This image shown below is the low speed circuit diagram for the 1955 Chevrolet Trucks. The electrical components shown inside are including circuit breaker, series field, shunt field, and resistor. In low speed circuit system, the contact Nos. 1 and 2 are closed and Nos.3 and 4 are closed. From source, the current passes the circuit breaker and energizes the series field. After passing through the series field, the power is divided; part is directed to the armature and the remainder is eliminated by being diverted to ground through the shunt field, through contacts No. 1 and 2, then to contact No. 4, and finally to contact No. 3 which is grounded. In following this path, it is best to remember that current always follows the path of last resistance, therefore in low speed, no current passes through the resistor because of the more direct path to ground. The major point to remember concerning low speed operation is that only about one-half of the power is used to drive the motor; the remainder is diverted to ground.