Devices for Retarding the Motion of Electrically Propelled Vehicles and other Moving Bodies.
Year: 1894

page_text: Date of Application, 18th Sept.. 1894-Accepted, 5th Jan., 1895
COMPLETE SPECIFICATION.
Devices for Retarding the Motion of Electrically Propelled Vehicles
and other Moving Bodies.
I, ELMER AMBROSE SPERRY, Gentleman, of No. 855 Case Avenue, Cleveland,
State of Ohio, United States of America, do hereby declare the nature of my
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 brakes for retarding or arresting motion, and
more particularly to magnetic brakes wherein the electric current is used for
energizing the magnet; certain details of construction; methods of support;
guiding; lubrication; bringing up the electrical terminals; methods, mechanism
and details for application and control of the brake, and also details of truck and
reel for use in connection with the brake magnets; and other structural details
which contribute to the cheapness and efficiency of the construction of electric
brakes. These are fully described and illustrated in the following Specification
and the accompanying drawings, the novel features being pointed out in the claims
hereto annexed.
In the drawings,
Figure 1 represents an isometrical view of a vehicle truck, partially in section,
with brake and motor applied.
Figures 2 and 3 are sectional views of the wheel and also of the brake applied
thereto.
Figure 4 is an elevation.
Figure 5 is a detail of my improved brake mechanism.
Figures 6 and 8 represent elevations, partially in section, of the controlling
device, circuits in diagram.
Figures 7 and 9 are plan views of the same.
Figures 10 and 11 are diagrammatic views of some of the connections when the
electric brake is used in connection with one or two motors.
Figures 12 and 13 are face views of the brake magnet with different modes of
attachment and support.
Figure 14 is a detail of a reel.
Figure 15 is a section of a brake magnet secured to the axle of the car and
co-operating reel.
Like letters and numerals of reference indicate similar parts throughout.
The mechanism is shown in connection with a car or tram truck, and may
operate in connection with either one motor as seen in Figure 1, or two or more
motors. In Figure 1, the motor is shown as supported in the middle of the truck-
frame and is provided with power connections to each axle. The brake mechanism
will be understood to be equally well adapted for retarding oscillatory, vibratory or
rectilinear motions as for arresting continuous rotary motion.
The application of the brake for arresting all kinds of motion is practically the
same, for in all cases the brake coil is brought in proximity to the moving part so
as to engage such moving part when energized and retard its motion. It will thus
be seen that the kind of motion, whether oscillating, vibratory, rectilinear or rotary,
does not in any way affect the application of the brake. When employed to arrest
rotary motion the brake application should be made as far from the centre of

page_text: rotation as practicable. If a wheel-shaped magnet is used mounted upon an
axle A, as for instance in Figures 12 and 13, the removal of a wheel B, would be
required before the brake could be applied. I have found, however, that by
making the brake in a crescent shape (Figures 1, and 4) I am enabled to easily
attach or remove it from the vehicle without disturbing any of the wheels, and
provide space for relief of magnetic stress when the lines are withdrawn and do not
flow through the masses immediately under or adjacent to the braking face. The
constant protrusion and withdrawal of lines causes the production of powerful eddy
currents in the masses discussed hereinafter, and which is a function of great value
in the power and operation of the brake. The gap between the magnet ends also
affords a space opposite the braking face in which a proper, and preferably a
conducting, lubricator H' for the said face can be applied. The lubrication is
found to reduce very materially the wear upon the surfaces, and the latter becomes
highly polished.
It is always found better to support the mass of the brake magnet, when for
instance use upon cars, upon the elastically suspended truck parts as cross bars D,
than to have it directly axle-mounted, although for some purposes this method may
be preferable and precludes direct attachment to the axle in any way, and
necessitates freedom of movement between the brake and the rotating part. It will
be readily understood that the rotating part may be a part of the wheel itself or an
extra piece suitably attached to either wheel or axle. Allowing B to indicate a car
wheel, a face B' is provided for the co-operation of the brake magnet C¹ supported
from the truck frame or any suitable portion thereof, as D, by the links D¹ through
the pins d d'. It will be noticed, especially in Figure 1, that the pins d and d¹ are
out of a vertical line in such a way that gravity acts to constantly withdraw
the brake from the wheel and hold it against any suitable abutment as collar G,
forming a guide between which and the brake magnet or projections therefrom is
inserted a separable wearing face F, provided with a cap F joining the two and at
the same time covering an oil cavity F" in each. It will be seen that this guide
holds the magnet laterally, but allows it freedom to move vertically. A coil Claps
back upon itself and winds around a movable core C" which is suitably secured to
the main body of the brake magnet C' as by bolt shown at J. The joint between
the core C and the body C¹ may be machined, the slot in this case being originally
carried out to the gap at both ends, and afterwards stopped by the removable
portions K, see Figure 4, which may be held in position in any suitable manner.
The coil C is smaller than the annular groove in which it lies, and in the space is
placed insulation b as for instance by pouring in a molten state, an insulating
substance such as sulphur, bitumen, paraffine or the like, up for instance to a point
in the groove covering the coil. Afterwards lead, babbitt, or like metal a may be
poured in the face slot, sufficient to make a solid face of the whole, smooth and
practically interrupted after being machined.
The action in retarding is a peculiar and novel one, and consists in the generation
of currents in the masses. The metal filling a is also found to be of great service
in aiding in the retarding by offering a ready conductor for the currents generated
the most intensely at or just under the face of the rotating element. For best
results the lubricator H should be of graphite, carbon or other conducting
substance which is found still further to greatly enhance the retarding effect of the
.brake as a whole. The magnetic "adherence" owing to a given magnetic density
is known. The coefficient of friction between the surface so adhering is also
readily determinable. The retarding influence, however, is found to vary with the
velocity, and at a velocity, say of sixty-five (65) revolutions a minute to be far in
excess of an amount of retardation that would be due to the friction caused caused by
the pressure of adherence. This action may be and probably is due to the Foucault or
eddy currents produced in the masses from a cutting of the lines of force circulating
therethrough and emanating from the stationary magnet. Under conditions of
velocity investigated, to this production of current can be traced much more
retardation than to the simple friction.

page_text: Any feature aiding the free circulation of these eddy currents is found to greatly
facilitate the action of the device. These have been named above, and are
primarily the perfect contact between the stationary and moving element, secondly,
a lubricant at this point which is a conductor, and thirdly, a non-magnetic electrical
conductor filling the circular gap a, all of which aids the currents which are
produced at the immediate surface of the rotating element to circulate freely,
which circulation is found to include the conductors on both sides of the joint or
air gap.
It will readily be understood that the rotating face might be of cylin Irical form
rather than disk-like, and might rise up from the shaft at, any convenient place
thereon or be separate from the wheel and fastened thereto, and the magnet might
be made in various forms, for instance, different spools of wire or of inclosed form
similar to that shown in the drawings but with a number of slots and coils filling
the same; or the magnet might be made to rotate, leaving the disk or co-operating
mass stationary.
The metal insertion a is also important as leaving no irregularities for the
lodgment of sand, gritty substances or dirt. This metal at the same time holds the
block K in place by the peculiarity and the contour of the groove between it
and the body of the brake magnet C. The inner faces of the groove are
preferably dove-tailed as shown in section Figure 3, so as to more readily hold
the metal in place. The gap in the crescent is wide enough to admit of the
largest axle to be used, and the lubricator therein may be either solid or fluid, and
is shown in the form of a graphite block, graphite carbon brush or the like,
contained in the cavity of the receptacle H and may be forced forward by the
pressure of the spring I, which spring may be said to feed the lubricator, or may
be held solidly in grooves, Figures 13 and 14.
In the details of bringing out the terminals shown in Figure 5, a clamp secures
the terminals after they have issued from the coil through the insulating bushing L,
one of them being grounded on the frame by the screw M, the end or head of
which is under the surface of the counterbore M' securing the wire in the hole m.
Attention is called to the free wire of considerable length which is in the
coil etc. each side of the clamp. Other details of the support of this wire
might be used, but the free wire and the bringing out of the ground terminal
and re-imbedding it into the material is found of value for the purpose of testing
the coil when desirable. An extra or free wire is found valuable to prevent
crystallization, and also when for any reason the terminals are disturbed through
accident or otherwise the free wire necessary for re-attachment is found of service.
It will be understood that any method of support of the brake magnet may be
employed without departing from the spirit of my invention. The one shown
affords attachment at a point above the center of gravity in one plane, and in the
center of the mass, or the center of gravity in the other plane, or the plane of the
magnet.
The use and operation will be readily understood from the foregoing. The
brake coil or coils may be supplied by current from any of the usual sources, as
for instance the current generated by the motor after being transformed into a
generator, from the central station, storage battery, primary battery or any of the
usual sources of electrical potential. Practically the whole of the mass of the
brake is energized by the coil, the coil being crescent shape after it is folded back,
upon itself. The mass could be energized by a single coil, the return of which
could be laid upon the back of the magnet, but in this event less of the turus
would be of service. The coil could also be continued to cross the gap and enter
the mass at the other side, but in this case the magnet would not be easy of
attachment and removal, and in either event it would be fully energized and
operated substantially as herein described.
The three poles or double magnetic circuit of the brake magnet renders only
one-half the thickness of "keeper" or co-operating armature necessary for a
given magnetic effect, and also shortens the magnetic circuit.

page_text: By referring to Fig. 3-the construction which enables me to bring three pole
faces in contact with the keeper, which in this case is the wheel B, will be readily
understood. The section through the brake coil near the bottom of the wheel
shows the core c' in contact with the wheel. To the back of the core c¹, is
fastened the outside case or covering of the coil which is bent around so that both
its edges come in contact with the surface of the wheel, the edges of the case or
cover being separated from the core c¹ by the non-magnetic portions a, a. It will
thus be seen that three concentric pole faces are presented to the surface of the
wheel, and that the two outer pole faces are of a polarity opposite to that of the
central pole face.
The form and construction of vehicle wheels which it has been found practicable
to cast from such material as is necessarily used in wheels of this class, on
account of chilling shrinkage and cracking, will be understood by the following
description.
Upon the axle A, Figure 2, rests the hub U, supporting the tread U', and
flange U. The brake surface B', is backed up by a mass of metal B for the
purpose of obtaining a sufficient quantity of iron for the necessary magnetic flux
and for other purposes such as proper strength, etc. This mass, though thicker
towards the axle A, and thinner at the outer edge owing to the different peripheral
lengths at these points, is still found heavy enough to draw the chill in the tread,
and in casting such wheels many have been spoiled and rendered useless. I have
found, however, that by making a certain inner contour, swinging the line inward
and in some instances under the tread U', making an undercut shown at point V,
and also on the other side which is for some purposes also necessary as at V',
I am enabled to cast the wheels with the proper density of chill on the tread Ui
and make the same durable. In some cases have found it necessary to bring
the inner and outer surfaces near enough together to form a neck at point V
thinner than the mass B". A number of designs have been made for connecting
the mass B with the hub U, but I prefer the curved portion shown at W which
is usually thinner than the mass B. The wheels may be made with perforations
through the mass, spokes, or without, and I find it in some cases preferable to
provide the laterally projecting webs W1.
As to the method of application and control of the electric brakes the general
plan show in my former Patent No. 9968-dated 22 May 1894 will be generally
employed, also the control and the conversion of the motor into a generator as
herein shown whereby separate handles are employed for such purpose in lieu of
the double use of one and the same handle.
So-called motor men not being experts often apply the motive power to cars
while the brake is yet active, and also attempt to apply the brake while the motor
is still active. The present invention is designed to obviate this by arrangement
for dissimultaneous operation so that one cannot be operated until the other is
thrown off.
Referring now to Figures 6, 7, 8, 9, 10 and 11, the line N indicates the floor of
the platform upon which are mounted the controllers N', N and M". These are
shown as having separate casings n' and " but they may obviously be all placed
within a single case. In either eveut there should be two handles. The handles O
are used normally to apply the power to the motor (current if it be an electric
motor) shown in Figure 6 as having a swinging movement on the lever O', and in
Figure 8, as having a rotary movement about or with the spindle O". Either of
these handles O or P may have any of the well known movements by means of
which their functions are performed. For instance, the handle P may be
attached to a lever similar to O" and swing instead of rotate, or both of the
handles may be fastened to slides and slide in grooves which are either rectilinear
or curved, and the invention extends to such constructions. In the figures the
handles are shown in their positions of rest in which they may be locked. The
locking, however, may occur at any predetermined position which may be known
as the "critical position" of the handles. The function of the handle P is

page_text: essentially different from that of the handle O. For instance, it may wind up a
brake chain P or may apply any power to operate the brake; it may be used to
signal for brakes; or perform functions which are necessary in connection with
the motor, trailer or power applier N' or N the former being shown in Figure 6
to be connected with the trolley T by wire and also to the motors P2 P3 by
wires
P p etc.
The motors are also connected with the operating handle P
by wires pl p¹ etc. The handle O and P in Figure 6 therefore constitute
switches for controlling the circuit relations of the motors P2 and P3 or either of
them.
The essence of one part of the invention resides in the interlocking device by
means of which the normal actuation or movement of one of the levers is caused
to effect the movement of the other. This may be carried into practice by
various methods, two of which are illustrated in the drawings, consisting in the
connecting link p¹¹, Figures 6 and 7, which connects the controller or portion
of the controller containing one handle with that containing the other. This
lever co-operates with the notched disk Q connected with the handle P either
direct or through the pivoted dog Q. The connecting link p" or the connected
parts are preferably given a tendency in one direction, to the left in the drawing,
by a spring or by the gravity of the latch Q pivoted at y in Figures 6 and 7.
The link pin Figures 8 and 9, is shown working in a horizontal plane and
the latch Qis dispensed with. The latch Q co-operates with the lever O'.
In the operation of the handle O an abutment is shown by means of which the
connection is actuated when the handle O is thrown to or near some predeter-
nined position, which may be one of its extreme positions when it abuts against
the ends of the connecting link pl. In Figures 8 and 9 a single sliding link p
is shown extending from one disk Q to the other disk R each bearing a notch
so located and of such depth that the end of the link serves to secure it
from rotation as in Figure 9. This is true only when the handle O is away
from its critical position as shown in this figure. When in its critical position
the end of the link p¹¹ may drop into the notch R' locking the disk k and
freeing the disk Q.
In Figure 10 the electrical connections are shown for a drum or cylinder S,
the upper end of which may be seen in Figure 6 and Figure 8 within the casing
when the controller or the side of the controller indicated at is used in
connection with an electric motor. The connections here shown are of a closed
circuit for the motor and the connections with its armature and field are reversed
relatively to their use when operating the car from the trolley current, the
principal features consisting in the fact, which may or may not always be
present, that the current is local and closed, Ar being the armature, S¹ the field,
and R the resistance by the cutting out of which the current generated by the
transformed motor may be controlled. Electric brake magnets for farther
arresting the train, or other device operated in the local circuit, are indicated
at C. Figure 11 shows a diagram of the circuits, for instance on cylinder S
when two motors are used, Ar and A being two armatures and F2 and F3 two
fields. In this instance the means of manipulation of the resistance R" is not
illustrated and the circuit is not complete and local except through the ground G³.
The operated device G¹ may or may not be present as shown in the circuit.
Here the current may pass one field in a direction similar to that taken when
used as a motor, and pass the other field in the opposite direction, the advantages
of which are well known.
The use and operation of the invention will be readily understood from the
foregoing; and the uses of the motor for braking purposes and the methods of its
Conversion into an electrical generator are well known and have been described in
the Specification of my said former Letters Patent, and being clearly shown herein
need not be further referred to.
A peculiarity in arresting the rotary motion consists in the fact that where axle-
mounted magnets are used the projections "d" are brought so in each case that

page_text: they shall be under their respective abutments, being the truck part D, Figures 12
and 13. An anti-rattling cushion of leather or the like T¹ may be used, and on the
other side is a rod R' and rubber cushion T¹ secured to the cross-bar of the truck.
The advantage of this arrangement consists in the fact that upon each application
of the brake, no matter in which direction the car is moving, the abutting pressure
is upward, and, lifting, tends to relieve the journal bearing at the axle of its friction
due to the weight of the supported mass, some of the weight in this event being
carried by the tendency of the brake to rotate. The advantage of this arrangement
over the old form of applying a brake shoe, which increases the pressure on the
journal, will be readily understood.
Other means can be provided for preventing rotation of the magnet, as the
links D' D', Figure 13. These are so slotted at T" that the pins d' are in or near
the top of the slots and a tendency to rotate during the braking action causes a
lifting and consequent relief of the pressure at the journal bearing as above
described. The brake magnet may be solid on the axle and co-operate with a
chain reel for winding the brake chain and applying the brakes. The novelty
consists in the method clasping the halves of one part together, being held by the
other or bolted part. The reel consists of halves t2t2 each having a dove-tailed
projection t¹ and a co-operating groove. These are slipped together longitudinally,
both being held against the axle and when once locked cannot be separated if
confined to a certain longitudinal space on the axle. This is afforded by the brake
magnet C' on one side and the collar t on the other. The dove-tailed slots are
lined with babbitt or like metal u facilitating manufacture. u¹ indicates the brake
chain and u the contact for the brake coil C.
It will be understood that other devices may be employed, for instance, the
latches and projections may be actuated by electro-magnets or by other mechanical
means, such as gearing and the like, without departing from the spirit of the
invention, and while it is designed to use all the above features in connection with
each other, yet it is obvious that some may be used without the others, and the
invention extends to such use.
Having now particularly described and ascertained the nature of said invention,
and in what manner the same is to be performed, I declare that what I claim is :-
1. In a brake for revolving machinery, a revolving part, an independently
supported brake magnet, and means mounted upon the revolving part for guiding
the magnet horizontally, and leaving same free vertically.
2. In a brake for arresting motion, a brake magnet presenting a lateral wearing
face, supports for the brake magnet above the center of gravity thereof, and
independent means for guiding the magnet.
3. In a brake for arresting motion, a moving part, a brake magnet, yielding
supports for the magnet and means for giving a constantly separating tendency
between the moving part and the magnet.
4. In a brake for arresting motion, a link attached to a support and extending to
the magnet, the points of attachment being in such a line that the weight of the
magnet tends to draw the same away from the moving part.
5. In a brake for revolving machinery, a revolving part, presenting a lateral
braking face, a brake magnet cc-operating with such face, a link attached to a
support and extending to the magnet in such alignment that the weight of the
magnet constantly tends to draw it away from the face of the revolving part when
the former is out of action, in combination with means connected with the revolving
part for confining the axle movement of the magnet.
6. In a brake for arresting motion, a moving part, a brake magnet, and a
support for the brake maguet attached at a point thereon above the center of
gravity.
7. In a brake for arresting motion, a moving part, a brake magnet, and a
support for the brake magnet attached at a point thereon above the center of
gravity in one plane, and at its center of gravity in the other.

page_text: 8. In a brake for revolving machinery, a revolving part, an mdependently
supported brake magnet, means mounted upon the revolving part for guiding the
magnet, and a wearing plate or portion between the guide and the magnet.
9. In a brake for arresting motion, a crescent-shaped electro-magnet.
10. In a brake for revolving machinery, a revolving part, an axle attached
thereto, a crescent-shaped brake magnet, the gap in the crescent being wider than
the axle.
11. In a brake for arresting motion, a crescent-shaped brake magnet, in
combination with a lubricator in the gap of the crescent.
12. In a brake for arresting motion, a crescent-shaped magnet, a groove sunk in
one of the faces of the magnet leading into the gap of the crescent from both ends
of the magnet, and a removable piece for such gap.
13. In a brake for arresting motion, a crescent-shaped magnet, a groove with a
contracted opening sunk in one of the faces of the magnet, and an energizing coil
in said groove.
14. In a brake magnet, a groove, a coil within the groove smaller than the
groove, and an insulating filling poured into the groove while in a molten state.
15. In a brake magnet, a groove, a coil within the groove smaller than the
groove, a filling for the body of the groove, and a separate filling for the mouth of
the same.
16. In a brake magnet, a groove, a coil within the groove smaller than the
groove, a filling for the body of the groove, and a separate filling for the mouth of
same consisting of metal.
17. In a brake magnet, a coil, two terminals therefor, one connected to the
body of the brake magnet and the other free, the former being brought to the
surface and re-imbedded in the body of the magnet substantially for the purpose
specified.
18. In a brake magnet, a coil, two terminals therefor, an insulating bushing
through which they are brought to the surface, a clamp for the terminals, and a
length of free wire between the bushing and the clamp.
19. In a brake magnet, a coil, two terminals therefor, one connected to the
body of the brake magnet and the other free, the former being brought to the
surface and re-imbedded in the body of the magnet, a screw for holding said
imbedded wire, and a counter-bore for the outer end of said screw.
20. In an electric retarding device for moving mechanism, a surfaced mass of
magnetic material and an electro-magnet with enlarged polar faces, the two being
mounted for relative movement, in combination with an electrical conductor on the
magnet connecting the said enlarged polar faces, and an energizing coil for the
magnet.
21. In an electric retarding device for moving mechanism, a surfaced mass of
magnetic material and an electro-magnet, the two being mounted for relative
movement, in combination with a recess provided in one of the masses, and an
electro-conducting lubricant within such recess.
22. In a brake for an electric car, a rotating axle, a portion upon such axle
organized to be gripped, a stationary gripping mechanism for such rotating portion,
a stationary portion supported by the car axle, a projection provided on the
gripping mechanism for arresting its movement, in combination with a co-operating
abutment on the stationary portion located each side of the axle above said
projection.
23. In a brake for an electric car, a rotating axle, a portion upon such axle
organized to be gripped, a stationary gripping mechanism for such rotating portion,
a stationary portion supported by the car axle, a projection provided on the
gripping mechanism for arresting its movement, in combination with a cushion
between the projection and the stationary portion.
24. In a wheel for a vehicle, a hub, a tread, a lateral face with a certain
thickness of metal backing same disposed between the tread and hub forming a
portion of the web of the wheel, and a contracted portion less in thickness both

page_text: exterior and interior thereto and between the face and the hub and the face and
the tread.
25. In a wheel for a vehicle, a tread, a flange, a hub, and a portion between the
tread and the hub presenting a lateral face, the contour of the face of the wheel
near the rim being such that the face of the flange swings inward and under-cuts
the said flange before reaching the portion bearing the lateral face.
26. In a wheel for a vehicle, a tread, a flange, a hub, and a portion between the
tread and the hub presenting a lateral face, the contour of the face of the wheel
near the rim being such that the face of the flange swings inward and under-cuts
both the flange and the tread before reaching the portion bearing the lateral face.
27. In a wheel for a vehicle, a tread, a flange, a hub, and a portion between the
tread and the hub presenting a lateral face, the contour of the faces of the wheel
near the rim being such that the faces of the flange and tread swing inward from
each side or edge and under-cut such flange and tread before reaching the portion
bearing the lateral face.
28. In a wheel for a vehicle a hub, a tread, a lateral face, with a certain
thickness of metal backing same disposed between the tread and hub forming a
portion of the web of the wheel, the back face of the said portion being thinner at
or near its outer circumference and thicker near or at its inner circumference,
substantially for the purpose specified.
29. A motor controller handle of a vehicle having a certain critical position, a
separate brake handle, and means for locking the brake when the controller handle
is in other than its said critical position.
30. A brake handle of a vehicle having a certain critical position, a separate
motor controlling handle, and means for locking the latter when the brake handle
is in other than its said critical position.
31. The combination with an electric motor, of two current intensity switches
therefor, a separate operating handle for each switch, and interlocking devices
between the handles.
32. The combination, with two or more operating handles, of interlocking
devices consisting in a notched portion connected with each handle, a moving
connecting link co-operating with such notches in such a manner that when the
link is inserted in one of the notches the movement of the other handle prevents it
from being forced out of engagement with such notch.
33. A disk like electro-magnet arranged for lateral presentation so constituted
as to present three concentric polar faces, and a magnetizing coil suitably arranged
about the central pole, said central pole being of opposite magnetic polarity to the
other two, as set forth.
Dated this 18th day of Santambor 1904
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C., Agents for the Applicant.