Improvements in Devices for Making and Breaking Surface-contact on Electrical Tramways.
Year: 1898

page_text: PROVISIONAL SPECIFICATION,
Improvements in Devices for Making and Breaking Surface-contact
on Electrical Tramways.
I, WILLIAM FREDERICK STAMP, of The Willows, Sunderland, in the County of
Durham, Electrical Engineer, do hereby declare the nature of said invention to
be as follows:-
My invention relates to closed conduit or surface-contact systems.
The contact is made in the following manner and I claim for it the following
advantages:
1st. That the possibility of a "live" plug to remain above the surface is
almost, if not entirely, obviated.
2nd. The contact plugs can be laid flush with the road thereby not affecting
other forms of traffic.
3rd. The plugs, when a car is not immediately over them, are held down by
spring or weight and are absolutely harmless and can not be interfered with as
they will only rise on the magnet under the car coming above and on the removal
of the magnet they slide back into their place switching off current at the same
operation and are dead" till the car is above again.
"
4th. Each switch is independent and the failure of one (should such occur) will
not in any way interfere with the others.
5. An electro magnet may be placed in the switch box to control the switch
and elevate the contact plugs as a safety device in case the car should run at so
high a speed and shoot the plugs without elevating them.
<
29
The magnet under the car is a permanent one and is provided with a "bobbin'
which is connected to the car circuit by a regulating switch which, when in
action, transforms the magnet into an electro-magnet in case of loss of power
and can be set by means of the switch at the required strength and, when the
permanent magnet has gained its lost energy, can be switched off again. The
plugs are made of soft iron and have a small piece of copper let in the top which,
when drawn up by the car magnet, rubs against a strip of copper let into the
car magnet and each plug in succession is held there by the magnetic force till
the car has passed when they are each in succession released and slide back into
place again flush with, or slightly below, the street or road level. The plugs
are made a good working fit and are kept permanently greased and oiled to make
them water tight and should not freeze but, in case of emergency, a system of
steam or hot water pipes are introduced into the boxes which are fed by a force
pump from the generating station and can be used on such occasion.
A connection is made from the cable on both of the switch pole pieces, so that
if any one of them should fail to come into contact the current still passes and
does not affect the others at all and this is an important feature as the cable
becomes practically a third rail.
One plug makes contact just before the other leaves and by this means the car
gets an uninterrupted supply and the circuit is never broken the switches can be

page_text: fitted with carbon "breaks" if necessary and with fuses but, as the circuit is
never broken, this is not essential.
Dated this 6th day of December 1898.
T. J. DANSON, F.Ch. Inst.P.Agents,
Agent for Applicant, Newcastle-upon-Tyne.
Improvements in Devices for Making and Breaking Surface.contact
on Electrical Tramways.
I, WILLIAM FREDERICK STAMP, of The Willows, Sunderland, in the County of
Durham, Electrical Engineer, 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:-
The apparatus, shown in the accompanying drawing is composed of an iron or
steel plunger which is raised by the magnet placed on the car bottom (and by
this action makes contact with the two roller contact and is carried off again
by the adjustable weight which is set in the switch box.
THE MAGNET OR COLLECTOR.
Shown on the portion of the drawing Fig. 3 is formed of a series of electro
magnets AA set at a distance of 1 ft. apart, the bobbins being cased in to
protect the winding, the cores and collector being of tempered steel which is
tempered to retain residual magnetism.
The collector B has a strip of copper C let into a grove cut in the centre, on
which the plug makes contact.
The carrier for the collector is formed of a steel bar with shoulders to which
the collector is bolted at the bottom and the magnet keep at the top. A washer
is pinned to the shaft and a spiral spring I keeps this in place, but allows it to
raise should anything get under the collector and force it up. The length of the
collector varies according to the length of car to which it is to be attached. The
bobbins are connected in series, and to a switch on the car which regulates the
supply of current from the main circuit to them.
The road switch boxes Figs. 1, 2 are composed of the following parts, the
plunger C is made of tempered steel bored out to take the 3 copper rod V encased
in mica tubeing, E the copper stud A at the top having two small holes in it
for screwing up with and is screwed into the 3 copper rod and has a mica
washer B under it which is let into the boss of the steel plunger, completely
insulating the copper rod. A cascing of brass or gun metal d is let into the
iron casting to take the steel plunger.
The plunger is turned less in diameter than the hole bored in the brass
allowing a side and is fitted with an indian rubber ring G let into the steel
plunger, the space above this being filled with oil or grease to ensure the boxes
being watertight. And at the same time allowing the plunger to move up and
down freely.
The 3 round copper rod is connected to the switch-arm by a connecting link
of gun metal H.
The switch arm is composed of a long gun metal arm with a
heavy contact end piece I, and is fitted with an adjustable weight J, which is
sel so that it carries the switch off as soon as the magnet on the car bottom
releases it's hold. This weight can be set anywhere on the back portion of the
arm,

page_text: The arm is connected also by a length of felicable wire, which is fastened to
the arm by means of a small screw and washer and also to the copper rod in the
same manner. This is to prevent sparking at the ends of the connecting rod
when in motion. The spring contacts are composed of a copper or carbon
roller L which is drilled to take a screw through the centre, and are thus fixed
to the carrier. Which is rounded at the back the latter portion being turned to
a smaller diameter than that of the front portion. A spiral spring R is passed
over the end of the carrier and fits in between the shoulder of the carrier and the
end of the main casting keeping the contact pressed forward and at the same
time allowing the roller to move backward or forwards, the whole is held in
position by a small screw P which works in a slot at the top of the main casting.
The connection is taken from the contact by a sweating terminal M which is
bolted to the bottom of the contact block, and is connected direct on to the
feeder cable which runs past the side of the switch box.
The action of the apparatus is as follows, the magnet fixed to the bottom of
the car on comeing immeaditely over the plugs attracts, and draws them up
against the collector and forms the complete circuit which goes through the
motor back to the car rails. All the contacts are connected direct on to the
cable the failure of one should such occur will not therefore at all effect the
others. The weighted end of the arm comeing down as the plunger rises forces
the contacts apart, and makes contact, the end of the arm being slightly tapered
is forced off by the action of the rollers pressing up against it and by the help
of the weight is carried off, as soon as the car releases its hold and thus remains
dead till the car is over it once more. The switch and contacts are mounted on
a slate base N, and are screwed to the bottom of the box by means of bosses
cast on the box.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
By the action of an electro magnet placed on the car bottom which attracts a
steel plunger and draws the switch arm between 2 spring contacts making the
complete circuit and thereby propelling the car along the lines. Each plug
being independent of the others and set flush with the road.
1.
f Dasemaling
1000