Chevrolet DB90 Series, Service Manual

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S ec. 12-218
CHASSlk ELECTRICAL AND INSTRUMENTS^
Ignitidin R e sisto r
S ta rtq r Magnetic
Switch
Chokd Relay
Enginfe C ontrol
Switch
r Switch
Switch
Junction Block
Voltage R egulator
Relay
S tarte
Choke
Field
10 S ta rte r Interlock
Relay
11 A m m eter Shunt
12 30-Amp. C ircu it
B re a k e r
13 M aster C irc u it
B re a k e r - 70-Amp.
With 61- o r 62-Amp.
G en erato r
90-Amp. With
130-Amp. G en erato r
Figure $ —Rear C hassis Junction (“ R” M odels) (Typical)
NECESSAiRY WITH CIRCUIT BREAKER OPEN and
do not attempt to "jump" a c r o ss breaker term in als
in sid e con sole to b y -p a ss this protective device.
Any Condition which ca u ses an overload on the
circu it w ill cause the b im eta llic elem ent to open
the circu it and fo rce the r e se t button outward, thus
d e-en erg izin g c ir cu its p rotected by the circuit
break er.
To en ergize the circu it, p r e ss the r e s e t button
cuit breaker "IN." If a repeated overload
ered, lo ca te and co rrect the cau se of the
on the cir
is encouni
overload.
AUTOMATIC RESET TYPE
CIRCUIT BREAKER
Automatic r e se t type circu it breakers are
used on S e r ie s RM80, S e r ie s 70-90 tilt cab
m od els, ajnd S e r ie s 90 tilt cab m od els. R efer to
"Circuit b rea k er Tabulation” at end of th is section
for circu it breaker am perage rating and location.
Automatic r e s e t type circu it b reak ers can be
identified jby a long "A ccessory" term inal stud and
a sh ort "Battery" term inal stud on the circuit
b reak er. Two nuts are used to attach term inal
lea d s to the circu it breaker.
An overload on the circu it, such a s a short,
w ill cau se the circu it b reaker b im eta llic elem ent
to open the circu it. When the elem ent c o o ls, the
circu it breaker w ill c lo se the c ircu it. T his off-and-
on c y c le w ill repeat until the sw itch controlling
the d efective circu it is turned off, or until the cause
of the overload has been located and corrected .
If the circu it breaker b eco m es inoperative
(burns out or stic k s closed ), the defective circu it
breaker must be replaced. C ircuit b rea k ers must
be in stalled so the feed or battery w ir e is connec­
ted to the "Battery” or short term inal and the w ire
or w ir e s carrying the circu it to the unit is con­
nected to the "Auxiliary" or long term inal.
IMPORTANT: When replacing a circu it breaker
u se a replacem ent circu it breaker having the sam e
am perage rating and voltage as stam ped on the unit
being replaced.
REMOTE RESET TYPE
CIRCUIT BREAKER
The rem ote r e se t type circu it breaker u sed on
som e conventional cab m odels has fu se clip adap­
to r s in stalled over the circu it b reak er term inal
studs. T h ese adapters snap into fu se clip s in the
fu se block. R efer to "Circuit B reaker Tabulation"
at end of this sectio n for circu it breaker am perage
rating and usage.
An overload on the circu it, such a s a short,
w ill cau se the circu it b reaker b im etallic elem ent
to open the circu it. A heating elem ent within the
circu it breaker w ill hold the b im eta llic elem ent
open until the sw itch controlling the d efective c ir ­
cuit is turned off or until the circu it b reaker is
rem oved from the circu it.
W ARN IN G
DO NOT remove an open c irc u it
breaker with bare hands. The heating
element will cause the c irc u it breaker to
rem ain hot as long as the c irc u it breaker
Is open.
It w ill req u ire approxim ately 35 secon d s for
the elem ent to cool su fficien tly to p erm it the c ir ­
cu it b reaker to com plete the circu it a fter the con­
trollin g sw itch is turned off o r the circu it breaker
is rem oved.
If a circu it b reaker opens, turn off the sw itch
controlling the d efective c irc u it or rem ove the
circu it b reaker. Wait approxim ately 35 secon d s
for the elem ent to cool, then turn on the con troll­
ing sw itch or in sta ll the circ u it b reaker in the fu se
block.
If the circu it breaker b ecom es inoperative
(burns out or stick s clo sed ), rep lace the circu it
breaker with a new unit of the sam e type and hav­
ing the sam e am perage rating and voltage as
stam ped on the c a se .
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT