PS Magazine - JULY 1981
PS, The Preventative Maintenance Monthly
ISSUE 344
JULY 1981
1
OI=ilom
\®[!1 ±²³f
Some of you newer drivers may Not
eveN kNow what RPM' meaNs. It±s
RevolUtioNs per MiNute²
A "revolutioN³ is 1 com´Lete turN of
your eNgiNe±s CraNkshaft² So, if your
tachometer shows 1,000 RPM, it
meaNs your craNk
shaFt is makiNg
1,000 turNs ´er
miNute² ANd this
back agaiN-µ,000 times ´er miNute¶
·ast? That±s oNLy high idLe s´eed fOr
a diesel/muLtifueL eNgiNe² At highway
cruisiNg s´eed, your eNgiNe maY Be
turNing over at more thaN twice that
RPM²
ThiNk about this: At 2,000 RPM,
your eNgi¸e±s craNkshaft is t¹rNiNg
ovr more thaN 30 times every secoNd!
IN just the time it takes for you to say
meaNs each ´istoN
t
·
"oNe thousaNd³, each ´istoN travels
is traveLiNg from
I
•
I
from bºttom to to´ aNd back agaiN
its Lowest ´oiNt
·´
L.lw±•
:
more thaN 30 times! Push rods, valves
to its highest
i
+
aNd other »arts are goiNg Like crazy!
´oiNt-aNd
²
.
¼our eNgiNe is buiLt to take tHat
s´eed-aNd eveN more²
}ut evEry eNgiNe±s aLso buiLt with aN
RPM Limit² That±s Not aN RPM you try
to reach-it±s the RPM you stay away
from²
That red arrow oN your tachometer
me½Ns just what it says¾A¿GÀR²
20
thiNk your eNgiNe WiLL work Like a brake aNd hoLd your s´eed dowNÁÂ
but you±re wroNg! ANd you Let s´eed buiLd uà uNtiL it±s too LateÄ
your b
Å
akes caN±t h
Æ
Ld you
Ç
back²
µ
NgiNe s´eed reaches
_
;¶
;
/
È
the ´oÉt where thÉgs start comÉg a´art²
«
?
Maybe you±re Lucky and a good eNough
¸
d
driver to steer cLear of aN accideNt,
/
¹-
but yoÊ tËar u´ a mighÌy ex´eNÍ
/
º
»
sive eNgiNe by fÎiLiNÏ to steer
¼
clear of "excessive RPM³Ð
/
½
¾
YOU THouGht ³'
´µ¶ ·¸¸ ¹AºE!
¼our tÑuck caN do oÒLy what you
aLlow it to² ¼ou±Ñe iN coNtroL² ¼ou
coNtroL steeriNg, fueL fLow, traNsmisÓ
sioN gear, traNsfer raNge, brakiNgÔ
aNd eNgiNe s´eed² DriviNg a big,
´owerfuL, heaviLyÕLoaded Army truck
is no job Ör someoNe who caN thiNk of
overs´eediNg the eNgiNe wheN you±re
traveliNg u´hilL-it±s easy to coNtroL²
oNLy oNe thiNg at a time²
if you don't cut
your road speed,
each sh±Ft down .
.²
TlNSMISsiO
'±
;
R
P
±²³´
t
i µ¶·;Ie
-·
"
±
•
toward DANGE³!
Remember, eNgiNe s´eed (RPM)
goes ×à as you shift
d»Wn¼
This±Ø how
you jack u´ your ´ower to get u´ a hiLl²
TheN you realLy shar´ÙN u´! As yoÊ
reach the to´ of the hiLL aNd start dowN
the other side, you kee´ your traNsmisÓ
sioN iN the same gear-aNd you
Ú
kee´
oNe eye gLÊed to that tachometer²
Kee´ your eNgine RPM weLL beloÛ
the taiL eNd of that red DA¿GÀR
arrow² Üse your Ýrakes² Þut you doN±t
"ride³ your brake ´edal or you±lL burN
´on't wa±t
tµll ±t's too
late¶·¸ use
·
your b¹akeº
¿o sweat-you kee´ shiftiNg to a u´ your brakes² Just gßve your brakes a
Lower gear as you Need more ´ower² jab oNce iN awhiLe if RPM starts
There±s Not much chàNce of your cree´iNg u´²
21
²
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