96

INVENTIONS OF NIKOLA TESLA.

easily brought up to speed. Thirdly, the synchronizing motormay be constructed so as to have a much more pronounced ten-dency to synchronism without lessening the facility with whichit is started.

Fig. 77 is a part sectional view of the two motors; Fig. 78 anend view of the synchronizing motor; Fig. 79 an end view andpart section of the torque or double-circuit motor; Fig. 80 adiagram of the circuit connections employed; and Figs. 81, 82,83, 84 and 85 are diagrams of modified dispositions of the twomotors.

Inasmuch as neither motor is doing any work while the currentis acting upon the other, the two armatures are rigidly connected,both being mounted upon the same shaft a, the field-magnets bof the synchronizing and c of the torque motor being secured to

the same base d. The preferably larger synchronizing motor haspolar projections on its armature, which rotate in very close prox-imity to the poles of the field, and in other respects it conformsto the conditions that are necessary to secure synchronous action.The pole-pieces of the armature are, however, wound with closedcoils e, as this obviates the employment of sliding contacts. Thesmaller or torque motor, on the other band, has, preferably, acylindrical armature f, without polar projections and wound withclosed coils a. The field-coils of the torque motor are connectedup in two series tr and i, and the alternating current from thegenerator is directed through or divided between these two cir-cuits in any manner to produce a progression of the poles orpoints of maximum magnetic effect. This result is secured byconnecting the two motor-circuits in derivation with the circuit