Wisconsin CDL — Air Brakes Practice Test 6

1.If you keep driving after the low air warning comes on, what limits your braking?

The parking brake locks the steering wheelControlled braking works only while air remains, and the spring brakes set at 20 to 45 psiThe compressor overheats and quitsThe stop lamps stop working first

2.What is 'brake lag' in an air brake system?

The half-second or more it takes air to reach and work the brakesThe delay before the compressor cuts inThe time a driver needs to notice a hazardThe gap between setting and releasing the parking brake

3.What is a 'wig wag' low-pressure warning device?

A buzzer that sounds when the parking brake releasesA gauge needle that flutters as the compressor loadsA light that flashes during the ABS bulb checkA mechanical arm that drops into your view when pressure falls below 60 psi

4.On a newer air brake vehicle, how do you set the parking (spring) brakes?

Pull the yellow, diamond-shaped knob outwardPush the yellow, diamond-shaped knob inwardHold the brake pedal down for several secondsTurn the red, round knob to the left

5.In stab braking, why must you wait for the wheels to start rolling before reapplying the brakes?

So the tanks have time to refillSo the ABS can reset itselfReapplying before the wheels roll keeps the vehicle from straightening outSo the drums have time to cool

6.When the low air pressure warning first activates, what is the correct action?

Keep driving until the spring brakes set themselvesPump the pedal to rebuild pressure fastGet the vehicle safely stopped immediately, while the service brakes still respondRelease the parking brake control to reset the system

7.Before driving a vehicle with dual air brakes, you should wait until pressure reaches at least what level in both systems?

60 psi85 psi100 psi150 psi

8.What color is the ABS malfunction lamp on a tractor, truck, or bus?

RedBlueGreenYellow

9.Why is it risky to let the spring brakes set themselves instead of stopping under control first?

The spring brakes only work above 60 psiThey apply the front brakes twice as hardThey always overheat the drums instantlyA light load or slick road can skid, and a heavy load stops slowly since the springs miss some axles

10.What is a dual air brake system?

One air system feeding two separate pedalsA system that switches between air and hydraulic brakingTwo compressors that share a single air tankTwo separate air brake systems run by one set of controls