Getting the air brake endorsement
You need the endorsement (code 15) to drive a vehicle with air brakes on a highway, other than a construction vehicle. Most vehicles with air-over-hydraulic brakes also need it.
- Complete an air brake course.
- Study ICBC's Driving Commercial Vehicles guide.
- Apply at a driver licensing office, bring your ID, pay the fee and pass the air brake knowledge test.
- Book and pass the air brake pre-trip inspection test. No road test is needed.
| Course type | What it includes |
|---|---|
| Certified course | 7 hours of classroom theory and 4 hours of practical training |
| Non-certified course | 7 hours of classroom theory |
- A passed knowledge test result is valid for one year.
- After three failed attempts, you must complete or repeat a 7-hour course.
- If you fail a knowledge test or pre-trip test, wait 7 days before retesting.
- On a commercial road test in a vehicle with air brakes, an air brake pre-trip inspection is included.
How an air brake system works
The basic parts of an air brake system.
- Air compressor, driven by the engine, pumps air into the tanks.
- Governor controls when the compressor cuts in and cuts out.
- Air tanks store the compressed air.
- Drain valve at the bottom of each tank removes water and oil.
- Foot valve (brake pedal) sends air to the brake chambers.
- Brake chamber: air pushes a diaphragm and push rod.
- Slack adjuster links the push rod to the camshaft.
- Brake drum, where the shoes press to slow the wheel.
An air dryer removes moisture before the air reaches the tanks. Water left in the system can freeze and block valves and lines, so drain the tanks. A safety valve lets air out if tank pressure gets too high. A low air warning, such as a light, buzzer or wig wag arm, tells you when pressure falls too low.
Spring brakes
Spring brakes are applied by powerful springs and held off by air pressure. If air pressure is lost, they apply. That is why you park with the spring brakes: they do not depend on air staying in the system. Do not apply hard service braking while the spring brakes are on, because the combined force can overload brake parts. Never take a spring brake chamber apart; the spring is under great force.
Controls and lines
- The parking brake control is a yellow, diamond-shaped push-pull knob.
- The trailer supply control is a red, eight-sided knob.
- The service line gladhand is usually blue, and the supply (emergency) line red.
- If the trailer breaks away, the tractor protection system keeps the tractor's air, and the trailer's spring brakes apply.
- A dual system has two circuits, so one can still brake if the other loses air.
Air brake checks
Check the compressor drive belt if it is belt-driven. Before you move, let the air pressure build to normal and make sure the low air warning has gone off. During your checks:
- Pressure should build steadily, and the governor should cut out at the correct pressure.
- When you lower the pressure by fanning the brakes, the low air warning must come on before the spring brakes apply.
- Check for air leaks with the brakes applied, because leaks drain air when you need it most.
- Check brake adjustment by measuring push rod stroke with the brakes fully applied. Too much stroke means the brake is out of adjustment.
- Test the brakes at low speed. The vehicle should stop in a straight line.
Brakes that are not adjusted or not working properly can bring a fine of up to $2,000. On a vehicle with 16 brakes, each does about 1/16 of the work, so one bad brake makes the others work harder and get hotter.
Braking safely
- Air brake lag time is about 4/10 of a second, on top of about 3/4 of a second to perceive and 3/4 of a second to react.
- Doubling speed needs four times the stopping power. Doubling weight needs twice as much. Doubling both needs eight times.
- A tractor-trailer can stop from 100 km/h in as little as about 7 seconds, but only with every brake working.
- Brake smoothly and steadily. Fanning (pumping) wastes air.
Brakes reach about 120 °C in normal stops and should not go above about 250 °C. Hot brakes fade. Retarders, such as engine, exhaust, hydraulic and electric driveline retarders, slow the vehicle without using the service brakes, which keeps them cooler. Engine retarders work best at higher rpm and lower road speed, so choose your gear before the hill.
If your speed rises on a downgrade, brake hard enough to cut 10 to 15 km/h while the brakes are still cool, then shift to a lower main gear. In water, keep slight, steady brake pressure, and afterward brake lightly to dry the brakes. Anti-lock brakes are required on air-brake commercial trailers and on trucks and buses over 4,560 kg built since April 1, 2000.
Before you drive an air-brake vehicle
Air brakes are safe and powerful, but only when the system is in good order. Before you drive, walk around and look and listen for air leaks at the lines, gladhands and chambers. Check that the compressor belt, if there is one, is tight and not worn. Drain water from the tanks as your vehicle requires.
In the cab, start the engine and watch the gauges. Pressure should build at a normal rate, and the low air warning should go off once there is enough air. Do not release the parking brakes and move off until the pressure is normal. When you first drive away, test the brakes at low speed: the vehicle should stop smoothly and in a straight line, without pulling to one side.
If anything is wrong, such as a leak, a slow build-up, a warning that will not go off or a brake that pulls, do not drive. Report it so it can be repaired. A vehicle with a brake defect is a danger to you and everyone around you.
Key numbers at a glance
| What | Number |
|---|---|
| Endorsement code | 15 |
| Certified course | 7 hours theory + 4 hours practical |
| Non-certified course | 7 hours theory |
| Knowledge test result valid for | One year |
| Failed attempts before a course is required again | Three |
| Wait after a failed knowledge or pre-trip test | 7 days |
| Air brake lag | About 4/10 of a second |
| Normal brake temperature | About 120 °C |
| Brake temperature not to exceed | About 250 °C |
| Speed drop when braking on a downgrade | 10 to 15 km/h |
| Fine for poorly adjusted brakes | Up to $2,000 |
Common mistakes to avoid
- Fanning the brakes. It wastes air and lowers system pressure.
- Parking on service brakes. Air can leak away; the spring brakes hold mechanically.
- Applying hard service braking with the spring brakes on. The combined force can overload brake parts.
- Moving off before the air builds. Wait until pressure is normal and the warning is off.
- Light, constant braking down a long hill. The brakes heat up and fade. Brake firmly to cut 10 to 15 km/h, then use a lower gear.
- Ignoring the low air warning. Pull over and stop safely as soon as you can.
Preparing for the pre-trip inspection test
The air brake pre-trip inspection test checks that you can inspect the system and recognise problems. Practise the full sequence until it is automatic. As you check each part, say out loud what you are looking for and what a defect would look like. Know where each control is: the yellow diamond parking brake knob, the red eight-sided trailer supply knob, the gauges and the low air warning. Remember that one brake out of adjustment makes the others work harder, so check every wheel.
How far you travel before the brakes work
Before your brakes start to slow you, three things happen. You see the danger (perception, about 3/4 of a second), you move your foot to the pedal (reaction, about 3/4 of a second), and the air travels through the lines to the brakes (lag, about 4/10 of a second). That adds up to about 1.9 seconds.
At 100 km/h, a vehicle covers about 28 metres every second. So in those 1.9 seconds it travels about 53 metres before the brakes even begin to work. Only then does the braking distance start. This is why heavy vehicles need a long following distance, and why speed matters so much: doubling your speed needs about four times the stopping power.
A simple study plan
- Read this guide once from start to finish, without trying to memorise everything.
- Read the matching chapters of the ICBC Driving Commercial Vehicles guide. Mark every number, limit and time you find.
- Take the first practice test. Write down each question you get wrong and look up the rule.
- Make a one-page list of key numbers, and test yourself on it every day.
- Take the other practice tests until you score at least 80% every time.
- Finish with the mock exam, timed if the real test is timed.
Short, regular study works better than one long session. Twenty or thirty minutes a day for two weeks will help you remember more than one long night before the test. Read each question to the end before you look at the answers, and watch for words like minimum, maximum, before and after.