Year: 1887

page_text: Date of Application, 22nd Feb., 1887.
Specification Accepted, 22nd Apr., 1887.
[Communicated from abroad by WALTER HARRIS KNIGHT, of 33, School Street,
Boston, Massachusetts, Electrical Engineer.]
I, JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman 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 means for connecting mechanically an electric motor to its
load and is especially adapted to motors on a constant potential circuit that are required
to operate mechanism at a variable speed.
It consists of devices whereby the ratio between the rates of rotation of the motor
and its load may be varied at will from zero to a maximum without interrupting the
connection between them or the operation of the motor.
The leading features of this gear are first that it is positive, that is, that through it
the motor acts upon its load without possibility of slippage, such as is liable to take
place with friction gears and belts and any motion of the motor is necessarily followed
by movement of the load; second, that it is variable, that is, that it can be changed
gradually and without interrupting its operation, so that the ratio between the speed of
the motor and that of its load can be whatever the operator may desire, this variation
taking place between positively operating parts, and having such. a range that the
speed of the load or driven mechanism may be increased from zero to a maximum
while that of the motor remains nearly constant.
I am aware that various attempts have been made to secure a changeable gear for
motors on a constant potential circuit, distinct sets of spur gearing with a clutch for
throwing either set into operation have been proposed; it has also been suggested that
conical pulleys with belts or friction wheels be employed, and adjustable reciprocating
gear is also not new, but none of these have the qualities of positiveness and
variability while in operation to the extreme degree, by which my invention is
characterized

page_text: More specifically my Invention consists in a reciprocating device to which motion is
imparted by the motor and which imparts motion to the driven mechanism by a step
by step action, this transmitter is made variable by having two parts, one of which is
constantly actuated by the motor and the other is movable relatively thereto from a
position of dead centre so as to have a variable throw imparted to it.
My invention also consists in various details of construction and especially in certain
features adapting it for railway service.
It is illustrated in the accompanying drawing wherein.
Figure 1. is a side elevation of the device applied to a railway vehicle, the axles,
being in section and only the operating parts being shown.
Fig
igure 2 is a plan view of the same.
Fig
igure 3 is a view of the crank without eccentrics.
Figure 4 shows one of the eccentrics.
Figure 5 shows the parts of the clutch in detail.
Figure 6 is a modified form of clutch.
Figure 7 shows a mechanical controller.
Figure 8, 9 and 10 show a hydraulic controller.
Figure 11 shows a spring connection between the armature and its shaft.
Figure 12 shows the hydraulic brake.
Figure 13 shows the motor connected to an ordinary distribution circuit of sub-
stantially constant potential. The circuit of a storage battery is one to which my
device is especially adapted.
In Figures 1 and 2. A A are the two axles of a vehicle to be propelled by an
electric motor, and a is the shaft of a rotary electric motor placed midway between
them the motion of the motor shaft a is imparted to the axles A A by means of my
new transmitting gear which consists of reciprocating clutches on the axles with
connecting rods extending to a variable crank or eccentric on the shaft.
In Figure 3 it will be seen that the shaft a terminates in two rectangular cranks a²
extending from the shaft in diametrically opposite directions; b. b. are two discs,
having rectangular openings fitted over a a' upon which as bearings they are free to
slide laterally and oppositely. They can thus be moved from their normal positions
concentric with shaft a, to a position eccentric thereto, as is shown in figures 1 and 2.
The discs b b. are embraced by straps e e from each of which extend two connecting
rods ff leading to the clutches which will be described hereafter. It will readily be
perceived that when b b. are concentric with the shaft no motion whatever will be
imparted to the straps and connecting rods, but that as b b. are moved outward on
their bearings a³ a³ a reciprocating motion combined with a rotary motion will be
given to the straps, which becomes practically a simple reciprocating motion at the
clutch; the amplitude of this motion being determined by the degree of eccentricity
of the discs. The degree of eccentricity of the discs, is completely under the control
of the operator of the machine being variable at will from zero, to a maximum with-
out interfering with the continuity of action of the mechanism, so that the motor may
run free or exert a greater or lesser leverage upon its load with a consequent and
corresponding variation in the speed at which the load moves. This is accomplished
by the following means: upon each disc b. is a lug b¹ projecting from its periphery in
a direction at right angles to the plane of the disc, the lug upon one disc extending
inwards and that on the other disc extending outwards, so that they both come into a
common plane at right angles to the axis of the shaft. These lugs form nuts in which
work the opposite ends of right and left handed screw c which has a bearing in the
circular head a' between the two cranks a' a'. In the centre of screw c is a pinion c¹
which engages with a rack d adapted to move axially in shaft a which is hollowed out
to receive it.
By the movement of this rack longitudinally both discs may be thrown out simul-
taneously and equally and the action of the motor be gradually imparted to the
transmitter and its load.
The manner of actuating this rack will be described hereafter, attention being next
called to the clutch,

page_text: Upon each axle is securely fastened a clutch cylinder B. shown in elevation in
figure 1, in plan in figure 2, and in section in figure 5. This cylinder is hollow and is
divided into two parts by partition so that one cylinder serves for two clutches one
upon each side. There will therefore be four clutches two acting upon each axle and
connected respectively with the rods ff extending in opposite directions from the
motor. As the clutches are all alike a description of one will serve for all.
Fitting the interior of the cylinder is a gripping ring / which in the form shown in
figure 1 is constructed in three annular segments and and has an opening left
in its circumference between segments and in which is inserted a binding cam or
dog k. This cam k has an upright arm to the end of which is journaled the end of
the connecting rod fand its function is, when turned by the pull of the rod upon the
arm, to spread or distend the gripping ring until it presses so tightly upon the clutch
cylinder, that any further movement of the cam carries with it the cylinder, and
rotates the axle. In figure 1. the cam is shown in dotted lines in its binding
position, the amount of its "play" between segments 13 and 1 being greatly exag-
gerated, in fact it fits quite closely and has its corners slightly rounded. It is apparent
from the description thus far given, that the cam. will bind, upon the movement of the
rod from either direction while it is essential to its operation that it should move freely.
in one direction carrying the gripping ring with it. The direction of movement of
the vehicle will obviously depend upon the direction in which the cam binds and in
which it moves freely, so that this should be determinable at will for the purpose of.
reversing the vehicle when desired. The manner of accomplishing this will be
understood from a further consideration of the drawing.
Cam k is supported at its pivotal point by an arm h which has a bearing upon a
arm g having in turn a bearing on the axle.
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the
similar arm
Upon the inner side of the arm h are fixed two stops m and m¹³ one upon each side
of the cam k.
Arm in its bearing on g is concentric thereto but g in its bearing on the axle is
eccentric thereto, if therefore the outer end of g be thrown over in one direction the
inner end of h, will be thrown in the opposite direction carrying stops m and m¹ with
it. By this means either m or m¹ will be moved over laterally until it comes against
the lower end of cam k, the effect of which will be understood by an inspection of
figure 1, taking for example the upper right hand clutch. When in that clutch the
connecting rod f tends to move from right to left pulling on arm h and the outer end of
cam k. the body of the cam being free to move relatively to h will tend to lag behind,
and its opposite corners binding against segments and will distend the gripping
ring as described before and turn the clutch cylinder and axle A.
When however, it has completed its stroke and starts to return from left to right
the stop m', which may be called the releasing stop, and which it is to be borne in
mind is carried by supporting arm h, comes against the lower end of k and prevents
its lagging behind the supporting arm so as to bind in the segments; the cam has
instead a Hat square bearing against segment and turns the gripping ring loosely
around in the cylinder.
It will be seen that a rapid repetition of this action gives a series of impulses to the
axles which by the momentum of the load are converted into a practically continuous
rotation. The two clutches on each axle act alternately, so that while one is pulling
the other one is going free. They are also upon opposite sides of the axle, one above
and the other below, by means of which I preserve a balanced side pressure on the
motor shaft, for diagonally opposite clutches will be pushing or pulling simultaneously,
so that they mutually counteract each others reaction on the shaft, a feature of great
importance in a rapidly moving mechanism.
It will be readily seen that the movement of the connecting rods imparted thereto
by the crank-the eccentric being considered as a crank with a wrist pin larger in
diameter than the shaft is an harmonic movement, that is, with each stroke it starts
from a state of rest and gradually increases in speed to a maximum and thence again
decreases in speed to a state of rest.
The rate of speed of any point in the connecting rod in a horizontal direction would

page_text: be represented graphically by a regular undulating curve, this at least is the tendency,
while on the other hand the rate of speed of the axle for a given load and a given
throw of the driving eccentrics, should be constant and capable of representation by a
straight line.
Suppose then the transmitting mechanism to be rigid, and for a constant armature
speed the clutch would act upon the axle for only an instant in each double stroke,
the undulatory curve representing the clutch speed would meet the straight line
representing the axle speed at a series of maximum points only.
The result would be, that unless a large number of clutches were used, acting
successively on the axle, a series of impulses would be imparted by the clutch so
sudden as to be almost blows and undue wear of the parts would ensue as well as a
disagreeable pounding uncomfortable for travellers on the vehicle, while in starting a
load up a hill the momentum due to one impulse would not be sufficient to maintain
the motion till the next impulse, I surmount the difficulty here involved by placing at
some point in the train of mechanism between the armature and its load an elastic
medium through which the transmitter must act. This modifies to a large degree the
harmonic tendency of the reciprocating parts and distributes the action of each clutch
upon the axle over a larger part of its stroke.
I have found this elasticity to be best attained by introducing a spring between the
armature and its shaft. The kind of spring best adapted for this purpose is illustrated
in figure 11.
O represents the armature, its hub o being loose on the shaft; o¹ is a disc made in
halves and clamped tightly to the shaft, and between it and hub o is a series of steel
spring rods o², the disc being fast on the shaft and the armature and hub being loose,
a slight spring of the armature relatively to the shaft is easily obtained.
I have now fully explained my transmitting gear, though a modified but very
desirable form of it as well as the controlling mechanism remains to be explained, and
I will say here that for the purpose of more clearly defining the invention I consider
the transmitting gear to be in two parts one of which is continuously operated by the
motor while the other part is movable relatively to the first from a position of dead
centre where it receives no motion therefrom to an eccentric position where it receives
therefrom a motion greater or less as the operator may desire. In the form described
the first part is the cranks a which are driven constantly by the shaft a, and the
second part includes the discs b, the clutches and intermediate connections. The
discs it is true are constantly rotated by the cranks but in reciprocating movement,
which alone is essential to the operation of the clutches and axle, the discs partake of
the nature of the second part of the gear, and should be considered as belonging to it.
I do not intend to limit myself to the variable eccentric herein shown since other
well known mechanical substitutes therefor such as a sliding link may be employed.
The modified form of clutch is shown in figure 6. In this form the three part
gripping ring is replaced by a light loop of steel or brass the ends having a slight
tendency to spring in against the cam k, the cam has a spring extension k¹, which
constantly presses the cam over into a binding position and has a bearing upon the
diametrically opposite point of the ring. By moving the ends of this spring from one
side to the other, the action of the clutch will be reversed. This is accomplished in
the following manner, the end of the spring is pivoted at point p¹ on the segment p
which in turn is pivoted to lug fastened to the ring 1. On the periphery of the
segments prests a rod C having two straps attached to it which are connected
respectively to opposite ends of the arc of the segment. The rods C from opposite
clutches are drawn in contrary directions by an intermediate lever D which is worked
from opposite ends of the vehicle.
14
The connecting rods in this form of clutch are connected to opposite sides of the
same eccentric strap, so that they may work directly upon the cams without an offset
such as is necessary when from the same eccentric, rods extend to clutches upon
opposite sides of cylinder B. When this arrangement of rods is adopted it is necessary
in order to secure the balanced strain to have the two clutches on one axle both below,
and those on the other axle both above. The ring is circumferentially adjustable.

page_text: In controlling this gear connected with motors on a constant potential circuit, is
involved all the control necessary for the complete working of the motor.
It is wholly mechanical, there being no artificial resistances or circuit breakers
necessary, the motor runs constantly in a constant direction so that the lead of the
brushes may be constant also, both in direction and degree; a simple series-wound
motor is all that is required and the central station regulation is much simplified.
I have found it desirable that the brake mechanism for the vehicle and the rack
controlling the gear, should both be capable of operation by the same device, so that
one controlling lever or wheel is all that is necessary for the management of a car,
in addition to the reversing mechanism which will only be operated at comparatively
long intervals.
In stopping the car the rack and brake should be worked suc-
cessively, while in starting, the reverse order should be followed in order that the
brakes shall never be set while the motor is acting on the axles.
In figure 7 a mechanical arrangement for working the brake and rack is shown.
D is a spocket wheel on the ordinary brake spindle of a street car, by means of
which the ordinary brake apparatus can be worked positively in both directions.
This
This consists as usual of a lever E pivoted centrally beneath the car and connected
at each end to draw rods extending to join the spocket chain working on wheel D.
From opposite sides of the centre of E rods F extend to brake beains G.
is the cominon brake mechanism in use on street cars. In addition I provide a
lever K which has at one end a slotted pivotal bearing and at the other a swivelled
journal-box enclosing the rotating head of a rack d. A connecting rod H joins the
levers E and K and is so held by guides H' that it both slides and turns upon them.
This permits the end of K which carries the end of rack d to move in a straight line.
The two extreme positions of the apparatus are shown by the full lines and dotted
lines respectively, the former showing the normal position with the rack clear in,
where it is held by the spring M.
It will thus be necessary in starting the car to turn the spindle against the pull
of the spring M and in stopping to simply let go of the handle, when the spring
will throw in the rack and bring the brake shoes close to the wheel where they
may be set by a further turn of the spindle given by hand. The rack is therefore
always in before the brakes are set, and the brakes are always released before the
rack is drawn out.
Figures 8, 9, 10 and 12 show a device for working the brake and the rack
hydraulically.
A compression cylinder containing oil or other fluid is controlled by the operator,
and from thence a pipe leads to a second cylinder where by means of a piston the
pressure is transmitted to the rack and brake; Air of course may be substituted for
the oil.
L figures 9 and 10 is a cylinder in which moves a piston by means of a screw on
the lower end of the ordinary brake spindle N.
This spindle is intended to be operated as in the mechanical brake, the spring is in
this case wound around the shank of the spindle. The handle at the top is loose on
the spindle but has a projection which is normally held by the weight of the handle in
engagement with the teeth of a crown wheel fastened to the spindle, so that to stop
the vehicle, the handle is lifted and the spindle allowed to turn under the force of the
spring till the rack is forced in and the brakes are in position to be set. From the
compression cylinder L a pipe leads to the cylinder P in which the head of a rack d
works as a piston; which is drawn into the cylinder by air pressure, and is forced
out by hydraulic pressure. When the rack d is forced completely out of the cylinder
and into the hollow motor shaft, the oil is then forced up through the valve U into the
cylinder R against the force of the plate spring T.
Outside of the cylinder R is a niovable cylinder Q which is connected with the
brake mechanism as shown in figure 12 which is a well known toggle movement,
adjustable by means of turn buckle W₁ between the lower ends of the rods W.
Pipe Z leads to a similar arrangement upon the other side of the vehicle.
When the oil pressure is released the weight of the brake shoes and the air pressure

page_text: combined expel the oil from the cylinder R through the valve V and release the brakes
before the rack is drawn in.
Figure 10 shows the system in diagram and also shows more than one controlling
mechanism on the same system of piping.
When two or more motors are used on the same car or train it will be of great service
to have their transmitting gear controlled from a common point.
In all forms of controlling mechanism the gear will be in action while the said
mechanism will be practically stationary. When a single car is used, as in tramway
service, a compressing cylinder L will be placed on each end of the car so that it can
travel in each direction without turning around.
The reversing mechanism is so shown in figure 6. In the first described clutch all
the reversing arms g extend practically from the axle and are connected by a common
rod g² which is controlled from either platform as is shown in figure 6. The motor
and the gear will all be enclosed in a well known manner so as to be protected from
dust and weather.
In order to close the circuit through the motor and give it its initial rotation without
injury from a sudden excess of current, I provide a resistance between the line and the
motor through which the current can be gradually admitted to the machine. This
resistance consists of a pile of plates or otherwise shaped piece of metal, preferably
iron or steel which rest in contact with one another so as to give a superficial resistance
to the passage of the current through the mass. A contact lever or other movable
device makes connection electrically with any point in the series of pieces so that any
desired number of them may be in circuit or the whole of them may be cut out entirely.
Although a mass of iron shot, or a pile of iron rods may be used, I prefer thin sheet
iron plates about 6 inches square, or of any other size adapted to the current to be
carried.
These plates are set on edge and packed face to face and a "jack-knife" lover
arranged below them so as to strike the lower edges in succession and slightly lift the
plates from their bearings. They then rest on the lever and make good electrical
connection with it, while the lever being one terminal of the circuit and the last plate
of the series being the other terminal, all the plates from the end of the pile to the
point of contact of the lever are in the circuit. Since this point of contact shifts
rapidly along the pile as the lever is raised and lowered, the number of plates in the
circuit is varied from zero to a maximum by the position of the lever.
When the maximum number of plates are in circuit the resistance is practically
infinite and by gradually moving the lever the current is admitted slowly until the
maximum speed of the motor is attained when no resistance should be left in.
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.
First. The herein described variable transmitting gear for use between an electric
motor and mechanism operated thereby substantially as herein before described.
Second. A positive transmitting gear between an electric motor and its driven
mechanism variable at will without interruption of the operation of the motor
substantially as hereinbefore described.
Third. A transmitting gear between an electric motor and its driven mechanism
that is variable from zero to a maximum so that the motor may be allowed to run free
substantially as herein before described.
Fourth. A transmitting gear between an electric motor and its driven mechanism
having reciprocating parts that are variable at the will of the operator so that the ratio
of speed of the motor to that of the mechanism may be changed as desired substantially
as herein before described.
Fifth. A variable reciprocating transmitting gear between an electric motor and its
driven mechanism having an elastic medium so that the harmonic motion of the
reciprocating part may be converted into a uniform motion of the rotating part
substantially as hereinbefore described.
Sixth. A transmitting gear between an electric motor and its driven mechanism

page_text: consisting of a reciprocating part acting intermittently on the mechanism and having
a motion imparted thereto by the motor which is variable at will substantially as
hereinbefore described.
Seventh. Two or more variable transmitting gears between an electric motor and
its driven mechanism and a common device for varying them simultaneously and
equally at the will of the operator substantially as hereinbefore described.
Eighth. A variable and reversible transmitting gear between an electric motor and
its driven mechanism controllable at the will of the operator substantially as herein-
before described.
Ninth. Two or more reversible transmitting gears between an electric motor and its
driven mechanism with a common reversing device therefor substantially as herein-
before described.
Tenth. An electric motor on a circuit of constant potential and mechanism driven
thereby, with means for manually controlling the same without artificial resistances or
circuit breakers, consisting of a transmitting device between the motor and mechanism
variable at the will of the operator from zero to a maximum, substantially as herein-
before described.
Eleventh. An electric motor combined with driven mechanism, an intermediate
variable transmitting gear, a brako for the mechanism and a common controlling
device for the brake and gear substantially as hereinbefore described.
Twelfth. The combination of an electric motor, a railway vehicle, a variable
transmitting gear and a varying device for the gear extending to the point of control
on the vehicle and forming the main regulating device of the speed of the vehicle
substantially as herein before described.
Thirteenth. Two or more motors each having a variable transmitting gear between
it and its driven mechanism and a common controlling device for the several gears
substantially as herein before described.
Fourteenth. The details of construction of the above described transmitting gear
whereby it may be varied at will and applied to the propulsion of Railway vehicles
substantially as herein before described.
Fifteenth. The rheostat, consisting of a series of plates or pieces of iron or steel
forming a superficial resistance to the passage of the current with a variable point of
contact whereby the resistance can be controlled at will substantially as hereinbefore
described.
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