Page 33 - DDS Commercial Driver Manual 2021-2022

SECTION 2 : DRIVING SAFETY

• The nature of the cargo makes a stop manda- TEST YOUR KNOWLEDGE
tory under state or federal regulations.
• Such a stop is otherwise required by law. Subsections 2.15 and 2.16
When stopping be sure to:
• What factors determine your selection of • What type of vehicles can get stuck on a
• Check for traffic behind you while stopping a “safe” speed when going down a long, railroad-highway crossing?
gradually. Use a pullout lane, if available. steep downgrade?
• How long does it take for a typical
• Turn on your four-way emergency flashers. • Why should you be in the proper gear tractor-trailer unit to clear a double track?
before starting down a hill?
2.15.5 – Crossing the Tracks
• Describe the proper braking technique
Railroad crossings with steep approaches when going down a long, steep
can cause your unit to hang up on the tracks. downgrade.
Never permit traffic conditions to trap you
in a position where you have to stop on the These questions may be on the test. If you can’t answer them all, re-read subsections 2.15
tracks. Be sure you can get all the way across the and 2.16
tracks before you start across. It takes a typical
tractor-trailer unit at least 14 seconds to clear a
single track and more than 15 seconds to clear
a double track. • Steepness of the grade. share of the work. Brakes out of adjustment will
Do not shift gears while crossing railroad • Road conditions. stop doing their share before those that are in
tracks. adjustment. The other brakes can then overheat
• Weather. and fade, and there will not be enough braking
2.15.6 – Special Situations If a speed limit is posted, or there is a sign available to control the vehicle. Brakes can get
indicating “Maximum Safe Speed,” never ex- out of adjustment quickly, especially when they
Be Aware! These trailers can get stuck on ceed the speed shown. Also, look for and heed are used a lot; also, brake linings wear faster
raised crossings: when they are hot. Therefore, brake adjustment
warning signs indicating the length and steep-
• Low slung units (lowboy, car carrier, moving ness of the grade. must be checked frequently.
van, possum-belly livestock trailer). You must use the braking effect of the engine 2.16.4 – Proper Braking Technique
as the principal way of controlling your speed.
• Single-axle tractor pulling a long trailer The braking effect of the engine is greatest when Remember. The use of brakes on a long and/
with its landing gear set to accommodate a it is near the governed rpms and the transmis- or steep downgrade is only a supplement to the
tandem-axle tractor.
sion is in the lower gears. Save your brakes so braking effect of the engine. Once the vehicle
If for any reason you get stuck on the tracks, you will be able to slow or stop as required by is in the proper low gear, the following are the
get out of the vehicle and away from the tracks. road and traffic conditions. proper braking techniques:
Check signposts or signal housing at the cross-
ing for emergency notification information. Call 2.16.2 – Select the Right Gear Before • Apply the brakes just hard enough to feel a
911 or other emergency number. Give the loca- Starting Down the Grade definite slowdown.
tion of the crossing using all identifiable land- • When your speed has been reduced to ap-
marks, especially the DOT number, if posted. Shift the transmission to a low gear before proximately five mph below your “safe”
starting down the grade. Do not try to down- speed, release the brakes. (This brake ap-
shift after your speed has already built up. You
2.16 – Mountain Driving will not be able to shift into a lower gear. You plication should last for about three seconds.)
may not even be able to get back into any gear • When your speed has increased to your
In mountain driving, gravity plays a major role. and all engine braking effect will be lost. Forc- “safe” speed, repeat steps 1 and 2.
On any upgrade, gravity slows you down. The ing an automatic transmission into a lower gear For example, if your “safe” speed is 40 mph,
steeper the grade, the longer the grade, and/or the at high speed could damage the transmission you would not apply the brakes until your speed
heavier the load--the more you will have to use and also lead to loss of all engine braking effect. reaches 40 mph. You now apply the brakes hard
lower gears to climb hills or mountains. In coming With older trucks, a rule for choosing gears enough to gradually reduce your speed to 35
down long, steep downgrades, gravity causes the is to use the same gear going down a hill that mph and then release the brakes. Repeat this
speed of your vehicle to increase. You must select you would need to climb the hill. However, new as often as necessary until you have reached
an appropriate safe speed, then use a low gear, trucks have low friction parts and streamlined the end of the downgrade.
and proper braking techniques. You should plan shapes for fuel economy. They may also have Escape ramps have been built on many steep
ahead and obtain information about any long, more powerful engines. This means they can go mountain downgrades. Escape ramps are made
steep grades along your planned route of travel. up hills in higher gears and have less friction to stop runaway vehicles safely without injur-
If possible, talk to other drivers who are familiar and air drag to hold them back going down hills. ing drivers and passengers. Escape ramps use
with the grades to find out what speeds are safe. For that reason, drivers of modern trucks may a long bed of loose, soft material to slow a run-
You must go slowly enough so your brakes have to use lower gears going down a hill than away vehicle, sometimes in combination with
can hold you back without getting too hot. If the would be required to go up the hill. You should an upgrade.
brakes become too hot, they may start to “fade.” know what is right for your vehicle. Know escape ramp locations on your route.
This means you have to apply them harder and Signs show drivers where ramp are located.
harder to get the same stopping power. If you 2.16.3 – Brake Fading or Failure Escape ramps save lives, equipment and cargo.
continue to use the brakes hard, they can keep Brakes are designed so brake shoes or pads
fading until you cannot slow down or stop at all.
rub against the brake drum or disks to slow 2.17 – Driving Emergencies
2.16.1 – Select a “Safe” Speed the vehicle. Braking creates heat, but brakes are
designed to take a lot of heat. However, brakes
Your most important consideration is to select can fade or fail from excessive heat caused by Traffic emergencies occur when two vehicles
a speed that is not too fast for the: using them too much and not relying on the are about to collide. Vehicle emergencies occur
engine braking effect. when tires, brakes, or other critical parts fail.
• Total weight of the vehicle and cargo. Following the safety practices in this manual
Brake fade is also affected by adjustment. To
• Length of the grade. safely control a vehicle, every brake must do its can help prevent emergencies. But if an emer-
gency does happen, your chances of avoiding

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