ments to be made and no parts that require frequent renewal. The rectifier can be used on any 100 to 120-volt, 60-cycle circuit, charging three cells at a rate of 8 to 81⁄2 amperes.

The Entz Electric Transmission.-In the Entz electric transmission system shown at Fig. 289 there are two dynamos arranged tandem fashion. These are connected up mechanically in such a way that the efficiency is much higher than that secured by the use of the gasoline-electric systems described at other points in this book. The field frame of the first dynamo is attached to the crankshaft of the engine, and when the armature circuit is closed, the armature will also revolve and thereby propel the car, acting exactly the same as a slipping clutch, the amount of slip being subject to control. The armature is attached directly to the driving shaft, as is that of the motor placed back of the generator. When one transmits power through a slipping clutch, one cannot get any more from it than is put into it. If friction clutch slips fifty per cent., one-half of the energy supplied to it is converted by friction into heat. Similarly in the dynamo or generator of the Entz system, if that member turns only half as fast as the field frame, only one-half of the power supplied to the field is mechanically transmitted. The other half appears in the form of an electric current in the armature circuit. If the armature were short circuited, then all of this electrical energy would be converted into heat. Under conditions of light running, however, when the high gear or direct drive would be used in a car equipped with a sliding gear transmission, the armature of the Entz system is short circuited, but the slippage and loss then amounts to only a few per cent.

When the resistance to car movement is greater, so that a lower gear must be employed in the gear driven cars, with the Entz system, the current produced in the first armature by the slip is sent to the windings of the motor where it produces useful mechanical power. As the armature of the motor is secured to the propeller shaft it transforms the electrical energy produced by the slip at the generator to mechanical power, which supplements that transmitted by the generator armature. The windings of the second machine are such that the electric system can increase the torque or turning effort of the engine three times, at the same time reducing the speed

of driving pinion rotation at the rear axle to one-third that of the engine speed. The engine is permitted to develop its full power, and to turn at such speed as is necessary to secure this effect, and when the resistance to road wheel rotation is such that these must turn slower, instead of slowing up the engine speed it may be kept at the same point and the armature of the generator allowed to slip and generate current, which is then directed to the second machine.

This system was first devised eight or nine years ago, and has been recently reintroduced in an improved and simplified form. The appearance of the unit is clearly shown at Fig. 289. Bolted to the rear of the engine crankshaft is an aluminum housing, which carries the electrical system. Two arms on this crank case rest on the chassis frame to support it. Inside of the housing is another case bolted to a flange at the rear end of the crankshaft. This is the frame of the forward unit of transmission, which carries the field coils, and which acts as a fly-wheel for the engine. To the rear end of the stationary outside housing the field frame of the rear electrical unit, which is intended to be stationary, is attached. The armatures of both units are carried upon a large tubular shaft supported by annular ball bearings. The armature shaft is connected directly to the propeller shaft, and when the car is standing still, the armature shaft is stationary, whereas when running in the high speed position of the controller lever, it turns at practically the same speed as the engine crankshaft.

The action may be described as follows: When the car is standing still with the engine running, the field of the forward electrical unit, which is called the "generator," is rotated with the engine crankshaft to which it is fastened while the armature remains stationary. At this time all electrical circuits are open and there is no tendency for the engine to drive the car. When the controller lever is thrown into the first, or "soft start," position, a circuit is closed through both the generator and the rear unit, which is called the motor. The generator then begins to produce a cur rent which is fed into the motor. At the same time there is power applied to the armature shaft equal to the engine tendency to turn the shaft in the same direction as the crankshaft. The current

produced by the slip owing to the difference in speed between generator field and armature, is being fed into the motor, which also turns the shaft in the same direction as that produced by the mag

Fig. 290.-Wiring Diagram of Complete Automobile Lighting System Without Starting Motor.

netic clutch. In other positions of the controller up to the high speed position different arrangements of resistances change the speed ratio between engine and propeller shaft, but there are no off points between the various notches, so the application of power to the wheels is not interrupted in changing speeds. When the

high speed position is reached, there is no electrical connection between the generator and the motor. The former is short circuited, and acts as an electrical or magnetic clutch. When it is desired to secure reverse speeds, a mechanically operated planetary reverse gearing is used, which changes the direction of rotation of the driving pinion. When the controller lever is in "off" position, the rear unit is short circuited and it will act as an electrical brake, preventing the car coasting down hill faster than ten miles per hour. When actually applied in a car, current may be shunted from the generating unit to charge a battery, which may be used for lighting and ignition, and the current of which may be directed through the electrical machine when it is desired to start the engine.

Typical Lighting System.-In order to show clearly the wide use that is made of electric current, even on cars not provided with an electric starting motor, wiring diagrams are shown at Fig. 290 which represent the frame and body wiring of a Packard touring car without starting motor. This wiring is used solely for conveying battery current to the lamps and other current-consuming units, which includes a Klaxon horn and speedometer light in addition to the usual lighting equipment of six lamps. Two rear lamps are provided, one of these the usual red signal specified by law, the other is a white light used to illuminate the license tag. In order to make it possible to remove the body from the chassis without destroying the wiring, the current conductors are run in two independent groups, one being secured to the body, the other running through suitable conduits attached to the frame. The upper view shows the body wiring with the storage battery connected, though this member is carried by the frame and has a connector which may be readily broken when desired to join the battery with the body junction box. Among the appliances carried by the body may be mentioned the side lamps, the speedometer and dash lights, the Klaxon horn, and the two tail lamps. The arrangement of the wiring is clearly shown in the illustration, the method of running the wires from the junction box to the various units is clearly defined. Attached to the chassis are the two head lights, the storage battery, and the lighting generator. In this system the generator is used to charge the storage battery, the cur