Brake System Functionality Quiz

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Questions and Answers

You should know that your brakes are fading when?

You have to push harder on the brake pedal to control your downhill speed.

If the spring brakes are on, you should push the brake pedal.

False

Repeatedly pressing and releasing the brake pedal may result in?

Loss of air pressure.

The driver must be able to see a low pressure warning which comes on before pressure in the service air tank falls below?

60 PSI. Signup and view all the answers

If your truck or bus has dual parking control valves, you can use pressure from a separate tank to?

Release the emergency/spring/parking brakes to move a short distance. Signup and view all the answers

The brake pedal in an air brake system controls?

The air pressure applied to put on the brakes. Signup and view all the answers

To check the free play of manual slack adjusters of S-Cam brakes, you should?

Park on level ground, chock the wheels, release the parking brakes, and pull on the slack adjusters. Signup and view all the answers

Parking or emergency brakes of trucks and buses can be legally held on by _____ pressure.

Spring. Signup and view all the answers

Emergency stab braking is when you?

Brake as hard as you can, release the brakes when the wheels lock, put on the brakes again when the wheels start rolling. Signup and view all the answers

The most common type of foundation brake found on heavy vehicles is the?

S-Cam. Signup and view all the answers

If your truck has a dual air system and one of the systems is low on pressure,?

Either the front or rear brakes will not be fully operational. Signup and view all the answers

The most important thing to do when a low pressure warning light comes on is to?

Stop and safely park as soon as possible. Signup and view all the answers

With air brake equipped vehicles, the parking brakes should be used anytime the vehicle is parked.

True Signup and view all the answers

The air compressor governor controls?

When air is pumped into the air tanks. Signup and view all the answers

The stop light switch?

Turns on the brake lights to warn drivers behind you. Signup and view all the answers

For air brake systems in good condition, the air compressor should start pumping at about _____ psi.

<ol start="100"> <li></li> </ol> Signup and view all the answers

The air loss rate for a straight truck or bus with the engine off and the parking brakes off and the service brakes on should not be more than _____ psi in one minute.

<ol start="3"> <li></li> </ol> Signup and view all the answers

The braking power of the spring brakes depends on?

The service brakes being in adjustment. Signup and view all the answers

How should you check spring brakes application when air pressure drops below a certain level?

Park on level ground, chock wheels, release parking brake when you have enough pressure, shut the engine off, and repeatedly press and release the pedal. Signup and view all the answers

If you are driving down a steep grade and have reached a safe speed of 40 mph, you would apply the service brakes until your speed drops to _____ mph.

<ol start="35"> <li></li> </ol> Signup and view all the answers

The air brake lag distance at 55 mph on dry pavement adds about _____ feet to your stopping distance.

<ol start="32"> <li></li> </ol> Signup and view all the answers

How should you check that your service brakes are working properly?

Park on level ground, wait until normal air pressure is reached, release the parking brake and move forward slowly at about 5 mph, then apply the brakes firmly using the brake. Signup and view all the answers

Emergency controlled braking is when you?

Apply the brakes as hard as you can without locking up the brakes. Signup and view all the answers

Which of these is not a proper time to apply the parking brake?

If the brakes are very hot (e.g. just after coming down a steep grade). Signup and view all the answers

All air brakes equipped vehicles have a supply pressure gauge.

True Signup and view all the answers

If air pressure does NOT build up to normal within the correct amount of time?

Your air pressure may drop too low during driving, requiring an emergency stop. Signup and view all the answers

Excessive use of the service brakes results in over heating which can lead to?

Expansion of the brake drums. Signup and view all the answers

The proper method of braking when going down long and or steep grades, after selecting the proper gear is to brake until your speed is about _____ mph below your 'safe' speed then release your brakes.

<ol start="5"> <li></li> </ol> Signup and view all the answers

Under normal conditions in order to engage the parking brake the driver must first _____ the air out.

Let. Signup and view all the answers

Study Notes

Brake System and Functionality

Brake fading occurs when more pressure is needed on the pedal to control downhill speed.
Never push the brake pedal if the spring brakes are engaged.
Repeatedly pressing the brake pedal can result in a loss of air pressure.
A low pressure warning light activates before service air tank pressure drops below 60 PSI.

Dual Air and Parking Control

Dual parking control valves allow the use of pressure from a separate tank to release emergency/spring parking brakes for short movements.
Parking brakes on trucks and buses are legally held by spring pressure.
Always use parking brakes when parked, especially in air brake-equipped vehicles.

Brake Testing and Maintenance

To check manual slack adjusters of S-Cam brakes, park on level ground, chock wheels, release parking brakes, and pull on adjusters.
For air brake systems, the compressor should begin pumping at around 100 PSI.
Ensure service brakes are functioning by moving slowly at 5 mph, releasing parking brake, and applying brakes firmly.

Stopping Distance and Braking Techniques

Emergency stab braking requires braking hard, releasing during wheel lock, and reapplying when wheels roll again.
For controlled braking, apply brakes hard without locking them up.
Air brake lag distance adds approximately 32 feet to stopping distance at 55 mph on dry pavement.

Performance and Air Loss

Air loss rate should not exceed 3 PSI in one minute for a straight truck or bus with the engine off and parking brakes off.
Insufficient air pressure can result in brakes malfunctioning, requiring the driver to stop safely.
Excessive use of service brakes can cause overheating leading to brake drum expansion.

Safe Operation Practices

During steep descents, apply service brakes to reduce speed to 35 mph from 40 mph, then release.
The air compressor governor manages when air is pumped into air tanks.
Do not apply parking brake if brakes are overheated after descending steep grades.

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Description

Test your knowledge on brake system functionality, including common issues like brake fading and the importance of parking brakes in air brake-equipped vehicles. This quiz also covers maintenance procedures and the significance of proper brake testing. Challenge yourself to understand the critical aspects of vehicle safety and braking.