A further movement of the controller handle causes the fingers to leave segments M and O and No. 2 motor is open-circuited until finger 15 makes contact with segment N. When this takes place the motors are in multiple. On the successive points after this the external resistance is cut out in the same manner as previously described.
By reference to [Fig. 22], it will be noticed that the leads to the motors and the resistances are tapped on wires of the cables connecting the two controllers on the ends of the car. The two ends of these wires, with the exception of the armature wires, lead to similar binding posts on the two controllers. The armature wires are interchanged connecting at one controller into binding post A A, while the other end connects into binding post A. This change of connection is necessary in order that the reverse handles be forward for forward direction of movement of the car.
Fig. 25. Forward Position of Reverse.
To reverse a series motor it is simply necessary to reverse the direction of flow of the current in either the armature or field. For several reasons, it is advantageous in the case of the street railway motor to reverse the current in the armature rather than in the field. Figs. [25] and [26] show how this is accomplished. The squares shown in the figures represent the lugs on the reverse cylinder as shown in [Fig. 21]. With the reverse handle in one position ([Fig. 25]), the large lugs are under the reverse fingers, and current passes from finger 19 to finger A1, and from finger 15 to finger A2. [Fig. 26] shows the relative position of reverse fingers and lugs for the reverse position of the controller handle. In this case the current passes from finger 19 to A A1, and from finger 15 to finger A A2. The effect is to change the direction of flow in the armatures while that in the fields remains the same as may be observed by the arrows.
Fig. 26. Reverse Position of Reverse.
Wiring of Type L Controllers. The type L controller, shown in [Fig. 27], while accomplishing the same results as the type K, is wired in a radically different manner. The circuit is opened in changing from series to multiple connections. The controller handle makes two complete revolutions in moving from the series to the multiple position. It is geared to the rheostatic cylinder in such a manner that the first half of both the first and second revolutions gives this cylinder one complete turn. During the second half of the revolution the cylinder is returned to its original position. The controller handle is so connected to the commutating arm that this stands in a central position for the off position of the handle. At the beginning of the first revolution it is swung to the left, throwing the motors in series. At the beginning of the second revolution it is moved to the right, putting the motors in multiple.
The rheostats instead of being wired in series are connected in multiple. Current passes from the blow-out coil to the bottom fingers of the controller S, and thence to the rheostats. On the first point the current returns over R1 to the controller cylinder. It passes off through a collar at the base of the cylinder through No. 1 cut-out, and the reverse, which is shown in the central position, to No. 1 motor. On returning to the controller over E1 it passes to the upper section of the commutating arm. In the diagram this is shown in the central position. In series it is thrown to the left. The current then passes from the commutating arm to No. 2 cut-out, and to No. 2 motor. Movement of the controller handle further multiplies the paths through the rheostats and finally, when fingers S rest on the cylinder, the rheostats are short-circuited. If the controller handle is moved still farther, the rheostat cylinder is returned to the off position and the commutating arm is thrown to the left. With the arm in this position the current divides, one portion passing to No. 1 motor as before and to ground by way of the upper section of the commutating arm; while the other branch goes by way of the lower section of the commutating arm to the cut-out switch for No. 2 motor and thence to the motor.
