Improvements in Power Transmitting Devices, especially applicable to the Electrical Propulsion of Vehicles.
Year: 1892

page_text: Date of Application, 1st Mar., 1892--Accepted, 2nd Apr., 1892
Improvements in Power Transmitting Devices, especially applicable
to the Electrical Propulsion of Vehicles.
I, BENJAMIN JOSEPH BARNARD MILLS of 23 Southampton Buildings in the
County of Middlesex, Patent Agent, do hereby declare the nature of this invention,
a communication to me from Edward Hibberd Johnson, of 44 Broad Street, New
York City, in the United States of America, Electrician, and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement :-
The present invention relates to an arrangement of gearing for electrically
propelled vehicles in which the motor is connected with the running gear of the
vehicle through a frictional connecting device whose frictional engagement is fixed,
or in other words, a device whose members have a degree of frictional engagement
or relation which is fixed and unchanged during the operation of the device, as
distinguished from one in whose operation the friction members are moved into
increasing or decreasing frictional engagement.
The fixed frictional engagement proportioned to the capacity of the motor, so
that when the motor is called upon to exert power greater than that which it is
designed for, the friction device will slip and prevent the increase, of the strain
on the motor.
The invention consists mainly in employing such a device in connection with
means for enabling the motor to start and to apply its power gradually.
A loose connection is employed between the motor and the frictional connecting
device and an elastic cushion is provided so situated and arranged with reference
to the motor that the first operation of the motor when it is started is to compress
the said elastic cushion, and the power is not applied to move the car until it has
accomplished this compression to an extent dependent upon the load which exists
on the car in any case, at which time the loose connection arrives at an effective
engagement; the motor is thus provided with a gradual load and is allowed to
make one or more revolutions before the full load is placed upon it and to attain
the degree of efficiency required to enable it to start the car with a moderate
current.
In carrying the invention into effect it is preferred to provide one or more of
the wheels of the car with a friction surface and to place upon or in connection
with a hollow shaft surrounding the axle a friction ring in engagement with such
friction surface so that when the ring is turned, the car may be started. The said
friction ring is so constructed that the amount of its frictional engagement with
the wheel is adjustable, and it is adjusted so that it will slip when the load is too
great for the motor. The motor is connected with a screw mechanism mounted
upon the car axle, and consisting of one or more threaded nuts moveable along the
hollow shaft extending along the axle. Upon the hollow shaft in proximity to the
screw mechanism is a spiral coiled spring, the other end of which is suitably held
from longitudinal movement, so that the first movement of the motor is applied to
the compression of the spring and this continues until the spring is so compressed
that the nut will not travel further along the shaft but will take hold of the shaft
and turn the friction member connected therewith so as to start the car, unless the
load on the car is too great, in which case the friction member is caused to slip on
the wheel.
The hollow shaft on the axle forms a support independent of the wheel for
the screw mechanism and friction member. By making the wheel loose on the
axle these parts could be fixed upon the axle and the loose hollow shaft dispensedi
with

page_text: The friction member is referred to as being connected with the hollow shaft.
It is preferred however, that the operating connection between them shall be of
such character that when the motor is not in operation the friction member shall
be entirely disconnected from the shaft, so that the motor may be at such times
disengaged entirely from the car wheels. To this end there is fixed upon the
shaft in proximity to the friction ring, and so as to receive the pressure of the
spring or elastic cushion, an intermediate connecting plate, normally held by
another spring out of engagement with the friction member, but adapted to
positively engage the friction member on being turned from its normal position.
Thus the first movement of the motor and compression of the spring causes the
intermediate connecting device to be brought into engagement with the friction
member in readiness to start the car, when the spring has been further compressed
sufficiently to prevent the threaded sleeve from travelling further along the shaft
and to cause it to turn said shaft and start the car.
The invention is illustrated in the accompanying drawing.
Figure 1. is a plan view of a portion of the truck of an electric railway car
provided with the invention, portions of the same being shown in section;
Figure 2, a front elevation of a portion of the axle with the connecting devices
in vertical section;
Figure 3, a cross section on the line 3-3 of Figure 2; and
Figure 4, a cross section of the intermediate connecting plate on the line 4-4
of Figure 3.
A indicates a portion of the truck frame, and B is the electric motor supported
thereon for propelling the car. The wheels C. C. are fixed upon the axle D.
The motor B is connected by a sprocket chain E, or other suitable gearing, with
a screw mechanism such as is set forth in the Specifications of Patents granted to
me numbered 14609 and 146094 of the year 1890 and in the Specification of an
application No. 5162 of the year 1891, the same consisting of two or more con-
centric sleeves threaded one upon another, the inner one being secured to the
sleeve F, which is placed upon the axle, by a spline or feather, and the outer one
being geared to the motor. G. G. are collars on the axle provided with
horizontal rollers for receiving the end thrust of the concentric sleeves. Coiled
upon the sleeve F at each end of the screw mechanism is a spring H or H. Each
of the two wheels C is shown as provided with gearing such as constitutes the
present invention, the arrangement of one wheel being shown in Figures 2. 3
and 4.
The wheel C is provided with a hollow hub I extending out over the axle and
secured to the wheel by bolts a, which bolts pass loosely through holes in the
wheel for a purpose to be presently explained. Placed within the hollow hub I
is the friction ring K, the same being made in two parts united together by the
screw-threaded bolts b, which, between the two halves of the ring, have placed
upon them nuts c.
By turning the nuts c, the two halves of the friction ring are made to engage
the inner surface of the hub I with a greater or less degree of friction. The
friction ring K is provided with two or more holes d within each of which is
placed a pin e normally projected from the hole by a spring f which is attached
to the plate y on one side of the ring.
Fixed upon the end of the sleeve F is a disc L which extends out close to the
hub and preferably has its periphery covered with leather or other soft material.
M is the intermediate connecting plate, which has a hub keyed to the sleeve F.
This plate is provided with grooves i, which are entered by the pins e of the
friction ring and at the middle of each groove with a hole k A light spring 1 is
placed between the plate M and the disc L to hold the plate M away from the
ring K. N is an electro-magnet supported above the ring I from the bottom of
the car, the coils of which are as indicated in the armature circuit of the motor,
so that the magnet is energized when current is applied to the motor.
The operation of these devices is as follows: When current is applied to the

page_text: motor, it turns the screw mechanism and half the concentric sleeves are moved in
one direction along the sleeve F so as to compress the spring H, while the other
half are moved in the other direction and compress the spring H'. The magnet N
being energized at the same moment, raises the hub I (the bolts a
being loose in
the wheel C) and ring K, so that the disc L, which is fixed to sleeve F, is brought
into engagement with the hub I and the sleeve F is prevented from turning,
whereby the screw mechanism is allowed to move along it. The spring H will
thus be compressed until it obtains sufficient tension to turn the plate M against
the spring a slight degree only of compression being sufficient to accomplish
this, and as soon as the same is turned enough to bring the holes opposite the
pins e, the pins are forced up by the springs and enter such holes, and so bring
the plate M into positive engagement with the friction ring K, and this being in
frictional engagement with the hub 1, the wheel C is turned and the car is started
as soon as the screw mechanism has compressed the springs sufficiently to enable
the load to be overcome.
When the motor is stopped, the screw mechanism runs back to its central
position, and the pressure on the plate M being relieved, it turns back to its
normal position under the influence of the spring 1, so that the pins e are dis-
connected from the holes and the motor is disconnected from the frictional
connecting device.
If in starting, the load is too great for the motor even with the efficiency which
it attains by the work performed by it in compressing the springs H, H', the
friction ring, whose engagement with the hub I has been previously determined,
will slip on said hub and allow the motor time to continue to increase its
efficiency until it can start the car without danger or until the load is relieved.
It will be seen that the screw mechanism which engages the hollow shaft or
sleeve and is moveable longitudinally thereon forms a loose connection between
the motor and the friction member, whose engagement is not normally effective to
start the load, but which is moved by the motor to a point at which it effectively
engages the shaft, this point being determined by the spring or elastic cushion
with reference to the load; and the spring forms a gradual starting load for the
motor which is independent of its connection with the actual load or does not form
the medium through which the motive power is transmitted from the motor to
the car wheels.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is-
1. In gearing or apparatus for transinitting power from an electric motor to the
wheels of a vehicle which it propels, a friction member having a predetermined
fixed frictional engagement with the running gear of the vehicle and a mechanical
connection with the motor, in combination with a gradual loading device for the
motor independent of its connection with the friction member, whether the cor-
nection of the motor with the friction member is a permanent one or is one
normally out of engagement and thrown into engagement by the movement of
the motor at starting.
2. The combination of a wheeled vehicle, an electric motor thereon, a shaft, a
friction member in fixed frictional engagement with the running gear of the vehicle,
a connection between said friction member and the shaft, a screw mechanism con-
sisting of concentric threaded sleeves, the inner one feathered on the shaft and the
outer one geared to the motor, and an elastic cushion opposing the longitudinal
travel of said sleeves, substantially as set forth.
3. The combination of the axle of a vehicle, a wheel fixed thereon, a loose
sleeve on the axle, a friction member in fixed frictional engagement with said
wheel, a connection between said friction member and said sleeve, a nut engaging
the said sleeve and moveable longitudinally thereon, a connection between the

page_text: motor and said nut, and an elastic
nut, substantially as set forth.
on opposing the longitudinal travel of said
4. The combination of a wheeled vehicle, an electric motor mounted thereon, a
shaft, a friction member in fixed frictional engagement with the wheel, the inter-
mediate connecting device on said shaft adapted to engage the friction member
and turn the same, the screw mechanism on the shaft connected with the motor,
and the interposed spring substantially as set forth.
Dated March 1st 1892.
B. J. B. MILLS,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.