Take Washington CDL Air Brakes Test Practice Questions - Washington Commercial Driver License (CDL) Air Brakes Knowledge Test Exam

QUESTION 1 / 25

For the Washington CDL Air Brakes knowledge test, what component compresses air for the air brake system?

Choose one answer below.

AThe air dryer✓BThe air compressor✓CThe brake chamber✓DThe slack adjuster✓

QUESTION 2 / 25

For the Washington CDL Air Brakes knowledge test, what is the typical air compressor governor cut-out pressure range?

Choose one answer below.

A60 to 80 psi✓B100 to 125 psi✓C125 to 140 psi✓D150 to 175 psi✓

QUESTION 3 / 25

For the Washington CDL Air Brakes knowledge test, at what pressure does the air compressor governor typically cut IN to resume pumping?

Choose one answer below.

A60 to 80 psi✓B100 to 125 psi✓C125 to 140 psi✓D145 to 150 psi✓

QUESTION 4 / 25

For the Washington CDL Air Brakes knowledge test, what is the purpose of the air dryer in the brake system?

Choose one answer below.

ATo cool the air before storage✓BTo remove moisture and oil before air reaches the tanks✓CTo increase compressed air pressure✓DTo warn the driver of low pressure✓

QUESTION 5 / 25

For the Washington CDL Air Brakes knowledge test, what is the function of the wet tank (supply or service reservoir)?

Choose one answer below.

AIt cools brake fluid✓BIt is the first storage tank where moisture collects before air moves to the other tanks✓CIt supplies air only to the trailer✓DIt activates the parking brakes✓

QUESTION 6 / 25

For the Washington CDL Air Brakes knowledge test, at what pressure does the safety valve in the supply tank typically open to release excess air?

Choose one answer below.

A100 psi✓B125 psi✓C150 psi✓D200 psi✓

QUESTION 7 / 25

For the Washington CDL Air Brakes knowledge test, what is the role of the foot valve (also called the treadle or service brake valve)?

Choose one answer below.

AIt locks the parking brake✓BIt supplies air to the brake chambers in proportion to how hard the driver presses the pedal✓CIt drains water from the tanks✓DIt controls the trailer air supply✓

QUESTION 8 / 25

For the Washington CDL Air Brakes knowledge test, what does the brake chamber do?

Choose one answer below.

AStores compressed air for emergencies✓BConverts air pressure into mechanical force through a pushrod✓CCools brake drums during use✓DActs as a backup for the parking brake✓

QUESTION 9 / 25

For the Washington CDL Air Brakes knowledge test, what is the role of the slack adjuster on an S-cam brake?

Choose one answer below.

AIt cushions the impact of hard braking✓BIt transfers force from the pushrod to the S-cam and can be adjusted to compensate for lining wear✓CIt bleeds water from the system✓DIt limits maximum air pressure✓

QUESTION 10 / 25

For the Washington CDL Air Brakes knowledge test, what does the S-cam do in an S-cam drum brake?

Choose one answer below.

AIt releases air from the lines✓BIt rotates between the brake shoes, forcing them outward against the drum✓CIt cools the brake drum✓DIt activates the low-pressure warning✓

QUESTION 11 / 25

For the Washington CDL Air Brakes knowledge test, how are spring (parking) brakes held in the released position?

Choose one answer below.

ABy engine vacuum✓BBy a hydraulic line✓CBy air pressure applied against the spring✓DBy a mechanical lock that the driver releases✓

QUESTION 12 / 25

For the Washington CDL Air Brakes knowledge test, what is the shape and color of the parking brake control knob in most modern CMVs?

Choose one answer below.

AA red 8-sided (octagonal) knob✓BA yellow diamond-shaped knob✓CA green round knob✓DA blue square knob✓

QUESTION 13 / 25

For the Washington CDL Air Brakes knowledge test, what is the shape and color of the trailer air supply control on a tractor?

Choose one answer below.

AA yellow diamond knob✓BA red 8-sided (octagonal) knob✓CA blue triangular knob✓DA green round knob✓

QUESTION 14 / 25

For the Washington CDL Air Brakes knowledge test, what is a dual air brake system?

Choose one answer below.

AA system that uses two compressors✓BA system with two completely separate air systems (primary and secondary), each controlling brakes on different axles✓CA system that uses both air and hydraulic fluid✓DA system with air-cooled drums✓

QUESTION 15 / 25

For the Washington CDL Air Brakes knowledge test, at what pressure must the low air pressure warning device activate at the latest?

Choose one answer below.

AAt 30 psi✓BAt 60 psi or higher✓CAt 90 psi✓DAt 120 psi✓

QUESTION 16 / 25

For the Washington CDL Air Brakes knowledge test, while driving, the low air pressure warning light comes on. What should you do?

Choose one answer below.

AContinue to your destination but watch the gauge✓BBring the vehicle to a safe stop as soon as possible and find the problem✓CApply the parking brake while still moving✓DPump the brake pedal to build pressure✓

QUESTION 17 / 25

For the Washington CDL Air Brakes knowledge test, how often should air tank drain valves be operated to remove water and oil?

Choose one answer below.

AOnce a year✓BAfter every long trip only✓CDaily✓DOnly when the warning light comes on✓

QUESTION 18 / 25

For the Washington CDL Air Brakes knowledge test, what is the maximum allowable air loss rate for a single vehicle with the brakes released (static leak rate)?

Choose one answer below.

A1 psi per minute✓B2 psi per minute✓C3 psi per minute✓D4 psi per minute✓

QUESTION 19 / 25

For the Washington CDL Air Brakes knowledge test, what is the maximum allowable air loss rate for a combination vehicle with the brakes released?

Choose one answer below.

A1 psi per minute✓B2 psi per minute✓C3 psi per minute✓D5 psi per minute✓

QUESTION 20 / 25

For the Washington CDL Air Brakes knowledge test, what is the maximum allowable air loss rate for a single vehicle with the brakes APPLIED (applied leak rate)?

Choose one answer below.

A2 psi per minute✓B3 psi per minute✓C4 psi per minute✓D5 psi per minute✓

QUESTION 21 / 25

For the Washington CDL Air Brakes knowledge test, what is the maximum allowable air loss rate for a combination vehicle with the brakes APPLIED?

Choose one answer below.

A2 psi per minute✓B3 psi per minute✓C4 psi per minute✓D6 psi per minute✓

QUESTION 22 / 25

For the Washington CDL Air Brakes knowledge test, during the air brake pre-trip inspection, how do you test the low air pressure warning device?

Choose one answer below.

AStart the engine and watch the gauge✓BBuild air pressure to governor cut-out, shut off the engine, turn the key to the on position, and fan the brakes until the warning activates✓CApply the parking brake and listen for the alarm✓DDrain the wet tank only✓

QUESTION 23 / 25

For the Washington CDL Air Brakes knowledge test, during the air brake pre-trip, how do you test that the spring brakes apply automatically?

Choose one answer below.

AApply the foot brake hard while driving✓BContinue fanning the brakes until air pressure drops far enough; the spring brakes should apply between roughly 20 and 45 psi✓CPull the parking brake at 60 psi✓DDrain the secondary tank only✓

QUESTION 24 / 25

For the Washington CDL Air Brakes knowledge test, in normal stops with air brakes, you should:

Choose one answer below.

AStab the pedal hard, then release✓BApply the brakes firmly and steadily until you slow enough to safely shift to neutral or a lower gear✓CApply the parking brake✓DPump the pedal rapidly✓

QUESTION 25 / 25

For the Washington CDL Air Brakes knowledge test, what is controlled braking in an emergency stop with air brakes?

Choose one answer below.

APressing the pedal as hard as possible and holding it✓BApplying the brakes as hard as you can without locking the wheels, then releasing slightly if wheels lock✓CUsing only the parking brake✓DPumping the pedal rapidly✓