Missouri CDL: General Knowledge Practice Test

Not quite. The answer is The weight of a vehicle changes its height.

Your truck's height will vary depending on how much weight you're hauling. An empty or lightly loaded vehicle will ride higher than one that is weighed down with heavy cargo. Don't put all your trust in posted road clearance signs. The height of the roadway may have changed since the sign was posted.

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 retarders in poor weather.

Not quite. The answer is hold the triangles between yourself and oncoming traffic.

As you carry the reflective triangles to place them around your vehicle, hold them between yourself and traffic to help you stay visible to other drivers.

Not quite. The answer is at least a one-year suspension of your CDL.

Under Missouri law, if you are convicted of DWI in a CMV for the first time, you will face a fine of up to $1,000, a jail sentence of up to six months, or both. Furthermore, you will be disqualified from driving CMVs for at least one year. If you are convicted of DWI for a second time within a five-year period, you will face a fine of up to $2,000, a jail sentence of up to one year, or both. Furthermore, you will be disqualified from driving CMVs permanently, ending your career in commercial driving. [RSMo § 577.010],

Source: 49 CFR 383.51

Not quite. The answer is Trucks, truck tractors, semitrailers, full trailers, and tractor-pole trailers with a gross vehicle weight rating of more than 10,000 pounds

Federal cargo securement rules apply to trucks, truck tractors, semitrailers, full trailers, and tractor-pole trailers with a gross vehicle weight rating of more than 10,000 pounds.

Not quite. The answer is 43%

Federal regulations impose maximum weight limits on CMVs traveling on interstate highways. The maximum allowable GCWR is 80,000 pounds. The single axle weight rating is 20,000 pounds, and the tandem axle weight rating is 34,000 pounds. This weight rating is for typical tandem axles that are spaced 40 to 96 inches apart, from center to center. 34,000/80,000 = about 43%. If both the drive tandems and trailer tandems are each carrying their maximum allowable weight of 34,000 pounds, that leaves only 12,000 pounds (about 14% of the weight) for the steering axle, even though the maximum allowable weight is 20,000 pounds.

Not quite. The answer is Downshifting allows engine compression and friction to help the brakes slow the vehicle.

When you're about to start down a long downgrade, release the gas pedal, shift into a low gear, and use engine braking to slow your vehicle. Don't try to downshift after your speed has already built up. You will not be able to shift into a lower gear then. You may not even be able to get back into any gear, and all engine braking effect will be lost. If you try to downshift an automatic transmission after your speed has already built up, you may damage the transmission.

Not quite. The answer is must be shown immediately if an officer requests it.

If you're transporting hazardous materials, a law enforcement officer may stop you to inspect your vehicle. The officer may check your logbook (or electronic logging device), shipping papers, vehicle placards, and the HazMat endorsement on your CDL. If your logbook is not up to date, you may be cited and placed out-of-service for some specified amount of time.

Not quite. The answer is 1 year.

For a first offense of driving a commercial vehicle while under the influence of alcohol or drugs, you will lose your CDL for at least one year. In fact, you will also lose your CDL for a first offense of driving with a blood alcohol concentration (BAC) of 0.04% or higher, even though 0.04% is below the legal limit for licensed adult car drivers.

Not quite. The answer is park in an open area.

If your vehicle catches fire, pull off the road and park in an open area away from anything that might catch fire, such as buildings or trees. Especially avoid parking your burning vehicle near a gas station!

Not quite. The answer is Brakes absorb more heat to stop heavier vehicles.

Brakes use friction to convert the kinetic energy of your moving vehicle into heat. However, overuse of the brakes (which can happen if you don't use engine braking enough) can generate so much heat that brakes can fade (lose their effectiveness) or fail.

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 Start to turn your vehicle after you reach the center of the intersection.

Long vehicles are prone to significant off-tracking (the rear wheels following a quite different path than the front wheels). With two lanes going in your direction, enter the intersection from the outside lane because you may have to swing right to make the left turn. Make sure you have reached the center of the intersection before you start the left turn. If you turn too soon, the left side of your vehicle may hit another vehicle.

Not quite. The answer is at least 20%

The North American Standard Out-of-Service Criteria employs the "20 percent rule" for brakes: the vehicle must be put out-of-service if at least 20 percent of its brakes are defective. However, the vehicle must also be put out-of-service if any of its front (steering) axle brakes are defective.

Not quite. The answer is Bobtail tractor

The brakes and suspension of a truck are designed to handle heavy cargo. Trucks that are empty or only lightly loaded take longer to stop because the stiff suspension springs and strong brakes give poor traction and make it easier to lock the wheels. (This is not usually the case for buses, however.) Likewise, "bobtail" tractors (tractors without semitrailers) can take even longer to stop than an unloaded tractor-trailer. Be very careful when driving a "bobtail" tractor.

Not quite. The answer is Vibration

If the vehicle thumps or vibrates heavily, it may be a sign that one of the tires has gone flat. With a rear tire, that may be the only sign you get. A blowout is more likely to make a loud bang than a hiss.

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 refuse to haul the load.

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 regulations exempt certain amounts and types of hazardous materials from placarding, but states may impose more stringent requirements. Check with the Missouri Department of Transportation.

Source: 49 CFR 172.500

Not quite. The answer is 7 pounds.

One gallon of diesel fuel weighs about 7 pounds, meaning that a full fuel tank in a tractor-trailer can weigh well over 1,000 pounds. Bear this in mind when calculating how your vehicle can remain within legal weight limits.

Not quite. The answer is Both of the above

You will be disqualified from operating a CMV for at least 60 days if you are convicted of any of the following offenses at railroad crossings: (1) failing to slow down and check that the tracks are clear; (2) failing to stop if a train is approaching; (3) failing to stop before driving onto the crossing; (4) failing to ensure that there is sufficient space for you to drive completely through the crossing without stopping; (5) failing to obey a traffic control device or the directions of an enforcement official; (6) failing to negotiate the crossing because of insufficient undercarriage clearance.

Source: 49 CFR 383.51