DOT Vehicle Maintenance & Repair Standards 2

Question 1

Under FMCSA regulations, what is the minimum acceptable brake lining thickness for a drum brake on a steering axle?

Accepted Answer

1/8 inch

Answer

FMCSA regulations require a minimum brake lining thickness of 1/8 inch (4.8 mm) on steering axle drum brakes before the vehicle is placed out of service.

Question 2

A DOT inspector finds a hydraulic brake line with a visible crack but no active leakage. How should this be cited?

Accepted Answer

Out-of-service condition

Answer

A cracked brake line is an out-of-service condition under 49 CFR 393.45, as it presents an imminent risk of brake failure regardless of current leakage status.

Question 3

Which federal standard governs the performance requirements for commercial motor vehicle brakes?

Accepted Answer

49 CFR Part 571 FMVSS 121

Answer

Federal Motor Vehicle Safety Standard 121 (49 CFR Part 571.121) establishes the air brake performance requirements for new commercial vehicles.

Question 4

During a roadside inspection, a tire on a non-steering axle measures 2/32 inch tread depth. What is the correct action?

Accepted Answer

Out-of-service the vehicle

Answer

A tread depth of 2/32 inch or less on any non-steering axle tire is an out-of-service condition per CVSA standards.

Question 5

What is the maximum permissible free play in a manual slack adjuster on a 15-inch brake drum?

Accepted Answer

1.5 inches

Answer

For a 15-inch brake drum, the maximum allowable pushrod travel (free play) for a manual slack adjuster is 1.5 inches per CVSA out-of-service criteria.

DOT Inspector Certification Practice Test

DOT Inspector Certification Practice Test

DOT Vehicle Maintenance & Repair Standards 2