PS Magazine - MARCH 1981
PS, The Preventative Maintenance Monthly
ISSUE 340
MARCH 1981
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In some equipment, the battery "negative± (ground) cable iS connected
directLy to the frame. In others, the ground cable is connected tO the engine-
and, of course, the engine is connected to the frame²
Battery positive
:
("Hot±) cable connects
to wiring harNesses
coming from all
ELectrIcaL comPoneNts
²LectricalLY
t³e same
²lEctrIcitY flows
t³Rough t³e wirE
²lectricitY flows
t³roug´ t³E frame
2
f±"VOlt
baT
t
er
i
es
arE
c
o
nne
C
²
E
d
³n
Sµ¶ie·
F´r
µ4-voL¶
p·weR
s
u
P
p
l
y
BA¸¹Eºy
g»¼uNd.•½
.
"
±
T³is is a lighting
circuit In a 24-volt
elEctrIcal sYstem.
¸AM¹
¾a¿ÀD
Á
ÂÃ
24-vlts
ºa»¼
½¾
GroU¿D
-
³7
´µ"/
,
.±²³´
µ¶
ÀlECtrIcItÁ flows t³roug³ t³e FramE aNd ot³er
Parts Of t³E c³ÂssIs w´eN t³E switc³ is closed Ã
Ä
TÅIs sYmbol in
a schematic
staNds for
a ground
connectionÆ
Çr some
sc³ematics
use t³is sYmboL
for a ground
ÈoNNectIOnÉ
There are No wires
connecting these
Electrica ÊY-opeËted
gages to groundÌ
ThEre's jÍst metal-toÎ
metal coNtact
Ï
the
gage case Ðor moÍnting
brackEt) to the gaÑe
cluster panel ÌÌÌ the
cluster panel to Òhe
instrÍment panel ÉÌÉ the
instrÍment paneL to
the trÍck cab ÌÌÉ the
cab to the frame
A
³sending unit± is in the circuit For certain gages, like the Oil pres´ure gage² µil
pres´ure contrOls the amount of electricity going thrOugh the sendinG unit²
This electricity controls the electricity that Operates the gage² ¶hat's hOw low
oil pre´sure makes the gage show a low pre´´ure reading²
¶·.
-²³´
ition
Ó
a
!
er
Ô
sWitch
or
master
switch
Õircuit
ÖAÑe
breaker
×endinÑ
Ø,
Ínit
ÕLÍster
panel
_·
ÙnstrÚment
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r
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×Ê'ÈÈ shÍW ÍÌÈY ÍÌÉ sYmÒÍÈ ÔÍÅ ÉÇchÖ
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