Air Brakes: ICBC Class 4 Practice Questions
Get comfortable with Air Brakes before test day. Same style of questions ICBC actually asks, an instant score, and a clear look at where you need more practice.
Practise Air Brakes
One question at a time, just on this topic. Once you're done, you'll get your score and a full breakdown of every answer. 80% is a pass, and there are 18 questions in the bank to draw from.
Practise Air Brakes NowSample questions
A taste of what's in this category, with the answer and why. Hit practise above for the full set.
What does the low-air-pressure warning device alert you to?
- A The parking brake is engaged
- B The brakes are fully released
- C The compressor is cycling normally
- System air pressure has dropped to an unsafe level
Why: The low-air-pressure warning (light/buzzer, often with a wig-wag) activates when pressure drops to an unsafe level so you can stop before the brakes fail.
The low-air-pressure warning device must activate no lower than approximately:
- A 700 kPa (100 psi)
- B 140 kPa (20 psi)
- 380 kPa (55 psi)
- D 1,000 kPa (145 psi)
Why: The warning device is defective if it fails to activate by about 380 kPa (55 psi); many activate earlier, around 414 kPa (60 psi).
What is the job of the air compressor in an air-brake system?
- To pump and build air pressure for the system
- B To apply the brakes directly
- C To release the parking brake
- D To cool the brakes
Why: The compressor pumps air to build and maintain the pressure stored in the reservoirs that the system uses to apply the brakes.
What does the governor do in an air-brake system?
- A Controls the steering
- Controls when the compressor pumps air (cut-in and cut-out)
- C Measures tire pressure
- D Operates the horn
Why: The governor controls the compressor, telling it to load (cut-in) when pressure is low and unload (cut-out) when the system is full.
The governor "cut-out" pressure (when the compressor stops loading) is typically about:
- A 55 psi (380 kPa)
- B 70 psi (483 kPa)
- C 200 psi (1,380 kPa)
- 125 psi (862 kPa)
Why: Cut-out commonly occurs around 125 psi (about 862 kPa), within the normal operating range; it must not exceed 145 psi (1,000 kPa).
The governor "cut-in" pressure (when the compressor starts loading again) is typically about:
- A 160 psi (1,100 kPa)
- B 20 psi (140 kPa)
- 100 psi (690 kPa)
- D 40 psi (275 kPa)
Why: Cut-in is commonly around 100 psi (about 690 kPa); the system normally operates between roughly the cut-in and cut-out pressures.