Alabama CDL: Double & Triple Trailers Practice Test

Not quite. The answer is Hook the converter dolly to the front semitrailer.

To couple standard doubles, the first step is to correctly position the dolly in front of the second semitrailer. You can do this by hand or by picking up the dolly with the first semitrailer. Either way, the dolly must be connected to the first semitrailer before proceeding further. Once this is done, back the tractor, first semitrailer, and dolly until you back the dolly underneath the second semitrailer. Only after you've checked and tested the coupling, and connected all the air lines and electrical lines, should you raise the landing gear.

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 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 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 only the more common types of combinations.

The official state 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 Older models may lack spring brakes.

All converter dollies built since 1975 are required to have spring brakes. All converter dollies built since 1998 are required to have antilock brakes as well.

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 There should be none.

When the rear trailer is properly coupled to the converter dolly, there should be no space between the upper and lower fifth wheel. (Similarly, when the front trailer is properly coupled to the tractor, there should be no space between the upper and lower fifth wheel either.) If there is visible space, something is wrong. Don't drive the vehicle until you have corrected the problem because the trailer might come loose.

Not quite. The answer is the trailer will be raised slightly when the converter dolly is backed under it.

To connect the rear trailer to the converter dolly, the trailer must be at the right height. It should be slightly lower than the center of the dolly's fifth wheel so that the trailer will be raised slightly when the dolly is pushed underneath it.

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 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 slowly pull clear of the converter dolly.

The last step in the process of uncoupling twin trailers is to slowly pull clear of the converter dolly. The other two choices are previous steps in this process.

Not quite. The answer is a yellow lamp on the left side.

A converter dolly with antilock brakes is required to have a yellow ABS lamp on its left side. All converter dollies built since March 1, 1998 have antilock brakes.

Not quite. The answer is Brake and downshift in the curve.

Before entering a curve, slow down to a safe speed and downshift into the right gear. This lets you use some power through the curve to help keep the vehicle stable through the curve. It also allows you to speed up as soon as you are out of the curve.

Not quite. The answer is A truck has less traction when it's empty than when it's fully loaded.

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.

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 March 1998.

Antilock brakes have been required on all tractors built since March 1, 1997. Antilock brakes have been required on all trailers, converter dollies, buses, and single trucks built since March 1, 1998.

Not quite. The answer is One second for every ten feet of your vehicle

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.

Not quite. The answer is that you can pull straight through.

When parking a long vehicle, you should look for a parking space that you can go straight through rather than back out of. Also note the layout of the parking lot and your parking space's location within it so you won't have difficulty exiting the parking space later.

Not quite. The answer is the shut-off valves, the converter dolly or dollies, and the air brakes on all trailers.

To inspect a double or triple, first inspect it just as you would inspect any combination vehicle. Then check that the shut-off valves are open on all trailers but the last trailer. Check each converter dolly to be sure that the pintle hook is properly latched.