CDL doubles and triples practice test 3

D: Closed. The converter dolly air tank drain valve should be CLOSED. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.3.1 Additional Checks, page 7-4.

A: The pintle-eye is in place in the pintle hook, the hook is latched, and safety chains are secured. Be sure the pintle-eye of the dolly is in the pintle hook, the pintle hook is latched and safety chains are secured to the trailer(s). Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.3.1 Additional Checks, page 7-4.

B: That it is secured. If a spare tire is carried on the converter gear (dolly), make sure it is secured. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.3.1 Additional Checks, page 7-4.

C: Open the emergency line shut-off valve at the rear of the last trailer and listen for air escaping. At the back of the last trailer, open the emergency line shut-off. Hearing air rush out shows the whole system is charged. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.4.1 Additional Air Brake Checks, page 7-4.

D: Apply the trailer hand brake (or the service brake pedal). Use the trailer handbrake to provide air to the service line, then open the service line valve at the rear to check that service pressure goes through all trailers. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.4.1 Additional Air Brake Checks, page 7-4.

A: That the shut-off valves on the trailers and dollies are in the OPEN position. Silence from either line usually means a closed shut-off valve. Make sure the valves on every trailer and dolly are open, because air must reach the back for all brakes to work. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.4.1 Additional Air Brake Checks, page 7-4.

B: The trailer air supply control should pop out (go to emergency) when pressure falls into the manufacturer's range, usually 20 to 45 psi. Step on and off the brake pedal to reduce tank pressure; the trailer air supply (tractor protection valve) control should pop out when pressure falls into the specified range, usually 20 to 45 psi (49 CFR 393.43). Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.4.1 Additional Air Brake Checks, page 7-4.

C: An air hose or trailer brake leak could drain all the air from the tractor, putting on the emergency brakes with possible loss of control. If the tractor protection valve fails, a hose or trailer brake leak could drain all the tractor's air, causing the emergency brakes to come on with possible loss of control. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.4.1 Additional Air Brake Checks, page 7-4.

D: Charge the system, check that the trailer rolls freely, then pull out the trailer air supply control and pull gently on the trailer to see that the brakes are on. With the trailer system charged, make sure the trailer rolls freely. Then stop, pull out the air supply control (or set it to emergency), and tug gently with the tractor to confirm the trailer emergency brakes hold. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.4.1 Additional Air Brake Checks, page 7-4.

A: With normal air pressure and parking brakes released, move forward slowly and apply the trailer brakes with the hand control. Check for normal pressure, release the parking brakes, move forward slowly and apply the trailer brakes with the hand control (trolley valve); you should feel them come on. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.4.1 Additional Air Brake Checks, page 7-4.

B: With the foot pedal, which applies air to the service brakes at all wheels. Use the hand valve only for testing. In everyday driving, brake with the foot pedal, which applies the service brakes at every wheel. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 7.4.1 Additional Air Brake Checks, page 7-4.

C: Because of the danger of making the trailer skid. The trailer hand valve should only be used to test trailer brakes; using it in driving risks making the trailer skid. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.2.1 Trailer Hand Valve, page 6-4.

D: All the air might leak out, unlocking the brakes on trailers without spring brakes. Never use the hand valve for parking because the air might leak out and unlock the brakes on trailers that don't have spring brakes; use parking brakes and chocks. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.2.1 Trailer Hand Valve, page 6-4.

A: Red. Emergency lines are often coded red to keep them from being mixed up with the blue service line. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.2.4 Trailer Air-lines, page 6-5.

B: Supplies air to the trailer air tanks and controls the emergency brakes. The emergency line supplies air to the trailer air tanks and controls the emergency brakes; losing pressure in it makes the trailer emergency brakes come on. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.2.4 Trailer Air-lines, page 6-5.

C: In the service and supply air lines at the back of trailers used to tow other trailers. Shut-off valves sit in the service and supply lines at the rear of any trailer built to tow another, so the lines can be closed when nothing is hooked on behind. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.2.7 Shut-off Valves, page 6-6.

D: By the emergency (supply) line from the tractor. Trailer and dolly air tanks are filled by the emergency (supply) line from the tractor and provide the pressure used to operate the trailer brakes. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.2.6 Trailer Air Tanks, page 6-6.

A: Wheel chocks. Trailers without spring brakes rely on air in the trailer tank; it eventually leaks away, leaving no brakes, so use wheel chocks when you park them. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.2.8 Trailer Service, Parking and Emergency Brakes, page 6-6.

B: Brake as you always have, using only the force needed to stop safely and stay in control. With ABS on the tractor, trailer or both, brake the same way: use only the braking force needed to stop safely and stay in control, and back off if needed. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.3.2 Braking with ABS, page 6-7.

C: You still have regular brakes; drive normally, but get the system serviced soon. A failed ABS leaves the normal brakes working, so keep driving normally but have the ABS repaired soon. Missouri Commercial Driver License Manual (AAMVA model CDL manual, Version 4.0): 6.3.2 Braking with ABS, page 6-7.