IMPROVEMENTS IN APPARATUS FOR THE TRANSMISSION OF POWER BY ELECTRICITY
Year: 1881

page_text: LETTERS PATENT to John Hopkinson, of 4, Westminster Chambers, in tho
City of Westminster, C.E., for an Invention of "IMPROVEMENTS IN
APPARATUS FOR THE TRANSMISSION OF POWER BY ELECTRICITY."
PROVISIONAL SPECIFICATION left by the said John Hopkinson at the Office
of the Commissioners of Patents on the 7th July 1881.
JOHN HOPKINSON, of 4, Westminster Chambers, in the City of Westminster,
C.E. "IMPROVEMENTS IN APPARATUS FOR THE TRANSMISSION OF POWER BY
ELECTRICITY."
My Invention relates to apparatus for the transmission of power by electricity,
whereby the force of dynamo electric or magneto electric machines may be utilized
under advantageous conditions for the purposes of hoisting or raising and lowering
heavy bodies, for the propulsion of vehicles, and for other purposes.
In carrying out my Invention as applied, for example, to the construction of a
hoist, I employ a dynamo-electric or magneto-electric machine in combination with
a pulley or barrel fitted with the device known as the Weston friction coupling or
clutch, the machine and the pulley or barrel so fitted being carried in a suitable
frame, and arranged by preference the one over the other, and connected by
toothed or other suitable gearing for transmitting motion from the machine to the
said pulley or barrel, over which passes the tackle carrying the load to be raised or
lowered. Any suitable capstan or windlass may be used in this arrangement.
The dynamo-electric or magneto electric machine is fitted with devices for
reversing the direction of rotation of the armature of the machine, as described in
the Specifications to former Letters Patent granted to me, and dated and numbered
respectively the 21st June 1879, No. 2481; and the 14th November 1879,
No. 4653.
I also employ a spring or springs for the purpose of automatically moving the
said devices for regulating the direction of the motion of the machine to a neutral
point, so that when the pulley or barrel is locked by the action of the friction

page_text: coupling or clutch; on the strain being removed from the rope or chain suspended
therefrom the motion of the machine shall likewise be arrested.
The spring or springs may be applied in other cases where the devices described
in my said former Specifications are employed for the purpose of throwing them out
of contact, and automatically arresting the motion of the machine.
If desired, two or more dynamo-electric or magneto-electric machines may be
employed in conjunction. When so used they are rendered particularly adapted
for the propulsion of tram engines, tram cars, and other vehicles, so as to obtain
required variations in the speed by the employment of a switch so arranged as to
throw the said machines into parallel circuit or into scries, according as it is
desired to drive the electro-locomotive or vehicle at full speed or at a less speed.
In lieu of two or more complete machines a single machine having two or more
independent circuits may be used.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Hopkinson in the Great Seal Patent Office on the 7th January
1882.
JOHN HOPKINSON, of 4, Westminster Chambers, in the City of Westminster,
Civil Engineer. "IMPROVEMENTS IN APPARATUS FOR THE TRANSMISSION OF
POWER BY ELECTRICITY."
My said Invention relates to apparatus for the transmission of power by
electricity, whereby the force of dynamo electric or magneto electric machines
may be utilized under advantageous conditions for the purpose of hoisting or
raising and lowering heavy bodies, for the propulsion of vehicles, and for other
purposes.
In carrying out my said Invention as applied, for example, to the construction
of a hoist, I employ a dynamo electric or magneto-electric machine in combination
with a pulley or barrel fitted with the device known as the Weston friction
coupling or clutch, the machine and the pulley or barrel so fitted being carried
in a suitable frame, and arranged by preference the one over the other, and
connected by toothed or other suitable gearing for transmitting motion from the
machine to the said pulley or barrel, over which passes the tackle carrying the
load to be raised or lowered. Any suitable capstan or windlass may be used in
this arrangement.
The dynamo electric or magneto-electric machine is fitted with devices for
reversing the direction of rotation of the armature for the machine, as described in
the Specification to former Letters Patent granted to me, dated and numbered
respectively the Twenty first June, One thousand eight hundred and seventy nine,
No. 2481; and the Fourteenth November, One thousand eight hundred and
seventy nine, No. 4653.

page_text: I also employ springs for the purpose of automatically moving to a neutral point
the said devices for regulating the direction of the motion of the machine, so that
when the pulley or barrel is locked by the action of the friction coupling or clutch,
on the strain being removed from the rope or chain suspended therefrom the motion
of the machine shall likewise be arrested.
The springs may be applied in other cases where the devices described in my
said former Specifications are employed for the purpose of throwing them out of
contact, and automatically arresting the motion of the machine.
If desired, two or more dynamo-electric or magneto-electric machines may be
employed in conjunction. When so used they are rendered particularly adapted
for the propulsion of tram engines, tram cars, and other vehicles, so as to obtain
required variations in the speed by the employment of a switch so arranged as to
throw the said machines into parallel circuit or into series, according as it is desired
to drive the electro-locomotive or vehicle at full speed or at a less speed.
In lieu of two or more complete machines a single machine having two or more
independent circuits may be used.
In order that my said Invention may be better understood I will describe in
detail one mode of carrying it into effect, but it is obvious that the essential
features of the Invention may be carried out in other ways and applied to slightly
different purposes.
Figure 1 represents in elevation an electric hoist for raising weights attached to
either end of the chain A, which hangs over the chain pulley B. C is a dynamo
electric machine, which, in the example illustrated in the Drawings, is connected
with the pulley B by gearing C₁, and for convenience is arranged above the
pulley B, the whole of the parts being carried by a suitable frame B'. D is a
reversing arrangement, such as is described in the Specification to former Letters
Patent granted to me, dated the Fourteenth November, One thousand eight hundred
and seventy nine, No. 4653; or that described in the Specification to other Letters
Patent granted to me, dated the Twenty first June, One thousand eight hundred
and seventy nine, No. 2481, may be substituted therefor, by which arrangements
are effected the reversal of the direction of motion of the armature or revolving
portion of the machine by changing the position of the points of contact of the
brushes d, or the equivalent devices, and the commutator or collector e. Within
the pulley B, or if more convenient on any other of the shafts, is the screw a of the
Weston clutch, which is shewn in section in Figure 2. The action of this clutch
in its various forms is well known. If a weight be hanging on one end of the
chain A the pulley B will turn on the screw a, and will clamp itself to the ratchet
wheel K, which are held by detents B: If the dynamo electric machine C rotates
in the direction of lowering the weight the clamping action is released.
Figure 3 is a view of the reversing gear seen from the inside; Figure 4 shews
the same as seen from the outside. E is a double spring, each limb of which presses
strongly against a fixed stud F. G is a wheel carrying the holders c of the
brushes d, which are in contact with the commutator e; this wheel is moved in
order to change the position of the points of contact of the brushes d with the
commutator e, and thus start the apparatus by the act of pulling the hand cord H,
and when so moved in either direction the stud I presses against one of the
springs E, at once encountering considerable resistance therefrom. When the cord H
is released, and the wheel G consequently set free, the spring E will force the
system carried by the wheel G into the neutral position indicated in the Drawings,
in which the contact pieces f, electrically connected with the brushes d, are situate
centrally between the binding screws or terminals g, and the hoist will cease to
move.
In order to economically vary the speed of a tram car, tram engine, or other
vehicle driven by electricity, two dynamo electric machines may be used on the
car engine or vehicle, and when high speed is desired these are arranged in parallel
circuit; when a low speed and greater tractive force is required they are arranged
in series.

page_text: Figures 5 and 6 shew a key or switch suitable for effecting these changes,
although of course many other forms of switch may be used; Figure 7 is a diagram
shewing the connections. a, b, c, d, represent the terminals of the two dynamo
electric machines C, C. L, M, are fixed pieces; L is connected to a and to one of
the main leads; M is connected to d and to the other main lead. N and P are two
springs; N is connected to c; P to b. Q is a metal cross piece (indicated by dotted
lines in Figure 5) actuated by a lever R. When the lever is in the position shown
by the full lines in Figure 6 the machines are coupled parallel; when in the
position indicated by the dotted lines in Figure 6 the machines aro in series. The
switch can easily be modified so as to alter the connections of more than two
machines, or may be used for a single machine with two or more independent
circuits.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-
First. The use of the spring E in combination with the reversing arrangement
forming the subject of Letters Patent, No. 24817, or No. 465370, for the purpose
of throwing the brushes or equivalent devices into a neutral position, substantially
as hereinbefore described.
Second. In a machine driven by electric power the use in combination of the
reversing arrangement forming the subject of Letters Patent, No. 248179, or
No. 4653, and of the self holding Weston clutch, substantially as hereinbefore
described.
Third. The method of varying the speed of a tram car, tram engine, or other
vehicle propelled by electricity by using two or more dynamo electric or magneto
electric machines or dynamo electric or magneto electric machine with two or more
independent circuits, and throwing them into parallel circuit or series according as
a high or low speed is desired, substantially as herein before described.
In witness whereof, I, the said John Hopkinson, have to this my Specification
set my hand and seal, this Sixth day of January, One thousand eight
hundred and eighty two.
JOHN HOPKINSON. (L.S.)