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is delivering current to the battery which is charging it; the amount of charge or discharge at any time can be read from the scale on the face of the amperemeter. Some of these instruments have the words "charge” and “discharge” under the scale in order to enable the operator to read the instrument correctly.
Another important element is the lighting switch, which is
usually mounted at some point within convenient reach of the car driver. This is often placed on an instrument board on the back of the cowl in connection with other registering instruments. As ordinarily constructed, the switches are made up of a number of units, and the wiring is such that the head, side and tail lamps may be controlled independently of each other. For simplicity and convenience of installation, the switch is usually arranged so that all circuits are wired to parallel connecting members, or "busbars,” placed at the rear of the switch.
WHEN DISCHARGED CONTINUOUSLY AT RATES REQUIRED FOR ORDINARY
* This capacity may be obtained by intermittent discharges of a few hours each during a period of three days or more.
How Storage Battery Shifts Gears.-A new system of gear shifting has been recently developed which depends on the use of electric current to shift the gears instead of the usual hand lever. The steering wheel is shown at Fig. 59, with the various speed
changing buttons let into a box attached to the steering post. The wiring is outlined. The operation of shifting a gear is very simple, consisting merely
of depressing the COMMON BUS
clutch pedal and pressing down on the switch button marked with the gear ratio desired.
The system is not HORN
complicated, the gears being controlled by solenoid coils, one being used for each forward speed and one
for reverse. Two 3rd
switches are utilized
between the battery COILS
and the coils, a knife switch controlled by the clutch pedal and
a push-button located BATTERY
on the steering wheel. All changes of gears
are controlled by the Fig. 59. — Wiring Diagram Showing
knife switch, and the
the Method of Connecting the Vulcan Electric push-buttons on steerGear Shift with the Battery and Control ing wheel merely arSwitch.
ranges the circuit for the particular speed
desired. The first movement is the regular operation of the clutch, but a continued operation of the clutch lever actuates the knife switch.
Current flows from the battery through the solenoid coil and pulls a plunger against a magnet with a force which is given as
Fig. 60.—Simplified Diagrams Showing How Current Passed Through
the Solenoid Will Draw in Iron Core Piece, Which May be
Made to Shift the Gears. 40 to 100 pounds. This energy is transmitted through an arm to the gear-shifting fork and gear in exactly the same manner as if the gears were operated with a hand lever. The plungers are normally in a neutral position. When the button is pressed on the control member, current passes through the coil around one of the plungers, drawing it against the magnet. It is said that
the current required to make the shift is about 17 amperes, and it is claimed, further, that three hundred speed changes may be made with less current consumption than is required in starting the motor with an electric-starting device. An advantage claimed for this electric gearshift is that the gears cannot be stripped, for the reason that the clutch must be disengaged before shift can be made, and the gears are always in neutral before the coils can accomplish the change.
Batteries for Electric Automobiles.—Any practical form of storage battery may be used for automobile propulsion. Either the Edison or lead-plate type batteries prove satisfactory for this work. The lead-plate forms have thin plates to keep the weight down and make for quicker charging and discharging. The usual discharge rate is about two volts per cell, the amperage depending upon the resistance to vehicle motion. It is said that the annual maintenance cost of the ordinary lead-plate cell is about 60 per cent. of its original cost. A special vehicle type, called the “Iron Clad” (previously described), will cost about 30 per cent. of its initial purchase price annually to maintain it in proper condition. The Edison battery occupies about one-third more space