of the mechanism. When applied in this manner the engine crankshaft is turned over in exactly the same way as it would be by the hand crank, which, of course, is replaced by the countershaft assembly driven from the electric machine. The front end of the countershaft is provided with a conventional form of clutch to make it possible to crank the engine by hand in exactly the

Fig. 215.-Wiring Diagram of Bijur-Scripps-Booth One Unit Starting and Lighting System.

same manner as is ordinarily done after the starting crank is properly engaged. As the starting crank is only used in cases of emergency where the battery has become depleted or where some trouble exists in the electrical machine, it is made detachable so that it can be carried in the tool box. The Northeast Universal System functions in exactly the same manner as the built-in system designed for specific makes of cars.

Bijur Starting and Lighting Systems.-Three types of Bijur Starting and Lighting Equipments are manufactured; the simplest is the single unit, in which one machine acts either as a motor or generator, as conditions demand. The motor-generator equip

ment is generally chain driven from the crankshaft at a ratio of approximately three to one. This type of machine assumes the function of a generator at about 100 r. p. m., so that with ordinary rear axle ratios the generator function takes place and the battery begins to charge at low car speeds. This machine iş provided with a shunt and series winding which act differentially when operating as a generator and cumulatively when operating as a motor. The voltage of the generator is variable as the regula tion is for current. At low speeds, the current is maintained sub

Fig. 216.-Wiring Diagram of Bijur-Apperson Two Unit Starting and Lighting System.

stantially constant, but diminishes at high speed. The regulation is effected by the differential action of the shunt and series field, and also by reason of the fact that the shunt field is connected between one of the main brushes and an auxiliary or regulating brush.

As shown by the diagram at Fig. 215, which shows the electrical equipment on the Scripps-Booth car, no automatic switch. is used. Connection between the motor generator and the battery is made with a hand switch, and the motor-generator draws cur

GENERATOR

rent from the battery until the gas motor begins operating under its own power and acquires a speed sufficient to drive the electrical unit at a speed of about 1,000 r. p. m. As this corresponds to an engine speed of about 330 r. p. m., the carburetor throttle is usually adjusted so the engine cannot be throttled down to a speed below the cut-in point of the motor-generator. This is done to eliminate the non-stalling feature and to prevent the battery

discharging when a car is left standing idle. The Bijur one unit. system is designed to operate on 12 volts.

having a series

The other has Considering the

There are two two-unit systems, one of these starting motor and constant current generator. a constant voltage generator and series motor. former the constant current generator is a shunt wound machine, the regulation being effected by the shunt field being connected between one of the main brushes and an auxiliary or regulating brush. The units are self-contained and require no separate mounting or connecting of the automatic switch, which is mounted inside the aluminum housing on the commutator end of the machine. These machines are reversible and the connections between

battery and generator may be made without regard to polarity, a very valuable feature. Even if wrong connections are made, the generator will reverse and assume the correct polarity to charge the battery. Each machine is provided with a fuse in the field curcuit to prevent injury in case the circuit and the battery is opened. Running the generator under these conditions would result in an abnormal rise in voltage which would damage the field windings except for the protection offered by the fuse. The

application of the constant current machine is shown in the wiring diagram of the Appearson system at Fig. 216.

The constant voltage generators are also shunt wound and regulation is effected by varying the excitation in this winding. The principal circuits for the regulating mechanism are shown in wiring diagrams at Fig. 217. The method of operation is as follows: In series with the shunt regulation is obtained

winding 11 is a fixed resistance 12, and by short circuiting this resistance when the generator voltage falls below normal and removing the short circuit when the generator voltage rises above normal. The regulator for performing this operation consists of an iron core 14 with a single winding 13, this winding being connected across the generator brushes. The current in this winding and the resultant pull or magnetic attraction of the core depends, therefore, upon the voltage of the generator. The vibrating armature 15 is pulled away from the core by a spring. When the spring pull predominates, the

Fig. 219.-Battery Charging Curve of Bijur Generator with Voltage Regulator.

armature moves away from the core, closes contacts 17 and 18, and provides a low resistance path around the resistance 12. The field current increases and the generator voltage builds up; when it exceeds its normal value the magnetic pull of the core predominates and the armature is attracted to the core, thus