Rhode Island CDL: Double & Triple Trailers Practice Test

Not quite. The answer is Use your mirrors to keep an eye on your tires.

Clean and adjust your mirrors as part of your pre-trip inspection, when your vehicle is parked. Adjust each mirror to show some part of your vehicle as well as the roadway. You can adjust your mirrors accurately only when your trailers are straight. While you're driving, use your mirrors to keep an eye on your tires. It's one way to spot a tire fire. However, no matter how carefully you adjust your mirrors, there will still be blind spots that your mirrors cannot show you.

Not quite. The answer is Slow to a safe speed before entering the curve, then accelerate slightly through it.

The safest way to take a curve is to slow down before the curve and then accelerate slightly through the curve. Braking in a curve risks a skid.

Not quite. The answer is only the more common types of combinations.

The official CDL manual's section on double and triple trailers usually describes how to couple and uncouple the more common types of double and triple combinations. However, there are other ways of coupling and uncoupling the many types of truck-trailer and tractor-trailer combinations that are in use. To learn how to couple and uncouple the vehicles you will be driving, consult the manufacturer's or owner's specifications.

Not quite. The answer is use controlled or stab braking.

Hard braking and turning at the same time is likely to cause a skid. You should brake in a way that will keep your vehicle in a straight line and allow you to turn if necessary. If you need to brake suddenly to avoid a crash, use controlled braking or stab braking (but don't use stab braking if your vehicle has antilock brakes).

Not quite. The answer is park the vehicle in a straight line on firm level ground.

To uncouple the rear trailer, the first thing you do is park the vehicle in a straight line on firm level ground. Apply the parking brakes to keep the vehicle from moving. If the second trailer doesn't have spring brakes, chock its wheels.

Not quite. The answer is slow down.

You should always be able to stop within the distance you can see ahead. Your low-beam headlights let you see only about 250 feet ahead. At 55 mph, your vehicle will travel 250 feet in just 3.1 seconds – not enough time to notice and safely avoid a hazard that's within 250 feet of you. At 30 mph, your vehicle will travel 250 feet in 5.7 seconds.

Not quite. The answer is 20 to 45 psi.

The tractor protection valve keeps air in the tractor or truck brake system should the trailer break away or develop a bad leak. The tractor protection valve is designed to close automatically when the air pressure falls into the range specified by the manufacturer, typically 20–45 psi.

Not quite. The answer is B.

If you swing wide to the left before you turn right, another vehicle may try to pass you on your right while you are turning. Instead, as shown in path B, make the right turn with the rear of your vehicle as close to the curb as possible and turn wide as you complete the turn. This will deny other vehicles enough room on the right to try to pass you.

Not quite. The answer is Use the engine brake or speed retarder.

A retarder supplements the braking force on the drive wheels. On a slippery surface, this may cause the wheels to lock, resulting in a skid. Turn off your retarder when driving on wet, icy, or snowy roads. Instead, slow down, increase your following distance, and try to brake gently.

Not quite. The answer is a separate air tank.

Federal regulations require brakes on every wheel of a combination vehicle, including the wheels of the semitrailers and converter dollies. Like semitrailers, dollies have their own air brakes and their own air tanks.

Source: 49 CFR § 393.42

Not quite. The answer is Charge the trailer's air tank and then disconnect the emergency air line.

If the second trailer doesn’t have spring brakes, drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, and disconnect the emergency air line. This will set the trailer emergency brakes (assuming the slack adjusters are correctly adjusted). Chock the wheels if you have any doubt about the brakes.

Not quite. The answer is Open the air tank petcock.

You release the dolly's brakes by opening the air tank petcock or (if the dolly is equipped with spring brakes) using the dolly's parking brake control.

Not quite. The answer is leaks of air or hydraulic fluid

Check the landing gear as part of your walk-around inspection. Check that no parts are missing and it isn't bent or damaged. If the landing gear is power operated, check its hoses, fittings, and other parts for signs or sounds of escaping air or hydraulic fluid.

Not quite. The answer is apply light pressure on the brakes.

Avoid driving through deep puddles or flowing water if possible. If not, slow down and downshift into a low gear. Gently press on the brakes and maintain pressure for a short distance when you are out of the water. This will heat up the brakes and dry them out. (However, don't overdo it, or the brakes may overheat.) Then apply the brakes to make a test stop when it is safe to do so.

Not quite. The answer is Neither of the above will cause it.

Despite what footnote 5 in 49 CFR 393.11 says, Operational Policy 15 of the North American Standard Out-of-Service Criteria states that a converter dolly must have one stop lamp, one tail lamp, and (if the dolly obscures the tractor's rear turn signals) turn signal lights, but only when the dolly is being towed singly and is not towing a trailer. In a full multi-trailer configuration, the rearmost trailer must have working stop lights and taillights, of course.

Not quite. The answer is Rocky Mountain double

A double pup trailer consists of two 28.5-foot trailers, known as "pup trailers." A double pup trailer is also known as an STAA trailer, named for the Surface Transportation Assistance Act (STAA). This standard-double configuration is the only type of double trailer that is allowed nationwide. A Rocky Mountain double trailer consists of a 40- to 53-foot trailer followed by a 28.5-foot pup trailer. Rocky Mountain doubles are allowed in certain Western states. A turnpike double trailer consists of two 48-foot trailers. Turnpike doubles can be found traveling on expressways in the Eastern states.

Not quite. The answer is How the rear wheels follow a different path from the front wheels in a turn

Off-tracking is defined as the different paths taken by the front and rear wheels in a turn. The longer the vehicle, the greater the difference will be. As a result, the path followed by a tractor will be wider than the path of the rig itself. To compensate, you must steer the tractor wider to keep the rig from overrunning the curb or hitting some object.

Not quite. The answer is slightly raised.

When connecting the rear trailer to the converter dolly, lock the trailer brakes and raise the trailer landing gear slightly off the ground so it won't be damaged if the trailer moves. Then pull forward with the trailer brakes still locked, to check that the rear trailer is locked onto the converter dolly. If it's not, at least the landing gear will keep the rear trailer from falling onto the ground.

Not quite. The answer is directly in front of the converter dolly.

Back the first trailer into position in front of the tongue of the dolly. Hook the dolly to the pintle hook on the first trailer. Then latch the pintle hook securely. Raise the dolly's landing gear.

Not quite. The answer is The rig may jackknife.

Check your mirrors to monitor your trailers and see if a trailer has begun to skid. Do this every time you have to brake hard. Once the wheels of a trailer begin to skid, the risk of jackknifing is high. Once the trailer swings out of your lane completely, you may not be able to prevent a jackknife.