Page 36 - Draft 2023 2024 CDL Manual w Modernization Info

SECTION 2: DRIVING SAFETY

Respond to Tire Failure. When a tire fails, Trailers will have yellow ABS malfunction 2.18.7-Braking If ABS Is Not Working
your vehicle is in danger. You must immediately: lamps on the left side, either on the front or Without ABS you still have normal brake
• Hold the Steering Wheel Firml . If a front rear corner. functions. Drive and brake as you always have.
y
tire fails, it can twist the steering wheel out Dollies manufactured on or after March 1, Vehicles with ABS have yellow malfunction
of your hand. The only way to prevent this 1998, are required to have a lamp on the left side. lamps to tell you if something isn't working.
As a system check on newer vehicles, the
is to keep a firm grip on the steering wheel malfunction lamp comes on at start-up for a As a system check on newer vehicles, the
with both hands at all times. bulb check, and then goes out quickl On older malfunction lamp comes on at start-up for a
y.
• Stay Off the Brake. It's natural to want to systems, the lamp could stay on until you are bulb check and then goes out quickly. On older
systems, the lamp could stay on until you are
brake in an emergency. However, braking driving over five mph. driving over five mph.
when a tire has failed could cause loss of If the lamp stays on after the bulb check, or If the lamp stays on after the bulb check, or
control. Unless you're about to run into some­ goes on once you are under way, you may have
thing, stay off the brake until the vehicle has lost ABS control. goes on once you are under way, you may have
slowed down. Then brake very gently, pull In the case of towed units manufactured lost ABS control on one or more wheels.
Remember, if your ABS malfunctions, you
off the road, and stop. before it was required by the Department of still have regular brakes. Drive normally, but
Transportation, it may be difficult to tell if the
• Check the Tires. After you've come to a unit is equipped with ABS. Look under the ve­ get the system serviced soon.
stop, get out and check all the tires. Do this
even if the vehicle seems to be handling all hicle for the ECU and wheel speed sensor wires 2.18.8-Safety Reminders
coming from the back of the brakes.
right. If one of your dual tires goes, the only • ABS won't allow you to drive faster, follow
way you may know it is by getting out and
looking at it. 2.18.4- How ABS Helps You more closely, or drive less carefully.
When you brake hard on slippery surfaces • ABS won't prevent power or turning skids­
2.18-Antilock Braking in a vehicle without ABS, your wheels may lock ABS should prevent brake-induced skids or
Systems (ABS) up. When your steering wheels lock up, you jackknifes, but not those caused by spinning
the drive wheels or going too fast in a turn.
lose steering control. When your other wheels
ABS is a computerized system that keeps lock up, you may skid, jackknife, or even spin • ABS won't necessarily shorten stopping dis­
your wheels from locking up during hard brake the vehicle. tance. ABS will help maintain vehicle control,
ABS helps you avoid wheel lock up and main­
applications. tain control. You may or may not be able to stop but not always shorten stopping distance.
ABS is an addition to your normal brakes.
It does not decrease or increase your normal faster with ABS, but you should be able to steer • ABS won't increase or decrease ultimate
stopping power-ABS is an "add-on" to your
around an obstacle while braking, and avoid
braking capability. ABS only activates when skids caused by over braking. normal brakes, not a replacement for them.
wheels are about to lock up.
ABS does not necessarily shorten your stop­ • ABS won't change the way you normally
ping distance, but it does help you keep the 2.18.5-ABS on the Tractor Only brake. Under normal brake conditions, your
vehicle under control during hard braking. or Only on the Trailer vehicle will stop as it always stopped. ABS
Having ABS on only the tractor, only the only comes into play when a wheel would nor­
2.18.1 - How Antilock Braking trailer, or even on only one axle, still gives you mally have locked up because of over braking.
Systems Work more control over the vehicle during braking. • ABS won't compensate for bad brakes or poor
Sensors detect potential wheel lock up. An Brake normally. brake maintenance.
When only the tractor has ABS, you should
electronic control unit (ECU) will then decrease be able to maintain steering control, and there • Remember: The best vehicle safety feature is
brake pressure to avoid wheel lockup. is less chance of jackknifing. But keep your eye still a safe driver.
Brake pressure is adjusted to provide the
maximum braking without danger of lockup. on the trailer and let up on the brakes (if you can • Remember: Drive so you never need to use
safely do so) if it begins to swing out.
ABS works far faster than the driver can re­ your ABS.
When only the trailer has ABS, the trailer is
spond to potential wheel lockup. At all other less likely to swing out, but if you lose steering • Remember: If you need it, ABS could help to
times the brake system will operate normally. control or start a tractor jackknife, let up on prevent a serious crash.
2.18.2 -Vehicles Required to Have the brakes (if you can safely do so) until you
regain control.
Antilock Braking Systems 2.19-Skid Control and
The Department of Transportation requires 2.18.6-Braking with ABS Recovery
that ABS be on: When you drive a vehicle with ABS, you A skid happens whenever the tires lose their
• Truck tractors with air brakes built on or after should brake as you always have. In other words: grip on the road. This is caused in one of four
March 1, 1997. • Use only the braking force necessary to stop ways:
• Other air brake vehicles, (trucks, buses, trail­ safely and stay in control. • Over-braking. Braking too hard and locking
ers, and converter dollies) built on or after • Brake the same way, regardless of whether up the wheels. Skids also can occur when us­
March 1, 1998. you have ABS on the bus, tractor, the trailer, ing the speed retarder when the road is slip­
• Hydraulically braked trucks and buses with or both. pery.
a gross vehicle weight rating of 10,000 lbs or • As you slow down, monitor your tractor and • Over-steering. Turning the wheels more
more built on or after March 1, 1999. trailer and back off the brakes (if it is safe to sharply than the vehicle can turn.
Many commercial vehicles built before these do so) to stay in control. • Over-acceleration. Supplying too much pow­
dates have been voluntarily equipped with ABS. There is only one exception to this procedure. er to the drive wheels, causing them to spin.
2.18.3 - How to Know If Your Vehicle If you drive a straight truck or combination with • Driving Too Fast. Most serious skids re­
sult from driving too fast for road conditions.
working ABS on all axles, in an emergency stop,
Is Equipped with ABS you can fully apply the brakes. Drivers who adjust their driving to conditions
Tractors, trucks, and buses will have yellow don't over-accelerate and don't have to over­
ABS malfunction lamps on the instrument panel. brake or over-steer from too much speed.

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