Vehicles and for other Purposes.
Year: 1887

page_text: Date of Application, 25th Oct., 1887
Complete Specification Left, 13th Mar., 1888
Complete Specification Accepted, 27th Apr.. 1888
Vehicles and for other Purposes.
I, WILLIAM DANTON SANDWELL, of 151 Mayall Road, Herne Hill, in the County
of Surrey, Electrical Engineer, do hereby declare the nature of this invention to be
as follows:-
My invention relates to electric motors for driving tramcars and for other
purposes.
In using an electric motor it is well known that after a time the armature will
become heated. For this reason two machines are frequently employed so that after
the armaturo of one machine has become heated it may be allowed to stand while it
cools, the other machine being employed in the meantime.
This arrangement has the defects that it is very expensive and that the machines are
very heavy which latter defect when the motors are applied to tramway vehicles is a
great disadvantage.
The object of my present invention is to obtain all the advantages of two machines
at a lower cost and with less weight than heretofore, and to this end my said invention
comprises the improvements hereinafter described.
According to my said invention I employ two armatures in combination with one
set of field magnets, so that after one armature is heated it can be replaced by the
other. In practice I find it very advantageous to move the magnets relatively to the
armature, but it is obvious that I can also move the armatures relatively to the magnets.
The magnets or the armatures may be moved by any suitable means, for instance by
screw gearing or by racks and pinions.
In addition to the advantages hereinbefore mentioned the present invention possesses
the further advantage that the armature which is not in use is not enclosed within the
field magnets, so that the air is free to circulate around the same, whereby the cooling
takes place more rapidly than would otherwise be the case.
1007
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements relating to Electric Motors for Driving Tramway
Vehicles and for other Purposes.
I, WILLIAM DANTON SANDWELL, of 151, Mayall Road, Herne Hill, in the county
of Surrey, 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 :-
My invention relates to electric motors for driving tramcars and for other
purposes.
In using an electric motor it is well known that after a time the armature will
become heated. For this reason two machines are frequently employed so that after
the armature of one machine has become heated it may be allowed to stand while it
cools, the other machine being employed in the meantime. This arrangement has the
defects that it is very expensive and that the machines are very heavy, which latter
defect when the motors are applied to tramway vehicles is a great disadvantage.
The object of my present invention is to obtain all the advantages of two machines
at a lower cost and with less weight than heretofore, and to this end my said invention
comprises the improvements hereinafter described.
According to my said invention I employ two armatures in combination with one
set of field magnets so that after one armature is heated it can be replaced by the
other. In practice 1 find it very advantageous to move the magnets relatively to the
aruatures, but it is obvious that I can also move the armatures relatively to the magnets.
The magnets or the armatures may be moved by any suitable means for instance by
screw gearing or by racks and pinions.
In addition to the advantages hereinbefore mentioned, the present invention possesses
the further advantage that the armature which is not in use is not enclosed within the
field magnets, so that the air is free to circulate around the same, whereby the cooling
takes place more rapidly than would otherwise be the case.
To enable my invention to be clearly understood I will describe how it may be
· carried into practice by reference to the accompanying drawings in which
Figure 1 is a plan of a motor adapted to be applied to a tramway vehicle for driving
the same, and
Figure 2 is a plan of mechanism through the medium of which the power of the
motor is communicated to one of the axles of the vehicle, the said figure forming a
continuation of figure 1 from the dotted line.
Figure 3 is a sectional side elevation of the mechanism shown in figures 1.
and 2, and
Figure is an end view of the same.
Figure 5 is a plan view illustrating the modification of my invention wherein the
arimatures are adapted to be moved relatively to the field magnets.
Referring to figures 1 to 4, a is the frame of the motor, which frame has upwardly

page_text: extending brackets (by means of which the motor can be suspended from the floor of
a tramway vehicle, as shown in figure 3) and slide bars c.
d, d are the field magnets which at their ends are provided with sockets e adapted to
slide upon the bars cand ff are rack bars which are connected with the said field
magnets and in engagement with rack pinions g, g on a shaft h, so that when the said
shaft is rotated the field magnets can be caused to slide upon the bars e in one or other
direction as desired.
i is the armature shaft which carries two armatures j, k, the said shaft being
supported in bearings in the frame a.
7, are the commutators of the armatures j, k respectively and m m, n n are sets of
brushes adapted to bear upon the same; the brushes m, m being designed to make
contact with their respective commutators when the armatures are rotating in one
direction and the brushes n, n when they are rotating in the opposite direction.
It will be noticed that each commutator has two sets of brushes in connection with
it. In practice however, I prefer to use one armature when travelling in one direction
and the other when travelling in the opposite direction, for instance the armature.j
when moving in the direction of the arrow 1, figure 3, and the armature & when moving
in the opposite direction. In this case the brushes n, n of the commutator and the
brushes m, m of the commutator can be drawn back within their holders. In case,
however that either armature becomes incapacitated the provision of two sets of
brushes enables the remaining armature to be used for travelling in both directions.
In order to allow of placing one or other of the sets of brushes in contact with the
commutators as desired, the brushes m, m, n, n of each commutator are mounted upon
a four-armed bracket o fixed to the frame of the machine, and extensions on the brush
carriers are connected by links p, p to two arms q, g of a three-armed lever, having
slight rotary movement relatively to the shaft i. The other arm of the said three-
armed lever is connected with a rods through the medium of which the three-armed
lever can be moved. When the rod s is moved in one direction the brush carriers and
their brushes are caused to oscillate upon their pivots thus moving one set of brushes
into contact with the commutator, and the other set out of contact, and vice versa.
The movement of the three-armed lever may be produced by any desirable means,
as shown in the drawing however, the movement.is effected automatically at the same
time that the field magnets are being moved from one armature to the other. The
movement in this case is effected through the medium of a pinion t engaging with the
tooth-sector u secured to a shaft u, upon which are fixed two levers attached at their
free ends to the rods s, s of the respective commutators.
บ
The movement of the armature-shaft, as shown in the drawings, is communicated to
the axle w of the vehicle through the medium of the pulley, the belt al, the
pulleys, the shafts a³, and the gear-wheels & engaging with other gear-wheels.c³
on the axle w.
In figures 2 and 4 I have shown three sets of gear-wheels, ³ for enabling the
motor to be run at an uniform speed notwithstanding the varying grades and curves
of the road, whereby the efficiency of the motor is maintained.
Each gear-wheel a is mounted upon a separate shaft a³, the three shafts being
arranged one within the other and each carrying a pulley over either of which the
belt can run according to the desired speed of the car relatively to the motor.
y is a bell-shipper by means of which the belt can be placed upon either pulley as
required.
L
Although I have hitherto described my improvements as applied to a tram-car, I
wish it understood that I do not limit myself to this particular application, as it is
obvious that they may be used for other purposes without departing from the nature of
my invention.
The modification of my invention wherein the armatures and their shaft are
moveable relatively to the field magnets as illustrated in figure 5. In this figure the
armature shaft is supported in bearings in the brackets y and is connected with the
driving pulley by means of a spline joint y'. The armatures j, kare mounted in a
sliding frame having the extensions which slide upon the rods 2, 3. One of these

page_text: rods is screw-threaded so that by rotating the same the sliding frame with the armatures
can be moved.
I would observe that I do not confine myself to the employment of any particular
constructions of armature and field magnets, as such constructions may be varied as
desired.
Although I have described my improvements as applied to electric motors it is to
be understood that they are also applicable to dynamo electric machines.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I wish it to be understood that
I do not claim placing two armatures on the same axle, one only of such armatures
being operative at the same time, but what I claim is :—
1. In an electric motor the employment of two armatures in connection with one
set of field-magnets, the said armatures and field-magnets being arranged in such a
manner that they can be moved relatively to each other for enabling either armature
to work in the magnetic field for the purposes specified.
2. In an electric motor the combination of two armatures with one set of field-
magnets, the said field-magnets being adapted to move longitudinally with the armature-
shaft so that the said field-magnets can be arranged to work in conjunction with either
armature, substantially as described.
3. The modification of my invention wherein the armatures are adapted to be moved
relatively to the field-magnets as set forth.
4. The application to a tramway or other vehicle of an electric motor such as herein-
before described, substantially as set forth.
5. The manufacture and use of the improved electric motor constructed and
arranged substantially as hereinbefore described with reference to the accompanying
drawings.
Dated the 13th day of March 1888
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.