These brush-holders are mova
ble arcs concentric with the center the
commulator shaft.
I have shown the moving cores Figs.
1885. These brushes caused,
however, great sparking upon the commu
tator. all cases the adjustment may
be such that current flows over the aux
iliary brush when the dynamo running with
its normal load. this manner the part M'is com
pletely cut out, and the part has con
siderably smaller resistance than the whole
length the field-wire the machine excites
itself, whereupon the auxiliary brush isshifted 80
automatically its normal position.
Myimprovementhas, besides, the advantage
to facilitate the self-exciting the machine
in all cases where the resistance the field- 70
wire very great comparatively the resist
ance the main circuit the start—for in
stance, arc-light machines. the armature will correspondingly
varied. and 5,
these are constructed that the force exerted
for adjusting practically uniform through
the whole length motion.
In Fig. understood that the adjustment
of the main brushes causes variations the
strength the current independently the
relative position said brushes the aux-
35 iliary brush. When the brushes are moved directly by
electrical devices, shown Figs. Pinckney,
WALLACE SERKELL.
In Figs. attached the auxiliary
brush holder The adjustment effected
by means spring and screw tightener.
Signed this 13th day May, D.
NIKOLA TESLA,
Witnesses:
Geo.336,961
in the shunt through O
', and the magnetism of
the cores will partially neutralized the
point greatest magnetism shifted, that it
will more less remote from approach-
5 ing the armature, and hence the aggre
gate energizing actions the field magnets
. iron piston, the
45 solenoid Fig. instead solenoid, ati iron tube
inclosing coil shown.
In the form indicated Fig. the solenoid should
be connected both and move
them toward away from each other. 55
I aware that auxiliary brushes have been
used connection with the helices the
field-wire; but these instances the helices
received the entire current through the aux
iliary brush brushes, and said brushes could 60
not taken off without breaking the circuit
through the field. aud indicate the main-
40 brush holder, carrying the main brushes, and
C the auxiliary-brush holder,carrying the aux
iliary brush. and
5 convenient devices for obtaining the re
quired extent motion with very slight
30 changes the current passing through the
helices.
25 There are several known devices for giving
motion proportion electric current. the regula-
io tion effected shifting the point great
est magnetism, and Figs. The piston the
coil attached both brush-holders and 50
€'. this case I
place the auxiliary brush near pref
erence contact with the brush shown 75
Fig.
15 The relative positions the respective
brushes may varied moving the auxil
iary brush the brush may remain qui
escent and the corep connected the main
brush holder A', adjust the brushes
20 their relation the brush if, how
ever, adjustment applied all the
brushes, seen Fig. and the same
effect produced the action the cur
rent the shunt passing through the neu
tralizing-helix. improvement the auxiliary
brush causes very little sparking, and 65
can taken off without breaking the circuit
through the field-helices.
.
I claim invention—
The combination, with the commutator hav
ing two more main brushes and auxil
iary brush, the field -helices having their 85
ends connected the main brushes, and a
branch shunt connection from interme
diate point the field-helices the auxiliary
brush, and means for varying the relative po
sition upon the commutator the respective 9c
brushes, substantially set forth
