Saskatchewan Commercial study guide: key rules on all 19 topics

Free Saskatchewan Commercial study guide: 481 key points from the SGI Professional Driver's Handbook in plain words, organised by topic, each topic linked to its practice questions.

By the Canada Exam Prep Editorial Team · Updated October 17, 2026

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This study guide collects our notes on every topic of the Saskatchewan Commercial Knowledge Tests (Class 1–4 and Air Brake) on one page: 481 short points in our own words, grouped by topic and by handbook section. Read it from top to bottom before your first practice test, or jump to a topic from the list below.

Each topic ends with a link to its practice questions, so you can check what you just read straight away, and a link to the official chapter for the full wording. The notes summarise the SGI Professional Driver's Handbook from the SGI (Saskatchewan Government Insurance); they do not replace it, and where our notes and the official source differ, the official source wins.

Study these notes as flashcards →

Licence classes, endorsements and exams

What Class 1, 2, 3 and 4 licences allow, novice-driver limits, A, G and S endorsements, learner endorsements, the knowledge papers each class writes, Class 1 MELT and commercial medical standards.

Practise Licence classes, endorsements and exams questions Flashcards Official chapter

Ch. 1 Classified licence system (pp. 1–9)

You must hold the licence class for the vehicle you drive; being unpaid or not owning the vehicle is no exemption.
Exams are needed if you were never licensed, have not held that Saskatchewan class within five years, hold a licence Saskatchewan does not honour, want a higher class or an endorsement, or your licence is not valid.
Novice drivers (Class 7, or Class 5 with a Novice 1 or 2 restriction, or the out-of-province equivalent) cannot get Class 1–4, school bus or heavy trailer privileges.
Class 1: power units with semi-trailers, and trucks towing units heavier than 4,600 kg; also covers Classes 2–5.
Class 2: buses seating more than 24 passengers while carrying passengers; also covers Classes 3–5 and Class 1 as a learner with the endorsement.
Class 3: trucks with more than two axles (not farm-registered Class F), towing no more than 4,600 kg; power units with more than two axles when not towing a semi-trailer; also Classes 4–5.
Class 4: buses seating 24 or fewer while carrying passengers; taxis (PT) and rideshare (LV) carrying 9 or fewer; PB/PC vehicles carrying 24 or fewer for hire; ambulances used for hire; also Class 5.
Class 4 taxi, limousine and rideshare drivers file a criminal record check with their company every year; an unsatisfactory check can bring a T restriction (no passengers for hire).
None of Classes 1–4 allows air brakes, motorcycles or school buses without the matching endorsement.
Minimum age for Classes 1–4: 18, and not a novice driver.

Farm-plated vehicles and Endorsements (pp. 9–12)

Farm-plated 2- and 3-axle trucks, even with air brakes, can be driven on a Class 5 without the air brake endorsement.
A farm 2-axle power unit towing any trailer needs Class 1; a farm 3-axle power unit not towing needs Class 3 (3A with air brakes).
A endorsement: needed for any vehicle with air brakes, except farm-licensed Class 3 or 5 trucks; air-over-hydraulic brakes do not need it.
A endorsement requirements: written air brake test, adjust a manual slack adjuster on a model and explain automatic slack adjusters, practical demonstration on equipment you supply.
Without the A endorsement you may drive air-brake vehicles as a learner beside someone whose licence has it.
G endorsement (heavy trailer): towing a trailer over 4,600 kg (10,141 lb.) including its load needs Class 1 or a G endorsement on Class 2–5; G allows two-axle trucks (not power units) towing heavy trailers.
The 4,600 kg is the weight of the trailer(s) and contents, not the tow vehicle; two trailers are counted together.
S endorsement (school bus) can be added to a Class 1–5 licence; road test in the right size of bus: unrestricted means at least 36 student passengers (six rows of seats count as 36).
"Student passengers" means three passengers per seat.
Learner endorsements 1–4: age 18, not novice, written tests, vision and medical, supervised by someone who has held that class for 365 days within the last three years.

Examinations (pp. 12–15)

Papers: Sign 30 questions, Basic Class 5 20, Class 1 20, Class 2 15, Class 3 10, Class 4 10, Air Brake 18, Heavy Trailer 20, School Bus 15.
Class 1 writes Sign, Basic and the Class 1, 2, 3 and 4 papers; Class 2 writes Sign, Basic, 2, 3, 4; Class 3 writes Sign, Basic, 3, 4; Class 4 writes Sign, Basic, 4.
Knowledge exams may be attempted once per day; they are based on this handbook, the Saskatchewan Driver's Handbook and the Air Brake Manual.
Book and pre-pay on MySGI or with a motor licence issuer; walk-ins at Regina and Saskatoon Central, 8 a.m.–4 p.m., Monday to Saturday.
The vision test is part of the knowledge exam appointment.
Road tests include a highway turn-about; Class 1 adds offset and alley dock backing and coupling/uncoupling.
In a standard transmission for Class 1, 2, 3 or S (over 24 passengers) you must show clutch use through all gears; 13- or 18-speed: split the top range (Class 1).
Testing in an automatic or electronic-shift vehicle may restrict you to those transmissions.
A road test is rescheduled if the vehicle shows a dangerous goods placard, lacks an inspection decal, is unsafe or dirty, or the heavy trailer weighs under 4,600 kg.

Class 1-4 medical standards (pp. 16–18)

A Commercial Driver's Licence Medical Report must be submitted and approved before any testing.
Conditions that may block a commercial licence include seizures, some heart or insulin-dependent diabetic conditions, blackouts, head injuries, and vision or hearing problems.
Medical renewals: every five years at 18–45, every three years at 46–65, every year at 66 and older.
An unsatisfactory medical can bring an L restriction: no Class 2, Class 4 or rideshare vehicles.
Under the Canada–U.S. reciprocity agreement a valid Class 1, 2 or 3 licence proves medical fitness; Class 4 drivers of buses seating more than 10 are also covered.
Drivers with medical waivers get a W restriction: no commercial driving in the United States.

Driver condition, speed and following distance

Distraction, fatigue, alcohol and drugs, night vision and glare, the six driving conditions, traffic tempo, the time-based following count for long vehicles, tailgaters, intersections, railway crossings and the danger zone.

Practise Driver condition, speed and following distance questions Flashcards Official chapter

Ch. 2 Attitude and driver condition (pp. 19–22)

Defensive driving means always being willing to yield to other drivers and pedestrians.
Driver condition (physical, mental, emotional fitness) is the most important of the six driving conditions.
Inattention causes the greatest number of collisions; make your eyes move about every two seconds to avoid a blank stare.
Most collisions happen near home on familiar roads.
Hand-held phones are banned in Saskatchewan; experienced (non-GDL) drivers may use mounted hands-free phones activated by voice or one touch.
Drowsy driving is as dangerous as impaired driving; lack of sleep is the most common cause.
Fatigue-related collisions peak 1–4 p.m. and 2–6 a.m.
The National Safety Code allows up to 13 hours of commercial driving a day, but SGI recommends a rest stop at least every two hours.
Coffee, radio and open windows only help briefly; prevention is sleep, regular breaks, a 20–40 minute mid-afternoon nap and not driving through normal sleeping hours.
Impaired driving is the leading cause of fatal collisions in Saskatchewan; there is zero tolerance for drug-impaired driving.
Alcohol combined with another drug multiplies impairment rather than simply adding to it.

Night vision and speed (pp. 23–24)

At night slow down and increase following distance; overdriving your headlights means you cannot stop within the lit area.
Recovering from oncoming glare takes up to five seconds and can reach 25 seconds as people age.
If you suspect a glare-recovery problem, see an eye professional and tell SGI's Medical Review Unit.
Posted limits are maximums for ideal conditions; adjust for six conditions: driver, vehicle, light, weather, road, traffic.
Driving faster than the traffic tempo eats into your following distance and adds lane changes and fatigue; driving much slower invites rear and side conflicts.

Following distance and tailgaters (pp. 24–26)

Caravanning (trucks or buses following closely to cut wind) is prohibited by law.
Taxis, ambulances, police vehicles and vans: at least a three-second gap.
Trucks, buses, power units and combinations: round the vehicle length to the nearest metre and divide by three to get the count in seconds (15 m = 5 seconds).
Lengthen the count on rain, snow or ice, and leave room for others to merge in front.
With a tailgater behind, stop gradually and help them pass; on an upgrade with a passing lane, slower vehicles use the right lane.

Intersections, railway crossings and danger zones (pp. 27–30)

Never enter a limited-view intersection faster than you can stop; cover the brake to cut reaction time.
Never pass in or approaching an intersection; do not use your size to bluff for the right of way.
Large vehicles need more time to clear and stop at railway crossings and can hang up on tracks.
Choose your gear before the crossing and do not shift on the tracks.
If stalled on tracks, get out and move away toward the oncoming train, then call the posted railway number or 911.
The danger zone is the area ahead in which you cannot stop; it grows with speed and poor surfaces.
Doubling weight needs double the braking force; doubling speed needs four times; doubling both needs eight times.

Braking, passing, parking and backing

Smooth stops, downgrades and retarders, combination braking, ABS warning lights, passing and being passed, curves, gear shifting, mirrors, parking on grades, warning devices for stopped vehicles, and safe backing.

Practise Braking, passing, parking and backing questions Flashcards Official chapter

Ch. 2 Braking and retarders (pp. 31–33)

A normal stop on level road needs one brake application, eased off near the end to avoid a jerk.
On ice, threshold brake to keep wheels from locking (follow the maker's instructions with ABS).
On a steep grade choose a gear low enough to control speed, usually one gear below the one used to climb, and use the engine retarder.
If you reach an unsafe speed going downhill, brake and downshift; being on a hill is no excuse for a collision.
Heated drums expand away from the linings, causing brake fade or failure; worst on long downgrades from highway speed.
Trailers over 1,360 kg (3,000 lb.) must have service brakes.
On steep downgrades keep engine rpm at least 200–300 below the maximum governed rpm.
Avoid unnecessary engine retarder use in cities; be careful on slippery roads, where a retarder can lock drive wheels and cause a jackknife.
Choose the gear before starting down a grade, not on it.
Balanced braking: the foot valve applies trailer brakes at the same pressure as tractor brakes; the hand valve applies trailer brakes alone.
Brake gently in curves and on wet or icy roads; over-braking can cause a skid or jackknife.
After driving through water, test the brakes and drag them lightly to dry them.

ABS (pp. 33–34)

ABS releases pressure only on a wheel that is about to lock, keeping stability.
ABS lights are amber and marked ABS; trailer lamps are near the left rear red side marker; dollies have one on the left side.
Vehicles built after March 1, 2001 that can tow have two dash ABS lights (tractor and trailer).
At ignition the light comes on for a few seconds and goes out; staying on means a fault; never lighting means a bulb, wiring or controller problem.
A working ABS is a CVSA roadside inspection item.

Passing, curves, sharing the road (pp. 35–39)

Do not wave following drivers past; when they pass, help them finish, slowing if needed.
Do not encourage passing across solid lines.
Air turbulence is strongest just ahead of the truck, beside the fuel tank area and right behind the trailer.
Pass on the right only with two or more lanes your way, or when the vehicle ahead is turning left and you need not use the shoulder; never pass on the shoulder.
Before entering a street from an alley or lane in a city or town, yield to pedestrians and vehicles.
Slow down before a curve and apply gentle power through it; braking in a curve can cause a skid or jackknife.
Motorcycles need a full lane; their size makes them look farther away and slower; check twice for them.
Most engine makers recommend about 85% of governed engine speed for normal operation; double-clutch on most manual truck transmissions.
Downshift before the crest of a hill; if brakes fail on level road, shift down and use engine compression.

Visibility, parking and warning devices (pp. 40–42)

Class 1, 2, 3 vehicles, school buses and vans depend heavily on mirrors; convex mirrors help in tight spaces.
Wide loads need mirrors that reach beyond the load.
Park at least 153 m (500 ft.) from an intersection when stopping for a break; never block the view of an intersection.
With a semi-trailer, apply spring brakes on both power unit and trailer when parked.
Manual transmission on a grade: lowest forward gear facing uphill, reverse facing downhill; two-speed axle and auxiliary transmission in low range.
With a curb: front wheels right facing downhill, left facing uphill; no curb: straight truck wheels sharply right; tractor-trailer wheels straight, brakes set, wheels blocked.
Never use the trailer hand valve to hold an unattended parked vehicle.
Clear of the roadway, not disabled, under four hours: hazard lights. On the road, disabled or over four hours: three warning devices — about 3 m (4 paces) on the traffic side behind, and about 30 m (40 paces) ahead of and behind the vehicle.

Backing (pp. 43–47)

The driver is always responsible when backing, even with a guide.
Avoid unnecessary backing, use a guide, back toward the driver (view) side, and back out of traffic rather than into it.
Before backing into a dock: four-way flashers, horn, back to the view side, use a guide.
Without a guide: set the park brake, walk around and check clearances, then flashers and horn before backing slowly in short stages.
Offset backing (driver side): wheel hard right to angle the trailer, back until the tractor tires line up with the middle of the landing gear, then wheel hard left.
Alley dock from the driver's (left) side is recommended because the left mirror shows the space.

Tires, fire safety, fuel efficiency and winter driving

Tire pressure and heat, tire matching, carbon monoxide, fire prevention and extinguishers, flares, fuel-saving habits and idling, plus the essential winter checks and the six hazards of winter driving.

Practise Tires, fire safety, fuel efficiency and winter driving questions Flashcards Official chapter

Ch. 2 Tires and carbon monoxide (pp. 48–49)

Traction between tires and road decides how much control you have.
Under-inflation, overloading or too much speed make a tire flex more and overheat.
Heat raises tire pressure, which is normal; never bleed air from a warm tire — check and adjust pressure cold.
Over-inflation wears the centre of the tread and reduces road contact; under-inflation wears the outer edges and makes hydroplaning more likely.
Never mix bias and radial tires on the same axle; duals must be within 12.5 mm (1/2 in.) of each other in diameter.
Carbon monoxide is odourless, colourless and tasteless; check the exhaust for leaks, never run the engine in a closed garage, and get fresh air if you feel dizzy or drowsy.

Fire (pp. 50–52)

Never start a vehicle with a fuel leak; shut off the engine when refuelling; ground the nozzle against the filler pipe.
Overheated flat or soft tires should be removed; do not move until they cool.
Dragging brakes make heat that can ignite hub grease; check hubs and drums often.
Water spreads gasoline or oil fires; smother them with an extinguisher, sand or dirt.
Use just enough extinguisher to knock flames down and keep some in reserve.
For electrical fires disconnect the battery cables first.
On a combination unit, if safe, separate the tractor from the trailer.
Fight fires with the wind at your back; for an under-hood fire open the hood only slightly.
B.C. dry chemical extinguishers handle grease, oil, gasoline and electrical fires; A.B.C. also handles paper and cloth.
Petroleum haulers need an extinguisher rated at least 20 B.C. or two of 10 B.C.; CO2 extinguishers are for open spaces.
Most school buses need at least 2A-10 B.C.; 2000 or newer buses at least 3A-40 B.C.; mount in a quick-release holder in view of the driver.
Vehicles wider than 2,060 mm (81 in.) operating outside a city, town or village must carry three flares (reflectors, triangles or electric lanterns) visible at 150 m; lanterns must last 12 hours.

Fuel efficiency (pp. 52–55)

Road transportation produces nearly 30% of Canada's greenhouse gas emissions.
Cutting aerodynamic drag by 10% improves fuel efficiency about 5%; air deflectors save 3–10%.
About 1% of fuel is wasted for every 10 psi of under-inflation.
Warm up 3–5 minutes (longer below 0 °C) without revving; start moving with zero throttle.
Every 10 km/h above 90 km/h uses about 10% more fuel.
Progressive shifting before maximum governed rpm (usually 1,200–1,600) saves fuel and wear.
Snow-covered roads increase fuel use 15–20%.
A class 8 truck idling at 900 rpm burns up to four litres an hour; shut the engine off when stopped.

Winter driving (pp. 145–150)

Removing or backing off front brakes in winter does not help; it lengthens stops and increases jackknifes.
Winter checks: coolant, tires, wipers, heater and defroster, lights, balanced brakes, exhaust, battery, winter-grade fifth-wheel grease, windows and mirrors.
Summer-grade fifth-wheel grease can stiffen in the cold and interfere with steering.
Six winter hazards: poor traction, reduced ability to stop, temperature effects, ice polished by traffic, reduced ability to see and be seen, jackknifing.
In deep snow, turn the wheels side to side and rock gently; do not spin the wheels.
Ice and snow can need three to 12 times the dry stopping distance.
Ice gets more slippery as temperature rises; braking distance can double between −18 °C and about 0 °C.
A heavily loaded truck at 100 km/h needs about 138 m to brake.
In fog or heavy snow use low beams.
A jackknife past 15 degrees is almost impossible to recover, and it can reach 15 degrees in about one and a half seconds.
Drain air tanks daily in winter and leave them empty when not in use.

Vehicle condition and trip inspections

The PMVI program and inspection decals, who needs a daily trip inspection, Schedules 1 to 3, minor and major defects, the trip inspection report, the circle check order, brake response tests, en route and post-trip checks, and lighting.

Practise Vehicle condition and trip inspections questions Flashcards Official chapter

Ch. 4 Periodic Motor Vehicle Inspection (pp. 68–69)

Taxis, limousines and rideshare vehicles: PMVI every 12 months.
Commercial buses and vans: 12 months inside Saskatchewan, 6 months if operating extra-provincially.
Any vehicle seating 15 or more including the driver: 12 months.
Power units 22,000 kg or more operating only in Saskatchewan: 6 months; trucks: 12 months.
Extra-provincial power units 11,794 kg or more: 6 months; trucks: 12 months.
Trailers, dollies, jeeps and boosters with air brakes: 12 months; LPG, CNG and LNG systems: five years.
Inspections are done by certified mechanics at certified Vehicle Safety Inspection Stations.
Carry the certificate in the cab; on semi-trailers keep it in the outside document holder.
The expiry decal goes on the left window of power units, the right window of buses and school buses, and the left front corner of semi-trailers.

Trip inspection standards (pp. 70–72)

Trucks and power units over 11,794 kg registered gross weight, buses seating more than 10, and any trailers they tow must be inspected once every 24 hours while in use.
Schedule 1: trucks, tractors, trailers over 11,794 kg. Schedule 2: buses seating more than 10 including the driver, and trailers towed by a bus. Schedule 3: motor coaches with air ride, air brakes and automatic adjusters.
Minor defects must be fixed before the next trip inspection; a major defect means the vehicle cannot be driven until repaired.
The report (paper or electronic) must show the plate or unit number, odometer, carrier, date and time, location, the inspector's printed name and a signed declaration.
Carry the reports for the current and previous day and the inspection schedule; show them to a peace officer on request.
It is an offence to drive, or let someone drive, a vehicle with a defective part.
Before a Class 1–4, G or S road test you name and point out each item and describe what you check, without help or a checklist.

Systematic trip inspection (pp. 73–103)

Recommended order: engine compartment, exterior, interior, brake response tests.
Walk counterclockwise from the front down the driver side so you face oncoming traffic; it is sometimes called a circle check.
Before starting: set the parking brake, shut off the engine, block the wheels (Class 4 lists no blocking).
Check engine oil cold and never remove the radiator cap; never check belts with the engine running.
Loose lug nuts can show as rust trails or shiny rings around the nut.
Brake pedal travel must not exceed 80% of available travel under heavy force.
Fire extinguisher required in commercial vehicles wider than 2,060 mm; three flares or reflectors if wider than 2,060 mm outside an urban municipality.
Class 4 (bus 24 or fewer, ambulance for hire, taxi or limousine) has no applicable inspection schedule and a typical taxi has four tires and rims to inspect.
A Class 2 motor coach has at least eight tires; a Class 3 truck at least ten; a Class 1 combination at least 18.
Brake response test: with the park brake applied, try to pull ahead gently; then release it, move slowly and apply the foot brake.
En route checks: tires, rims, lug nuts, hubs, brakes, coupling and electrical connections, lights, load security, leaks; use look, listen, smell and feel.
Post-trip defects are recorded on the trip inspection report started that day.
Vehicles 2.06 m (80 in.) or wider need clearance lights (amber front, red rear) and three identification lights (red at rear, amber at front).

Taxis, ambulances, emergency and tow vehicles

What Class 4 covers for hire, criminal record checks and the T restriction, emergency vehicle rules and the duties of other drivers, slowing to 60 km/h, tow truck lights and taxi driving practices.

Practise Taxis, ambulances, emergency and tow vehicles questions Flashcards Official chapter

Ch. 1 Licence Class 4 and Class 5 (pp. 5–7)

Class 4 covers ambulances used for hire, taxis and rideshare vehicles carrying 9 or fewer, and buses or PB/PC vehicles carrying 24 or fewer.
Taxi, limousine and rideshare drivers file a criminal record check with the company every year; an unsatisfactory check can bring a T restriction: no passengers for hire.
An experienced Class 5 driver may drive a taxi or rideshare vehicle seating 10 or fewer with two years post-GDL experience and a satisfactory record (under 12 points in two years, no impaired-driving suspension in 10 years).
Taxis, limousines and rideshare vehicles need a PMVI inspection every 12 months.
Taxis, ambulances, police vehicles and vans should keep at least a three-second following distance.

Emergency vehicles (pp. 131–132)

Emergency vehicles: police, firefighting (including municipal fire pumpers) and ambulances.
Normal rules of the road are suspended only while responding to a call (or chasing a suspect in a serious crime) and only while continually using siren and flashing lights.
Emergency drivers must still use due care and remain responsible for safe operation; they must not use the exemption when not on an emergency.
Other drivers must yield to an emergency vehicle with lights and siren, pull parallel to the right edge, and if in an intersection clear it and stop beyond.
Do not assume other drivers have seen or heard you; in cold weather with windows closed, sirens are hard to hear.
Drivers must slow to 60 km/h when passing a stopped emergency vehicle with flashing lights, unless it is on the other side of a divided highway.

Recovery vehicles (tow trucks) (pp. 132–133)

Use the tow truck's flashing lights only when the tow truck or the vehicle being helped is a hazard or obstruction.
A vehicle in tow needs temporary tail, brake and signal lights at its rear.
Flashing lights give a tow truck no special right-of-way privileges.
Remove wrecked vehicles and clean up collision debris; post a flagperson if a tow line crosses the highway.
Towing that makes the combination longer than the legal length needs a permit.
Drivers must slow to 60 km/h passing a stopped tow truck or service vehicle with amber, or amber and blue, flashing lights, unless it is across a divided highway.

Taxis (pp. 133–134)

Taxis travel about 64,000 km a year, close to four times the average car.
Pressures include radios and meters, emergencies, passengers urging speed, and unruly or intoxicated passengers.
Speeding and ignoring traffic controls in heavy traffic saves only a few minutes.
A taxi driver must obtain a criminal record check.
Check the vehicle before a shift; report defects to the dispatcher, and have a seriously defective taxi towed rather than driven.

Vehicle weights and dimensions

Legal length, width and height limits, A, B and C trains, axle definitions, overheight and power lines, red flags, clearance and amber lights, weight systems, spring road bans, permits and weigh scales.

Practise Vehicle weights and dimensions questions Flashcards Official chapter

Ch. 3 Interpretation (pp. 56–63)

Weights and dimensions are set by regulations under The Highways and Transportation Act, 1997; permits are available for oversize or overweight loads.
Posted signs limiting size or weight must always be obeyed, whatever your permit says.
A-train: tractor and semi-trailer towing a second trailer with an A-dolly (single hitch).
B-train: tractor and semi-trailer towing a second semi-trailer on a fifth wheel mounted at the rear of the first.
C-train: second trailer connected with a C-dolly (two parallel arms on two hitches).
A converter dolly (axles, fifth wheel, drawbar) turns a semi-trailer into a full trailer.
A bus is a motor vehicle designed to carry more than 15 passengers.
Tandem axle group: two axles more than 1 m and not more than 1.85 m apart. Tridem: three equally spaced axles with a spread of 2.4–3.7 m.
In an axle group, adjacent axles may differ in weight by no more than 1,000 kg.
A lift axle can raise its wheels off the road.

Vehicle dimensions (pp. 63–66)

Single vehicle: maximum 12.5 m long.
Combinations other than trains: maximum 23 m; A or C train 26 m; B train 27.5 m.
When towing two trailers, the lead trailer needs at least two axles or must be a fifth-wheel or gooseneck trailer.
Maximum width of vehicle and load: 2.6 m; mirrors may extend 30 cm and tie-downs 10 cm beyond that.
House trailers moved between sunrise and sunset: up to 3.05 m wide.
Maximum height: 4.15 m unless a permit says otherwise; know your total height at all times.
Low clearances may be unposted: underpasses, alley fire escapes, tree limbs, canopies, wires, shop doors; snow buildup reduces clearance.
Most power and telephone lines over provincial highways clear 5.2 m; above that, check with SaskPower and SaskTel.
Over-dimension loads: red flags at the extremities by day, clearance lights at night, and amber flashing lights on the cab.
Trucks with rear overhang need care in narrow alleys and tight turns.
Oversize farm equipment may travel between sunrise and sunset, except on certain high-traffic designated highways; the exemption does not cover equipment loaded on a truck or trailer.

Weight (p. 67)

Axle weights and gross weights are separate limits; you may exceed neither the registered weight nor the highway limit.
Saskatchewan has Primary, Secondary and Municipal highway weight systems; primary highways allow heavier gross weights.
Spring road bans usually start in March or April.
Overweight permits are limited to loads that cannot practically be divided.
Trucks must report to weigh scales when a sign directs them.

Truck handling: off-tracking, turns and turn-abouts

Turning radius and off-track, positioning for curves, left and right turns with a long unit, steering a semi-trailer backward, U-turns and the highway three-point and two-point turn-abouts.

Practise Truck handling: off-tracking, turns and turn-abouts questions Flashcards Official chapter

Ch. 6 Steering forward (pp. 104–110)

How sharply a vehicle turns depends on the front-wheel turning radius and the off-track of the rear wheels.
The inside front wheel pivots more sharply than the outside one.
Off-track: rear wheels follow a shorter radius than the front wheels; the longer the wheelbase, the greater the off-track.
A semi-trailer unit has off-track at the tractor's rear wheels and even more at the trailer's rear wheels.
On a curve to the right keep the front wheels near the centre line so the rear wheels do not drop off the edge; on a curve to the left keep the front wheels near the right edge so the rear wheels stay out of the other lane.
Left turns start from the left lane and should end in the left lane of the new street; keep the trailer within one metre of the centre line or curb to block traffic from passing on your left.
Where two or more lanes may turn left, use the lane furthest to the right for a wider radius.
Right turns start from the right lane close to the curb and end in the first available lane; position the trailer to block traffic passing on your right.
Soft shoulders may not support heavy vehicles during a turn.
Running rear wheels over curbs or sidewalks damages tires and endangers pedestrians.
The critical point of a turn is when the tractor is at its sharpest angle to the trailer, because mirror vision is limited.
Turning left from a one-way street with no multiple turn lanes: start from the far left and keep the trailer within one metre of the left side.

Steering backward, U-turns and turn-abouts (pp. 111–113)

When backing a semi-trailer, turn the tractor's front wheels opposite to the direction you want the trailer's rear to go.
A normal right-angle backing pattern is an S-shaped curve; otherwise the unit jackknifes.
Never U-turn a power unit and semi-trailer in a city, town or village; drive around the block. A U-turn is possible only on a wide divided four-lane highway when traffic permits.
Three-point turn-about: choose an intersection with a solid base, wide shoulders and clear views; turn off and stop well off the highway; flashers and horn; back straight across the highway when all four directions are clear; then turn onto the highway.
Two-point turn-about (no hard-surfaced intersection): signal right and get into the right lane, pass the intersection and stop with the trailer at least 9 m (30 ft.) past it, flashers and horn, start steering left about 9 m before the trailer reaches the approach, back in until straight, then signal and turn left onto the highway.
Use a guide whenever possible, because the two-point turn-about means backing to your blind side.

Loads, cargo securement and bills of lading

Weight distribution on trucks and trailers, securing and covering loads, overhang flags and lights, special cargos and livestock, prohibited shipments and what a bill of lading must contain.

Practise Loads, cargo securement and bills of lading questions Flashcards Official chapter

Ch. 6 About loads and loading (pp. 114–116)

Poor weight distribution can overload one axle or set of tires even when the total load is legal, and can bend the frame and misalign steering.
Load evenly side to side; a heavy load on one side overloads one spring and can lock the brakes on the light side.
A concentrated load belongs just ahead of the rear axle with its longest side on the floor.
Loading too far back lifts weight off the front tires and can make steering almost impossible.
A truck is designed for about 90% of the cargo on the rear tires and 10% on the front.
A trailer's cargo should be split equally between its rear tires and the fifth wheel.
Tailgate loading (all weight at the rear) should never be done.
A single unit truck's central loading point is midway between the back of the cab and the tailgate; a semi-trailer's is about the middle of the trailer.

Securing loads and projections (pp. 117–118)

Both driver and owner are responsible for making sure no load drops on the highway.
Check lashing ropes and binder cables periodically for slack or chafing.
Loose material (wood chips, refuse, gravel, stones) must be completely covered with a tarp; littering is chargeable to driver and owner.
An overhang must carry a red flag at its end from sunrise to sunset and a red light at its rear at night.
Extra-wide or long loads need a permit and the warning signs the permit requires.

Special cargos, livestock, prohibited shipments (pp. 118–119)

A vehicle used mainly to carry petroleum products or flammable or explosive liquids, loaded or empty, must stop at all uncontrolled railway crossings, as far right as possible and at least 5 m (15 ft.) from the nearest rail.
Livestock haulers must keep the vehicle clean and not overcrowded, protect animals from undue heat or cold, and separate different classes of livestock with a partition.
Take curves carefully with livestock, because the animals shift as the vehicle moves.
A public service vehicle carrying passengers must not carry live animals, acids, explosives, flammable materials or anything disagreeable or dangerous to passengers.
Food must not be stored or carried in premises used for vehicles, livestock or acids.

Bills of lading (p. 120)

A carrier must issue a bill of lading when it accepts freight for a public service vehicle.
It lists the carrier, shipper, place of acceptance, consignee, delivery place, contents and gross weight of each container, and any other participating carrier.
The original stays with the carrier; a duplicate original stays with the driver while the freight is aboard; another goes to the shipper on request or to the consignee.
Shipper and carrier sign to confirm the list is correct; no one may sign a bill they know is wrong.
The driver must show the duplicate bill of lading to a peace officer on demand.

Transporting dangerous goods

Reporting duties, TDG training certificates, consignor, carrier and consignee responsibilities, the nine hazard classes, labels, placards and UN numbers, routes and where the shipping document goes.

Practise Transporting dangerous goods questions Flashcards Official chapter

Ch. 10 Safe transport of goods (pp. 151–152)

Dangerous goods rules are harmonized across Canada and apply to air, marine, rail and road transport.
The person in charge must report immediately any release of dangerous goods, a reportable dangerous occurrence or collision, the loss or theft of certain goods, and a delay in delivering certain explosives.
Anyone who handles, offers or transports dangerous goods must be trained or work under the direct supervision of a trained person.
The employer must ensure training; the trained person receives a Transportation of Dangerous Goods certificate, renewed every 36 months.
Consignor (shipper): supplies the safety marks and product identification number, and the shipping document or waste manifest, to the first carrier.
Carrier: displays the right safety marks, replaces lost or damaged ones, makes sure documents travel with the load, segregates loads, refuses non-compliant shipments, keeps documents for two years.
Consignee: completes and forwards waste documents, and meets consignor requirements when returning uncleaned empty containers or vehicles.

Classifying and safety marks (pp. 152–153)

Nine classes: 1 explosives, 2 gases, 3 flammable liquids, 4 flammable solids, 5 oxidizing substances, 6 toxic and infectious, 7 radioactive, 8 corrosives, 9 miscellaneous.
Labels go on packages, cylinders and drums; placards go on large containers (over 450 L) and transport units.
A UN/product identification number is four digits (gasoline is UN1203) and is required for trailerload, truckload or bulk quantities.
Dangerous goods routes in cities, towns and villages are set by civic bylaw and posted with signs.

Documentation (pp. 153–154)

The consignor makes sure the shipping document is complete, in the required order, signed and given to the first carrier.
Driver in the cab: one copy within reach or in a pocket on the driver's door. Driver out of the cab: on the driver's seat or in the door pocket.
A detached trailer with dangerous goods left in a parking area: leave a copy with the person in charge of the area.
Otherwise keep the document in an accessible, identifiable waterproof container attached to the unit.
After unloading, if residue still creates a hazard, the document is marked "RESIDUE – LAST CONTAINED" until the unit is reloaded or cleaned and purged.
Waste dangerous goods travel with the prescribed manifest.
Placarded vehicles must stop at uncontrolled railway crossings.
A placarded vehicle cannot be used for a road test.

Buses and passenger safety

Class 2 buses, loading zones, bus turns and leaving the curb, passenger precautions, railway crossings with passengers, standing passengers, refusing passage and the Class 2 bus trip inspection.

Practise Buses and passenger safety questions Flashcards Official chapter

Ch. 1 Licence Class 2 (p. 3)

Class 2 covers buses seating more than 24 passengers while carrying passengers, plus Classes 3, 4 and 5.
Class 2 applicants write the Sign, Basic, Class 2, Class 3 and Class 4 papers and take a trip inspection and road test in a Class 2 vehicle.
The Class 2 trip inspection uses Schedule 2 or 3 and covers at least eight tires on a motor coach, all emergency exits and their alarm, passenger seats and interior lights.

Passenger carrying vehicles (pp. 126–131)

Safe operation comes before schedules.
Approach a loading zone so you can make a slow, smooth stop; keep doors closed until fully stopped; stop as close to the curb as possible.
Make sure the doors are closed before moving off, then accelerate smoothly.
Common causes of passenger injuries: poor positioning at the stop, loading where unsafe, sudden stops or starts with standees, sharp fast turns, misuse of doors — all preventable.
Every passenger vehicle must have at least two exits.
Sharp right turn: approach 1–1.5 m (3–5 ft.) from the curb, block traffic from passing on the right, go straight until the side street's curb line shows through the front door.
Left turn: start from the left lane about 1 m (3 ft.) from the centre line; go straight until the intersecting curb line shows through the front left window.
Leaving the curb: check the mirror and also look over your left shoulder; signal only when ready to move; watch the rear overhang near poles and pedestrians.
Parked-car clues: wheels turned out, driver at the wheel, exhaust, brake lights.
Avoid backing a bus; if you must, go slowly with a guide.
Before leaving the bus: stop the engine, remove the key, set the brakes, lowest gear for a manual (out of gear for an automatic).
Keep doors closed while moving; never load beyond licensed capacity.
At uncontrolled railway crossings a bus carrying passengers stops as far right as possible, at least 5 m (15 ft.) from the nearest rail, and may open the door to listen.
Do not collect fares, load or unload while moving, or chat unnecessarily with passengers while driving.
No passenger may sit to the driver's left; a sedan may seat at most two passengers on the front seat beside the driver if there is room.
Standing is not allowed on public service vehicles except local transit; no riding on running boards or fenders; transit standees must not block the driver's right-side view.
Passage may be refused only when the vehicle is full, or the person is intoxicated, disorderly or using profane language.

School buses and the S endorsement

Who may drive a school bus, re-testing every five years, safety lights and stop arm distances, what a school bus driver must and must not do, railway crossing steps, loading and unloading students.

Practise School buses and the S endorsement questions Flashcards Official chapter

Ch. 8 Becoming a school bus driver (p. 135)

Age 18, Class 1–5 licence, not a novice driver, medical and school bus exams, and the S endorsement.
A Class 5 licence is the minimum and allows a school bus with up to 15 passengers; air brakes also need the A endorsement.
The S endorsement must be renewed by re-testing every five years; a reminder comes 90 days before the anniversary, and re-testing inside that window keeps the original date.
A current satisfactory medical must be on file with SGI.
The daily trip inspection is the driver's responsibility; school bus inspections use Schedule 2 and include safety lights, stop arm, strobe light, first aid kit and emergency exits.
Clean floors, steps, mirrors, windows, seats and exterior weekly or more often.

School bus driver regulations (pp. 136–137)

Turn on safety lights at least 100 m before stopping where the limit is over 50 km/h, and at least 25 m before where it is 50 km/h or less.
Use the strobe light whenever carrying passengers outside a city, town or village.
Use the stop arm when stopped to load or unload, unless a municipal bylaw prohibits it.
At a school on a two-way street, stop on the school's side so students step directly onto the sidewalk.
Objects students cannot hold go as low and as close to the front barrier as possible, not higher than the barrier.
A driver must not drink alcohol in the eight hours before driving a bus.
Never leave passengers on the bus unless an interlock is set, or the engine is off, key removed and parking brake on.
Headlights and tail lights must be on; all passengers seated before moving.
No backing on school grounds without a responsible person guiding.
Never carry firearms, explosives or other dangerous items.
Before entering a provincial highway, stop 4–10 m from the travelled portion (inside towns over 1,000 people it is not treated as a highway).
Safety lights only while stopping or stopped to load or unload; stop arm only while stopped to load or unload.

Railway crossings (p. 138)

School buses stop at every railway crossing unless automatic signals show it is clear.
Steps: signal right and move right; cancel the signal and turn on four-way flashers at least 100 m before (over 50 km/h) or 25 m (50 km/h or less); stop 4–10 m from the crossing; open the door and look both ways; close the door; cross without shifting gears; check mirrors; then flashers off, left signal and rejoin traffic.

Notifying the employer and driving techniques (pp. 139–144)

Promptly tell the school board or employer about convictions under the Criminal Code, The Traffic Safety Act or alcohol laws, any licence suspension or restriction, and any medical condition affecting safe driving.
Brake gently over a long distance with the wheels straight, because passengers are not secured.
The S road test includes backing straight and a two-point turn.
Drive in the centre of the lane; convex mirrors cover the right side.
Pass only on a long straight stretch with at least 50 seconds of sight distance.
At a stop: stay at least 1 m (3 ft.) from waiting students; set the parking brake and shift to neutral while loading.
In urban areas without safety lights, unload on the student's side of the street near home, and if they must cross, near an intersection after the bus has cleared it.
Report motorists who pass illegally to police with the licence plate number.
Emergency evacuation training information comes from the Saskatchewan Safety Council.

Coupling, uncoupling and trains

Coupling and uncoupling a tractor-trailer with air ride suspension step by step, tug tests, landing gear, hooking up a pup-train and converter dolly, safety chains, draw-bar rules and breakaway brakes.

Practise Coupling, uncoupling and trains questions Flashcards Official chapter

Ch. 6 Coupling a tractor-trailer with air ride suspension (pp. 121–122)

Inspect the area in front of the trailer, align the tractor and back slowly until the fifth wheel is just ahead of or slightly under the trailer, not against the kingpin.
Tractor checks: air lines and cord secure, fifth-wheel horns tilted down, jaws open (unlocked), fifth wheel firmly mounted, slide pins locked, enough grease.
Trailer checks: couplers undamaged, kingpin and apron not worn or cracked, kingpin lined up with the jaws, trailer height right for the fifth wheel, axle slide pins locked, trailer secured, cargo secure.
Dump the tractor air suspension and back under the trailer, stopping before the kingpin; restore normal ride height; back slowly until the jaws lock.
Do at least two tug tests and look to confirm the jaws are closed around the kingpin.
Connect the electrical cord and check trailer lights; connect air lines; push in the red trailer supply button; check gauges and the hand valve.
Make sure trailer air bags inflate, raise both landing gear legs and stow the handle.
Drive ahead slowly and apply the trailer brakes with the hand valve; all trailer wheels should be turning before the test.

Uncoupling (p. 123)

Choose level, firm ground; park in a straight line; chock trailer wheels if needed.
Deflate trailer air bags; lower the landing gear (dolly pads if loaded or on poor ground) until most weight is off the tractor but the trailer still rests on the fifth wheel.
Disconnect lines and stow them in the dead-end couplers.
Unlock the fifth wheel, pull ahead until the kingpin clears the jaws, dump the air suspension, then pull ahead until the fifth wheel is out from under but the frame is still under the trailer.
Confirm the landing gear and ground hold the trailer, then drive clear and restore ride height before leaving.

Train or pup-train and connecting vehicles (pp. 124–125)

A train pulls another trailer behind the tractor-trailer using a converter dolly.
Pull with steady power on straight stretches; if the rear trailer fishtails, apply trailer brakes lightly and increase power.
Avoid sudden lane changes, sharp turns and speeds too fast for conditions.
Check the rear hitch, safety catch, chains or cables, and that air lines between trailers do not sag.
Hook-up order: park and brake the rear trailer, line up the dolly with its kingpin, couple tractor and lead trailer, back up to the dolly, inspect the hitch, hook the dolly tongue to the pintle hook by hand and fasten the latch, chain and safety pin.
Cross the safety chains so a broken tongue is held off the road.
Some companies colour-tape service and emergency lines on dollies to prevent mix-ups.
Draw-bars must attach directly to the vehicle frame; any coupling other than a fifth wheel needs an auxiliary chain or cable of equal strength.
Except for pole trailers, the draw-bar may not exceed 1.83 m (6 ft.).
If a trailer whips or swerves, slow down and stop to find the cause.
Trailers with brakes must have a device that applies them automatically if the trailer breaks away.

Tractor-trailer operation and the Class 1 licence

What a Class 1 licence covers, MELT training hours, the Class 1 road and trip inspection test, fifth-wheel checks, combination braking, jackknifing, offset and alley dock backing, and heavy trailers.

Practise Tractor-trailer operation and the Class 1 licence questions Flashcards Official chapter

Ch. 1 Licence Class 1 and examinations (pp. 2, 12–15)

Class 1 is for power units with semi-trailers and trucks towing units heavier than 4,600 kg; it also covers Classes 2–5.
Requirements: age 18 and not novice, medical, vision, six knowledge papers (Class 1, 2, 3, 4, Basic, Sign), MELT, trip inspection and road test in a Class 1 vehicle.
Mandatory Entry-Level Training: at least 121.5 hours — 47 classroom or online, 17.5 in the yard, 57 behind the wheel — in 11 modules, each of which must be passed.
Visitors and temporary foreign workers cannot drive semis on their existing licence; they need MELT and a Saskatchewan Class 1.
MELT must be completed before booking the Class 1 road test; the training school updates your SGI file.
Class 1 road test vehicle: a three-axle power unit and at least a 48 ft trailer.
The Class 1 trip inspection uses a random block of components; you list defects and say what action you would take.
Heavy trailer learner privileges need only the medical and heavy trailer written tests; full Class 1 learner privileges need all seven papers.

Class 1 trip inspection (pp. 74–79)

Tractor and trailer are inspected coupled; a typical combination has at least 18 tires and rims.
Fifth-wheel checks: mounted securely to the frame, jaws closed around the kingpin, locking handle locked, slide locking pins locked.
Trailer checks include reflective tape covering at least 50% of each side, glad hands connected without leaks, landing gear raised with the handle stowed, all four tandem slide pins locked, rear impact guard intact.
Brake response tests: trailer emergency brakes on and tractor brakes off, pull gently; tractor park brakes on and trailer brakes off, pull gently; then trailer service brakes with the hand valve; then the foot brake.

Combination handling (pp. 32–33, 37, 46–47)

Foot valve applies tractor and trailer brakes together at equal pressure; the hand valve applies trailer brakes alone and can add trailer pressure during a foot application.
Over-braking in curves or on slippery roads can jackknife a combination.
Engine retarders on slippery roads can lock the drive wheels and jackknife a tractor-trailer.
Applying gentle power through a curve helps counter centrifugal force.
With a semi-trailer parked, apply spring brakes on both units; on a hill without a curb leave the tractor wheels straight and block the wheels.
Offset backing to the driver side and alley dock from the driver side are part of the Class 1 road test.

Jackknifing (p. 149)

Tractor jackknife: the tractor's rear skids sideways. Trailer jackknife: the rear of the trailer swings around.
Beyond about 15 degrees a jackknife is almost impossible to recover, and it can get there in about 1.5 seconds.

Air brakes: who needs the A endorsement and braking principles

When the A endorsement is required, heat, friction and traction, how weight and speed change braking power, leverage and air pressure, and the three parts of stopping distance.

Practise Air brakes: who needs the A endorsement and braking principles questions Flashcards Official chapter

Ch. 1 Requirements for A Endorsement (p. 1)

An A endorsement is needed to drive a vehicle with air brakes.
Not needed: Class 3 or 5 vehicles licensed as farm trucks, and trucks with air-over-hydraulic brakes.
You may drive an air-brake vehicle as a learner beside someone with an A endorsement, if your licence covers that vehicle type.
To qualify: pass the written air brake test and complete a practical demonstration, unassisted and without a checklist, on equipment you provide.
Book through 1-844-TLK-2SGI or MySGI.

Heat, energy, traction, friction (pp. 2–3)

The engine turns heat energy into motion; brakes turn motion back into heat through friction.
Traction is the tire's grip on the road; the final factor that moves or stops a vehicle is traction, not the engine or brakes.
Friction resists movement between two surfaces; brake linings pressed on drums make friction and heat.
Drums absorb heat and pass it into the air; how much heat a drum can absorb depends on its metal thickness.
Stopping in one tenth of the time it took to accelerate needs ten times the acceleration power.
A poorly adjusted brake makes the other brakes do more than their share and overheat.
Most linings work best around 120 °C, should not exceed 250 °C, and fail around 300 °C.

Speed, weight, distance and leverage (pp. 3–5)

Brake power needed varies directly with weight and with the square of speed.
Double the weight: double the stopping power. Double the speed: four times. Double both: eight times.
No vehicle has enough braking power once it exceeds its limits.
A lever multiplies force: a 4:1 lever turns 100 kg of push into 400 kg.
psi means pounds per square inch.
120 psi on a 30 square inch diaphragm gives 3,600 lb. of force; through a 6-inch slack adjuster that is 21,600 inch-pounds (1,800 foot-pounds) of torque.

Stopping distance (p. 6)

Stopping distance = reaction time + brake lag + braking distance.
Reaction time is about 3/4 to 1 1/2 seconds; brake lag in a well-maintained air system is about 4/10 of a second.
Braking distance depends on lining friction, drum heat dissipation and tire grip.
Even with well-adjusted brakes a heavy vehicle will not stop as quickly as a passenger car.

Air brake components and system operation

Compressor and governor pressures, reservoirs and draining, foot valve, brake chambers, S-cam brakes and disc brakes, safety valve, check valves, gauges, relay and quick-release valves, low air warning, ratio valve and air dryer.

Practise Air brake components and system operation questions Flashcards Official chapter

Ch. 3 Basic system components (pp. 8–11)

Five basic components: compressor (builds and keeps pressure), reservoirs (store air), foot valve (draws air for braking), brake chambers (turn air into mechanical force), shoes and drums or rotors and pads (make friction).
Compressors are gear or belt driven, run whenever the engine runs, and are loaded or unloaded by the governor; self-lubricated compressors need their oil checked and changed.
The governor cuts out at 120–145 psi (828–1,000 kPa) and cuts in at no less than 100 psi (690 kPa), normally 20–25 psi below cut-out.
Reservoirs must hold enough air for several applications if the engine stops; you cannot apply more pressure than is in the reservoir.
Every reservoir has a draincock; drain all reservoirs completely once a day when in use.
The foot (treadle) valve delivers more air the farther it is pressed; releasing it exhausts air from the service brakes.
A service brake chamber's diaphragm pushes the push rod when air enters; a return spring pulls it back when air is released.
S-cam brakes: the slack adjuster turns the cam, the rollers force the shoes against the drum; front brakes have chamber and slack adjuster on the backing plate because of steering.
Thin or distorted drums, weak return springs, wrong linings, poor adjustment or grease on linings make braking erratic.
Air disc brakes have an internal automatic adjuster inside a sealed unit.

Basic system operation and additions (pp. 12–18)

Supply (wet) reservoir: first tank from the compressor, where most water and oil collect; service reservoir supplies the brakes.
Safety valve: protects the supply reservoir, usually set at 150 psi; if it blows, the governor is faulty and needs a qualified person.
One-way check valve between supply and service reservoirs stops air flowing back if the compressor or supply tank fails.
The dash air pressure gauge is plumbed after the service reservoir.
Relay valve near the rear chambers reduces brake lag on long vehicles; the foot valve line becomes a control line.
Low air warning: switch after the supply reservoir, activates below 60 psi (414 kPa); the light is mandatory, the buzzer optional; stop and find the cause.
Stop light switch: air-operated electrical switch that lights the brake lights on any application.
Quick-release valve: exhausts air near the chamber so brakes release faster.
Front axle ratio valve: reduces front brake pressure on light applications, full pressure from about 60 psi; older trucks may have a dash switch cutting front pressure by 50%.
Air dryer: desiccant filter removing most moisture before the reservoirs, helps prevent freeze-ups; reservoirs must still be drained daily.

Dual-circuit systems and spring brakes

Primary and secondary circuits, what happens when one fails, spring-brake chambers, parking-brake valves and the pressures at which spring brakes drag and apply, compounding, blended air, the modulator valve and caging.

Practise Dual-circuit systems and spring brakes questions Flashcards Official chapter

Ch. 5 Dual air systems (pp. 19–23)

Almost all heavy vehicles use a dual-circuit system so one failure does not cause total brake loss.
Air goes from the supply reservoir through one-way check valves to the primary and secondary reservoirs.
Normally the primary reservoir operates the rear brakes and the secondary operates the front brakes.
The dual foot valve is two valves in one, one section per circuit.
If one circuit fails, the other keeps working; braking is lost only if both circuits lose air.
Each circuit has a low pressure warning and a gauge.

Spring brakes and parking (pp. 24–25)

A spring-brake chamber acts as service brake, emergency brake and parking brake; it is always on the front axle of a tandem and often on both.
Spring brakes are applied by spring force and released by air pressure, the opposite of a service chamber.
They make reliable parking brakes because they need no air to hold.
Never take a spring brake apart; the spring can cause serious injury.
If air cannot be restored, the spring can be compressed with the wind-off (caging) bolt.
With a push-to-release park valve, spring brakes may start dragging below about 70 psi and fully apply between 20 and 45 psi.
If the park button does not pop out, walk back and check: slack adjuster and push rod at 90° means applied.
Some toggle valves do not apply automatically; when air is restored the brakes release unless the toggle was set to park.
Compounding: a service application with the park brake on; it can damage components, so release the park brake before a foot application.
An anti-compound line releases spring-brake pressure equal to the service pressure applied.

Blended air, two-way check valve and modulator (pp. 27–29)

Blended air for the park control valve comes from both circuits through a two-way check valve.
The two-way check valve sends air from whichever source has higher pressure, so a single-circuit failure does not apply the spring brakes.
With a modulator valve, a primary circuit failure lets the foot valve apply the drive-axle spring brakes in proportion to pedal pressure.
Below 70 psi the spring brakes drag; at about 20 psi the dash valve exhausts the rest and they apply fully.
After all air is lost, the only ways to move are repairing and recharging, or caging the brakes with the wind-off bolts.

Tractor and trailer air systems

The tractor protection system, trailer-supply valve, supply and service lines, gladhands, the hand valve, relay emergency valve, breakaways and line ruptures, bobtail valve and trailer spring brakes.

Practise Tractor and trailer air systems questions Flashcards Official chapter

Ch. 6 Tractor protection system (pp. 31–33)

The trailer-supply valve and the tractor protection valve form the tractor protection system, which keeps the tractor's air if there is no trailer or the trailer breaks away; it must activate at no less than 20 psi.
Trailer-supply valve: usually a red octagonal dash button; it controls the tractor protection valve and charges the trailer reservoirs through the supply line. Also called the emergency valve.
It is fed through a two-way check valve from the higher-pressure circuit.
Automatic types close when pressure drops to about 20 psi; some buttons do not pop out, so confirm the spring brakes applied.
Manual types have NORMAL and EMERGENCY positions and must be moved to EMERGENCY by hand.
Rapid air loss in the supply line causes "dynamiting", an emergency application of the trailer brakes.
The tractor protection valve opens its service-line port once supply-line pressure reaches 45 psi.
The supply line holds the same pressure as the highest-pressure circuit when the supply valve is open; the service line holds air only during a brake application.
Hand valve ("spike"): applies only the trailer brakes; used for coupling and uncoupling, and gently to help straighten a skidding tractor — never when the trailer skids; never as a parking brake.

Gladhands, bobtail valve and trailer system (pp. 34–36)

Two-way check valves let the trailer get a higher application than the tractor when both hand and foot valves are used.
Gladhands: clean them, join seals at 90° and snap down; use dead-end couplers or lock service and supply gladhands together when bobtailing; secure lines so they do not bounce.
Bobtail proportioning relay valve reduces service pressure when no trailer is attached, shortening stops; the pedal must be pushed farther.
The trailer reservoir has a draincock; the relay emergency valve relays air to trailer chambers, makes an emergency application if the supply line parts, and has a check valve so trailer air cannot flow back.
Test the relay emergency valve by closing the supply valve or disconnecting the supply line with the valve open.

Applications and failures (pp. 38–50)

Foot application: trailer brake pressure equals foot valve control pressure, minimizing lag.
Trailer brakes must never hold an unattended parked vehicle.
Breakaway: supply line loss triggers the trailer emergency application, the supply valve closes, the tractor keeps its air.
Service line rupture: nothing happens until you brake; a held application then bleeds tractor air until the protection system closes and the trailer goes into emergency.
Supply line rupture: trailer brakes apply at once and the supply valve closes; tractor air shuts off immediately or bleeds to at least 20 psi.
Loss of supply reservoir air: check valves keep primary and secondary air for a limited number of stops.
Spring-brake trailers have a trailer spring-brake valve that isolates front and rear service reservoirs, ignores slow supply leaks, and applies spring brakes after a rapid supply loss.

Brake adjustment and air brake pre-trip tests

Why poor adjustment causes brake failure, push rod stroke limits, manual and automatic slack adjusters, the hammer test, service tests, steep downgrade checks, and pre-trip air tests for single and combination units.

Practise Brake adjustment and air brake pre-trip tests questions Flashcards Official chapter

Ch. 7 Within an inch of your life (pp. 52–53)

Poor brake adjustment is the most common cause of brake failure.
A type 30 chamber has 2 1/2 in. of stroke; a correctly adjusted brake has about 1/2 in. of slack, leaving 2 in. in reserve; at 1 in. of slack it must be adjusted.
At an 80 psi application, component stretch makes a 1 in. slack brake stroke 1 3/4 in.; a hot drum adds about 1/2 in. more.
Lining wear the thickness of three sheets of paper adds about 1/4 in. of stroke and can bottom out the chamber.
Poorly adjusted brakes can lengthen stopping distance by up to 75%.
Badly adjusted brakes may feel fine under light braking; the problem appears under moderate to heavy braking.
Check by prying the slack adjuster to pull the push rod out; 1 in. or more of travel means adjustment is needed.
Stroke limits depend on chamber size, e.g. type 30 is 2 in. and type 30 long-stroke is 2 1/2 in.

Slack adjusters and adjustment (pp. 54–57)

Slack adjusters link the push rod to the camshaft and keep stroke and lining clearance right, manually or automatically.
Automatic slack adjusters must be checked daily: under 1 in. when pulled by hand, under 2 in. when applied.
Two to four 100 psi applications a day usually keep automatics adjusted; up to 12 if badly out; still out means a qualified person must repair them.
Do not adjust automatics yourself unless a mechanic or trainer who knows that type has trained you.
Preferred manual check: mark the push rod released, make a full application, mark again; compare with the 1 1/2 in. maximum.
Adjust so there is 1/2 to 3/4 in. of travel when pulled by hand; tap the drum: a ringing sound means clear, a dull sound means drag.
Service tests: slack adjusters move freely; released angle more than 90°; at a 20 psi application no less than 90° and equal travel on all.
Push rod force stays steady to 2 in. of stroke, then drops sharply.
The practical test includes adjusting a manual slack adjuster and explaining how automatic ones are adjusted.
At "trucks stop here, check brakes" signs: check compressor pressure, push rod travel, air leaks, gladhands and lines, and drum, bearing and tire temperatures.

Pre-trip procedures (pp. 58–61)

Start with the park brake set, wheels blocked and tanks drained if possible; check compressor, belts and lines.
Governor: cut-out 120–145 psi; fan the brakes until cut-in, normally 20–25 psi lower but at least 100 psi.
Single unit, engine off, full foot application held: no more than 1 psi loss in one minute.
Combination unit: no more than 4 psi loss in one minute.
Fan the brakes: low air warning at no less than 60 psi; the trailer supply valve should shut off at no less than 20 psi.
Build-up test at 600–800 rpm: 85 to 100 psi in less than two minutes (time the primary needle, trailer not charged).
Combination: break the service line (no air loss), break the supply line (trailer brakes apply, no loss from the trailer line, tractor air shuts off at no less than 20 psi).
Final tests: park brake hold, trailer emergency hold, hand valve, then a foot-brake application while moving slowly.
The driver alone is responsible for the braking system being safe before the vehicle moves.

Written in our own words from: SGI Professional Driver's Handbook

FAQ

Saskatchewan Commercial study guide: common questions

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