Mississippi CDL — Air Brakes Practice Test 7

1.Which sequence matches the manual's normal stop in an air-braked truck with a manual transmission?

Clutch in first, then press the pedal hard, then shift to neutralPress the pedal and ease off as needed, clutch in once rpm nears idle, then pick a starting gear when stoppedPress the pedal hard, pull the parking brake knob, then clutch inShift to neutral, coast, then brake only in the last few feet

2.Your truck has a brake system failure. To bring it to a stop, the emergency brake system relies on parts of which other systems?

The engine cooling and fuel systemsThe service brake and parking brake systemsThe trailer hand valve and the turn signalsOnly the front-axle brake chambers

3.Braking hard on a slick road in a vehicle without ABS, you lock the rear wheels but not the steering wheels. What is the main danger?

Losing all steering control at the frontNothing, since only steering-wheel lockup mattersA skid, a jackknife, or even a spinThe spring brakes applying on their own

4.Total stopping distance for a vehicle with air brakes is made up of four distances. Which of these is NOT one of them?

Perception distanceBrake lag distanceBraking distanceCoasting distance

5.A parked truck slowly loses all its air overnight through a small leak. Why does its parking brake keep holding?

The governor locks the wheels when pressure dropsThe safety valve traps enough air to keep the brakes onIts spring brakes are applied by mechanical spring force, which does not depend on airThe ABS holds the brakes until the engine restarts

6.You watch your air gauge climb to about 125 psi and then hold steady. What is the most likely reason it stopped rising?

The safety valve opened to dump the extra airA leak is letting air out as fast as it comes inThe compressor broke down once the tanks were fullThe governor reached its cut-out point and stopped the compressor from pumping

7.During controlled braking in an emergency, how should you handle the steering wheel while the brakes are applied?

Turn sharply to steer around the hazardLet go of the wheel until the vehicle stopsKeep steering movements very smallRock the wheel back and forth to keep the tires rolling

8.A bus has lost its main air pressure, and you are holding in the spring-loaded button of its dual parking control valves to move it. What happens when you let go?

The bus keeps rolling until the separate tank refillsThe service brakes lock upThe low air warning shuts offThe spring brakes come back on

9.Besides making the drums expand, what does excessive heat do to the brake linings?

It causes chemical changes that lower their frictionIt makes them grip harder until they lockIt turns them into a better heat shieldIt has no effect on the linings themselves

10.After heavy brake use, your tank pressure sinks to around 100 psi. In a properly working system, what should happen next?

The governor lets the compressor start pumping againThe spring brakes start to applyThe low air warning light comes onThe safety valve closes to conserve air