Montana CDL: Double & Triple Trailers Practice Test

Not quite. The answer is do both of the above.

In bad weather or mountain driving or on slippery roads, use extreme caution. When you drive a double or triple, you're pulling a lot of dead axles with just a few drive axles. This increases the chance of loss of traction, causing a skid. Also, rearward amplification makes the rearmost trailer much more prone to rolling over. Drive slowly around curves and turns and avoid sudden moves.

Not quite. The answer is enough to remove some of the trailer's weight from the converter dolly.

Lower the landing gear of the second semitrailer enough to remove some of the trailer's weight from the converter dolly. This will make it easier to pull the dolly out from under the trailer.

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 may have poor traction due to bouncing and wheel lockup.

Trucks brake best when they are used as they were designed: to carry a properly balanced load. Empty trucks actually have longer stopping distances than loaded trucks because they have less traction.

Not quite. The answer is slightly raised.

To test the coupling of the dolly to the second trailer, you'll pull the tractor forward so the dolly will pull against the kingpin of the second trailer. Before doing so, raise the trailer's landing gear slightly. This will prevent damage if the trailer moves, and prevent the trailer from falling onto the ground if the dolly pulls away from the trailer.

Not quite. The answer is drive through quickly.

If you drive through water at higher speeds, your tires may lose their grip of the road and start to skid. When driving through water, slow down and shift into a low gear. Increase engine rpm and apply the brakes gently to keep the brake linings pressed against the brake drums or discs. This will help keep contaminants out of the brakes.

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

Use the mirrors to keep an eye on your tires. It's one way to spot a tire fire. But your mirrors don't eliminate all blind spots. Your truck still has large blind spots, often called No-Zones.

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 Never

Older vehicles may be equipped with manual front-wheel limiting valves. A control in the cab allows the driver to cut air pressure to the front brakes in half. It was thought that doing this would help reduce front-wheel skids on slippery roads. According to the CDL manual, however, more recent tests have shown that front-wheel braking is safe even on icy roads. Federal regulations now prohibit manual front-wheel limiting valves in vehicles manufactured since March 1, 1975. Automatic ratio valves, which limit front-axle braking only when brake applications are approximately 60 psi or less, are still permitted. These valves cannot be controlled manually by the driver. Note: The advent of antilock brakes (ABS) may make automatic ratio valves less useful as well.

Source: 49 CFR § 393.48

Not quite. The answer is You must drive a double or triple very smoothly to avoid a rollover or jackknife.

Take special care when pulling two or three trailers. Doubles and triples are more likely to turn over than other combination vehicles because of the "crack-the-whip" effect. You must steer gently when pulling trailers. To prevent the trailers from rolling over, you must steer gently and go slowly around corners, on-ramps, off-ramps, and curves.

Not quite. The answer is Turnpike double trailer

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 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 sometimes lack antilock brakes.

All trailers and converter dollies built since March 1, 1998 are required to have antilock brakes (ABS).

Not quite. The answer is You need about four times as much braking distance at 40 mph as at 20 mph.

Your 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). Your vehicle's braking distance increases as the square of your speed. For example, you need about four times as much braking distance at 40 mph as you do at 20 mph.

Not quite. The answer is Both (a) and (b)

Take special care when pulling two or three trailers. In bad weather, under slippery conditions, and in mountain driving, you must be especially careful. There is a greater risk of skids and loss of traction. Also, doubles and triples need more space because they can’t be turned or stopped suddenly. Maintain a greater following distance. Make sure you have large enough gaps before entering or crossing traffic.

Not quite. The answer is closed; latched

When you do a walk-around inspection, you must ensure that the converter dolly is properly connected to the front trailer. Check that the pintle hook of the front trailer is locked onto the eye hook of the converter dolly and properly latched. Otherwise, the dolly could come loose. Even worse, if the dolly comes loose while it's still coupled to the rear trailer, the tow bar could fly up, possibly injuring someone.

Not quite. The answer is you couple the third trailer to the second trailer before you couple them to the first trailer.

A triple combination vehicle has four units (not counting the converter dollies): a tractor and three trailers. You couple a triple as follows: 1. Couple the first trailer to the tractor the same way that you couple any combination vehicle. 2. Couple the third trailer to the second trailer using the method for coupling doubles (which will involve the use of a converter dolly). 3. Move another converter dolly into position. 4. Couple the tractor and first trailer to the second and third trailer using the method for coupling doubles (which will involve another converter dolly).

Not quite. The answer is either of the above, if available.

You can secure the second trailer with either the spring brakes or the emergency air line. For an extra margin of safety, chock the wheels too.

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 10

The formula for following distance is one second per ten feet of vehicle length, plus an extra second if you are traveling over 40 mph. Therefore, for a 100-foot vehicle traveling at 30 mph, you should leave a following distance of 100/10 = 10 seconds. (At or below 40 mph, you do not add an extra second.)

Not quite. The answer is 3

In this context, articulation or pivoting means movement between two units separated by a joint, such as between a tractor and a trailer. The standard or STAA double combination in the CDL handbook has 3 points of articulation: (1) the fifth wheel of the tractor; (2) the pintle hook of the front trailer; (3) the fifth wheel of the converter dolly.