Improvements in Signal Systems for Electric Railways.
Year: 1899

page_text: Date of Application, 30th Oct., 1899—Accepted, 27th Jan., 1900
COMPLETE SPECIFICATION.
Improvements in Signal Systems for Electric Railways.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of
this invention (which has been communicated to us from abroad by Samuel B.
Stewart, residing at Schenectady, County of Schenectady, State of New York,
United States of America, Electrical Engineer), and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement: --
This invention relates to surface contact electric railways, the object being
to provide a series of signal devices located along the track or adjacent thereto,
capable of automatic control to indicate the condition of the contact devices and
act as a telltale showing whether or not they are "alive." This is desirable in
order to avoid danger from the exposed contacts to people or animals crossing
the tracks, and permits casualties from this cause to be avoided by notifying
motormen or other employees when the magnetically-operated circuit-controlling
devices are out of order.
In carrying out our invention we provide a series of electrically-controlled
signal devices adjacent to the track and connected with the surface contacts so
that when any one of the latter is charged with potential the signal device will
be operated. We provide also a magnetically-controlled device for automati-
cally throwing a resistance into the circuit which controls the signal device,
after the signal has been operated. We preferably arrange the circuit so that
this resistance may serve also for toning down the current in the "pick up"
magnet after the circuit closer has been operated.
Our invention therefore comprises, in connection with a sectional or dis-
tributed contact electric railway system, a signal device electrically controlled
and supplied with current only when the distributed contacts are alive with
current. It comprises also other more specific features which will be hereinafter
particularly described and claimed. In the accompanying drawings, Fig. 1 is
a front elevation showing the mechanical construction of a signal device embody-
ing our improvements; Fig. 2 is a diagram of an electric railway system showing
the mode of controlling the signal device.
Referring first to Fig. 1, we house within a box capable of being opened and
closed by a door, a signal controlling magnet 1. the armature 2 of which is pivoted
to a bent or bell crank lever 3, on the end of which is mounted a semaphore or
signal-disk 4. A counter-weight 5 is attached to the bent lever or its axis so
as to give easy control of the signal-disk. The latter, when in the position shown
in the drawing, is hidden by the door of the box, but when the magnet is ener-
gized, its armature 2 is attracted and a slot-and-pin connection permits sufficient
freedom of movement with relation to the short arm of the lever 3 to raise the
disk 4 into registry with a window in the top of the box. The wall back of this
window may be painted any suitable colour, say white, and the semaphore blade
or disk may be painted a contrasting colour.

page_text: In the box is also mounted a controlling magnet, commonly designated as a
"pick up," magnet, 6, which operates an armature on which is carried an insu-
lated bridge-piece 7 formed of a bundle of thin phosphor-bronze or copper
laminac, and adapted to bridge the terminals 8, 8ª connecting respectively with
a supply main or feeder and with an exposed contact of the railway system,
commonly a rail or conducting spot on the track surface rigidly supported and
adapted to be engaged by a collector rail or shoe carried by a travelling car.
The circuit breaker is provided also with a blow-out magnet 9 which provides
a dense magnetic field, and blows out the arc tending to form between the auxi-
liary carbon contacts in a shunt around the circuit breaker at which the circuit
is opened a moment later than the rupture between the bridge-piece 7 and the
terminals 8, 8ª. An are interrupting circuit-breaker of this type of construction
is known in the art, and need not therefore be more elaborately discussed.
Referring now to Fig 2, it will be seen that the signal controlling magnet 1
is electrically connected with the surface contact 10, and the circuit-controlling
or pick-up" magnet 6 is connected with the surface contact 10". The travel-
ling car, represented at 11, is provided with two shoes electrically connected
and engaging, respectively, the surface contacts 10, 10. The surface contacts
in the type of system shown are rails, and the collectors short shoes or brushes
engaging said rails. These parts might obviously be reversed and the contacts
be distributed metal spots adapted to be bridged by collector rails mounted on
the car as the latter travels along the line of way. The circuit breaker con-
trolled by the pick-up magnet is shown at 7, and the blow-out coil or magnet
at 9. We provide a resistance 12 adapted to be interposed between the signal-
controlling magnet and the pick-up-magnet respectively and the ground wire
or return 13. The armature of the pick-up magnet 6 operates a lever 16 on
which is mounted a movable bridge-piece adapted to open a normal short-circuit
around this resistance, thereby cutting the resistance in on the signal coil and
the pick up coil and preventing overheating in case of a failure to open the cir-
cuit after the car has passed. The car carries a battery 14, by which a momen-
tary current may be supplied to the pick-up magnet if the contact-rail should
be disconnected from its feed, wire, as it would be in case of a stop.
As thus organized, the signal. operates as follows: the normal condition is
shown at the right in Fig. 2, and the active position when a car passes, at the
left. The car in passing from one rail section to the next causes its collector
brushes or shoes to bridge the adjacent rail ends, thereby diverting a branch
current from the contact rail it is just leaving to ground through the one in
advance, and energizing both the signal magnet 1 and the pick-up magnet 6,
the former over a path from the contact 10, blow-out magnet 9, signal magnet,
across the bridge-piece 17, and around the short-circuit for the resistance 12.to
the ground wire or, return rail 13. A second branch is diverted through the
magnet 6 from the conductor '10" and bridge-piece 17 to the ground return.
The pick-up magnet thereby operates the circuit closer, bringing the bridge
piece 7 across. terminals 8, 8, and a rod 15 pivoted on the armature engages
the spring-pressed lever 16 and opens the short-circuit around the resistance 12,
thereby cutting in said resistance and preventing damage if the circuit should
remain closed for a prolonged period, and reducing the amount of energy needed
to maintain the signal in position. This is evidently possible, since. the amount
of magneto-motive force necessary to hold a magnet closed is much smaller. than
that necessary to close it.
It will be evident. now that as a car passes any signal and renders alive the
surface. contact it accompanies, the signal will be displayed in plain view of
the motor-man; if it should not be displayed, he will be advised that the circuit-
controlling apparatus is out of order; and if it be already displayed before he
reaches the. section. he will be advised that it exposes a live conductor on the
track and needs immediate attention for the protection of other than railway
traffic

page_text: Having now particularly described and ascertained the nature of our said in-
vention (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 sectional contact railway system, a magnetically controlled signal
device for the several sections, having its controlling magnet included in a return
branch from the contact to which it corresponds.
2 In a sectional contact railway system, a magnetically controlled signal
device for the several sections, a controlling magnet therefor, and means for
reducing the current in the magnet after the signal has been operated.
3-In a sectional contact railway system, a magnetically controlled signal
device for the several sections, a controlling magnet therefor, in a return branch
from its corresponding contact, and means for cutting resistance into said branch
after the signal has been operated.
4A signal system for an electric railway, comprising an electrically-con-
trolled signal device cut into circuit with the supply wire by the transit of a
car, a resistance, and means for cutting said resistance into the signal-control-
ling circuit after the signal has been operated.
5-A signal system for a sectional contact electric railway, comprising a
plurality of signal devices corresponding to contact sections, a pick-up magnet
controlled by the position of a travelling car for rendering the sections alive,
and a signal-controlling circuit for each signal device in permanent connection
electrically with its corresponding contact section.
6-A railway signal comprising an operating magnet, an armature therefore,
and a rock-shaft having a semaphore and counterweight secured thereto on arms
at right angles to each other.
THE BRITISH THOMSON-HOUSTON CO. LTD.,
.
J. J. MANHEIM,
A. R. MONKS,
Directors.
ALFRED CLEMENTS,
Assistant Secretary.