201,063. Stevens, A. H., (Ahlm, C. E. F.). Aug. 22, 1922. Dynamos and motors combined for transmitting power; electromechanical power transmission systems.-An electromechanical power transmission system comprises a dynamoelectric machine mounted on the driving shaft, a second dynamoelectric machine connected to the driven and driving shafts through epicyclic gearing, a brake for holding the planet carrier of the gearing to obtain reversal, and a controller for the dynamo-electric machines whereby both run as motors to start the engine and alternately as generator and motor to obtain varying speeds. The armatures of the dynamo-electric machines are provided with a common field system having shunt and series windings. Apparatus. The engine shaft 10, Fig. 1, carries the armature 20 of a dynamo-electric machine and a sun gear 53, Figs. 1 and 3, connected to the driven shaft 12 through planet wheels 54 and an internally geared member 50. A second armature 25 is mounted on a sleeve 27 secured to an extension 27a through a sleeve 27<b>; the extension 27<a> carrying a sun gear 62, Figs. 1 and 2. The gear 62 is connected to planet wheels 60 through idlers 61. The planet wheels 54 and 60 are mounted on shafts 55 journalled in members 56 and 57, which, with a member 70, is rotatably mounted and is adapted to be held by a band-brake 80. The field magnets of the armatures 20 and 25 are provided with series windings SF and shunt windings sf so arranged that opposite poles are of north and south polarity respectively. Starting. To start the engine the controller is moved to position o, Fig. 6, and the switch Y is closed. Under this condition both armatures 20 and 25 act as motors, current being supplied from the battery X, both armatures and the shunt-field winding sf being connected in parallel and in series with the series field-winding SF. First running position. The controller is moved to position 1 to short-circuit a resistance R. Under this condition the armature 25 operates as a generator and the armature 20 as a motor to assist the engine, the circuits being as follows : positive terminal of armature 25, lead II, contactor c, segment q, contactor a, lead G, series parallel SF, contactor e, segment r, lead J, armature 20, lead K, contactor g, segment s, contactor f, lead I, to negative terminal of armature 25. A record circuit is also established from lead J to lead Z, resistance 0, armature N in its unattracted position, reky winding M, lead L, shunt field winding sf to lead K and thence to the negative terminal of the atmature 25. If the voltage is sufficiently large, the relay M attracts its armature N and the resistance 0 is replaced by the battery X through the lead V. The field windings SF. sf assist each other in this condition of running. Second and third running positions. In these positions of the controller both armatures 20 and 25 act as generators. The armature 25 rotates in the opposite direction to the armature 20 and its circuit is closed in the second position through a resisbnce R and the series field-winding SF, and the circuit of the armature 20 is closed through the lead Z, battery X, lead V, and the shunt-field winding sf. In the third position the resistance R is short-circuited to lower the speed of the armature 25 and thereby increase the speed of the shaft 12. Fourth and fifth running positions. In these positions, the armature 20 acts as a generator and the armature 25 as a motor rotating in the same direction as the engine. In the fourth position the circuits are as follows: positive terminal of armature 20, lead J, contactor d, segments v, x, contactor f, lead I, armature 25, lead H, resistance R, contactor b, segment t, contactor a, lead G, series field-winding SF, contactor e, segments w, y, contactor g to negative terminal of armature 20. A record circuit is also established through lead Z, battery X, lead V and the shunt fieldwinding s, f. In the fifth position. the resistance R is short-circuited. Braking position. The controller is moved to position 1<1> and in this position the armature 20 acts as a generator tending to operate the armature 25 as a motor in the reverse direction. The armature 25, resistance R and series field-winding SF are connected in series across the armature 20, and the shunt field-winding sf is connected across the armature 20. Reversing. The direction of rotation of the shaft 12 is reversed by holding the members 56, 57 and 70 against rotation by means of a brake 80.