Vehicle Inspection and Basic Control
What this domain tests
This domain asks whether you can inspect a commercial vehicle before driving and control it from the first move. Expect questions on inspection order, tire and brake criteria, air-pressure checks, and a safe start-up sequence.
Core rules
- Do a complete walk-around: leaks, belts, hoses, lights, tires, wheels, coupling, emergency equipment.
- Steer tires need at least 4/32 inch tread; all other tires at least 2/32 inch. Look for cuts, bulges, and exposed cord.
- For a dual air system, pressure should build from 85 to 100 psi within 45 seconds. With the engine off, leakage should be no more than 2 psi per minute with the service brake released, or 3 psi single/4 psi combination with it applied.
- Start with the parking brake set, transmission in neutral or park, mirrors and gauges checked. Release the parking brake only after air pressure is adequate.
Worked example
A driver finds a front tire at 3/32 inch and a rear tire at 3/32 inch. The front tire fails because steer tires need 4/32 inch; the rear tire passes the 2/32-inch minimum. The driver should replace the steer tire before moving.
Traps
Checking only the center tread, skipping slack adjusters, and releasing the parking brake before pressure builds are common misses. A quick glance is not a pre-trip inspection.