Texas CDL — Air Brakes Practice Test 3

11.How do your brake lights come on in a vehicle with air brakes?

A cable connected to the brake pedal pulls the light switch closedThe governor completes the light circuit at cut-in pressureThe alternator senses engine braking and powers the lightsAn air-pressure-operated electric switch turns on the lights when you brake

12.On newer air-braked vehicles the parking brake control is a yellow, diamond-shaped knob. On older vehicles, what might it look like instead?

A red octagonal button on the steering columnA green square switch on the floorA foot pedal to the left of the clutchA round blue knob or a lever

13.You park an air-braked truck and leave the cab to make a delivery. What does safe practice require you to do first?

Leave the engine running so tank pressure cannot dropApply the parking brakes by pulling the yellow diamond-shaped knob outPush the yellow knob in to lock the spring brakesHold the treadle valve down with a block of wood

14.The safety relief valve on an air tank is usually set to open at what pressure?

100 psi125 psi150 psi200 psi

15.A roadside inspector finds a vehicle's brakes out of adjustment and its air system leaking beyond the allowed rate. What can happen to that vehicle?

Nothing, as long as the driver notes the defect in the logbookIt only needs repair at the next scheduled maintenance intervalIt can be placed out of service until the brakes are repairedThe driver may continue if the trip is under 100 miles

16.The parking and emergency brakes on trucks, tractors, and buses have to be held on by mechanical force such as springs. Why can't air pressure do that job?

Air pressure can slowly leak away and let the brakes releaseAir pressure is too weak to hold a heavy vehicle in placeAir would freeze inside the brake chambers overnightHolding the brakes with air would wear out the compressor while parked

17.As part of the seven-step air brake check, how do you test that the low pressure warning signal works?

Rev the engine to 2,000 rpm and watch the supply gaugePull the trailer air supply knob and listen for a buzzerShut the engine off, turn the key on, and fan the pedal until the warning activatesOpen a drain valve until the tanks are completely empty

18.If a leak drains all the air out of the brake system while you drive, what physically applies the spring brakes?

Hydraulic backup pressureThe force of powerful springs no longer held back by air pressureThe electric stop light switchVacuum stored in a reserve tank

19.In Texas, you take the CDL skills test in a truck that is not equipped with air brakes. What happens to your license?

It is issued with a restriction prohibiting you from driving air-braked vehiclesIt is denied until you retake the general knowledge testNothing changes, since air brakes are covered by the vision screeningYou receive a temporary 30-day air brake permit

20.You are braking hard in a tractor-trailer where only the tractor has antilock brakes. What should you watch for?

The trailer swinging out; ease off the brakes if it does and you safely canThe tractor's steering wheels locking, since tractor ABS cannot prevent thatThe ABS lamp flashing, which is your signal to pump the pedal rapidlyNothing extra, because the tractor's ABS keeps the trailer from skidding too