot and secured by means of a nut,
whereupon the hooks at b and c are respectively set over and under the cross-wire.
It will be seen that in this case also the pull of the cross-wire imparts to the insu-
lator a turning moment opposed to that resulting from the curve.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. An insulator for suspending by a cross-wire or cross-wires and supporting a
curved overhead-wire, constructed so as to furnish means of attachment for the
cross wire or wires such that the insulator can be thereby given a turning moment
to compensate for the pull towards the centre of curvature exerted by the over-
head wire upon the insulator-clip and tending to throw the insulator out of the
vertical position.
2. An insulator according to the preceding claim in which there are two lateral
arms adapted to be approximately horizontal and upwardly extending respectively
when in position so that the point of attachment of one arm will be higher than
that of the other in order to give the compensating turning moment (Fig. 1).
3. An insulator according to Claim 2 in which the upwardly extending arm is
provided with several points of attachment so that by attaching the cross-wire to
a higher or a lower point the turning moment may be varied as required (Fig. 2).
4. An insulator according to Claim 1 for use on already stretched and fixed
wires, in which the points of attachment of the two arms are provided with hooks
bent in opposite directions to engage under and over the cross-wire respectively,
and the insulator is provided with a threaded projection having a slot in which the
cross wire can be inserted and secured by means of a nut (Fig. 3).
Daten this in day open v.
W. LLOYD WISE,
46, Iincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.