This schematic shown below is the high speed circuit diagram for the 1955 Chevrolet Trucks. The components shown in this schematic are as following: shunt field, resistor, circuit breaker, series field, and shunt field. Moving the wiper control on the dash panel further closes the high speed circuit. For high speed operation, all contacts are open with the exception of Nos. 3 and 4 which produces the following electric flow: From the source, current flows through the circuit break and energizes the series field as in low speed operation. Upon leaving the series field, the current once again divides; half going directly to the armature and the remainder through the shunt field. However, with only contacts No. 3 and 4 closed, the current is forced to flow through the resistor to reach ground via the jumper to No. 4 and finally to No. 3 contact and ground. By forcing the current through the resistor, the flow through the shunt field is slowed considerably, consequently more current is forced to flow through the armature to reach ground and the motor speed is increased proportionately.