Improvements in or relating to Trolleys for Overhead Systems of Electric Traction.
Year: 1896

page_text: Date of Application, 20th Oct., 1896-Accepted, 21st Nov., 1896
COMPLETE SPECIFICATION.
Improvements in or relating to Trolleys for Overhead Systems of
Electric Traction.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 38, Parliament
Street, Westminster, in the County of London, Electrical Engineers, do hereby
declare the nature of this invention (which has been communicated to us from
abroad by Norman C. Bassett, of Lynn, in the County of Essex, State of
Massachusetts, United States of America), and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
The present invention relates to under-running trolleys for overhead systems
of electric traction and has for one of its objects to utilize the buffer spring
for the purpose of assisting the lifting springs when the trolley is in its lowest
or horizontal position, at the same time using it in the usual manner to relieve
the shock when the trolley leaves the overhead conductor and moves upward
due to the lifting springs.
A further object of the invention is to provide a trolley which is capable of
a very wide range of movement, and one in which the upward pressure on the
trolley pole is less in the lower position than in the upper, and provided with a base
occupying a minimum amount of vertical space.
In carrying out our invention, the support for the trolley pole is mounted on a
transverse shaft which is supported by means of a suitable base mounted on the
car roof. Between the support and an extending arm, mounted on the base,
are the lifting springs which are so arranged that their lifting effect is much less in
their extreme lower positious than in the upper; this prevents to a large degree
the tendency of the trolley to leave the overhead conductor when in places where
the roof of the car and conductor approach each other closely. The buffer spring
is made in the form of a spiral and is mounted on the shaft which forms a transverse
axis of the support for the trolley pole; this spring is provided with two free ends,
which are adapted to be engaged by lugs on the base and on the trolley pole
support. The spring is so arranged that an extreme movement of the trolley pole
in both the horizontal and vertical direction will increase the tension of the spring;
in the former case it will assist the action of the lifting springs and in the latter
case oppose them.
In the accompanying drawings,
Fig. 1 is a side elevation of a trolley embodying my invention;
Fig. 2 is a plan view;
Fig. 3 is a section on the line 3-3 of Fig. 1; and
Fig. 4 is a sectional view taken on the line 4-4 of Fig. 2.
The base A is mounted on a suitable bearing K, the latter being secured to the
roof of the car, and is so arranged that the trolley base is free to revolve thereon
around the shaft M as a center. The base A is provided on one side with an arm B
which forms a support for the lifting springs C, and on the other side with two
arms or projections a and a¹; these are provided with lugs J and N respectively
which engage with the ends of the buffer spring H. In addition to the above, the
projections a, a form a support for the shaft G, the latter forming a pivot for
the trolley support E.
The trolley support E is provided at its lower end with two arms c, c' extending
outside of the projections a, a¹ of the base and connecting them in a web E

page_text: provided on its under side with a lug I adapted to engage with the buffer spring H.
On the upper end of the trolley support E is a clamp F adapted to clamp the
trolley pole in position; the pole is not shown, for the reason that it forms no
part of the invention; any suitable connection may be employed, either metal or
wood.
On the outer end of the arm B is a cross piece to which all the springs C are
secured; the springs are supported at the other end by means of two plates
connected to the screw threaded rods D. Extending through the support E is a
shaft L provided at its outer ends with flattened portions which form bearing
surfaces for the adjustment nuts on the rods D; this shaft being free to turn as the
trolley moves up and down.
Referring to Figs. 3 and 4, the action of the trolley will be described. The
longer end of the buffer spring H is under the lug N, which is formed integral
with the projection a' of the base A, and is held thereby against upward movement.
The lug on the under side of the web El engages with the shorter end of the
spring H, and a movement of the trolley in a direction of the arrow tends to
wind up the spring around the shaft G as an arbor, and if for any reason the
trolley comes off the overhead conductor, the spring H will relieve the shock
occasioned thereby. The spring H when the trolley is approaching its upward
limit, opposes the action of the lifting springs C, but the latter are in such a
position that they greatly overpower it.
If now the trolley is moved in the opposite direction a certain distance, the
short end of the spring H will engage with the lug J which is formed integral with
the base, and the trolley support E is relieved from the pressure of this end of the
spring; if the trolley continues its downward movement until it assumes a position
"substantially horizontal with respect to the roof of the car, the longer end of the
spring H will be engaged by the end of the web E, shown in dotted lines, and
press it downward, thus increasing its tension, the opposite end remaining in
engagement with the lug J. When this end of the spring is in engagement
. with the web E, the lifting spring C and the center of revolution of the
support E will be very nearly on the same line, so that the spring will exert
very little lifting effect, but the spring H being under torsional strain, (the
amount depending upon the position of the trolley), will aid them in raising
the arm to a position where the effective strength of the lifting springs C is
sufficient to raise the trolley.
The spring H and the lugs N and J, and the lug I and the web Fare- so
arranged that when the spring is to be used as an assisting spring, it is wound
or coiled up from the longer end, whereas when it is to be used as a buffer
spring, it is wound up from the shorter end.
Having now particularly described and ascertained the nature of this invention
(as communicated to us from abroad) and in what manner the same is to be
performed, we declare that what we claim is :-
1. In a trolley for overhead systems of electric traction, the combination of
a support for the trolley pole, à base to which the support is pivoted, lifting
springs secured to the support and the base, and a spring acting to "assist the
lifting springs when the trolley is in the lower position.
2. In a trolley for overhead systems of electric traction, the combination of
a support for the trolley pole, a base to which the support is pivoted, lifting
springs secured to the support and the base, and a spring acting as a buffer
spring in the upper positions of the trolley, and as an assisting spring in the
lower positions.
3. In a trolley for overhead systems of electric traction, the combination of
a base, an arm extending from the base forming a support for the lifting
springs, projections from the base forming a support for a shaft upon which the
trolley support is pivoted, lugs on the base and on the support, áud a spiral spring
engaging with a lug on the support and a lug on the base.

page_text: 4. In a trolley for overhead systems of electric traction, the combination of a
base provided with two projecting arms, a support for the trolley pole provided with
a similar pair of arms, a shaft extending through the arms and forming a pivot for
the support, a spiral spring surrounding the shaft, a lug on the support, and a lug
on the base engaging with the spring in certain positions of the trolley and other
lugs on the base and support engaging with the spring in certain other positions of
the trolley.
5. In a trolley for overhead systems of electric traction, the combination with a
base to which the lifting springs and the support for the trolley pole are secured,
springs tending to raise the trolley to a vertical position at all times, and a spiral
spring adapted to be coiled or wound from one end when used as a buffer spring,
and wound or coiled from the other end when used as an assisting spring.
Dated this 20th day of October 1896.
For the Applicants,
J. C. CHAPMAN,
70, Chancery Lane, London, W.C., Chartered Patent Agent.