Oklahoma CDL: Double & Triple Trailers Practice Test

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 a coupling device that connects a semitrailer to the rear of a tractor-trailer.

The converter dolly connects a semitrailer to the rear of a tractor-trailer, forming a double or triple combination.

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 Open at the rear of the front trailers and closed at the rear of the last trailer

Air must travel through the air lines of the tractor and all trailers – and that's all. Open the shut-off valves at the rear of each trailer but the last one to enable the air to flow to the trailer behind it. Close the shut-off valves at the rear of the last trailer to keep air from escaping.

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 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 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 The more sharply you turn, the greater the chances of a skid or rollover.

Don't turn any more than needed to clear whatever is in your way. The more sharply you turn, the greater the chances of a skid or rollover.

Not quite. The answer is supply air to the trailer air brake system with the tractor and then disconnect the emergency line.

If the second trailer lacks spring brakes, set the emergency brakes or chock the wheels.

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 The pintle eye of the dolly should be in place in the pintle hook of the trailer.

A pre-trip inspection of a double or triple combination vehicle includes an inspection of each converter dolly in the vehicle. Among other things, check the coupling of the dolly to the trailer in front. Make sure that the pintle eye of the dolly is in place in the pintle hook of the trailer, and the pintle hook is latched closed.

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 Some do; some don't.

All converter dollies built since 1975 are required to have spring brakes. Older converter dollies that don't have spring brakes have emergency air brakes, which work from the air stored in the trailer air tank.

Not quite. The answer is Allow much more space than is needed under ideal driving conditions.

The usual formula for following distance under ideal conditions is one second for every ten feet of vehicle length, plus an extra second if you are traveling at over 40 mph. The only thing the CDL manual says about following distance on slippery roads is that you should allow "much more space to stop." The Federal Motor Carrier Safety Administration (FMCSA) recommends doubling your usual following distance under poor driving conditions.

Source: "CMV Driving Tips - Following Too Closely," FMCSA, https://www.fmcsa.dot.gov/safety/driver-safety/cmv-driving-tips-following-too-closely

Not quite. The answer is Either (a) or (b)

Federal regulation 49 CFR 380.205 states that you must meet various requirements before you can start training to operate a triple long combination vehicle. These requirements include 6 months' immediately prior experience driving either a tractor/semi-trailer combination or a tractor/semi-trailer/trailer combination, with a gross combination weight rating (GCWR) of at least 26,001 pounds.

Not quite. The answer is 2

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 doubles described in your official state CDL handbook are connected with an A-dolly, which has a single drawbar connected to the front trailer. However, a B-double (also called a B-train double) has a two-drawbar B-dolly (or C-dolly), which is connected to two hitches in the front trailer. The two drawbar connections prevent this type of dolly from pivoting on the front trailer. The rear trailer connects to the dolly's fifth wheel. Hence, the only two pivot points are the tractor's fifth wheel and the B-dolly's fifth wheel. B-trains are legal in parts of Michigan and Washington State.

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 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 11

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 50 mph, you should leave a following distance of 100/10 + 1 = 11 seconds.

Not quite. The answer is fifth; one or two

A semitrailer can be connected to a converter dolly because, like the rear of a typical tractor, it has a fifth wheel and one or two axles.