An air hose shows wear through its outer cover into the reinforcing layer, but no leak yet. Is it defective?

Only if it is a trailer supply hose

No, unless the inner layer shows too

No, only leaking hoses are defects

Grease from a leaking wheel seal has reached a brake lining. Is the brake defective?

No, grease actually reduces wear

Only if the lining is also cracked

Only if it is on the steering axle

Ontario Air Brake (Z) overview

Ontario Air Brake (Z): Inspecting brake components

Lining contact, cracks, contamination and thickness, chamber leaks and matching sizes on the steering axle, slack adjuster length, drums, air lines, tanks and compressor belts.

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Inspecting brake components · Question 1Score 0/0

Which brake lining condition makes it defective?

Tip: press 1–4 to answer and Enter for the next question.

Study reference: MTO Air Brake Handbook (online edition, Feb. 2026), Ch. 9 Inspecting Air Brake Components

All 20 questions in this test

Every question and its answer choices. The correct answers and explanations appear when you take the test above.

Which brake lining condition makes it defective?
1. Dusty from normal daily use
2. Cracked, loose or missing
3. Warm after a short drive
4. Slightly darker in colour
An air hose shows wear through its outer cover into the reinforcing layer, but no leak yet. Is it defective?
1. Only if it is a trailer supply hose
2. No, unless the inner layer shows too
3. No, only leaking hoses are defects
4. Yes, it is a defect
How do you check that an air tank is secure?
1. Drain it and weigh the water
2. Check its paint for cracks
3. Tap it and listen for echoes
4. Look at it and try to move it
Grease from a leaking wheel seal has reached a brake lining. Is the brake defective?
1. No, grease actually reduces wear
2. Only if the lining is also cracked
3. Only if it is on the steering axle
4. Yes, it is defective
Which drum or rotor defect must you look for?
1. Cracks or breaks
2. Dust on the outer face
3. Light polishing marks
4. Surface rust after rain
An air line was repaired with a fitting not approved for air brakes. What is it?
1. Acceptable for one trip only
2. Acceptable if it does not leak
3. Acceptable on trailer lines only
4. A defect; it is not allowed
When should you inspect the air compressor?
1. With the engine stopped
2. While draining the tanks
3. While the governor is cutting in
4. With the engine at high idle
How is the size of an air brake chamber defined?
1. Diaphragm area in square inches
2. The weight of the empty chamber
3. The pushrod length in inches
4. The diameter of the air line
You find small holes on a brake chamber that were made by the manufacturer. What are they?
1. Corrosion that must be reported
2. Normal vent holes, not a defect
3. Impact damage needing repair
4. Signs the chamber was caged
When is brake lining thickness a defect?
1. When it is below the prescribed minimum
2. When it is above half its new thickness
3. Whenever any wear is visible
4. Only when metal touches metal
Two chambers look different but are from different makers. What should you conclude?
1. They must be different sizes
2. One of them must be defective
3. They cannot be on the same axle
4. They may still be the same size
On a steering axle, which slack adjuster condition is a defect?
1. Same length but different brand names
2. Unequal effective lengths
3. Different paint colours on each side
4. Both pushrods attached in the same hole
How should you check a brake chamber for leaks?
1. With only the spring brakes applied
2. With the chamber removed from the axle
3. With the engine off and no air at all
4. Spring brakes off, service brakes on
What does a driver's air brake component inspection mainly involve?
1. Measuring each drum's inside diameter
2. Removing wheels to see the shoes
3. Looking at visible parts
4. Taking the brake chambers apart
How should a compressor drive belt feel under firm hand pressure?
1. It should not move at all
2. It should give slightly
3. It should move several inches
4. It should slip off the pulley
What is a good way to pinpoint an air leak in a hose?
1. Pinch it shut with a pair of pliers
2. Spray it with a little brake fluid
3. Move it back and forth and listen
4. Wrap it tightly with electrical tape
What does a slack adjuster do?
1. Measures the pushrod stroke for you
2. Controls when the compressor cuts in
3. Drains moisture from the brake chamber
4. Acts as a lever on the camshaft
What is a slack adjuster's effective length?
1. Wheel centre to the drum edge
2. Chamber clamp to the pushrod tip
3. Camshaft centre to the clevis pin
4. Pushrod hole to the chamber vent
You apply the brakes and see a lining that does not touch the drum. What does it show?
1. A brake with new linings
2. A normal cold brake
3. A malfunctioning brake
4. A properly adjusted brake
Why must both brake chambers on a steering axle be the same size?
1. The law sets one size per truck
2. Different sizes cannot be bought
3. Unequal force can affect steering
4. Larger chambers use more air

Inspecting brake components: key rules to remember

Our summary of what the official handbook says on this topic, in our own words. Read it before or after the practice questions above, then check the original chapter. Read the official chapter ↗

General

The driver's inspection mainly means looking at the visible components for defects or anything abnormal.
Know the normal appearance of each part and the signs of present or developing defects.

Foundation brakes

When the brakes are applied the lining must contact the drum; when released it must be clear. Lining that does not touch the drum when applied means a malfunctioning brake.
Lining that is noticeably cracked, loose or missing is defective.
Lining contaminated with grease or oil (often leaking from the wheel) is defective and causes abnormal braking.
Lining worn below the prescribed minimum thickness is defective.
Damaged, missing or malfunctioning foundation components are defects; the vehicle may not be driven with any of them.

Brake chambers and slack adjusters

Chamber size is the diaphragm area in square inches; brakes at each end of an axle should have the same size for balanced braking, which matters most on the steering axle.
Chambers from different makers can look different even at the same size.
Check chambers for leaks with air applied (spring brakes released, service brakes applied); leaks are usually heard.
Vent holes made by the manufacturer are normal; holes or cracks from impact or damage make the chamber defective.
Slack adjusters are levers that multiply chamber force; effective length is the distance from the camshaft centre to the clevis pin.
Using the wrong pushrod hole changes effective length; slack adjusters on each side of a steering axle must have the same effective length.
Defects: audible leaks, cracks or non-manufactured holes, mismatched chamber size or mismatched slack adjuster length on a steering axle.

Drums, lines, tanks, compressor

Drums and rotors may be hidden by wheels or shields; cracked or broken drums or rotors are defects and often change how the brakes behave.
Air lines have an inner airtight layer, reinforcing layers and an outer cover; damage reaching the reinforcing or inner layer makes the line defective, even before it leaks.
Wear, cuts, abrasion and heat damage are typical line damage; moving a hose back and forth helps find a leak.
Only fittings designed and approved for air brakes may be used; improper fittings or repairs are prohibited.
Air tanks must be firmly attached; check by looking and by trying to move them, along with their brackets.
Inspect the compressor with the engine stopped: it and its brackets must be secure; a drive belt should give slightly under firm hand pressure, and a loose, cut or frayed belt is defective.

Study the Inspecting brake components rules as flashcards →