CDL Knowledge Practice Questions Answers (Explanation)

During bad weather or in mountains, it may not be safe to operate at legal
maximum weights.

Nothing but time will sober you up.

To correct a drive wheel braking skid, you should stop braking and
countersteer. Taking your foot off the brakes, will allow the rear wheels to roll
again and keep the rear wheels from skidding. As a vehicle turns back on course,
it has a tendency to keep on turning. Unless you countersteer, you may begin
skidding in the opposite direction.

If a front tire fails, it can twist the steering wheel out of your hands. To
prevent this, you need to keep a firm grip on the steering wheel with both hands
at all times. Braking when a tire has failed could cause loss of control. Unless
you are about to run into something, stay off the brake until the vehicle has
slowed down. Then brake gently, pull off the road, and stop.

All placarded vehicles must have at least 4 identical placards displayed: one each on the front, rear, left, and right side. They must be readable from all 4 directions. They must be at least 10 ¾ inches square, turned upright on a point, in a diamond shape.

Excessive speeding (15 mph over speed limit), reckless driving, improper or erratic lane changes, following a vehicle too closely, traffic offenses committed in a CMV in connection with a fatal traffic accident, driving a CMV without obtaining a CDL or having a CDL in the driver’s possession, and driving a CMV without the proper class of CDL and/or endorsements are all considered serious traffic violations.

Dry bulk, hanging meat, livestock, oversized loads, projecting loads,
special markings needed, piggyback trailers all require special attention.

Cargo should have at least 1 tie down for each 10 feet of cargo, with an
absolute minimum of 2 tie-downs.

Do not look directly at lights of oncoming traffic, look slightly to the right.

A broken leaf spring is a suspension system defect. Exhaust system
defects can let poison fumes into the cab or sleeper berth.

A. Blocking is used in the front, back, and/or sides of a piece of cargo to
keep it from sliding. Bracing is also used to prevent movement of cargo; it goes
from the upper part of the cargo to the floor and/or walls of the cargo
compartment.

Engine oil pressure should come up to normal within a few seconds after
the engine is started. When idling, normal oil pressure is 5 to 20 psi. When
operating, normal engine oil pressure is 35 to 75 psi.

A placard is used to warn others of hazardous material. The placard will
display a 4 digit code (identification numbers) that first responders can use to
identify hazardous materials.

A loud “bang”, vibrations, steering that feels heavy, and a vehicle that
starts to slide back and forth (or “fishtail”) are signs of a tire failure.

Do not apply the brakes while you are turning. It is very easy to lock your
wheels while turning. If that happens, you may skid out of control.

If you are stopping to help in an accident, you should park away from the
accident. The area immediately around the accident will be needed for
emergency vehicles.

Any medication, prescribed or not, that affects your driving ability is
prohibited. Use of a drug prescribed by a doctor is permitted if the doctor
informs the driver that it would not affect the driver’s safe driving abilities.

Engine oil pressure should come up to normal within a few seconds after
the engine is started. When idling, normal oil pressure is 5 to 20 psi. When
operating, normal engine oil pressure is 35 to 75 psi.

No matter how small the cargo, it should have at least 2 tie downs. Cargo
should have at least 1 tie-down for each 10 feet of cargo.

When driving in fog in the daytime, you should use your low beam
headlights and fog lights.

An active crossing is a type of railroad crossing that has a traffic control device installed to regulate traffic. A passive crossing has no traffic control device.

Gross vehicle weight rating is the value specified by the manufacturer as
the loaded weight of a single vehicle. Gross vehicle weight is the total weight of
a single vehicle including its load. Gross combination weight is the total weight
of a combination of vehicles including the load. Gross combination weight rating
is the value specified by the manufacturer as the loaded weight of a combination
vehicle.

Water can be used on wood, paper, or cloth fires. Never use water on electrical fires (can cause shock) or gasoline fires (it will spread the flames)

The weight of a cargo van changes its height. An empty van is higher than
a loaded one.

Spilled fuel, improper use of flares, under-inflated tires, dual tires that
touch, short circuits, loose connections, driver smoking, improper fueling, loose
fuel connections, flammable cargo, improperly sealed or loaded cargo, and poor
ventilation can all be causes of vehicle fires.

A regular dry chemical fire extinguisher can be used on class B (Gasoline,
OIl, Grease, Other Greasy Liquids) or class C (Electrical Equipment) fires.

If you operate a CDL required vehicle in interstate commerce, the vehicle, with few exceptions, is required to be registered under the International Registration Plan (IRP) and under the International Fuel Tax Agreement (IFTA). These federally mandated programs provide for the equitable collection and distribution of vehicle license fees and motor fuel taxes for vehicles traveling throughout the 48 contiguous U.S. states and 10 Canadian provinces.

You must inspect your cargo within the first 50 miles after beginning a
trip; after you have driven for 3 hours or 150 miles; and after every break you
take during your trip.

If the Anti-Lock Braking System is working properly, the ABS light
should come on and then turn off.

When you drive a vehicle equipped with ABS, brake as you normally do.
The only exception is if you drive a straight truck or combination with working
ABS on all axles, you can fully apply the brakes in an emergency stop. If your
ABS system is not working, you should still have normal braking functionality.

Cargo on an open bed should be covered to protect people from spilled cargo and to protect cargo from the weather.

When using a fire extinguisher, stay as far away as possible and aim at the
source or base of the fire

Too much weight on the steering axle can cause hard steering. Under-
loaded front axles can make the steering axle weight too light to steer safely.
Too little weight on the driving axles can cause poor traction. The drive wheels
may spin easily. Weight that is loaded so there is a high center of gravity
increases chances of a rollover.

For a cargo fire in a van or box trailer, you should keep the doors shut.
Opening the doors will supply with fire with oxygen and can cause it to burn
very fast.

An anti-lock braking system is a computerized system that keeps your
wheels from locking up during hard brake applications. It does not increase or
decrease your normal braking capability. ABS does not shorten your stopping
distance, but helps keeps the vehicle under control during hard braking.