Hudson 1948 - 1952, Service Manual

Page: 122 / 333

FUEL LEVEL INDICATOR
The fuel level indicator is of the constant voltage type. It
consists of a voltage regulator, panel indicator and a tank
level unit connected by a single wire system between the
units, Figure 107.
FIGURE 107
VOLTAGE REGULATOR:
Its function is to regulate the variable (input) voltage
available from the car storage battery, or the charging
system, to produce a constant 5.0 volt output to the gauges.
This regulator is a simple device, operating with a heater
bimetal in conjunction with a pair of contacts. It is temper-
ature compensated to produce correct constant voltage for
the gauge systems at all expected temperatures. It is mount-
ed. near the panel indicators at approximately their same
temperatures. The voltage regulator does not produce a
steady DC voltage output, but rather a pulsating voltage at
an effective constant average value of 5.0 volts. The input
source can, therefore, be DC intermittent or interrupted
DC, or AC, just so long as the average input voltage does
not drop below 5.0 volts. Input voltage lower than 5.0 volts
will result in proportionately low gauge indication. With
the constant voltage regulator (with input voltage normally
varying from 5.6 to 8.0 volts), input voltages in excess of 8.0
volts will not affect gauge indication accuracy, but will
overload the
overload the regulator contacts and may result in prema-
ture wear.
FUEL LEVEL GAUGE:
With the tank empty, the float holds the slide rheostat
(variable resistance) at maximum resistance causing the
gauge to read empty (E), Figure 108.
FIGURE 108
With the tank full, the slide rheostat is moved to the
minimum resistance point causing the gauge to read full (F)
with the ignition switch on. The use of a bimetal in the fuel
indicator provides stability of reading and eliminates
pointer fluctuation incidental to surging in the tank and the
float bobbing on the surface of the fuel, Figure 109.
FIGURE 109
4 - 38 FUEL SYSTEM & EXHAUST