Idaho CDL: General Knowledge Practice Test

Not quite. The answer is Look for an escape ramp or escape route.

If your brakes fail on a long, steep downgrade and your vehicle starts to pick up speed, you may not be able to downshift. Instead, find an escape route as soon as possible. Use an escape ramp if available or take the least hazardous escape route you can – such as an open field or a side road that flattens out or turns uphill.

Not quite. The answer is Axles

All of a vehicle's axles should be aligned perpendicular (a 90-degree angle) to the centerline of the vehicle. If the trailer axles are not properly aligned, the trailer may drift to one side, a condition commonly known as dog-legging or dog-tracking. At a roadside inspection, your trailer can be placed out of service for misaligned axles (49 CFR 393.207(a)). Another possible cause of dog-tracking is incorrectly adjusted tandems (if the trailer is so equipped).

Not quite. The answer is Engage the brakes hard and immediately.

Hard braking could cause the vehicle to go out of control, so brake gently only after the vehicle has slowed down and you have regained control.

Not quite. The answer is the brain tells the foot to push the brake pedal to the time the foot actually pushes the pedal.

Total stopping distance is the sum of your perception distance (how far your vehicle goes from when you see the hazard until your brain processes it), reaction distance (how far the vehicle goes from when your brain orders your foot to take action until your foot actually starts to brake), and braking distance (how far the vehicle continues to travel once you apply the brake). An average driver's perception time is about 1 3/4 seconds. His or her reaction time is between 3/4 second and 1 second. (Note: 55 mph is equal to about 81 feet per second. At this speed, a reaction time of 3/4 second is equivalent to a reaction distance of 61 feet.)

Not quite. The answer is All of the above statements are correct.

While retarders can help reduce the need for braking, they can make a skid more likely in inclement weather or whenever your wheels have poor traction. Therefore, you should always turn off your retarder in poor weather.

Not quite. The answer is Low beams, high beams, four-way flashers, and turn signals

During Step 4 and Step 5 of the Seven-Step Inspection Method, you'll check the various lights at the front of your vehicle to make sure that they're all working properly.

Not quite. The answer is both of the above.

Wet brakes can be weak, apply unevenly, or grab. This can cause loss of braking power, wheel lockups, pulling to one side or the other, and even a jackknife if you pull a trailer.

Not quite. The answer is can be incorrectly connected to non-polarized trailer couplers.

To prevent cross-connection of the supply and service lines, polarized gladhands and polarized trailer couplers are now available. The supply gladhands and couplers are shaped slightly differently from the service gladhands and couplers, making cross-connection impossible. However, polarized gladhands can still be connected to universal (non-polarized) trailer couplers, so cross-connection in this situation is still possible.

Not quite. The answer is To reduce emissions of nitrogen oxides (NOx)

The exhaust gases of diesel engines include nitrogen oxides (NOx), a major contributor to air pollution and acid rain. To reduce most nitrogen oxide emissions, diesel exhaust fluid (DEF) is sprayed into the stream of exhaust gases. DEF reacts with the NOx to form harmless nitrogen gas and water vapor. According to the official state CDL manual, the DEF tank should be kept more than 1/8 full. (Typically, a CMV uses about 1 gallon of DEF for every 50 gallons of diesel fuel.)

Not quite. The answer is both of the above.

How much liquid you can load into a tank depends on the following: (1) Heat makes liquid expand, so you must allow enough room at the top of the tank for outage. (2) A dense liquid may weigh so much that loading too much liquid into the tank may cause your vehicle to exceed state weight limits.

Not quite. The answer is All of the above are downsides.

Some emissions-control devices on diesel-powered trucks can adversely affect fuel economy and add to maintenance costs. For these reasons, some drivers have opted to "delete" (defeat or remove) the emissions-control devices and retune the engine to run well without the devices. However, doing so can cause you major problems. First, deleting an emissions-control device violates the federal Clean Air Act and federal regulations. The penalties include stiff fines. Second, a number of states, such as California, New York, and Minnesota, now require emissions testing of trucks. You will not be able to drive your truck there if it fails emissions testing there. Third, dealers and large reputable repair shops may refuse to service your vehicle after it's illegally modified. Fourth, if you ever wish to sell your vehicle, you must disclose its illegal modifications to potential buyers. If you sell the vehicle without disclosing this information, you risk legal action from the buyer after the buyer discovers the modifications. [40 CFR 1068.101],

Source: 42 U.S. Code 7522

Not quite. The answer is If you need to tilt the cab, secure loose items first.

Before you start to inspect your vehicle, take the ignition key with you to prevent anyone else from moving the vehicle while you're inspecting it. To inspect a cab forward (cab-over) vehicle, it may be necessary to tilt the cab to gain access to the engine compartment. Before doing this, secure any loose items inside the cab so they won't fall when you tilt the cab.

Not quite. The answer is 320 feet

Distracted driving is dangerous. 55 mph equals 80.7 feet per second. In 4 seconds, your CMV will travel 4 × 80.7 = 323 feet. For that entire distance, your eyes will be watching your phone, not the road. Studies have shown that drivers take an average of 3.8 seconds to dial their cell phones. The length of a football playing field (i.e., not counting the two end zones) is 300 feet.

Not quite. The answer is 6 months.

Under federal regulation 49 CFR 395.8, your carrier is responsible for keeping a copy of your duty logs and supporting documentation for six months. An example of supporting documentation is your fuel bills, with time stamps. As the driver, you must keep your copy of the log for today and the last 7 days.

Not quite. The answer is Poisonous fumes can enter the cab or sleeping compartment.

The exhaust system is designed to help remove toxic gases produced by the engine. A leak in the exhaust system can allow poisonous carbon monoxide (CO) to seep into the cab or sleeping compartment. A buildup of CO is more likely in cold weather, when you may have the cab windows closed.

Not quite. The answer is It depends on the state.

There is no national standard governing which tires must be chained on various types of commercial vehicles. Instead, each state can set its own rules. Some states have no such rules. In such cases, learn what is best for the type of vehicle you'll be driving, and chain up accordingly.

Not quite. The answer is HIGH; LOW

For forward gears, the range selector switch (usually located on the front of the gear shifter) lets you switch between the low-range gears (Low, 1, 2, 3, 4) and the high-range gears (Low, 5, 6, 7, 8). Flip the range selector switch down for the low range and up for the high range. The splitter button (usually located on the left side of the gear shifter) lets you "split" each gear into a lower gear (L) and a higher gear (H). Move the splitter button backward for the lower gear and forward for the higher gear. Thus, for gear 7L, the range selector should be in HIGH (up), and the splitter should be in LOW (backward).

Not quite. The answer is Spring hanger

Component P is a spring hanger. Note: Your state CDL handbook misidentifies this part as a "front axle hanger."

Not quite. The answer is plus or minus 5 mph.

According to federal regulation 49 CFR 393.82, the speedometer of a CMV traveling at 50 mph must be accurate to within plus or minus 5 mph, which would be a relative error of plus or minus 10%. This requirement applies to buses, trucks, and truck tractors.

Not quite. The answer is driving too fast for road conditions.

Always adjust your speed to fit current driving conditions including weather, visibility, tire traction, curves, and hills. In practice, this will sometimes mean driving at well below the posted speed limit.