Improvements in Electrically Propelled Cars and like Vehicles.
Year: 1897

page_text: Date of Application, 23rd Mar., 1897--Accepted, 3rd July, 1897.
•
COMPLETE SPECIFICATION.
Improvements in Electrically Propelled Cars and like Vehicles.
I JAMES FINNEY MCELROY, of Albany in the State of New York, one of the
United States of America, Mechanical 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 improvements in motor trucks; and the objects of my
invention are to provide a street car truck arranged in such a manner that the
noise now attendant upon the operation thereof will be greatly reduced; the
pounded" averted; the movement of the car rendered more smoothly attended
with less vibration; and so arranged that the brakes may be operated more quickly;
and the construction such that the truck may be made at less expense and capable of
greater endurance than those now in use.
I attain these objects by means of the mechanism illustrated in the accompanying
drawings, in which
Fig. 1 is a plan partly in section.
Fig. 2 is a side elevation.
Fig. 3 is a detail perspective view of the saddle F.
Fig. 4 is a section along the lines 1-2-3-4 on Fig. 1.
Fig. 5 is a plan of a modified form of truck.
Fig. 6 is a side elevation of Fig. 5.
Fig. 7 is a detail perspective view of the journal supports.
Fig. 8 is a plan partly in section, showing the connection between the rod R and
the yoke Y.
Fig. 9 is a detail view of the yoke Y.
Fig. 10 is a plan of a modified form of my invention.
Fig. 11 is a side elevation of Fig. 10.
Fig. 12 is a side elevation of a modified form of my invention.
Fig. 13 is a side elevation of a modified form of my invention, and
Fig. 14 shows the friction roller in contact with a ring mounted on the shaft.
Similar letters refer to similar parts throughout the several views.
In electric cars, the trucks provided with electric motors are now arranged in
such a manner that the armature communicates with the car axle by means of a
pinion on the motor shaft, which intermeshes with the spur wheel on the car axle.
The spur gear wheel is necessarily of smaller diameter than the drive wheel, for
the reason that the spur wheel must not reach to within five or six inches of the
ground. These spur gear wheels are expensive and quickly wear out, and when
the teeth on the pinion or the gear wheel break, the motor becomes inoperative
and it is absolutely unable to propel the car. When the pinions become slightly
worn, the smooth running of the wheels is interfered with, causing a step by step
motion, instead of a steady rotary motion, the steps being taken by successive
contacts of tooth and tooth. When wheels in this condition are caused to turn
rapidly, or are transmitting a large amount of energy, the successive contacts of
the teeth of the two sets of wheels produce a noise which is exceedingly unpleasant.
Because of this objection, the pinions and gear wheels are often obliged to be
CD 077

page_text: thrown away long before the teeth are worn to such an extent as to become
absolutely inoperative.
In the construction of large cars, practical railroad men have encountered
difficulties because of the desire to employ two independent trucks, it being almost
impossible to obtain tractive effect sufficient to operate heavy cars, unless all of
the wheels carrying the weight of the car are also employed in driving the car.
Thus, if a car has two trucks, each made of two pairs of wheels, it has been deemed
necessary especially where heavy grades are to be encountered, to place four motors
upon the car, one connecting to each pair of wheels. The cars must be so con-
structed that they will turn ordinary street corners, and therefore the wheel base
must be brought within such limits that the pair of wheels which tends to move.
upon the tangent of the curve, will slip sufficiently to follow the curve itself. On
this account, when a single truck is used, the distance between the centre of the
wheels, which constitutes the wheel base, is limited to about seven feet. This
short wheel base is used in cars having a length as great as twenty-five feet or more.
The result of the short wheel base, is that whatever motion is produced by irregu-
larities in the track, is enlarged in proportion to the length of the car to the wheel
base, so that ordinarily the up and down motion at the end of a car twenty-five
feet long is at least four times the amount of the motion at the wheel base.
It is for the purpose of overcoming these difficulties with the existing method,
that I have invented a traction system which makes practical the use of double
trucks with longer cars, anu where short cars are desired, does away with pinions
and gear wheels, and therefore the noise produced by those devices and the expense
incurred in their maintenance.
To accomplish this, I construct a truck A in which the two sets of wheels BB
belonging to the truck are brought closer together, giving a short wheel base in
the truck, so that it will turn corners more easily, and then placing between the
forward and rear sets of wheels, a friction roller preferably made of steel and so
arranging the truck as to cause a pressure between the friction roller C and
the faces of the car wheels B B. This pressure may be approximately equal to
the pressure of the wheel upon the track. I then connect an electric or other
motor so as to cause the rotation of the friction roller C and the friction between
the roller and the two sets of car wheels will cause, when the motor is operated,
the rotation of all the wheels of the truck in the same direction. I preferably
place a roller C between the wheels on both sides of the car, so that all of the four
wheels of the truck are driven by the same motor and all driven in the same direc-
tion. It is obvious that I may use but one friction roller in the truck, the same
being rotated from the armature shaft and then communicated to the forward
and rear wheels of that truck, and by means of the axles of each pair of wheels
communicate the motion to the wheels running on the opposite side of the car.
In
_constructing the truck so as to cause the two sets of drive wheels to bear against the
friction roller, a number of constructions may be followed, all of which have the
same object in view; namely, the increase of tractive effect between the friction
roller and the drive wheels by means of pressure. I preferably employ for this
purpose the weight of the car to produce the thrust, so that as the load of the car
increases, and hence the amount of power necessary to move the car up grade
increases, I also increase the tractive effect between the friction roller and the
drive wheels. I therefore construct a truck frame A which rests upon the bearings
of the drive wheels B B and enlarge the truck frame bearings d d of one or both
of the drive wheels, so that they may have a horizontal motion toward the friction
roller, as shown in Fig. 2; the journal boxes D D being capable of motion within
the truck frame. I then connect the journal boxes D D by means of suitable
links D D to the arm f on the saddle F; the saddle F carrying the weight of the
motor, the weight of the car, or both the weight of the motor and the weight of
the car.
It is evident that the downward pressure upon this saddle, which is
suspended from the bearings of the truck journals, draws those journals towards
each other, and by adopting the proper angle between the connections to the

page_text: saddle and the journal boxes, the pressure which may be brought to bear upon the
friction roller may be increased to any desired extent. I preferably construct
this saddle F in the form shown in Fig. 3, being provided with spring seats gy
in each corner of the frame composing the saddle; upon which seats g g is arranged
a spiral spring S, which forms a cushion for the supporting frame G, which is
constructed to fit within the saddle F, and which frame G is provided on its upper
surface with suitable wheels or rollers g for the purpose of allowing for the tree
rotating movement of the car body upon the frame G.
Secured to the frame G and projecting therefrom, I arrange a king bolt G
which projects into the car body. Beneath the frame G and within the saddle F,
I mount the motor H supporting the same with strong springs sufficient to carry
the weight of the motor, making elastic connections from the sides f¹ of the saddle,
or in any suitable manner. I arrange a guide arm J to each end of the saddle F,
which arm projects into a bearing in the bracket K secured to the frame A, and
has a rod passing through the guide arm' J, also through the bracket K; said rod j
carrying on each side of the bracket K, a spring k k, allowing for a slight horizontal
motion against the tension of the spring k; the bearing in said bracket also allow-
ing for a slight vertical movement of the saddle.
For the purpose of allowing for an up and down movement of the motor, I
usually arrange a flexible connection betwen the friction roller shaft c and the
armature, as at L. As thus arranged, the supporting frame G which rests in the
saddle F is capable of a slight vertical motion within the bracket K, and thus
allows for any, wear that may take place in the friction roller, or in the car wheels
themselves, so that in all circumstances, the weight of the car may be made to
operate to cause the desired pressure of the drive wheels upon the friction rollers.
It is well-known that the drive wheels do not wear evenly, and the wear of the
drive wheels by running on the roller comes more largely upon those parts of the
drive wheels which bear against the track, and the wear therefore comes upon that
portion near the flanges of the drive wheels..
It will be noticed that the friction roller is so placed in my truck that its bearing
upon the face of the drive wheels is greater against those portions of the drive
wheel which do not receive the wear of the track. Thus I make the drive wheels
wear evenly, as that part which is worn by contact with the rails, does not receive
the wear due to contact with the friction roller, but rather those portions either
outside or inside the plane of rail contact. In the construction of the friction
roller C. I preferably make a groove in the friction roller, as at c', in which the
Hanges of the two drive wheels which bear against it run. I preferably make
this construction such that the bearing against the flange will come in the line of
the face of the drive wheel itself. This construction makes it possible to operate
this device without any slipping whatever in any part of the friction roller in
contact with the drive wheels. It also serves another, important purpose. Since
the flanges of the forward and rear wheels both run in the same groove in the
friction roller, I employ this groove to lock the forward and rear sets of drive
wheels together; in such a way that when the forward wheels strike a curve,
causing a pressure parallel to its axis, the strain is not thrown upon the truck
frame, but is communicated through the interlocking of the flanges of the forward
and rear drive wheels to cause a re-shifting of the truck as a whole to meet the new
direction of motion of the truck. This interlocking arrangement prevents the
strain of side motion in one set of drive wheels being thrown upon the truck
frame, which in the ordinary construction of apparatus must be strong enough
to draw upon the rear set of drivers, producing slipping on one of the wheels of
this set sufficient to shift the truck to its new position.
I am also enabled by the use of this apparatus, to apply the brake to the wheels
of the truck, causing them to stop rotation quickly. This causes a slipping
between the friction roller and the faces of the wheels which would result in the
stripping of the cogs were pinions and gear wheels employed. In the same way,
the use of my apparatus prevents shocks coming from the sudden application of

page_text: current to an electric motor, which are taken up between the friction roller and
the drive wheels in part at least, which in the case of pinions and gear wheels
would strip these wheels of their cogs.
Instead of having the friction roller brought in contact with the surface of the
drive wheels, it is apparent that rings might be constructed upon the drive wheels,
or friction wheels may be constructed mounted upon the drive wheel shafts against
which the friction roller may bear and which may be caused to operate as herein
described, see Fig. 14.
I may also employ a different construction in which the journal bearings of
the drive wheels are supported in the truck frame in such a way that the wheels
are brought close together, the distance between them being less than the diameter
of the friction roller; the friction roller can then be placed either above the wheels
or below, and caused to wedge into the space between the two wheels, and in this
way the pressure between the friction roller and the drive wheels may be obtained,
causing, when the friction roller is rotated, the proper direction of rotation in the
drive wheels.
In applying this method of traction to cars employing only a single truck, it
is evidently necessary to place the wheels further apart in order to obtain proper
wheel base. In making this application of the friction roller, I preferably con-
struct a truck frame bearing, upon the journal boxes of the driving wheel axles,
as shown in Fig. 6. In building trucks of this kind, I preferably use two motors
HH, one for each pair of drivers; the friction roller being connected directly to
the motor shaft as already described, the motor being suspended preferably on
elastic suspension springs to the frame of the car body.
In the construction shown in Figs. 5 and 6, I connect by means of the rod R,
the yokes YY, which yokes contain a bearing for the friction roller C, said rod
holding the friction roller in a fixed position. I preferably make a bearing
between the rod R and the yoke Y, such that an up and down motion may take
place between the rod and the yoke. I construct a frame M upon each side of
the truck, upon which is supported the body A of the car, preferably interposing
between the two springs a a. To the frame M, I secure the yoke Y and arrange
the journal boxes D D of the wheels B B between the downward and upwardly
projecting arms N N', so arranged that said journal boxes D) are capable of move-
ment between the arms N N', which arms are placed at a diagonal to the vertical
through the drive wheels, the weight of the car tending to force the journal boxes
I toward the centre line of the car and thus draw the wheels toward each other.
It is apparent that the greater the weight on the car, the greater will be the
pressure of the drive wheels upon the friction rollers.
In Figs. 10 and 11, I show a modified construction of my truck. In this, the
weight of the car on the frame A forces downward the tie plate P, to which the
connecting links Pare attached; the journal boxes D D of the drive wheels being
capable of horizontal movement, the friction roller being also capable of horizontal
movement. It is apparent that the links P¹ connecting the journal boxes of both
the friction roller and the drive wheels, will, because of the weight of the car
resting upon the tie plate to which the links are secured, cause the contact between
the drive wheels and the friction roller to be maintained by the weight of the car.
In Fig. 12 I show a modified form of my invention, arranging the bell crank
lever Qmounted upon the lug Q' which is secured to the frame A carrying the
.weight of the car. One end of the bell crank lever Q rests in contact with the top
of the journal box D of the drive wheel, the other end in contact with the journal
box P of the friction roller. Thus, when the weight in the car is increased, the
upward pressure on one arm of the bell crank lever Q will tend to force the friction
roller against the drive wheel..
The reverse of Fig. 12 is shown in Fig. 13. In this case, the friction rollers are
fixed rigidly in position, the weight of the car is on one arm of the lever Q. The
tendency is to move the journal boxes D of the drive wheels toward the friction
roller.

page_text: The contact between the drive wheels and the friction roller is an elastic one,
because of the movable bearing of the drive wheels, or when the drive wheel
bearing is immovable as in the modification shown in Fig. 12, of the movable
bearing of the friction roller.
The friction roller does not sustain the weight of the car or of the truck, but
is left free to adjust itself between the drive wheels, or in connection with one of
the drive wheels, as the case may be.
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:
1st. In a truck, forward and rear sets of drive wheels, a friction roller placed
between them and arranged to rotate in contact therewith, constant contact main-
tained by the weight of the car acting on the movable bearing of the friction
roller, a motor connected with and adapted to operate said friction roller, for the
purpose set forth.
2nd. In a truck, forward and rear sets of drive wheels, a friction roller, a motor
connected with and adapted to operate said friction roller, said friction roller and
drive wheels so arranged in relation to each other that the roller shall be in con-
tact with one of the forward and one of the rear wheels of each set in such manner
that the rotation of the friction roller will put in revolution both sets of wheels
in the same direction, constant contact between the friction roller and the drive
wheels maintained by the weight of the car acting on the movable bearing of
the drive wheels, for the purpose set forth.
3rd. In a truck, forward and rear sets of drive wheels, journal boxes for said
wheels movable horizontally, a roller arranged to make frictional contact with
one of the forward and one of the rear wheels of each set a motor, said roller
connected therewith, a car mounted on supports connected with said movable
journal boxes, the weight of the car causing the drive wheels to press against the
roller, for the purpose set forth.
4th. In a truck, a friction roller, a motor adapted to impart rotary motion to
said roller, forward and rear sets of drive wheels engaging with said roller, the
bearings of said drive wheels movable horizontally, a frame adapted to carry the
car, a saddle supporting said frame, said saddle mounted in said truck, connections
between the journal boxes of the drive wheels and the saddle, the weight of the
car on the saddle forcing the drive wheels in contact with the friction roller, for
the purpose set forth.
5th. In a truck, the combination of a drive wheel, a friction roller, a movable
journal box for said drive wheel, a car mounted on said truck, means for connect-
ing the supports of said car with the movable journal box, the weight of the car
causing the journal box of the drive wheel to so move as to increase the pressure
of the drive wheel upon the friction roller, for the purpose set forth.
6th. In a truck, a friction roller, a motor adapted to impart rotary motion
thereto, a drive wheel in contact with said friction roller, a movable bearing for
said drive wheel, and means for increasing the pressure of said drive wheel against
said friction roller by the weight of the car acting on the journal box of said
drive wheel, for the purpose set forth.
7th. In a truck, a drive wheel, a roller in frictional contact therewith, a car
supported upon a frame, connections between said frame and the journal box of
the drive wheel and the friction roller, the weight of the car on the frame operat-
ing to draw the drive wheel and the friction roller together, for the purpose set
forth.
8th. In a truck, a motor, a drive wheel, a friction roller, said motor adapted to
impart a rotary motion to said friction roller, a movable bearing for said friction
roller in the truck frame, a car mounted on said truck frame, a lever connecting
the movable journal box of said friction roller to said motor, the weight of the car.

page_text: tending to force the friction roller against the drive wheel, substantially as
described.
Dated this 23rd day of March 1897
HERBERT HADDON & Co.
18 Buckingham Street, Strand, London, W.C., Agents to Applicant.