Traffic Laws

Study questions with answers

6 sample Traffic Laws questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. The safety relief valve in the first air tank is usually set to open at what pressure?

   Correct answer: 150 psi

   That valve guards the system against excess pressure and typically opens at 150 psi; if it vents air, a problem exists and a mechanic should look at it.

   Source: Connecticut CDL Manual, Section 5.1.6 (Safety Valve)

2. 2. Which statement about the low air pressure warning signal is true for air brake vehicles?

   Correct answer: Every vehicle with air brakes must have one

   A low air pressure warning device is mandatory on any vehicle equipped with air brakes.

   Source: Connecticut CDL Manual, Section 5.1.11 (Low Air Pressure Warning)

3. 3. Why is it important to drain the water that collects in the air tanks?

   Correct answer: In cold weather the water can freeze and cause the brakes to fail

   Compressed air carries moisture and a little oil that settle at the tank bottom; in freezing weather that water can turn to ice and knock out the brakes, so tanks must be drained fully.

   Source: Connecticut CDL Manual, Section 5.1.4 (Air Tank Drains)

4. 4. What is true of vehicles built since 1994 with respect to slack adjusters?

   Correct answer: They come with automatic slack adjusters, which still must be checked

   Since 1994, vehicles carry automatic slack adjusters; even though they adjust during hard stops, a driver still has to inspect them.

   Source: Connecticut CDL Manual, Section 5.3.2 (Walk-around Inspection)

5. 5. How often must you drain tanks that have manually operated drain valves?

   Correct answer: At the end of every driving day

   Manual drains, opened by a quarter turn or a pull cable, have to be emptied by the driver at the close of each day's driving.

   Source: Connecticut CDL Manual, Section 5.1.4 (Air Tank Drains)

6. 6. Air brake truck tractors are required to have antilock brakes if they were built on or after which date?

   Correct answer: March 1, 1997

   Truck tractors with air brakes made on or after March 1, 1997 must have ABS; most other air brake vehicles built on or after March 1, 1998 must have it as well.

   Source: Connecticut CDL Manual, Section 5.1.16 (Antilock Braking Systems)