Q Endorsement & Test Rules
Not publishedof exam
Braking Fundamentals
Not publishedof exam
Compressed Air & Reservoirs
Not publishedof exam
Vehicle Braking Circuits
Not publishedof exam
Tractor Air CircuitsTrailer Air CircuitSpring & Parking BrakesPark Valve Pop-OutPrimary vs Secondary
System Operation & Failures
Not publishedof exam
Circuit Failure SignsSupply Circuit FailureSecondary Circuit FailureTrailer Line FailureSpring Brake Cage Safety
Foundation Brakes & Adjustment
Not publishedof exam
Inspections & Downgrade Driving
Not publishedof exam
Quick Facts
- Exam
- AB Air Brake (Q)
- Format
- 30 MCQ
- Pass Score
- 25/30 (83.33%)
- Test Ends
- After 6 wrong answers
- Time Limit
- No limit
- Course
- 6.5 hrs + practical
- Practical Test
- 15 min limit
- Retest Rule
- Different day required
- Language
- English only
Air-Over-Hydraulic vs Air-Actuated Hydraulic
Air-Over-Hydraulic
- Some axles air, some hydraulic
- Needs Q or Class 1
Air-Actuated Hydraulic
- Air only boosts hydraulic system
- Q endorsement NOT required
Mixed axles vs boosted hydraulic
Test Format Facts
- 30 questions
- Total knowledge test length
- 25 correct
- Passing threshold (83.33%)
- 6 wrong
- Test ends automatically
- No time limit
- Untimed knowledge test
- English only
- No translated or paper test
- Different day
- Required for every retest
- Unlimited attempts
- No cap on retests
Approved Course Path
- 6.5 hours
- Minimum classroom training
- Practical training
- Instructor demo plus 2 practices
- 15 minutes
- Practical assessment time limit
- One-on-one
- Practical assessment format
- Notice of Completion
- Form for registry agent
- Valid licence
- Non-suspended Alberta licence needed
Q Endorsement Scope
- Q endorsement
- Required Class 1-5 air brakes
- Class 1 path
- Q earned before Class 1
- Single-motor farm
- Exempt from Q endorsement
- Farm combination
- Still needs Q for Class 1
- Air-over-hydraulic
- Needs Q or Class 1
- Air-actuated hydraulic
- Q NOT required
Stopping Distance Order
Perceive, react, lag, then brake
3/4 sec perceive3/4 sec react4/10 sec lagThen braking distance
Stopping Power Factors
- Traction
- Tire-road friction, biggest factor
- GVWR doubled
- Stopping power doubles
- Speed doubled
- Stopping power 4x
- Weight+speed doubled
- Stopping power 8x
- Brake condition
- Misaligned brakes overload others
Stopping Distance Parts
- Perception time
- About 3/4 second to see
- Reaction time
- About 3/4 second to press
- Brake lag time
- About 4/10 second, air travel
- Braking distance
- Travel during full brake force
- Total stopping distance
- Sum of all four distances
- Downgrade
- Increases stopping distance
- Upgrade
- Decreases stopping distance
Key PSI Checkpoints
60 warns, 120-135 cuts out
60 PSI: warning light120-135 PSI: cut-out20-25 below: cut-in20-45 PSI: park pop
Cut-In vs Cut-Out
Cut-Out
- Compressor stops pumping
- 120 to 135 PSI
Cut-In
- Compressor restarts pumping
- 20-25 PSI below cut-out
Stops vs restarts compressor
Compressor & Governor
- Compressor
- Engine-driven, supplies air
- Fast idle
- About 1200 RPM for test
- Build-up test
- 50 to 90 PSI
- Build-up time
- Within 3 minutes
- Cut-out
- 120 to 135 PSI
- Cut-in
- 20-25 PSI below cut-out
Low-Air Warning vs Governor Cut-In
Low-Air Warning
- Alerts driver by 60 PSI
- Signal to stop safely
Governor Cut-In
- Restarts compressor automatically
- 20-25 PSI below cut-out
Driver alert vs auto restart
Reservoirs & Air Quality
- Wet tank
- First reservoir, traps moisture
- Draining
- Often; fully drain each shift
- Air dryer
- Cools and dries compressor air
- One-way check valves
- Block backward air loss
- Safety valve
- Backup pressure relief device
Trailer Pop-Out Range
Park 20-45, trailer supply 40-60+
Park valve: 20-45 PSITrailer supply: 40-60+ PSIBoth spring-applied
Primary vs Secondary Circuit
Primary Circuit
- Controls drive axle brakes
- Nearest the brake pedal
Secondary Circuit
- Controls steer axle brakes
- Backs up primary failure
Drive brakes vs steer brakes
Tractor Air Circuits
- Supply circuit
- Compressor to wet tank
- Primary circuit
- Rear drive axle brakes
- Secondary circuit
- Front steer axle brakes
- Park/emergency circuit
- Controls the spring brakes
- Dual gauges
- Show each circuit pressure
Supply Line vs Control Line
Supply (Emergency) Line
- Fills trailer air reservoirs
- Applies trailer springs if lost
Control (Service) Line
- Sends variable pressure signal
- Matches pedal application force
Fills tank vs signals brakes
Trailer Air Circuit
- Supply (emergency) line
- Fills trailer air reservoirs
- Control (service) line
- Signals trailer brake force
- Glad hands
- Trailer air line couplers
- Tractor protection valve
- Isolates trailer air loss
- Trailer supply pop-out
- 40-60 PSI or higher
Spring Brakes vs Service Brakes
Spring (Park) Brakes
- Mechanical spring force applies
- Applies if air is lost
Service (Foot Valve) Brakes
- Air pressure applies force
- Capped by reservoir PSI
Mechanical park vs air service
Spring & Parking Brakes
- Spring brakes
- Air holds off, spring applies
- Park valve pop-out
- 20-45 PSI
- Compounding brakes
- Never combine spring plus service
- Caging
- Manual release; chock wheels first
- Breakaway protection
- Lost air auto-applies springs
Warning & Failure Response
- Low-air warning light activates→Stop safely, rebuild air(Below 60 PSI)
- One reservoir gauge keeps dropping→Suspect a failed circuit(Stop safely, get service)
- Supply circuit line ruptures→Check valves protect service air(Brakes still work)
- Secondary circuit fails→Steer axle brakes stop applying(Primary keeps park released)
- Trailer service line fails→Pull red trailer supply valve(Applies trailer spring brakes)
- Trailer supply line ruptures→Tractor protection isolates trailer air(Trailer springs auto-apply)
- Vehicle must move, no air→Cage the spring brake(Chock wheels first)
Circuit Failure Signs
- Failed circuit
- One gauge keeps dropping
- Reduced braking
- Stop safely, get repaired
- Supply failure
- Gauges stop rebuilding pressure
- Secondary failure
- Steer brakes stop applying
- Trailer service line failure
- Trailer brakes stop responding
- Trailer supply line loss
- Springs auto-apply immediately
Stroke Limit Ladder
Type 20 smallest, Type 30 long-stroke biggest
Type 20: 1-3/4 inType 30: 2 inType 30 long: 2-1/2 in
Automatic vs Manual Slack Adjuster
Automatic Adjuster
- Self-adjusts during each stop
- Still needs stroke checked
Manual Adjuster
- Needs scheduled hand adjustment
- Forcing it hides problems
Self-corrects vs hand-adjusted
Foundation Brake Parts
- Brake chamber
- Converts air into force
- Pushrod
- Transfers force to slack
- Slack adjuster
- Lever arm to S-cam
- S-cam
- Rotates, spreads brake shoes
- Automatic adjuster
- Self-corrects for lining wear
- Manual adjuster
- Needs scheduled hand adjustment
Pushrod Stroke Limits
- Type 20 chamber
- Max 1-3/4 in (45 mm)
- Type 30 chamber
- Max 2 in (51 mm)
- Type 30 long-stroke
- Max 2-1/2 in (64 mm)
- Measured applied
- Full application, not partial
- Brake fade
- Hot drum loses friction
- Uneven adjustment
- Overworked brakes can skid
Applied Leak Limits
4 for power unit, plus 2 per trailer
4 PSI power unit+2 PSI each trailer2-minute full application
Trip Inspection Sequence
- Vehicle on level ground→Chock wheels, visual check(Step 1)
- Engine off, key in run→Push red trailer supply valve(Park valve pulled out)
- Both trailer lines disconnected→Supply valve pops 40-60+(PSI or higher)
- Push yellow park control valve→Pump foot valve, check pop(20-45 PSI)
- Engine at fast idle→Build-up 50-90 PSI, 3 min(About 1200 RPM)
- Pressure built to system max→Governor cuts out 120-135(PSI)
- Pump brakes to reduce pressure→Governor cuts in 20-25 below(cut-out pressure)
- Full service brake applied 2 min→Max 4 PSI, +2/trailer(After pressure stabilizes)
- Chocks removed, springs released→Test foot valve, then trailer(Step 6 response test)
Trip Inspection Steps
- Step 1
- Chock wheels, visual check
- Step 2
- Tractor protection system check
- Step 3
- Park control valve check
- Step 4
- Supply circuit build-up check
- Step 5
- Air system leak test
- Step 6
- Service brake response test
Downgrade Driving Picker
- Approaching a long downgrade→Downshift before the crest(Use engine compression)
- Descending the grade→Apply steady, moderate pressure(Never pump the brakes)
- Before starting a descent→Test brakes, watch gauge(No abnormal pressure loss)
- Trailer hand valve overused→Risk trailer brake failure(Can cause a jackknife)
- Coming to a full stop→Even pressure, then ease off(Release just before stopping)
Leak & Warning Limits
- Low-air warning
- Activates by 60 PSI
- Applied leak test
- 2-minute full application hold
- Power unit limit
- Max 4 PSI loss
- Per trailer limit
- Plus 2 PSI loss
- Warning response
- Stop safely, rebuild air
Downgrade Driving Technique
- Downshift early
- Before descending the grade
- Engine compression
- Controls speed on grades
- No pumping
- Wastes air on long grades
- Retarders
- Assist descents, avoid poor conditions
- Overused trailer valve
- Can cause trailer brake failure
- Pre-descent test
- Check gauge, apply, watch loss
Common Traps
Cut-In vs Cut-Out Pressure
Cut-out stops near 120-135 ≠ Cut-in restarts 20-25 lower
Low-Air Warning vs Park Pop
Warning fires by 60 PSI ≠ Park pops 20-45 PSI
Free Play vs Full Stroke
Stroke measured fully applied ≠ Partial application hides defects
Supply Line vs Control Line
Supply fills trailer air tanks ≠ Control signals brake force
Primary vs Secondary Circuit
Primary brakes the drive axle ≠ Secondary brakes the steer axle
Caging Without Chocking Wheels
Caging releases the spring hold ≠ Always chock wheels first
Pumping Brakes On Downgrades
Pumping wastes air pressure fast ≠ Use steady moderate pressure instead
Last Minute
- 1.30 questions, 25 correct to pass
- 2.Test ends after 6 wrong answers
- 3.No time limit; retest different day
- 4.Governor cuts out 120-135 PSI
- 5.Cut-in is 20-25 PSI below cut-out
- 6.Build-up: 50-90 PSI in 3 minutes
- 7.Low-air warning lights by 60 PSI
- 8.Park valve pops 20-45 PSI
- 9.Trailer supply pops 40-60+ PSI
- 10.Leak cap: 4 PSI + 2/trailer
- 11.Chock wheels before caging spring brakes
- 12.Never pump brakes on long downgrades
- 13.Do not combine spring + service brakes
- 14.Downshift early; never pump on grades
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