Iowa CDL Practice Test

Not quite. The answer is Use the parking brake to hold the vehicle until the clutch engages.

When you start your vehicle, avoid rolling backward or else you may hit someone behind you. Set the parking brake whenever necessary to keep from rolling back. Release the parking brake only when you have applied enough engine power to keep from rolling back. If you have a manual transmission vehicle, partly engage the clutch before you take your right foot off the brake. On a tractor-trailer equipped with a trailer brake hand valve, the hand valve can be applied to keep from rolling back.

Not quite. The answer is the tracks have a steep approach.

Raised railroad crossings with steep approaches can cause your vehicle to get hung up on the tracks. This is more likely if you're driving a vehicle with low ground clearance (such as a lowboy, car carrier, or moving van).

Not quite. The answer is Every 15 to 20 seconds

While driving, you should scan the environment ahead of you every 12 to 15 seconds. But it's also important to constantly monitor the status of your vehicle. You should scan your instrument panel, including the gauges and warning lights, every 15 to 20 seconds.

Not quite. The answer is one-half times the weight of the cargo tied down.

Under federal regulations, the aggregate working load limit of the tie-downs used to secure cargo must be at least one-half times the weight of the cargo. Federal regulations also specify a formula to compute the aggregate working load limit of the tie-downs from the working load limits of the individual tie-downs. The _working load limit_ of an individual tie-down is defined as the maximum load that may be applied to it, as specified by its manufacturer. [49 CFR 393.106],

Source: 49 CFR 393.5

Not quite. The answer is The weight transmitted to the ground by one axle or one set of axles

Axle weight is the weight transmitted from one axle or a set of axles to the ground.

Not quite. The answer is Both of the above are advantages.

Steering to the left of a hazard can cause you to move into the path of an oncoming vehicle or a vehicle that is trying to pass you on the left.

Not quite. The answer is the vehicle does not require placards.

You must have a hazardous materials endorsement on your CDL to drive a vehicle that is placarded for hazardous materials. However, not all packages of hazardous materials require placarding your vehicle. Federal regulation 49 CFR 172.500 exempts certain amounts and types of hazardous materials from placarding, but states may impose more stringent requirements. Check with the Iowa Department of Transportation.

Not quite. The answer is read the weight limit sign.

The maximum weight will be posted in advance of a bridge. After going over a bridge, you may be asked to tell the examiner what the posted weight limit was.

Not quite. The answer is Pull off the road and get some sleep.

If you are drowsy, cold air, fresh air, or caffeinated beverages may make you feel more alert only momentarily. The only real solution is to get off the road as soon as possible and get some real rest.

Not quite. The answer is someone could start and move the truck.

While you are performing the pre-trip inspection, you do not want someone (such as a co-driver) who is unaware of your location to start your vehicle and accidentally injure you.

Not quite. The answer is To shift into a low gear when you're stopped

When driving a CMV with an unsynchronized manual transmission, you can shift gears by double clutching or floating the gears. To shift into low gear or reverse when your vehicle is stopped and the engine is idling, you can engage the clutch brake. This stops the transmission's input shaft (connected to the engine) from rotating, so you can smoothly shift into low gear or reverse. To engage the clutch brake, depress the clutch pedal all the way to the floor. Never engage the clutch brake while your vehicle is moving; doing so can damage the clutch brake.

Not quite. The answer is Quieter operation

For large CMVs, diesel engines offer several advantages over gasoline engines. A diesel engine's high compression ratio gives it higher thermal efficiency, and therefore, about 25% greater fuel efficiency. Diesel engines produce a lot of power at low rpms. Diesel engines can last more than twice as long as gasoline engines (although this obviously depends on the specific models of engines). Finally, diesel fuel is safer than gasoline. Gasoline is highly flammable, and its vapors are highly explosive. Diesel fuel won't burn readily unless it's compressed (as in the cylinders of diesel engines). However, diesel engines are typically louder than gasoline engines.

Not quite. The answer is Pitman arm

The Pitman arm is attached to the output shaft of the steering box. The Pitman arm changes the rotation of the output shaft into back-and-forth movement, which is used to turn the front wheels of the CMV. The torque arm (also known as a radius rod) and bearing plate are parts of a vehicle's suspension.

Not quite. The answer is When the tires skim over the road surface

On a wet road at lower speeds, modern tires will usually channel water away to maintain contact with the road. However, in deep water at higher speeds, the channeling action of the tires becomes less effective and the tires start to ride on a layer of water like water skis. This is called “hydroplaning.” It may result in a loss of braking and steering control.

Not quite. The answer is Both of the above

To drive safely on snowy surfaces, your tires should be in the best possible shape. Consider exceeding the federal minimum requirements on tire tread depth (4/32 inch for front tires and 2/32 inch for the other tires). Make sure that your exhaust system has no leaks. An exhaust leak can allow dangerous fumes to enter your cab or sleeper berth. This can be especially dangerous in cold temperatures in which you will be more likely to keep the windows tightly shut.

Source: 49 CFR 570.62

Not quite. The answer is are designed to stop runaway vehicles safely without injuring drivers and passengers.

Escape ramps are located on many steep mountain grades. Escape ramps are built to stop runaway vehicles safely without injuring drivers or passengers. Escape ramps use a long bed of loose, soft material such as gravel to slow a runaway vehicle, sometimes in combination with an upgrade. Regardless of the type of vehicle you're driving or the other options open to you to stop your runaway vehicle, always look for one of these escape ramps. They can save lives, equipment, and cargo.

Not quite. The answer is Differential

A differential uses a series of gears to accomplish several functions. First, it transfers torque from the driveshaft to the axle. Because the axle is at 90 degrees from the driveshaft, the differential also turns the torque by 90 degrees accordingly. The outside of a curved road is longer than the inside. On such a curve, the differential lets the outside half of the axle turn faster than the inside half of the axle, so that the outside wheels can cover a greater distance than the inside wheels. If there were no differential, the outside wheels would turn at the same rate as the inside wheels, causing at least some of the wheels to drag on the pavement.

Not quite. The answer is Stay off the brakes until the vehicle slows down on its own.

If a tire blows out, don't brake. Braking could cause you to lose control. Instead, let your vehicle slow itself down. Then brake very gently and pull over.

Not quite. The answer is a TWIC card.

The Transportation Worker Identification Credential, also known as TWIC®, is required by the Maritime Transportation Security Act for workers who need access to secure areas of the nation’s maritime facilities and vessels. To obtain a TWIC card, you must apply to the Transportation Security Administration (TSA), either at their website or in person at a TWIC application center. TSA will conduct a security threat assessment (background check) of you, and if all goes well, they will issue you a TWIC card. Note that if you have a valid TWIC card, you won't need to go through another security threat assessment to obtain a Hazardous Materials endorsement.

Not quite. The answer is one-third.

When a road is wet, stopping distance is increased, and you should reduce your speed by one-third. On snow, slow to one-half your usual speed. On icy roads, slow to a crawl and stop driving as soon as you can do so safely.