The Most Popular Brake System (Chapter 4: Pneumatic/Air Brake Systems) +7Quebec · CDL · English

Air brake systems are made up of a compressed air supply circuit plus two independent circuits: the primary circuit (P or 1) and the secondary circuit (S or 2). They activate service brakes on all wheels and work independently so if one fails the other continues to operate.

• ✓Primary circuit labelled P or 1
• ✓Secondary circuit labelled S or 2
• ✓Both circuits activate service brakes on all wheels
• ✓Circuits work independently; if one fails, the other operates normally
• ✓Installation may differ between vehicles

Air brakes are used on almost all modern heavy vehicles. They are more powerful than hydraulic systems, proven reliable, and easy to connect to other vehicles and air-powered equipment.

• ✓Usually more powerful than hydraulic systems
• ✓Proven reliability
• ✓Easy to connect to trailers and air-powered equipment
• ✓Compressed air also used for suspension

Backing up is difficult because you usually cannot see directly behind using mirrors alone, especially into small spaces. Back up as seldom as possible. Before backing, look at the surrounding area layout; if needed, get out to assess road surface, note stationary objects, and anticipate pedestrian/vehicle traffic. Check for overhead and side obstacles.

• ✓Back up as seldom as possible; get out to assess the layout if necessary
• ✓Check the road surface, stationary objects and potential pedestrian/vehicle traffic
• ✓Check for overhead and side obstacles before backing

Begin backing immediately after checking so the situation doesn't change. Backing slowly is key to safety — it makes correcting steering errors, estimating distances and stopping easier. Correct steering errors immediately.

• ✓Begin backing immediately after checking, before conditions change
• ✓Back up slowly to allow error correction and distance estimation
• ✓Correct steering errors immediately

With a bus or straight-body truck, turn the steering wheel toward the side you're steering the rear (right to back right, left to back left) until the reference points line up. With a trailer hitched to a tractor, the manoeuvre is opposite — turn the wheel in the direction OPPOSITE to where you want the trailer to go.

• ✓Bus/straight-body truck: steer toward the side you want the rear to go
• ✓Tractor-trailer: steer in the opposite direction from where you want the trailer to go
• ✓Back right: first turn wheel left so trailer goes right, then turn right so tractor follows

Backing up is difficult because mirrors cannot show what is directly behind. Back up as seldom as possible. Before backing, take a moment to study the surrounding layout, and if necessary get out to check the road surface, note stationary objects, anticipate traffic, and check for overhead/side obstacles.

• ✓Back up as seldom as possible with a heavy vehicle
• ✓Study the surrounding area layout before backing; get out to check if necessary
• ✓Check road surface condition and note stationary objects
• ✓Check overhead and side obstacles before backing

After checking the layout, begin backing immediately before conditions change. Backing slowly makes it easier to correct steering errors, estimate distances, and stop if needed. Correct steering errors immediately.

• ✓Begin backing immediately after checking the layout before it changes
• ✓Back up slowly to correct errors, estimate distance and stop safely
• ✓Correct steering errors immediately

Backing requires two visual reference points: the rear corner of your vehicle on the side you are backing toward, and the farthest rear edge of the loading dock/space. With a bus or straight-body truck, turn the wheel toward the side you steer the rear until the points line up. With a tractor-trailer, turn the wheel in the OPPOSITE direction from where you want the trailer to go.

• ✓Use two reference points: the rear corner of your vehicle and the far rear edge of the space
• ✓Bus/straight-body truck: turn the wheel toward the side you want the rear to go
• ✓Tractor-trailer: turn the wheel opposite to the direction you want the trailer to go
• ✓Maintain visual contact with both reference points and line them up

After dark, backing up so you obstruct the oncoming lane can make your trailer or semi-trailer hard to see. Use hazard lights, do not turn on high-beam headlights (they could blind others), and when possible plan to arrive on the same side as the loading dock.

• ✓Use hazard lights when backing at night
• ✓Do not use high beams — they can blind oncoming drivers
• ✓Plan to arrive on the same side as the loading dock when possible

Whenever possible, back up steering the rear toward the driver's (left) side because it lets you see part of the area behind through the left window and mirror. With a bus or straight-body truck you can use the left mirror more easily but must regularly check the right mirror and side window.

• ✓Back toward the driver's (left) side when possible for better visibility
• ✓Regularly check the right mirror and side window with a bus or straight-body truck

It is always better to have a reliable helper, especially when backing toward the right. Ensure the helper knows what to do and which signals to use, and watches the space behind and to the sides. The helper must remain visible to you at all times — stand behind and to the left when backing left, behind and to the right when backing right.

• ✓The helper must stay visible to the driver at all times
• ✓Backing left: helper stands behind and to the left; backing right: behind and to the right
• ✓Choose a reliable helper who understands the signals

Backing requires picking two visual reference points: the rear corner of your vehicle on the side you're backing toward, and the farthest rear edge of the loading dock/parking space. Maintain visual contact and line them up together.

• ✓Use two reference points: your rear corner and the far rear edge of the target space
• ✓Maintain visual contact and line the two points up side by side

To back a semi-trailer straight, if it veers left or right, turn the wheel to steer the tractor in that same direction to correct. If the trailer veers too far out of line, stop, pull forward to realign the tractor-trailer, then resume backing.

• ✓Correct a veering trailer by steering the tractor in the direction the trailer veered
• ✓If badly out of line, pull forward to realign before backing again

After dark, when backing so that you obstruct the oncoming lane, your trailer may be hard to see. Increase visibility using hazard lights, do not use high beams (they blind others), and when possible arrange to arrive on the same side as the loading dock.

• ✓Use hazard lights when backing up at night
• ✓Do not turn on high beams while backing—they blind other drivers
• ✓When possible, plan to arrive on the same side as the loading dock

Back up steering the rear toward the driver's (left) side when possible because it lets you see part of the area behind through the left window and mirror. With buses/straight-body trucks you are better positioned to use the left mirror but must regularly check the right mirror and side window.

• ✓Back toward the driver's (left) side when possible for better visibility
• ✓Use the left side window and left rearview mirror if the tractor-trailer angle allows
• ✓Regularly check the right mirror and side window during the manoeuvre

It is always better to have a reliable helper, especially when backing to the right. Ensure the helper understands the signals to use. When backing left, the helper should stand behind off to the left; when backing right, behind off to the right so they maintain visual contact.

• ✓Always better to use a helper, especially when backing toward the right
• ✓The helper must remain visible to the driver at all times
• ✓When backing left, helper stands behind off to the left; backing right, off to the right
• ✓Agree on signals with a reliable helper beforehand

To back a tractor-trailer to the right: first turn the wheel LEFT so the semi-trailer backs toward the right while aiming to line up the reference points; then turn the wheel RIGHT so the tractor also backs right, continuing until points line up side by side.

• ✓First turn the wheel left so the semi-trailer moves right
• ✓Then turn the wheel right so the tractor follows the trailer
• ✓Continue until the two reference points line up side by side

To back a tractor-trailer to the left: first turn the wheel RIGHT so the semi-trailer backs toward the left while aiming to line up the reference points; then turn the wheel LEFT so the tractor also backs left, continuing until points line up.

• ✓First turn the wheel right so the semi-trailer moves left
• ✓Then turn the wheel left so the tractor follows the trailer
• ✓Continue until the reference points line up side by side

When backing straight, if the trailer veers off, turn the wheel to steer the tractor in that same direction to correct. If the trailer veers too far out of line, stop, pull forward to realign, then begin backing again.

• ✓If the trailer veers off, steer the tractor in that same direction to correct
• ✓If the trailer veers too far, pull forward to realign then back up again

Employers must ensure drivers of dangerous substances are trained for their duties, and issue a valid training certificate.

• ✓Training must be directly related to duties and appropriate to the type of dangerous substances transported
• ✓The employer must issue a training certificate specifying the areas trained, subjects covered and expiry date
• ✓The certificate is valid for 36 months

Drivers must carry their training certificate, or be supervised by a certificate holder, whenever transporting dangerous substances.

• ✓Carry the original or a copy of your training certificate at all times when transporting dangerous substances
• ✓Alternatively, be under the direct supervision of a person carrying the original or a copy of his or her certificate

A copy of the shipping document must accompany dangerous substances to the point of delivery and be stored in a specified accessible location.

• ✓The shipping document copy must remain with the dangerous substances up to the point of delivery
• ✓If on board, store it in a protective jacket on the driver's side door or within easy reach
• ✓If not in the vehicle, place it in a protective jacket on the driver's side door OR on the driver's seat/visible location for anyone entering from the driver's side

Dangerous substances must be labelled with prescribed safety marks, and drivers must verify classification, marking and placard provision before taking possession.

• ✓Verify the substances have been classified before taking possession
• ✓Verify the shipper affixed appropriate safety marks (label, placard or sign) on containers
• ✓Placards must be placed on each end and each side of the vehicle
• ✓No container of dangerous substances may be placed on or in front of a motor vehicle's front bumper

Anyone handling or transporting dangerous substances on Québec public roads must comply with the Transportation of Dangerous Substances Regulation, which incorporates federal standards.

• ✓Compliance is required from the manufacturing/distribution site to the delivery/unloading site
• ✓The Regulation provides exemptions depending on type or quantity of substances
• ✓It incorporates by reference Transport Canada's Transportation of Dangerous Goods Regulations

Dangerous substances are grouped into nine classes with specific hazards and examples, each with prescribed placards.

• ✓Class 1 Explosives (1.1 mass explosion e.g. TNT; 1.2 projection; 1.3 fire hazard e.g. fireworks; 1.4 no significant blast; 1.5 very insensitive with mass explosion; 1.6 extremely insensitive)
• ✓Class 2 Gases (2.1 flammable e.g. propane; 2.2 non-flammable non-toxic e.g. nitrogen; 2.3 toxic e.g. carbon monoxide)
• ✓Class 3 Flammable liquids with flash point at or below 60.5°C (e.g. gasoline, ethanol, kerosene, diesel)
• ✓Class 4 Flammable solids/self-igniting/water-reactive; Class 5 Oxidizers and organic peroxides; Class 6 Toxic and infectious; Class 7 Radioactive; Class 8 Corrosive; Class 9 Miscellaneous

Class 1.4 explosives have quantity-based placard exemptions, and transporting certain explosives requires authorization from the Sûreté du Québec.

• ✓Placards are not required for Class 1.4 if quantity is equal to or less than 1,000 kg
• ✓Placards are not required for Class 1.4S regardless of quantity
• ✓In Québec, a driver transporting explosives listed under the Act respecting explosives must obtain authorization from the Sûreté du Québec

Employers must ensure drivers have training directly related to their duties and appropriate to the substances carried, and must issue a training certificate specifying the trained areas, subjects and expiry date.

• ✓Training certificate is valid for 36 months
• ✓Drivers must carry the original or a copy of their training certificate at all times when transporting dangerous substances
• ✓Alternatively, the driver must be under direct supervision of a person carrying their own certificate original/copy

Anyone handling or transporting dangerous substances on Québec public roads must comply with the Transportation of Dangerous Substances Regulation from the manufacturing/distribution site to delivery/unloading. It incorporates by reference Transport Canada's Transportation of Dangerous Goods Regulations, with some exemptions by type or quantity.

• ✓Compliance required from manufacturing/distribution site to delivery/unloading site
• ✓Regulation incorporates Transport Canada's Transportation of Dangerous Goods Regulations by reference
• ✓Exemptions may apply depending on the type or quantity of substances

Anyone taking charge of a dangerous substances shipment must obtain a copy of the shipping document containing the required information; it must remain with the substances to the point of delivery.

• ✓Shipping document must remain with the dangerous substances up to delivery
• ✓On board: store it in a protective jacket on the driver's side door or within easy reach
• ✓When not in the vehicle: place it in a protective jacket on the driver's side door OR on the driver's seat/visible location for anyone entering from the driver's side

Requirements concerning wipers and washer apply at all times, not only in bad weather. Check presence, condition, and working order of wipers: check for presence, switch them on, and check blade effectiveness. Effective blades sweep the windshield to remove dirt and ensure sufficient visibility.

• ✓Defect 6.A (major): The driver's side wiper is missing, not working, or does not sweep effectively
• ✓Defect 6.1 (minor): The passenger's side wiper is missing, not working, or does not sweep effectively

Check the washer system working order by switching it on and confirming it sprays washer fluid onto the windshield. An effective system sprays enough fluid to appropriate areas to provide sufficient visibility.

• ✓Defect 6.2 (minor): The washer system does not clean the windshield effectively (e.g. nozzle blocked/misadjusted, little or no fluid sprays)
• ✓Requirements apply at all times, not only in bad weather

Make the vehicle stable, start the engine, release the parking brake, and check the low air pressure indicator(s) (19.A, 19.1). If not already on, pump the brake pedal to lower pressure until the light/buzzer turns on or the wigwag drops. If indicators are already on at start-up, ensure gauge pressure is at least 380 kPa (55 psi) when they turn off. Then check compressor performance (19.B) by holding the brake pedal down while idling and confirming the compressor reaches and maintains at least 620 kPa (90 psi).

• ✓Release the parking brake and confirm low air pressure indicators activate below 380 kPa (55 psi)
• ✓Confirm indicators turn off at 380 kPa (55 psi) or more
• ✓Confirm the compressor reaches and maintains at least 620 kPa (90 psi) with the pedal held down

With the compressor working, let the engine idle (optionally about 1,000 rpm) and confirm the compressor switches off between 805 kPa (117 psi) and 945 kPa (137 psi) (19.3). Make sure air pressure is at maximum, turn off the engine, and check the brake system for leaks (19.C, 19.4) by pressing and holding the pedal while watching the gauge/listening. Restart the engine and slowly decrease pressure until the compressor switches back on before reaching 550 kPa (80 psi) (19.3).

• ✓Compressor must cut out between 805 kPa (117 psi) and 945 kPa (137 psi)
• ✓Compressor must cut back in before pressure falls to 550 kPa (80 psi)
• ✓Check for leaks by holding the pedal down and watching the gauge or listening for audible leaks

Apply the semi-trailer's parking brake, press the accelerator (without maxing RPM) and try to gently move forward to confirm it holds; then release. Repeat for the tractor's parking brake (apply tractor, release trailer, try to move, confirm it holds). Then check clutch (4.1), power steering (5.B) and service brakes (19.D) by releasing the parking brake, driving slightly forward, turning the wheel side to side to confirm free wheels and working steering, then stopping with clutch/service brakes. Check the accelerator (4.A, 4.1), engine exhaust for cab fume infiltration (16.A, 16.1), and brake lights (8.B, 8.1) if it can be done safely.

• ✓Confirm each vehicle's parking brake keeps the combination stationary when trying to drive forward (19.5)
• ✓Drive slightly forward and turn the wheel side to side to verify power steering and free-turning wheels
• ✓Watch for exhaust odours that may indicate fumes leaking into the cab through the floorboard

Make the vehicle stable, start the engine, release the parking brake, and check the low air pressure indicator(s) (19.A, 19.1). If not already on, pump the brake pedal to lower pressure until the light/buzzer turns on or the wigwag drops. If indicators are already on at start, do not lower pressure further, but ensure the gauge reads at least 380 kPa (55 psi) when indicators turn off. Then check compressor performance (19.B): with engine idling and compressor working, push the brake pedal fully down and hold, watch the gauge, and confirm the compressor reaches/maintains at least 620 kPa (90 psi).

• ✓Ensure the pressure gauge reads at least 380 kPa (55 psi) when the low air pressure indicators turn off
• ✓Confirm the compressor reaches and maintains at least 620 kPa (90 psi) with the pedal held down
• ✓Release the parking brake before the in-cab air brake test to engage all circuits

Check the pressure regulator cut-out (19.3): while the compressor works, let the engine idle and confirm the compressor switches off between 805 kPa (117 psi) and 945 kPa (137 psi); ~1,000 rpm speeds the rise. Ensure pressure is at maximum, turn off engine, and check for leaks (19.C, 19.4) by pressing/holding the pedal and watching the gauge or listening. Restart and check cut-in (19.3): slowly decrease pressure until the compressor switches back on and confirm it does so before reaching 550 kPa (80 psi).

• ✓Compressor must cut out between 805 kPa (117 psi) and 945 kPa (137 psi)
• ✓Compressor must cut in before pressure drops to 550 kPa (80 psi)
• ✓Check for leaks after building maximum pressure and turning off the engine, holding the pedal down

Check the semi-trailer's parking brake (19.5): apply it, press the accelerator gently, try to move forward, and confirm it holds. Check the tractor's parking brake (19.5): apply tractor brake, release trailer brake, try to move forward, confirm it holds. Then check clutch (4.1), power steering (5.B) and service brakes (19.D): release tractor brake, drive slightly forward turning the wheel side to side to confirm free-turning wheels and power steering, then brake to stop. Check the accelerator (4.A, 4.1) in neutral with parking brake applied, the exhaust system for cab fume infiltration (16.A, 16.1), and brake lights of the combination if it can be done safely.

• ✓Test both the semi-trailer's and the tractor's parking brakes separately for holding ability (19.5)
• ✓Turn the steering wheel side to side while driving slowly to confirm free wheel movement and power steering operation
• ✓Fill out and sign the circle check report and follow up on any detected defects

A Class 1 licence authorizes driving combinations of vehicles: double-axle road tractors (net weight 4,500 kg+) or triple-axle road tractors hauling trailers/semi-trailers, and Class 3 trucks hauling qualifying trailers. Holders may drive all other vehicle categories except motorcycles.

• ✓Class 1 covers double-axle road tractors (net weight 4,500 kg+) and triple-axle road tractors hauling one or more trailers/semi-trailers
• ✓Class 1 covers Class 3 trucks hauling a trailer/semi-trailer of 4,500 kg+ (for permanent equipment) or 2,000 kg+ for other trailers
• ✓A road tractor has no cargo space and is permanently equipped with a fifth wheel; Class 1 holders may drive all other categories except motorcycles

A Class 3 licence authorizes straight-body trucks: double-axle trucks (net weight 4,500 kg+) or any truck with three or more axles, and truck tractors (2 axles at 4,500 kg+, or 3+ axles) not hitched to a trailer/semi-trailer. It also covers hitched trailers under certain weight limits.

• ✓Class 3 covers double-axle trucks of 4,500 kg+ net weight or any truck with three or more axles
• ✓Class 3 covers a truck tractor (2 axles at 4,500 kg+ or 3+ axles) provided it is NOT hitched to a trailer or semi-trailer
• ✓Trailers are covered if under 2,000 kg net, or 2,000–4,500 kg only when carrying permanently equipped machinery/fixtures

Endorsements may be added to Class 1, 2, and 3 licences. F certifies air brake operation, M certifies manual transmission operation, and T certifies operating a road train (double road train over 25 m requiring a special permit, Class 1 only).

• ✓F endorsement certifies a Class 1/2/3 holder may drive a heavy vehicle with air brakes
• ✓M endorsement certifies driving a heavy vehicle with a manual transmission
• ✓T endorsement (Class 1 only) certifies driving a road train over 25 m requiring a special road train operating permit

A Class 2 licence authorizes driving a bus designed to carry more than 24 passengers, and a bus hitched to a trailer under 2,000 kg. Holders may drive all other categories except vehicle combinations (Class 1) and motorcycles.

• ✓Class 2 authorizes driving a bus designed to carry more than 24 passengers, plus a bus hitched to a trailer under 2,000 kg
• ✓Class 2 holders may not drive Class 1 combinations or motorcycles

You must stop at an inspection station when its lights are flashing if driving: a vehicle with a GVWR of 4,500 kg or more designed for transporting goods or permanently-attached equipment; a tow truck or tool vehicle; or a combination of road vehicles where at least one has a GVWR of 4,500 kg or more.

• ✓Stop when inspection station lights are flashing
• ✓Applies to goods vehicles with GVWR of 4,500 kg or more
• ✓Applies to tow trucks, tool vehicles, and combinations with at least one 4,500 kg unit

Certain exceptions apply, in particular trucks with a net weight of 4,000 kg or less registered as a passenger vehicle under vehicle registration regulations, or road vehicles used for recreational purposes.

• ✓Trucks with net weight of 4,000 kg or less registered as passenger vehicles may be exempt
• ✓Road vehicles used for recreational purposes may be exempt

All heavy vehicle brake systems, whatever the type, include a service brake (reduces speed via brake pedal), a parking brake (keeps vehicle stationary when parked), and an emergency brake (stops vehicle if service brake fails or a trailer breaks away).

• ✓Service brake reduces speed using the brake pedal
• ✓Parking brake holds vehicle stationary when parked
• ✓Emergency brake stops vehicle if service brake fails or trailer breaks away

An abnormally low brake pedal is a serious warning signal. You can temporarily increase braking pressure by pumping rapidly and repeatedly, but the brakes must be repaired right away.

• ✓Abnormally low pedal is a serious warning sign
• ✓Pump rapidly to temporarily increase pressure
• ✓Have brakes repaired immediately

Vehicles have a dual circuit brake system so braking is still possible if one hydraulic circuit fails, but you must press harder, only some wheels brake, and braking distance may increase. Repair before reusing the vehicle.

• ✓Dual circuit allows braking if one circuit fails
• ✓Requires harder pedal pressure; braking distance may be longer
• ✓Must repair before using the vehicle again

Power brakes require little pedal effort, but if the engine stalls you must apply much greater pressure. Driving is prohibited if the power brake system is not working properly.

• ✓Power brakes require little pedal effort normally
• ✓Engine stall requires much greater pedal pressure
• ✓Driving is prohibited if power brakes malfunction

The service brake pressure light comes on at start-up to confirm the hydraulic system works; if it stays on the system may be defective. The parking brake light indicates the parking brake is on.

• ✓Service brake pressure light staying on may mean a defective hydraulic system
• ✓Parking brake light indicates the parking brake is engaged