PS Magazine - MARCH 1981
PS, The Preventative Maintenance Monthly
ISSUE 340
MARCH 1981
ElectriciTy a± Work
A wire connecting the battEry posts is not a circuit you'lI find in your
equipmEnt. ±t doesn't do anything usEful² ³lEctricity goEs to work for you whEn
thE circuit includEs a "load´-lamp, motor, gagE, Etc²
Here's a simple working elEctrical circuit using only an ordinary flashlighT
battEry, a piEcE Of wirE and a lamp (thEµoad):
Bottom of
battery is
negative (-)
You can
use aN
unbent
w
The resistaNce-type
",
wiRe iN the lamp
:
.
ResIsts the floW of
±
eLectrIcity. This
makes the wiRe hot²
so hot that it glows³
just Like the wires ´N
an electric toasterµ
paper cLip
for the wire
ELectRicaL eNergy flows through
the wire and through the lamP
This is wHat
Symbol
-
the circuit
For lamp
looks liKe iN
_
a schematic
Sym¶ol
wiRing diagram
for battery
T
¶ne enD of the wire Contacts thE negativE (·) End of thE BattEry¸ ¹hE bottom
of the lamp base contacts the positive
(
+
)
end of thE battery. ¹he othEr end of
the wire contacts the side of the lamp basE¸ ¹he lamp lights up! ¹ouching the
wire to the lamp and then removing it is thE same as operating an ¶Nº¶FF
switch.
Most of the electrical circuits in your equipmEnt work pretty much thE samE
way.
·ire disconNected³
circuit bRokeN
·ith a switch to
break the circuit³
the schematic For
your simple circuit
L
¸¹º
º
oo
_
k
_
s
»
Li
_
ke
_
t
_
h
_
is
¼
½¾
SymboL
• ²
for switch
9
20
Chassis Ground-"2nD WIRe
³
A flashlight that has a mEtal casE is a lot »ikE thE Ele¼trical systEm in your
truck, tank, genErator, Etc² ¹he metal casE is part of thE ElEctrical circuit-just
likE the chass½is (frame, EnginE and instRumEnt panEl) of your truck or thE hull
of y
.
our tanK or PersonnEl carriEr¾ Most of thE Electrical compo¿Ents in your
EqÀpment are chassis groundEd²
¿LeCtricity tRavels tHru the coNtaÀt sÁRiNg .µ. tHru
th Metal case .
.. tHru tHe closed sÃitch .
.. tHRu
the contacÄ plate where tÅÆ lAmp's screÃÆD iÇ .
..
thru the side oF the lAmp ¶aÈÆ AÇD tHRu tHe
lAmp ÃirÆÉ
ÊËÌÆÍÎÏ ÐoÑÒÓÔÕÖ
×
btTeriEs
±hIS
fLASH´µg¶· U¸¹º»¼
lØÙÚ
, ½¾¿ÀJ1Á 3
VOlÛÜÝ
ÂÃÄÅ ÆÇ
bÈÉÊËÌÍ ÎÏÐ Ñ BÒFÓÔÕÖ×Ø
·
are
ÙONÚÛÜÝÞ
ßà 'áâãäåæçè.
éêë vìíîïðñ òó ôõÔ ö÷øùúûüý
þ ÿĀāj1Ă㥹
ĆćĈ ĉ
giv²
A.
pĊwċČčĎďĐđĒ ēĔ ĕ VĖėĘ
'
ęĚě
ĜĝĞğmĠġĢģ ĤĥĦ
³H´ flaµ¶L·G¸¹
ħĨĩĪī
•
Ĭĭ ĮįİıIJijĴĵĶķĸ
±
ĹĺĻļĽľ Ŀŀ
ŁłŃńŅņŇň ʼnŊ
ŋŌōŎŏŐ
PőŒœŔŕŖŊŗ
³vEry elEctrical componEnt of your Equipment is connEctEd by wirE to an
electrical wiring harnEss¸ All of this wiri¿g is co¿nEctEd to thE "positivE´ sidE of
the battery (or battEriES)¸
¹hEre's no wiring harnEss cÁnnEctEd to thE "nEgativE´ sidE. ±nstEad,
elEctricity travEls through thE chassis to thE "ground´ connEction of thE
ElEctrical componEnt²
21
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