BC Air Brake Knowledge Test study guide
BC Air Brake Knowledge Test · Work through your exam, one topic at a time.
The BC Air Brake Knowledge Test is the written knowledge component a British Columbia driver must pass to add an air brake endorsement to a driver's licence. It is aimed at drivers who will operate vehicles equipped with air-actuated braking systems - typically heavy commercial trucks, tractor-trailers, buses, and other fleet vehicles - where stopping depends on compressed air rather than hydraulic fluid. The BC Air Brake Knowledge Test study guide has 5 sections and about 2,210 words.
01Air Brake System Components and Their Function
Every air brake system stores energy, controls it and applies it. Learn the sequence: the compressor makes air; the governor loads and unloads the compressor between cut-in and cut-out; the reservoirs (wet tank plus primary and secondary dries) store it; the foot valve or treadle meters it; the relay valve at each axle delivers a large volume of air to the brake chambers ; the chamber pushrod moves the slack adjuster , which rotates the S-cam , forcing the shoes against the drum.
384 words, about 2 min02Air Supply, Compressors and Reservoirs
The compressor is engine-driven and engine-lubricated, so it must have a sound drive belt or gear and clean oil. The governor senses reservoir pressure and lets the compressor pump until cut-out (commonly about 120 to 125 psi), then unloads it until pressure falls to cut-in (commonly about 100 psi).
368 words, about 2 min03Pre-Trip Inspection and Leak Testing
Chock the wheels, drain all reservoirs and watch for moisture or oil, check the compressor belt, oil level and obvious damage, then start the engine and let pressure build at fast idle. Note the pressure where the governor cuts out.
383 words, about 2 min04Normal Braking Operation and Controls
Apply the treadle progressively and squeeze rather than stab. Air brakes have lag : pressure takes time to travel to the chambers and to exhaust afterwards, so plan stops early and brake earlier than you would in a car.
354 words, about 2 min05Emergency Braking and Backup Systems
If system pressure falls far enough, the spring brakes apply by themselves, typically beginning somewhere around 20 to 45 psi, and the low-pressure warning sounds by about 60 psi. On a combination vehicle the tractor protection valve closes at low pressure, trapping the tractor's remaining air so it can still brake, while the trailer's emergency relay valve applies the trailer spring brakes.
721 words, about 4 min