A great many different types of mechanical, and compressed air starters were devised and tried out as equipment by the manufacturers of automobiles a few years ago. These devices were either mechanically imperfect, or required considerable attention from the owner to keep them in working order and have all but disappeared from the market, being supplanted by the electrical starter, which has been perfected to a high state of efficiency and dependability.

The general principle of all electrical starters is much alike and they usually operate in much the same manner. The electrical force or current is produced by a generator driven from the engine. This current is collected, or held in storage by chemical reproduction plates in a storage battery. The battery, in turn, is connected to a small electric motor carried at the side of the engine.

The Generator.—The operating principle of current production of the generator is practically the same as explained in the magneto, which may also be termed a generator or dynamo.

A generator consists of an iron frame, a set of magnetic field windings, a wound armature with a commutator on the end, and a brush which collects the current from the commutator.

The current is induced in the armature by rotating it in a magnetic field. The amount of voltage induced in the armature-coil depends on its rotating speed, as the faster the armature turns, the greater the number of magnetic field lines cut, and the greater the amount of voltage induced in the armature coil.

The Regulator.—The generator is provided with a regulator to control the output rate of voltage when the engine is running at excess speeds. This is necessary to prevent the higher charging rate from overcoming the capacity of the storage battery. The regulating of the voltage output may be accomplished by mechanical or electrical means. The mechanical regulator usually consists of a governor which is timed to release the armature from the drive shaft when the engine reaches a certain rate of speed. The electrical regulator usually consists of a reversed series of field winding which acts against the force of the magnetic field, or of a bucking coil.

The Automatic Cut-out.—All types of generators which supply current to a storage battery are equipped with an automatic cut-out arrangement which is entirely automatic in action and requires no attention.

The function of the automatic cut-out is to prevent the current from flowing back to the generator when the current production of the generator is less than the charged strength of the storage battery. The cut-out may be located anywhere on the conductor, between the storage battery and the generator, and consists of a simple electro-magnet, which is operated by the direction of current flowage.

One Unit System.—The generator furnishes the current for ignition and starting, and is also reversible to act as a starting motor. The system is referred to as a one unit system.

Two Unit System.—When the starting motor and the generator act singly, and are contained in a separate casting, the system is referred to as a two unit system.

Three Unit System.—When the generator and starting motor are located as a separate unit, and when the ignition current is supplied by a magneto, this system is referred to as a three unit system.

The Starting Motor.—The starting motor is constructed in the same manner as the generator, and is simply a reversal of action. When cranking, the current from the storage battery flows through the motor winding and magnetizes the armature core. This acting upon the magnetism of the frame causes the turning effort.

Lubrication.—Regularly every two weeks, or every five hundred miles, two or three drops of thin neutral oil should be dropped into the oil wells supplying the armature bearings and usually located at each end of the armature shaft.

Care.—Regularly every two weeks, inspect all connections as a full volume of current will not flow over a loose or corroded connection. Never allow any oil or dirt to collect on the motor or generator, as it interferes with the terminal connection and misdirects the current, and the instrument soon becomes inoperative.

Fig. 85 shows the location of the two unit Bijur electrical starting and generating system mounted on an engine. The starting motor is bolted to the flywheel housing, and is provided with a square armature shaft which carries a pinion which can be moved horizontally on the shaft. This pinion meshes directly with teeth cut in the steel flywheel ring. No intermediate gears or roller clutches are used. The control lever connects through linkage to the shifting fork which shifts the pinion on the square shaft of the motor. The same foot pedal linkage operates the starting switch. Normally a spring holds the motor pinion out of mesh with the flywheel teeth and also holds the starting switch in the “off” position.

The Generator.—The generator is bolted to an extension on the crank case at the front side of the gas motor, and is driven by a silent chain from the crank shaft. After the gas motor attains a speed equivalent to a car speed of ten miles per hour on high speed, the generator begins to generate, and will generate a current which is highest at low speeds, and diminishes somewhat at higher speeds.

The machines are both self-contained as there are no regulators or automatic switches which require separate mounting.

The automatic switch for opening and closing the circuit between the generator and storage battery is mounted inside the generator. This switch is properly adjusted before the generator leaves the factory, and no further adjustments are necessary.

Two wires lead from the generator. One of these is connected at the starting motor to one of the heavy cables coming from the storage battery, while the other generator wire is grounded on the chassis, the chassis forming a part of the circuit. The generator polarity is reversible and the connections at the machine may be made haphazard and without regard to polarity. If connections are reversed at the generator, no damage will result, as the machine will automatically assume the correct polarity to charge the battery.

Fig. 86 shows the position of the Bijur starting system, and the relative neutral positions of starting pedal, motor pinion, and starting switch, when the starting equipment is not in action.

Fig. 86A shows the normal position of the various parts after the starting pedal has been depressed and just before the starting motor begins to operate. The pinion is now in full mesh with the flywheel ring and further depressing the starter pedal will close the switch.

Fig. 87 shows all the parts in their positions for cranking. The small gap between the collar on the shifting rod and clevis pin permits the switch rod to move and thus open the starting switch without moving the motor pinion when the starting pedal is released.

Fig. 87A shows the condition when on depressing the foot pedal, and sliding the pinion on the motor shaft towards the flywheel the pinion does not mesh with the flywheel, and the teeth butt. Depressing the foot pedal will close the starting switch strongly compressing the shifter spring. After the switch is closed the motor will begin to rotate and allow the pinion to slip into mesh with the flywheel. The motor will then crank in the normal way.

Fig. 88 shows a complete diagram of the Model N Hupmobile wiring system.