Improvements in Non-continuous Conductors for Electric Propulsion or Traction on Permanent Way.
Year: 1891

page_text: Date of Application, 7th July, 1891
Complete Specification Left, 7th Apr., 1892-Accepted, 2nd July, 1892
PROVISIONAL SPECIFICATION.
Improvements in Non-continuous Conductors for Electric Propulsion
or Traction on Permanent Way.
I, GEORGE PROKOFIEW of 13 Alkerden Road, Chiswick W., by profession a
Mechanic, do hereby declare the nature of this invention to be as follows:-
:-
I take pieces of iron rails (not steel ones) of 1 metre (393 in.) in length; to each
piece underneath and also in the middle of its length I attach a small box of
glass well isolated; the box contains a small piece of iron, while a well polished
piece of cable, ending with a flat piece of brass isolated from the rail, comes into
the box. These pieces of rails are put along the whole line required (of course
in the middle of it) at a distance of 2.7 metres from each other, while each box
is communicated to the cable running along the line. To the car two electro
magnets are attached and pass so close to the above mentioned rails as only not
to rub them. All the four poles of these electro magnets are in one line along the
car, so that two equal poles are within and two at the ends. When one of these
poles comes over a piece of rail it develops along the entire length of the piece
only one pole; then the piece of iron in the box is attracted, comes in contact with
the brass piece of the small cable and with the piece attached to the rail. By this
contact it conducts the current from the cable (coming of course from the central
station dynamo machine) to the rail and from the brushes to the car motor.
when the magnet comes to a position so that both of his poles influence the rail
and therefore develop two poles on the end of the rail, then the piece of iron which
conducts the current from the cable to the rail falls in virtue of its being in a
neutral position, thus separating the car from the cable. The poles of the electro.
magnets and the pieces of rails are arranged so, that in any moment one of the
rails serves as a conductor of the current, while the nearest rails are dead and are
thus safe for traffic.
But
D
"
G. PROKOFIEW.
COMPLETE SPECIFICATION.
Improvements in Non-continuous Conductors for Electric Propulsion
or Traction on Permanent Way.
1, GEORGE PROKOFIEW formerly of No. 13, Alkerden Road, Chiswick, but
now of No. 89, Aden Grove, Green Lanes, Islington, both in the County of
Middlesex, Electrician and General Engineer, do hereby declare the nature of
this invention and in what manner the same is to be performed to he particularly
described and ascertained in and by the following statement :-
My invention relates to improvements in non-continuous conductors for electric
propulsion or traction on permanent way, and its particular objects are (a) to
provide for the rapid demagnetisation, as soon as current is no longer required in
any section of the conductor, of that particular section, (b) to guarantee, in a
corresponding degree, to individuals and animals crossing or travelling along the
track, immunity from electric shocks, and (c) to effect considerable economies in
the costs of both installation and maintenance.
These objects are attained by means of the devices illustrated in the
accompanying drawings in which
Fig. 1 is a longitudinal section illustrating the application of the invention to a
street tramway and car:

page_text: ig. 2, a transverse section on the line 2-2 of Fig. 1:
Fig. 3, a plan of one car's length of a street tramway:
Fig. 4, a detail elevation, partly in section, of the contact-rail and box, and
Fig. 5, an inverted plan of Fig. 4 omitting the box-cover and the circuit-closer.
a, a are the contact-rails. They are laid as heretofore at equal distances along
the centre of the track flush with the surface of the latter, and together
constitute the non-continuous conductor. Each rail is made of soft iron because
of the well known superior magnetic properties of that metal as compared with
(say) steel, is about a yard or rather more in length, and is insulated from the
road by being set in a sufficiently thick bed of suitable material, e.g.,.asphalte.
But whereas it has been the practice with previous inventors to lay the contact-
rails close together, i.e., at a distance of only a few inches apart and sometimes to
use a double line of such rails, according to the present invention the contact-rails
are laid at considerable distances apart, each of such distances being equal to two
and a half times the length of a rail, and there is only one line of rails as
distinguished from the double line above referred to. The resultant economies
are (a) a saving in the first cost for rails and their insulites, proportionate to the
reduction of the number required, and () a saving in the cost of maintenance
inasmuch as there are fewer rails to keep in working order and not any leakage of
current from one rail to its neighbours even in wet weather. A further advantage
is the large proportion-2 to 1-of ordinary road surface to metal surface in the
line of the contact-rails, thereby diminishing in a corresponding degree the general
risk of horses slipping upon the latter.
.
c is an air-tight contact-box of glass or other material equally durable and
non-electrical. One box is fixed firmly to the centre of the underside or face of
cach contact-rail a, e.g., by bolts. and nuts as illustrated. This central position of
the box is of great importance. c is the box-cover. It carries an extension c² on
its inner face sufficiently long to reach nearly to the opposite face of the interior
but stopping short thereof for a distance sufficient to allow of the necessary
motion of the contact-closer described in the next paragraph. The insulite b is
continued underneath the box. As my invention requires only one contact-box to
each contact rail, it follows that the first outlay for this part of the invention as
well as the cost of maintenance is diminished pro rata.
d is the iron contact-closer. It lies normally upon the top of the said
extension ². d' is a spindle fast to and pendent from the contact-closer. It enters
a hole in the extension; which hole serves as a guide for the contact-closer in
the up and down motion of it referred to further on.
e is the main cable and f, fare branches, one to each box. Both main and
branches are insulated, as well as laid and protected in any suitable or well known
way. It is to be noted that the main cable is laid in a covered trough e¹ provided
for the purpose. This trough is water-tight and independent of the contact-rails a
and their insulites b, with the consequent advantage that any separation which may
be set up between rail and insulite as a result of unequal contraction and expansion
due to change of temperature, will be without effect in the direction of allowing
water to enter the said trough, so that the latter is permanently dry. The cover
of the trough is made in convenient lengths and fixed in any suitable way. The
branches are shewn as led through the side of the trough, the necessary holes
being closed water-tight.
y
A branch is led into the interior of each box where it is electrically connected
to a plate of thin brass. The plate is made of brass because this metal is
non-magnetic and resists the corrosive action of damp, but any other equivalent
material may be used. It is held in a cavity in the box c. g is a second plate of
like material and is supported in a corresponding position and opposite to the first
mentioned plate. f¹ is a second branch cable from the plate g¹ to the rail a to
which it is connected both mechanically and electrically in any convenient or
suitable way.
The two plates g, are either separated by a distance wide enough
to isolate them electrically or an insulite may be inserted between them.
It is

page_text: convenient for them to be in the same plane as illustrated. is an insulite
between the rail a above it and the plates g, g' and the contact-maker d below it.
is part of a tram-car. i, i are two electro-magnets. Pare the four pole-
pieces, the external two being either N or S and the internal two being respectively
the opposite. They are continued in the direction of the contact-rails a as far as is
prudent and are provided with spring contact-fingers ; or other devices proper for
establishing electrical contact between a pole and the contact-rail under it. The
magnets are provided with suitable guards which are fixed to but insulated from
the car.
k, are the conductors to the motor, (the latter through the other
magnet). is the armature of the motor and m the driving band to the pulley n
on the adjacent axle of the car.
The distance between the inner poles of the two magnets is less than the length
of a rail, and the positions of the two magnets relatively to those of the particular
two contact rails under the car are adjusted so as to provide for one of the said
rails passing current from the cable to the car at and by the time that the
other of them has lost the capacity of so doing thereby rendering it safely
non-electrical.
One reason for the two magnets being placed at a distance less than that which
separates two contact-rails and the reason why the internal or adjacent pole-pieces
are of the same polarity-N or S as the case may be, the external pole-pieces
being consequently both of the opposite polarity-S or N as the case may be-is
this that the said two internal poles may be capable of magnetising a contact-rail
as they pass it, and this they accomplish as follows:-
When they are both above the rail they constitute one pole-say for instance N-
and develop an S pole along the full length of the rail. The contact-rails
nearest to the one undergoing magnetisation are too far apart to be excited. The
above described position and action of the two internal poles of the two magnets
permits of the contact-rails being laid at considerable distances apart.
The operation of my invention is as follows. I assume that the car illustrated
in Fig. 1 is travelling to the right hand. As a pole-piece passes over the
central portion of a contact-rail or when a pair of pole-pieces is over the latter it
is magnetised, and the contact-closer d is drawn upwards until it joins the plates y
and, as illustrated with respect to the right hand circuit-closer in Fig. 1. Current
then flows from the main cable e through f, g, d, g', j and to the respective magnet
and thence to the motor. The path of the current from the said magnet is as
follows. It flows along the conductor as far as the junction of the latter with k²
where it is divided part flowing to the motor and part to the opposite magnet
whence it returns to the first mentioned magnet and thence to earth through the
car axle and wheel. Current is therefore always flowing through both magnets
so that stopping the car does not involve cessation of current but there is always
enough to re-start the car as soon as the brakes are taken off.
A salient feature of my invention is the provision for the rapid demagnetisation
of a contact-rail. It is now well known how important it is that complete
demagnetisation shall be effected before the contact-rail in question is uncovered
by the advance of the car, and that if such act of demagnetisation be imperfect or
lengthy, the contact-rail last exposed will remain charged with a dangerous or at
least a leaking quantity of current.
Now when one of my magnets is in such a position relatively to the contact-rail
under it that both its poles influence it equally, the ends of the latter become two
poles and the central portion of the rail is demagnetised or becomes neutral, or
when one pole-piece-say, the rear one-has passed the centre of the rail the
latter is equally demagnetised and the circuit is broken because there is not then
magnetism enough to keep the circuit-closer attracted. In other words excepting
when the pole-piece or pieces are immediately over it, the centre of the contact-rail
is neutral or practically neutral. This is why the circuit-closer is according to my
invention always under the centre of the rail and in addition of a sufficiently
restricted area to be beyond the influence of any magnetism in the rail elsewhere

page_text: than in the centre thereof. As a matter of fact, as a result of the construction
and positions set forth a contact-rail is thoroughly demagnetised before the
advancing car begins to uncover it.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. The combination of contact-rails together forming a single non-continuous
conductor and separate contact-boxes one under each rail, each individual circuit-
closer being placed centrally of the length of said rail, as set forth.
2. The combination of a single non-continuous conductor and separate circuit-
closers one to each of the contact-rails together forming the said conductor,
each circuit-closer opposite to what is the magnetically neutral centre of the said
rail so soon as the pole of the car-magnet has passed.
3. The combination with a roadway and the other necessary elements of au
electric circuit, of a non-continuous conductor consisting of a series of contact-rails
insulated from each other by a distance too great for a practical leakage of
current to be established from one rail to its neighbour.
4. The combination of a single non-continuous conductor consisting of a series of
contact-rails laid flush with the road along the centre of the track and at distances
apart not less than twice their own length, with separate contact-boxes one under
each contact-rail, and a circuit-closer under the centre of the said rail.
5. The combination of a magnet on the car, a contact-rail forming an insulated
part of a single non-continuous conductor and a single circuit-closer under the
central portion of the said rail with current conductors and motor.
6. The combination of two magnets having their internal pole-pieces of the
same polarity and separated by a distance less than the length of a contact-rail
and their outer poles of the opposite polarity, a non-continuous conductor and a
series of circuit-closers.
7. The use of a single current divided after passing the first of two magnets to
then excite the second and to drive the motor.
8. The combination of car, two magnets, their contact-fingers, an electro-motor,
and conductors adapted to deliver the current from the magnet first excited and
to pass part of it to the motor and part of it to the other magnet.
Deted the 7th dor of Anril 1892
PHILLIPS & LEIGH,
22, Southampton Buildings, Chancery Lane, W.C.,
Agents for the Applicant.