Commercial Driver Handbook ( PDF ) - California Department of ...

If coolant has to be added to a system without a
recovery tank or overflow tank, follow these steps:
• Shut engine off.
• Wait until engine has cooled.
• Protect hands (use gloves or a thick cloth).
• Turn radiator cap slowly to the first stop, which
releases the pressure seal.
• Step back while pressure is released from
cooling system.
• When all pressure has been released, press
down on the cap and turn it further to remove it.
• Visually check level of coolant.
• Replace cap and turn all the way to the closed
position.
Engine belts. Learn how to check V-belt tightness
on your vehicle by pressing on the belts. Loose belts
will not turn the water pump and/or fan properly.
This will result in overheating. Also check belts
for cracking or other signs of wear.
Hoses. Be sure the coolant hoses are in good
condition because a broken hose can lead to engine
failure and even fire.
Watch for bleeding tar. Tar in road surfacing
frequently rises to the surface in very hot weather.
Spots where tar “bleeds” to the surface are very
slippery.
go slow to prevent overheating. High speeds
create more heat for tires and engine. In desert
conditions, the heat may build up to the point where
it is dangerous. The heat will increase chances of
tire failure, tire fire, and engine failure.
mOuntAIn DRIVIng
In mountain driving, the force of gravity plays
a major role. The steeper the grade, the longer
the grade, and/or the heavier the load, the more
you will have to use lower gears to climb hills
or mountains. In going down steep hills, gravity
will tend to speed you up. You must select an
appropriate safe speed, then use a low gear and
proper braking techniques. You should plan ahead
and obtain information about any long steep grades
along your planned route of travel. If possible, talk
to other drivers who are familiar with the grades
to find out what speeds are safe.
You must go slowly enough so your brakes can
hold you back without getting too hot. If the brakes
become too hot, they may start to “fade.” This
means you have to apply them harder and harder
to get the same stopping power. If you continue
to use the brakes hard, they can keep fading (have
less stopping power) until you cannot slow down
or stop at all.
seleCt a “safe” speed
Your most important consideration is to select a
speed that is not too fast for the:
• Total weight of the vehicle and cargo.
• Length and steepness of the grade.
• Road conditions and weather.
If a speed limit is posted, or there is a sign indicating
maximum safe speed, never exceed the speed
shown. Also, look for and heed warning signs
indicating the length and steepness of the grade.
going doWnhill in the CorreCt gear
Use the braking effect of the engine as the principal
way of controlling your speed. The braking effect of
the engine is greatest when it is near the governed
rpms and the transmission is in the lower gears.
Save your brakes so you will be able to slow or
stop as required by road and traffic conditions.
Slow the vehicle and shift the transmission to a low
gear before starting down the grade. Do not try to
downshift after your speed has already built up.
You will not be able to shift into a lower gear. You
may not even be able to get back into any gear and
all engine braking effect will be lost. Forcing an
automatic transmission into a lower gear at high
speed could damage the transmission also and lead
to loss of all engine braking effect.
With older trucks, a rule for choosing gears is to
use the same gear going down a hill that you would
need to climb the hill. However, new trucks have
low friction parts and streamlined shapes for fuel
economy. They may also have more powerful
engines. This means they can go up hills in higher
gears and have less friction and air drag to hold them
back going down hills. For that reason, drivers of
newer trucks may have to use lower gears going
down a hill than needed to go up the hill. Find out
what is right for your vehicle.
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