45 topics · Updated 2026-09-17
Check your brakes before starting down any hill, regardless of brake system type — this is of the utmost importance no matter the grade.
On a gentle grade, letting up slightly on the accelerator may control speed. On a steep grade, check brakes, slow down and adjust to a safe speed, then select the appropriate gear before starting down. Avoid changing gears while descending. On very steep grades use engine compression and retarders if equipped.
Applying brakes repeatedly or continuously on a long grade can overheat them and cause failure when needed. This is why shifting into the right gear before descending is essential to maintain control all the way down.
When you must use brakes on a long grade: push hard enough to feel the vehicle slow (with air brakes, avoid pumping which reduces reservoir air pressure). Reduce speed to about 10 km/h below the safe speed, then release the brakes. Repeat when speed climbs back to the safe speed. Example: safe speed 50 km/h — brake down to 40 km/h, release, and re-brake to 40 when back at 50.
Checking your brakes before starting down a hill is of utmost importance regardless of grade steepness or brake system type. If it has been a while since the last circle check, repeat the brake check procedure.
On a gentle grade, easing off the accelerator may control speed. Before a steep grade, test the brakes by pressing the pedal, slow to a safe speed, and select the appropriate gear BEFORE descending. Avoid changing gears going down. On very steep grades use engine compression and retarders if equipped.
Repeated or prolonged brake use on a long grade can overheat brakes and cause failure. This is why the correct gear must be selected before descending. If braking is needed: push hard enough to feel the vehicle slow, and with air brakes avoid pumping (it reduces reservoir air pressure). Reduce to about 10 km/h below the safe speed, then release; repeat as needed.
Grade warning signs use a percentage — the higher the percentage the steeper the grade. If the grade extends more than one kilometre, that is indicated. A sign showing 15% and 3 km means a grade of 150 m per kilometre over at least 3 km. Some signs show two successive grades with different percentages.
Some places have signs requiring you to pull over and check your brakes; the sign shows the distance to the brake check area. On arrival the VÉRIFICATION sign requires a full stop before the Stop sign. The VÉRIFICATION sign applies to vehicles/combinations with a total loaded mass of at least 3,000 kg — drivers must check their own brakes after stopping.
Signs warn of steep grades. The higher the percentage, the steeper the grade. If a grade extends over one kilometre, the sign indicates it. A sign example of 15% over 3 km means a grade of 150 m for every kilometre over at least 3 km; stacked signs indicate two successive grades of different percentages.
Some places have signs requiring you to pull over at a specific spot to check brakes. A VÉRIFICATION sign indicates you must come to a full stop before the Stop sign. This applies to vehicles or combinations with a total loaded mass of at least 3,000 kg, whose drivers must check their own brakes.
Heavy vehicles have at least three reservoirs. The supply reservoir receives air directly from the compressor and feeds the other two service reservoirs, which supply air to the brake chambers near the wheels. Trailers and semi-trailers have their own reservoirs supplied by the tractor's service reservoirs.
Reservoirs store enough air to keep brakes working for a while if the compressor fails, but air can run out quickly depending on use, accessories, and system leaks. When this happens the low air pressure indicator warns and the emergency brake activates; pull over and get repairs.
The compressor draws in outside air, compresses it, and sends it to the supply reservoir. It is engine-driven and runs only when needed. Systems maintain a spread of 138 kPa (20 psi); commonly the compressor starts below 724 kPa (105 psi) and stops at 862 kPa (125 psi). The pressure regulator starts the compressor before 550 kPa (80 psi) and stops it between 805 kPa (117 psi) and 945 kPa (137 psi).
Clean air is essential; impurities build up from temperature and environment. Reservoirs must be bled completely every day using the air bleed valve on each. In winter, bleed after operating while the vehicle is still warm to prevent valves freezing open. Bleed even if an air purifier/dryer is fitted.
Most modern heavy vehicles have an air purifier located between the compressor and the supply reservoir. It filters and dries the air and removes impurities, but does not eliminate the need to bleed reservoirs.
Some vehicles such as buses have an additional emergency reservoir. If service brakes fail and emergency brakes engage, its air can move the vehicle a few metres past the stopping point.
During hydroplaning, do NOT apply the brakes—take your foot off the accelerator to maintain control. A blowout in one of the dual wheels on a semi-trailer is not felt strongly. If skidding, turn the steering wheel in the same direction as the skid. Hydraulic brakes CAN be affected by overheating. Emergency brakes take over when there is insufficient compressed air in the air brake reservoirs.
Endorsements may be added to Class 1, 2, and 3 licences. The F endorsement certifies authorization to drive a heavy vehicle with air brakes; the M endorsement certifies a manual transmission; the T endorsement certifies a Class 1 holder may drive a road train (double road train over 25 m) requiring a special permit.
Road signs warn of wildlife in wooded areas. Animals are attracted by headlights, so be especially alert at night. In high-risk areas, obey speed limits and be extra careful in reduced-visibility areas (bends, hills, roadside vegetation) and during early morning, dusk, and evening—particularly in May, June, October and November.
If an animal is on the road, slow down and press your brakes several times to alert motorists behind you. Watch for other animals nearby. Do not rely on gadgets like deer whistles, which have not been proven effective.
Since June 1, 2006, heavy vehicle owners must ensure their vehicles meet environmental standards controlling emissions and pollution control devices, benefiting air quality, maintenance and fuel savings.
Subject vehicles must have properly functioning pollution control devices, which may not be removed or modified except for defective replacement.
Carrier enforcement officers may test emissions and issue offence reports; non-compliant owners must repair vehicles and obtain compliance attestation.
Since June 1, 2006, heavy vehicle owners must ensure vehicles meet environmental standards for emissions control and pollution control devices. Standards aim to reduce emissions, improve maintenance and save fuel.
Carrier enforcement officers may measure emissions if visible fumes or odour give reasonable cause. Non-compliance leads to an offence report and repair obligations with strict deadlines.
When a vehicle is used by successive drivers within 24 hours, each must perform or accept a valid circle check before driving.
Special co-signing rules allow successive or relief drivers of buses, minibuses, tow trucks, and motor coaches to accept another driver's check.
Check the driver's side door opens without difficulty and all cab doors engage completely when closed. Open and close the driver's side door from outside and inside. Sleeper berth doors are not included. Applying pressure or re-closing may confirm engagement.
For buses and motor coaches, check that emergency exits (doors, windows, roof hatch) are accessible and open the emergency doors to confirm the warning buzzer or light works. Any object hampering access to an emergency exit is an obstruction.
For buses and motor coaches, check that emergency exits (doors, windows, roof hatch) are accessible and open the emergency doors to confirm the warning buzzer or light works.
A circle check may not be required for post-repair road tests if all specific conditions are met.
Fire department vehicles have specific inspection timing tied to outings and station stays.
For these vehicles that remain parked, weekend and holiday days do not count toward the 24-hour validity period.
Public transit buses/minibuses have a dual validity period whose earliest expiry governs, subject to specific conditions.
Heavy vehicles come in many configurations designed for varied uses, including single-unit and combination vehicles as well as passenger buses.
Heavy vehicle operation is governed by key laws including the Act respecting owners, operators and drivers of heavy vehicles, the Highway Safety Code, and the Transport Act, plus numerous regulations covering cargo, hours of service, load limits, and driver health.
While operating your vehicle, constantly monitor its performance. You need to be familiar with all dashboard indicators, buttons and levers to drive safely and efficiently, since dashboards differ across vehicle types.
Some indicators and gauges are more important than others and need to be checked or used more frequently.
Beyond basic indicators, several gauges are important for monitoring vehicle systems, especially air-brake-related pressures on heavy vehicles.
Brake hoses carry compressed air between adjacent vehicles. Red hoses generally supply air to the service brake chambers (via service reservoir) and release the parking brake; blue hoses activate the trailer/semi-trailer relay valve which allows air into the service brake chambers.
Each hose ends in a coupler; hitched vehicles have two couplers each. Match corresponding couplers of the same colour. To connect, fit couplers at a 90° angle and rotate until hoses line up straight.
If a road tractor is not hitched to a trailer, each brake hose coupler must be hooked to a dummy coupler. If no dummy couplers exist, attach couplers side by side and secure them to prevent hoses falling and dirt entering the system.
Red brake hoses supply air to service brake chambers (via the service reservoir) and release the parking brake. Blue brake hoses supply air to activate the trailer/semi-trailer relay valve, which lets air into the service brake chambers.
If a road tractor is not hitched to a trailer, hook each coupler to a dummy coupler. If there are no dummy couplers, attach the hose couplers side by side and secure them to keep hoses off the ground and dirt out of the system.
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