Air Compressor
Pumps air into the air storage tanks.
Getting Started: Understanding the CDL Air Brakes Test
Free knowledge base
CDL Air Brakes Test — key terms, tricks & tips
Everything from the course in one searchable place: 183 entries. Use it to review before a practice test or look up a word you forgot.
183 results
Air Tanks
Reservoirs for storing compressed air.
Getting Started: Understanding the CDL Air Brakes Test
Brake Chambers
Convert air pressure into mechanical force to apply brakes.
Getting Started: Understanding the CDL Air Brakes Test
Slack Adjusters
Mechanisms that adjust the distance of brake pushrod travel.
Getting Started: Understanding the CDL Air Brakes Test
Foot Valve
Driver-operated valve controlling air to brake chambers.
Getting Started: Understanding the CDL Air Brakes Test
Low Air Warning
Audible or visual signal when air pressure drops too low.
Getting Started: Understanding the CDL Air Brakes Test
Spring Brakes
Emergency and parking brakes, applied by springs when air pressure is lost.
Getting Started: Understanding the CDL Air Brakes Test
Glad Hands
Couplings used to connect air lines between vehicles.
Getting Started: Understanding the CDL Air Brakes Test
What to Expect on the CDL Air Brakes Test
To remember the three main air brake tests: 'LATE' – Loss of Air, Air Warning, Trailer (emergency brake pop-out).
Getting Started: Understanding the CDL Air Brakes Test
What to Expect on the CDL Air Brakes Test
California's CDL Air Brakes Test emphasizes detailed knowledge of the air brake system's components and the precise steps for the three air brake tests: the air loss rate, low air warning, and emergency brake pop-out tests.
Getting Started: Understanding the CDL Air Brakes Test
What to Expect on the CDL Air Brakes Test
Not knowing the specific pressure ranges for warnings and emergency brake activation.
Getting Started: Understanding the CDL Air Brakes Test
What to Expect on the CDL Air Brakes Test
Failing to demonstrate the proper procedure for checking slack adjusters manually.
Getting Started: Understanding the CDL Air Brakes Test
What to Expect on the CDL Air Brakes Test
Confusing the function of different air brake components, especially during the pre-trip inspection.
Getting Started: Understanding the CDL Air Brakes Test
Multiple-choice
Test format with options, only one correct
Getting Started: Understanding the CDL Air Brakes Test
Passing score
Minimum percentage of correct answers needed
Getting Started: Understanding the CDL Air Brakes Test
CDL Manual
Official state guide for commercial driver licensing
Getting Started: Understanding the CDL Air Brakes Test
Practice test
Simulated exam to prepare for the real one
Getting Started: Understanding the CDL Air Brakes Test
Air brake system
Vehicle braking system using compressed air
Getting Started: Understanding the CDL Air Brakes Test
Pre-trip inspection
Thorough check of vehicle before driving
Getting Started: Understanding the CDL Air Brakes Test
Stab braking
Emergency braking technique for air brakes
Getting Started: Understanding the CDL Air Brakes Test
Test Format, Scoring, and Study Tips
To remember to study the manual, practice, and review: 'MRP' – Manual, Review, Practice! Like a good 'MRP' (Meal, Ready-to-Eat) for your brain!
Getting Started: Understanding the CDL Air Brakes Test
Test Format, Scoring, and Study Tips
California's CDL manual emphasizes that the air brake test is separate from the general knowledge test. Pay close attention to the specific air brake components and their functions as detailed in the California Commercial Driver Handbook, especially sections on air brake system parts and inspection procedures.
Getting Started: Understanding the CDL Air Brakes Test
Test Format, Scoring, and Study Tips
Only skimming the CDL manual instead of thoroughly reading and understanding it.
Getting Started: Understanding the CDL Air Brakes Test
Test Format, Scoring, and Study Tips
Not taking enough practice tests or only memorizing answers without understanding the concepts.
Getting Started: Understanding the CDL Air Brakes Test
Test Format, Scoring, and Study Tips
Ignoring the specific state requirements or variations for the air brakes test.
Getting Started: Understanding the CDL Air Brakes Test
Governor
Controls when the air compressor pumps air.
Air Brake System Components Explained
Cut-in Pressure
Pressure at which compressor starts pumping.
Air Brake System Components Explained
Cut-out Pressure
Pressure at which compressor stops pumping.
Air Brake System Components Explained
Air Storage Tanks
Reservoirs that hold compressed air.
Air Brake System Components Explained
Wet Tank
First air tank; collects water and oil.
Air Brake System Components Explained
Drain Valves
Used to remove contaminants from air tanks.
Air Brake System Components Explained
Air Compressor, Governor, and Storage Tanks
Compressor PUMPS, Governor CONTROLS, Tanks HOLD. Think of a 'CPG' report for your air system's health!
Air Brake System Components Explained
Air Compressor, Governor, and Storage Tanks
The California CDL exam often asks about the specific cut-out pressure for air compressors, which is typically around 125 psi. Also, know that the safety valve will open if air pressure exceeds 150 psi to prevent tank rupture.
Air Brake System Components Explained
Air Compressor, Governor, and Storage Tanks
Forgetting to drain air tanks daily, leading to water/oil buildup and potential system damage or freezing.
Air Brake System Components Explained
Air Compressor, Governor, and Storage Tanks
Ignoring a continuously running compressor or a safety valve hiss, which indicates a dangerous governor malfunction.
Air Brake System Components Explained
Air Compressor, Governor, and Storage Tanks
Not checking the compressor drive belt during pre-trip, risking a sudden loss of air pressure on the road.
Air Brake System Components Explained
Brake Pedal (Foot Valve)
Controls air flow to brake chambers.
Air Brake System Components Explained
Foundation Brakes
Components at wheels that create friction.
Air Brake System Components Explained
S-Cam
Rotates to force brake shoes against drum.
Air Brake System Components Explained
Brake Drum
Rotating part against which shoes press.
Air Brake System Components Explained
Brake Shoes
Friction material pressed against drum.
Air Brake System Components Explained
Slack Adjuster
Connects pushrod to S-cam.
Air Brake System Components Explained
Air Pressure Gauges
Display air pressure in tanks.
Air Brake System Components Explained
Progressive Braking
Applying varying brake force smoothly.
Air Brake System Components Explained
Brake Pedal, Foundation Brakes, and Gauges
Think of the 'S' in S-cam for 'Squeeze' – it squeezes the brake shoes against the drum!
Air Brake System Components Explained
Brake Pedal, Foundation Brakes, and Gauges
The California CDL exam emphasizes knowing the minimum air pressure for safe operation (usually 100 psi or higher) and the pressure at which the low air warning light/buzzer comes on (typically 55-75 psi, but memorizing your vehicle's specific cut-in/cut-out pressures is key).
Air Brake System Components Explained
Brake Pedal, Foundation Brakes, and Gauges
Ignoring low air pressure warnings, which can lead to brake failure.
Air Brake System Components Explained
Brake Pedal, Foundation Brakes, and Gauges
Not understanding the difference between service brakes and parking/emergency brakes.
Air Brake System Components Explained
Brake Pedal, Foundation Brakes, and Gauges
Failing to check slack adjuster adjustment during pre-trip inspections.
Air Brake System Components Explained
Safety Valve
Releases excess air pressure (typically 150 psi).
Air Brake System Components Explained
Over-pressurization
Air pressure exceeding safe limits in the system.
Air Brake System Components Explained
Alcohol Evaporator
Injects alcohol to prevent ice in air lines.
Air Brake System Components Explained
Low Air Pressure Warning
Alerts driver if pressure drops below 55-75 psi.
Air Brake System Components Explained
Moisture Ejection
Automatic removal of water from air system.
Air Brake System Components Explained
Safety Valve, Alcohol Evaporator, and Warning Systems
Imagine a 'SAFE-T' valve like a pressure cooker's release, hissing to save the day. The 'ALCOHOL' keeps the 'ICE' away. The 'LOW AIR' warning is a 'RED LIGHT' that means 'STOP RIGHT NOW!'.
Air Brake System Components Explained
Safety Valve, Alcohol Evaporator, and Warning Systems
California exam tip: Be precise about the low air warning. The California CDL handbook states the warning must come on before air pressure drops to less than 60 psi in the air tanks. Memorize 'less than 60 psi' for the warning activation point.
Air Brake System Components Explained
Safety Valve, Alcohol Evaporator, and Warning Systems
Ignoring a continuous hiss from the safety valve, assuming it's normal.
Air Brake System Components Explained
Safety Valve, Alcohol Evaporator, and Warning Systems
Forgetting to check the alcohol evaporator level in cold weather.
Air Brake System Components Explained
Safety Valve, Alcohol Evaporator, and Warning Systems
Attempting to drive with the low air pressure warning light on.
Air Brake System Components Explained
Front Brake Limiting Valve
Reduces air pressure to front brakes on older vehicles.
Air Brake System Components Explained
Caging
Manually compressing a spring brake to release it without air.
Air Brake System Components Explained
Anti-lock Braking System (ABS)
Prevents wheel lock-up during braking, maintaining steering control.
Air Brake System Components Explained
Modulation
Rapidly varying brake pressure to prevent wheel lock-up.
Air Brake System Components Explained
Front Brake Limiting Valve, Spring Brakes, and ABS
Spring Brakes: 'S' for Spring, 'S' for Stop. Springs want to STOP the vehicle, air pressure releases the STOP.
Air Brake System Components Explained
Front Brake Limiting Valve, Spring Brakes, and ABS
The California CDL exam emphasizes knowing that spring brakes are applied by mechanical force (springs) and released by air pressure. Also, be aware that ABS is mandatory on newer vehicles and prevents wheel lock-up, but does not always shorten stopping distances.
Air Brake System Components Explained
Front Brake Limiting Valve, Spring Brakes, and ABS
Driving with the front brake limiting valve in 'full' on slippery roads (if equipped), risking front wheel lock-up.
Air Brake System Components Explained
Front Brake Limiting Valve, Spring Brakes, and ABS
Ignoring an ABS warning light, which indicates a critical safety system is not functioning.
Air Brake System Components Explained
Front Brake Limiting Valve, Spring Brakes, and ABS
Attempting to drive a vehicle with low air pressure after spring brakes have engaged, which can damage the system.
Air Brake System Components Explained
Dual Air Brake System
Two independent air brake systems for safety.
Mastering Dual Air Brake Systems
Primary System
Controls brakes on the rear axles of the vehicle.
Mastering Dual Air Brake Systems
Secondary System
Controls brakes on the front axles of the vehicle.
Mastering Dual Air Brake Systems
Redundancy
Having backup systems to prevent total failure.
Mastering Dual Air Brake Systems
Air Tank
Reservoir for storing compressed air.
Mastering Dual Air Brake Systems
Brake Chamber
Converts air pressure into mechanical force to apply brakes.
Mastering Dual Air Brake Systems
Brake Pedal
Driver control to activate the air brake systems.
Mastering Dual Air Brake Systems
Primary and Secondary Air Brake Systems
Think 'P' for Primary and 'P' for Power (rear wheels do most of the work). 'S' for Secondary and 'S' for Steering (front wheels are for steering).
Mastering Dual Air Brake Systems
Primary and Secondary Air Brake Systems
The California CDL exam emphasizes knowing which axles each system controls. Remember: Primary = Rear Axles, Secondary = Front Axles. Also, be ready for questions about what happens if one system fails.
Mastering Dual Air Brake Systems
Primary and Secondary Air Brake Systems
Confusing which system controls which axles (Primary for rear, Secondary for front).
Mastering Dual Air Brake Systems
Primary and Secondary Air Brake Systems
Believing that if one system fails, you have no brakes at all.
Mastering Dual Air Brake Systems
Primary and Secondary Air Brake Systems
Ignoring a low air warning from one system, thinking the other will compensate indefinitely.
Mastering Dual Air Brake Systems
Air Lines
Hoses carrying compressed air to brake chambers.
Mastering Dual Air Brake Systems
Separate Tanks, Lines, and Controls Explained
Think 'P' for Primary and 'R' for Rear, 'S' for Secondary and 'F' for Front. PR-SF!
Mastering Dual Air Brake Systems
Separate Tanks, Lines, and Controls Explained
The California CDL exam emphasizes that dual air brake systems are required on all new commercial vehicles and that each system must have its own air supply and lines.
Mastering Dual Air Brake Systems
Separate Tanks, Lines, and Controls Explained
Assuming a low air warning means total brake failure.
Mastering Dual Air Brake Systems
Separate Tanks, Lines, and Controls Explained
Not understanding which system (primary/secondary) corresponds to which axles.
Mastering Dual Air Brake Systems
Separate Tanks, Lines, and Controls Explained
Ignoring a low air warning because 'the other system is fine'.
Mastering Dual Air Brake Systems
Primary Air System
Supplies air to the rear brakes.
Mastering Dual Air Brake Systems
Secondary Air System
Supplies air to the front brakes.
Mastering Dual Air Brake Systems
PSI
Pounds per square inch, unit for air pressure.
Mastering Dual Air Brake Systems
Audible Buzzer
Sound alarm for low air pressure.
Mastering Dual Air Brake Systems
Red Warning Light
Visual alarm for low air pressure.
Mastering Dual Air Brake Systems
Governor Cut-in/Cut-out
Pressure range where compressor starts/stops.
Mastering Dual Air Brake Systems
Low Air Warning for Each System: Why it Matters
Think 'Sixty PSI, Stop Immediately!' for the low air warning threshold.
Mastering Dual Air Brake Systems
Low Air Warning for Each System: Why it Matters
The California CDL exam specifically emphasizes that the low air pressure warning must come on before air pressure drops to 60 psi in either the primary or secondary system. Memorize the 60 psi threshold.
Mastering Dual Air Brake Systems
Low Air Warning for Each System: Why it Matters
Ignoring the low air warning, assuming it's a false alarm or minor issue.
Mastering Dual Air Brake Systems
Low Air Warning for Each System: Why it Matters
Continuing to drive with a low air warning, risking complete brake failure.
Mastering Dual Air Brake Systems
Low Air Warning for Each System: Why it Matters
Not knowing the specific air pressure threshold (e.g., 60 psi) for the warning to activate.
Mastering Dual Air Brake Systems
FMCSA
Federal agency regulating commercial motor vehicle safety.
Mastering Dual Air Brake Systems
Air Loss
Decrease in air pressure within the brake system.
Mastering Dual Air Brake Systems
Partial Failure
One part of a system fails, while another part still functions.
Mastering Dual Air Brake Systems
Importance of Dual Systems for Safety
Think 'D.U.A.L.' – Don't Underestimate Air Loss! Always Look for two systems.
Mastering Dual Air Brake Systems
Importance of Dual Systems for Safety
The California CDL exam emphasizes understanding that dual air brake systems are mandatory for commercial vehicles and how they prevent total brake failure. Look for questions about 'separate systems' and 'backup braking'.
Mastering Dual Air Brake Systems
Importance of Dual Systems for Safety
Assuming a dual system means you can safely drive indefinitely with one system failed.
Mastering Dual Air Brake Systems
Importance of Dual Systems for Safety
Not understanding that the low air warning applies to *each* system independently.
Mastering Dual Air Brake Systems
Importance of Dual Systems for Safety
Confusing the dual system with a parking brake system.
Mastering Dual Air Brake Systems
Service Brakes
The foot-pedal controlled brakes used for stopping.
Mastering Dual Air Brake Systems
Dual Air Brake System: How It Works Together
Think 'P' for Primary, 'P' for Power (main braking). 'S' for Secondary, 'S' for Safety (backup).
Mastering Dual Air Brake Systems
Dual Air Brake System: How It Works Together
The California CDL exam emphasizes understanding the distinct roles of the primary and secondary systems and how a failure in one affects the other. Pay attention to which axles each system typically controls.
Mastering Dual Air Brake Systems
Dual Air Brake System: How It Works Together
Assuming one system is 'more important' than the other; both are critical.
Mastering Dual Air Brake Systems
Dual Air Brake System: How It Works Together
Ignoring a low air warning for one system, thinking the other will compensate indefinitely.
Mastering Dual Air Brake Systems
Dual Air Brake System: How It Works Together
Not understanding that a single system failure drastically reduces overall braking power.
Mastering Dual Air Brake Systems
Pushrod Stroke
Distance the slack adjuster pushrod moves when brakes are applied.
Comprehensive Air Brake System Inspection
Automatic Slack Adjuster
Device that automatically adjusts brakes as linings wear.
Comprehensive Air Brake System Inspection
Checking Compressor, Tanks, Lines, and Adjustment
To remember the air system checks: C.A.T.S. — Compressor, Air tanks, Tubes (lines), Slack adjusters.
Comprehensive Air Brake System Inspection
Checking Compressor, Tanks, Lines, and Adjustment
The California CDL exam emphasizes knowing the specific air pressure ranges: the air compressor must cut in no lower than 85 psi (some older systems 100 psi) and cut out no higher than 125 psi. Also, know that the air pressure must build from 85 to 100 psi in 45 seconds or less for single air systems, and from 85 to 120 psi in 45 seconds or less for combination vehicles.
Comprehensive Air Brake System Inspection
Checking Compressor, Tanks, Lines, and Adjustment
Forgetting to drain air tanks daily, leading to water/oil buildup and potential system damage.
Comprehensive Air Brake System Inspection
Checking Compressor, Tanks, Lines, and Adjustment
Ignoring a slow air pressure build-up or a compressor that doesn't cut in/out at the correct pressures.
Comprehensive Air Brake System Inspection
Checking Compressor, Tanks, Lines, and Adjustment
Manually adjusting automatic slack adjusters; this indicates a mechanical issue that needs professional repair, not just a quick fix.
Comprehensive Air Brake System Inspection
Pushrod
Part of the brake chamber that moves the slack adjuster.
Comprehensive Air Brake System Inspection
Brake Lining
Friction material that contacts the brake drum.
Comprehensive Air Brake System Inspection
Contamination
Presence of oil, grease, or fluid on linings.
Comprehensive Air Brake System Inspection
Overheating
Excessive heat, causing discoloration or damage.
Comprehensive Air Brake System Inspection
Minimum Thickness
Least allowable lining thickness, typically 1/4 inch.
Comprehensive Air Brake System Inspection
Inspecting Slack Adjusters, Drums, and Linings
SLACK: S-ize up movement (under 1 inch), L-ook for cracks on drum, A-ssess lining thickness (1/4 inch min), C-heck for contamination, K-eep it safe!
Comprehensive Air Brake System Inspection
Inspecting Slack Adjusters, Drums, and Linings
California CDL exams specifically emphasize the 1-inch rule for slack adjuster play. Be prepared to state this exact measurement and explain its significance.
Comprehensive Air Brake System Inspection
Inspecting Slack Adjusters, Drums, and Linings
Forgetting to release the parking brake before checking slack adjusters, leading to an inaccurate reading.
Comprehensive Air Brake System Inspection
Inspecting Slack Adjusters, Drums, and Linings
Not checking all slack adjusters, assuming if one is good, they all are.
Comprehensive Air Brake System Inspection
Inspecting Slack Adjusters, Drums, and Linings
Overlooking small cracks or minor discoloration on drums, which can escalate into major failures.
Comprehensive Air Brake System Inspection
Fanning Brakes
Repeatedly pressing and releasing the service brake pedal.
Comprehensive Air Brake System Inspection
Parking Brake
Brake system applied by springs when air pressure is released.
Comprehensive Air Brake System Inspection
Low Air Warning, Parking, and Service Brake Checks
LPS: Low Air (60psi), Parking (hold), Service (straight). Remember to check them in this order!
Comprehensive Air Brake System Inspection
Low Air Warning, Parking, and Service Brake Checks
On the California CDL exam, pay close attention to the exact psi for the low air warning. It MUST activate at or above 60 psi. Also, remember to state that the parking brake must 'hold the vehicle' and the service brakes must 'stop the vehicle in a straight line without pulling'.
Comprehensive Air Brake System Inspection
Low Air Warning, Parking, and Service Brake Checks
Forgetting to check the low air warning system, or not knowing the 60 psi threshold.
Comprehensive Air Brake System Inspection
Low Air Warning, Parking, and Service Brake Checks
Not performing the parking brake check by gently trying to move the vehicle.
Comprehensive Air Brake System Inspection
Low Air Warning, Parking, and Service Brake Checks
Skipping the service brake check, or performing it too quickly without observing vehicle behavior.
Comprehensive Air Brake System Inspection
Leak Test
Checks for air pressure loss in the brake system.
Comprehensive Air Brake System Inspection
Pop-out Test
Verifies the parking brake knob pops out when air pressure drops.
Comprehensive Air Brake System Inspection
Performing Leak, Low Air, Spring Brake, & Governor Tests
L-L-S-G: Leaks, Low air, Spring brakes, Governor. Remember this order for your pre-trip air brake tests!
Comprehensive Air Brake System Inspection
Performing Leak, Low Air, Spring Brake, & Governor Tests
For the California CDL exam, pay close attention to the specific PSI values for the low air warning (55 psi minimum) and the spring brake pop-out (20-45 psi). These exact numbers are frequently tested.
Comprehensive Air Brake System Inspection
Performing Leak, Low Air, Spring Brake, & Governor Tests
Forgetting to release the parking brake during the leak test, which can give a false reading.
Comprehensive Air Brake System Inspection
Performing Leak, Low Air, Spring Brake, & Governor Tests
Not holding the service brake firmly enough during the leak test, leading to an inaccurate pressure drop measurement.
Comprehensive Air Brake System Inspection
Performing Leak, Low Air, Spring Brake, & Governor Tests
Failing to check that the low air warning activates at the correct PSI, which could mean a critical safety device is faulty.
Comprehensive Air Brake System Inspection
Gladhands
Couplings connecting air lines between a tractor and trailer.
Comprehensive Air Brake System Inspection
Brake Linings
Friction material that presses against the brake drum to slow down.
Comprehensive Air Brake System Inspection
Pre-Trip Inspection: Air Brake Checklist
Remember 'CALM': Check Air lines, Adjust slack, Look for leaks, Monitor pressure.
Comprehensive Air Brake System Inspection
Pre-Trip Inspection: Air Brake Checklist
When checking air pressure, ensure the air pressure gauge is working and shows the correct pressure. The low air warning device must activate before air pressure drops to less than 60 psi in the air tanks.
Comprehensive Air Brake System Inspection
Pre-Trip Inspection: Air Brake Checklist
Skipping draining air tanks, leading to moisture buildup and potential system damage.
Comprehensive Air Brake System Inspection
Pre-Trip Inspection: Air Brake Checklist
Not checking under the vehicle for chafed air lines or damaged components.
Comprehensive Air Brake System Inspection
Pre-Trip Inspection: Air Brake Checklist
Ignoring minor air leaks, which can quickly become major problems on the road.
Comprehensive Air Brake System Inspection
Normal Stop
Gradual, controlled braking for routine stops.
Operating Vehicles with Air Brakes Safely
Emergency Stop
Rapid braking to stop quickly in critical situations.
Operating Vehicles with Air Brakes Safely
Controlled Braking
Applying brakes firmly without locking wheels; releasing if lock occurs.
Operating Vehicles with Air Brakes Safely
Snub Braking
Applying brakes hard, then releasing completely to cool.
Operating Vehicles with Air Brakes Safely
Brake Fade
Loss of braking power due to overheating.
Operating Vehicles with Air Brakes Safely
Engine Braking
Using engine resistance in low gear to slow vehicle.
Operating Vehicles with Air Brakes Safely
Normal, Emergency, and Downgrade Braking
Think 'S-N-U-B' for downgrades: S-elect gear, N-arrow speed range, U-se brakes hard, B-reak for cooling.
Operating Vehicles with Air Brakes Safely
Normal, Emergency, and Downgrade Braking
The California CDL exam frequently tests knowledge of downgrade braking. Remember the safe speed principle: 'You should be able to stop within the distance you can see ahead.' For downgrades, the California Driver Handbook explicitly states to use a gear that allows you to control your speed without excessive use of the service brakes.
Operating Vehicles with Air Brakes Safely
Normal, Emergency, and Downgrade Braking
Riding the brakes continuously on downgrades, leading to overheating and brake fade.
Operating Vehicles with Air Brakes Safely
Normal, Emergency, and Downgrade Braking
Pumping the brakes on a vehicle equipped with ABS during an emergency stop.
Operating Vehicles with Air Brakes Safely
Normal, Emergency, and Downgrade Braking
Not anticipating stops, resulting in harsh, sudden braking that wears out components faster.
Operating Vehicles with Air Brakes Safely
ABS
Anti-lock Braking System; prevents wheel lock-up during braking.
Operating Vehicles with Air Brakes Safely
Brake Lag
Time delay from pedal press to brake application in air systems.
Operating Vehicles with Air Brakes Safely
Wheel Chocks
Wedges placed to prevent a parked vehicle from rolling.
Operating Vehicles with Air Brakes Safely
Jackknife
When a tractor-trailer folds like a pocket knife during braking.
Operating Vehicles with Air Brakes Safely
Braking with ABS, Parking, and Brake Lag
ABS: Always Brake Smartly (to keep steering).
Operating Vehicles with Air Brakes Safely
Braking with ABS, Parking, and Brake Lag
The California CDL exam emphasizes knowing that ABS prevents wheel lock-up and helps maintain steering control, but does not necessarily shorten stopping distance. Also, be precise about parking brake usage and wheel chocking rules for grades.
Operating Vehicles with Air Brakes Safely
Braking with ABS, Parking, and Brake Lag
Pumping the brakes when ABS activates, which defeats its purpose.
Operating Vehicles with Air Brakes Safely
Braking with ABS, Parking, and Brake Lag
Forgetting to chock wheels when parking on a grade.
Operating Vehicles with Air Brakes Safely
Braking with ABS, Parking, and Brake Lag
Underestimating the impact of brake lag on total stopping distance.
Operating Vehicles with Air Brakes Safely
Controlled Braking, Stab Braking, and Avoiding Fade
FADE: F-requent A-pplication D-estroys E-fficiency. (For brake fade)
Operating Vehicles with Air Brakes Safely
Controlled Braking, Stab Braking, and Avoiding Fade
California CDL exam questions often focus on preventing brake fade on long downgrades. Keywords to look for include 'mountain grades,' 'long downhill,' and 'overheating brakes.' Remember that using a lower gear and snub braking are key strategies.
Operating Vehicles with Air Brakes Safely
Controlled Braking, Stab Braking, and Avoiding Fade
Relying solely on service brakes on long downgrades, leading to brake fade.
Operating Vehicles with Air Brakes Safely
Controlled Braking, Stab Braking, and Avoiding Fade
Using stab braking on a vehicle equipped with functioning ABS, which can confuse the system.
Operating Vehicles with Air Brakes Safely
Controlled Braking, Stab Braking, and Avoiding Fade
Not recognizing the early signs of brake fade, such as a soft pedal or increased stopping distance.
Operating Vehicles with Air Brakes Safely
Parking Brake Control
Dashboard valve to engage or disengage the parking brake.
Operating Vehicles with Air Brakes Safely
Spring Brake Application
Automatic engagement of spring brakes when air pressure is critically low (20-45 psi).
Operating Vehicles with Air Brakes Safely
Air Dryer
Removes moisture and oil from compressed air.
Operating Vehicles with Air Brakes Safely
Safety Relief Valve
Protects the air system from over-pressurization.
Operating Vehicles with Air Brakes Safely
Proper Use of Parking Brake and System Management
P.A.R.K. (Pressure Air Releases Key) – Remember, you need enough Air Pressure to Release the Key (parking brake).
Operating Vehicles with Air Brakes Safely
Proper Use of Parking Brake and System Management
On the California CDL exam, pay close attention to the specific air pressure ranges for low air warnings (usually below 60 psi) and automatic spring brake application (20-45 psi). Know that the parking brake is spring-applied and air-released.
Operating Vehicles with Air Brakes Safely
Proper Use of Parking Brake and System Management
Driving with the parking brake partially engaged.
Operating Vehicles with Air Brakes Safely
Proper Use of Parking Brake and System Management
Not chocking wheels on a grade, especially without a curb.
Operating Vehicles with Air Brakes Safely
Proper Use of Parking Brake and System Management
Ignoring low air pressure warnings and continuing to drive.
Operating Vehicles with Air Brakes Safely