Improvements in Electric Brakes for Electric Railway Cars and other Electrically Operated Mechanisms.
Year: 1898

page_text: Date of Application, 8th Nov., 1898-Accepted, 7th Jan., 1899
Improvements in Electric Brakes for Electric Railway Cars and other
Electrically Operated Mechanisms.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of this
invention (which has been communicated to us from abroad by Frank E. Case,
residing at Schenectady, in the County of Schenectady, State of New York, United
States of America, Electrical Engineer), 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 the art of electric braking, and to that class of
brakes in which an electro-magnet is energized at desired times, and by its effect
upon a moving part of the machine brings the apparatus to rest. These devices
find their most useful application in electrically operated railways and tramways
in which the electro-magnets are usually fixed and of disc-like form, co-operating
with a disc rotating with the axle.
The invention aims to provide in this class of apparatus, a form of support
which makes it possible to apply the brake-shoe to the outside of the wheel,
instead of placing it as has heretofore been customary, between the wheel and
the motor. Many modern forms of electric motor demand the entire axle length,
on account of the large output now required, and thus no space is left within
the wheel-base in which to put the brakes.
In carrying the invention into practice the brake-shoe is mounted upon the
axle box, and a portion of the wheel is either "faced off" or a properly machined
disc is applied to the wheel against which the shoe may rub. To avoid variation
of the air gap and consequent irregularity in the braking action, a limiting
device of any suitable kind is employed, such that the brake shoe is compelled to
follow the end-play of the axle whenever the latter moves to a position which
would otherwise increase the air gap beyond the desired limit. In this way a
result not hitherto obtainable can be accomplished in that there may be employed
an integral annular brake shoe and "disc" or rubbing surface with which the
brake shoe co-operates. Heretofore it has been necessary to cut both shoe and
disc in order to mount them, or else leave a gap through which the axle may pass;
in the present construction this is not required.
The drawings annexed show an embodiment of the invention. Fig. 1 is a side
elevation of a car wheel and a part of a truck to which the improvement has been
applied; Fig. 2 is a partial section upon the line 2-2 of Fig. 1; Fig. 3 is a
side elevation partly in section upon the line 3-3 of Fig. 2 of the car wheel
and shoe, with the axle-box removed: Fig. 4 is a representation of a brake-shoe
detached, and Fig. 5 is a side elevation of the "disc," so-called, and Fig. 6 is
a section on the line 6-6 of Fig. 4.
A general idea of the arrangement of the mechanism is obtained best from
Fig. 2, to which reference will first be made. In describing this figure, reference
is also had to Figs. 1 and 3, which show other views of the same parts.

page_text: A is the tread of the wheel, B is the web mounted on the axle C; to the
web is affixed by the bolts E, E, the disc D) which thus revolves with the wheels.
Also affixed to the web by the screws L, L, is the collar F, against the inner face
of which bears the web H2, formed upon the brake-shoe H. The latter is a
single casting forming approximately, an annulus completely. closed; in this it
differs from all other shoes heretofore used, none of them being an integral
structure. The disc D may also, if desired, form a complete annulus; both of
these parts may be easily slipped over the journal.
M is the journal box mounted, in the case illustrated in a pedestal composed
of back and front plates n, n, held together by bolts N, N. Secured to the journal
box in any desired manner, or made in one with it, is a bar G, having a horizontal
portion G; upon this part of the bar rests the brake-shoe H. At the top and
bottom of the shóe are lugs H¹, H', in suitable bearings in which rest other
lugs I, I, which prevent the rotation of the shoe when it is energized and applied
to the disc or annulus D. In a groove in the shoe is the coil Q, held in place by
a suitable filling, and disposed eccentrically to the metal, so as not to cause the
disc D to wear in grooves.
As seen in Fig. 1, the bars 0 of the truck-frame are carried on the journal
box in the usual way, and springs P are provided wherever it is necessary or
desired.
Fig. 4 shows the rubbing face of the shoe, with the coil shown in dotted lines.
Fig. 5 shows the annulus or disc D, forming the rubbing surface against which
bears the brake shoe. It is provided with a stiffening flange d, and bolt-holes e, e,
for attaching it to the wheel the flange d bears against the wheel center and
lessens the strain on these bolts. The disc is, as will be seen, an integral annulus,
the utility of which has been already pointed out.
The construction shown in Fig. 6 is sufficiently apparent from the reference
"letters, which indicate the same parts as in the other figures.
It will be seen that the mounting of the brake shoe outside of the wheel-base
forms an important feature of the invention, and that other devices are devices
for limiting the air gap to a determined maximum, and for allowing play of
the shoe between limits; and the support, more especially, of the shoe in practi-
cally invariable relation to the axle, which is found to be conveniently accomplished
by placing it upon the axle-box.
Having now particularly described and ascertained the nature of our said inven-
tion, (as communicated to us from abroad) and in what manner the same is to be
performed, we declare that what we claim is:-
1. In a brake for an electrically operated mechanism, the combination of a
wheeled axle or similar moving part, with a stationary electric brake shoe sup-
ported outside of the wheel base, and in substantially invariable relation to the
axle.
2. In combination with a wheeled axle mounted in a truck-frame, suitable
journal boxes, an electric brake shoe, and means for supporting the shoe from a
journal-box.
3. The combination with a rotating axle, of an annulus or disc fixed to the axle
and forming a surface against which a brake-shoe may rub, a journal box, an
electric brake-shoe, and means for supporting the shoe from the journal-box, so
that it is outside of the wheel-base.
4. The combination with a rotating axle and wheel, of an electric brake-shoe
supported by the journal-box outside of the wheel-base, and means for maintaining
an air-gap not greater than a determined maximum between the shoe and the
part with which, when magnetized, it has frictional engagement.
5. The combination in an electric brake, of a wheeled axle, a disc or annulus
rotating therewith, a journal-box, an electric-brake-shoe, a support for the shoe
carried by the journal-box, stops for preventing the rotation of the shoe, and a
stop for limiting the air-gap.

page_text: 6. As a new article of manufacture, an annular electric brake-shoe formed in
a single piece.
7. As a new article of manufacture, an integral annular shoe for an electric
brake, provided with bearings for fixed stops to prevent its rotation.
8. As a new article of manufacture, an integral annular electric brake-shoe,
having a coil chamber, a bearing for supporting the shoe and lugs forming bearings
to prevent its rotation.
9. As a new article of manufacture, an integral annulus forming the rubbing
surface against which the brake-shoe bears, provided with means for attaching it
to the moving part of the mechanism.
10. As a new article of manufacture, an integral annulus forming the rubbing
surface which the brake-shoe bears, provided with a stiffening flange and bolt-
holes for attaching it to the car-wheel.
Doted this AL 2
1000
THE BRITISH THOMSON-HOUSTON CO., LTD.,
A. R. MONKS,
W. MARTINDALE,
Directors.
ALFRED CLEMENTS,
Assistant Secretary.