Air Brakes Flashcards
A low air pressure warning signal should activate:
When tank pressure falls below 60 psi.
Why should you regularly drain the air tanks?
Because compressed air contains some water and the water collects in the
tanks
Vehicles equipped with Anti-Lock Braking Systems (ABS) have ____ malfunction lamps
to indicate when the ABS is not working
Yellow
A dual air brake system:
Consists of two separate air brake systems that share a single set of controls.
A safety valve is set to open at ____ pounds per square inch (psi).
150
Air pressure should build up in a single air system within:
Three minutes.
Some air brake systems use alcohol:
To reduce the risk of ice forming in air brake valves.
Spring brakes come on
When too much air pressure is lost.
On trucks and buses, where are ABS malfunction lamps located?
On the instrument panel
Before driving a vehicle with a dual air brake system, you must wait for the air
compressor to build a minimum of ____ in both the primary and secondary systems.
100 psi
Anti-Lock Braking Systems (ABS)
Are equipped in addition to other braking systems and do not reduce normal
braking power.
If using air tanks with manually operated drains, how often should you drain the tanks?
Every day
The parking brake should be:
Used whenever you park your vehicle.
If the brake pads rub against the brake drums and create too much heat:
The brakes may stop working
A low air pressure warning signal:
Is required on vehicles with air brakes.
Foundation brakes are used
At each wheel.
The air compressor governor controls:
When the air compressor pumps air into the air storage tanks.
When traveling down a steep downgrade:
Shift into a lower gear, then use brakes to supplement the braking effect of the
engine.
To confirm that a trailer has ABS, you can:
Look under the trailer for wheel speed sensors coming from the back of the
brakes.
Dollies equipped with ABS are required to have malfunction lamps located where?
On the left side
The ____ tells a driver how much pressure is in the air tanks
Supply pressure gauge
When inspecting your brakes, a slack adjuster should move ____ from where it is
attached to the push rod.
No more than one inch
Before driving a vehicle with air brakes, you should ensure that the spring brakes come
on automatically when:
Air pressure falls below 45 psi.
During an applied leakage test, the maximum leakage rate for a double combination
vehicle is:
4 psi in a minute.
During an applied leakage test, the maximum leakage rate for a triple combination
vehicle is:
6 psi in a minute.
Front wheel braking works:
Under all conditions.
When you press the brake pedal in a vehicle with S-cam brakes, air pressure pushes out
the rod and moves the
Slack adjuster.
Friction inside a brake drum is caused when the brake shoes and linings:
Push against the inside of the drum.
Braking mechanisms are located ____ a brake drum.
Inside
When a brake pedal is pressed and the S-cam is turned, the S-cam:
Presses the brake shoes against the inside of the brake drum.
To inspect slack adjusters on S-cam brakes, you need to:
Chock the wheels and disengage the parking brake.
How should you test the low pressure warning signal?
Rapidly press and release the brake pedal.
Before starting down a hill, be sure to:
Switch into a low gear.
During an applied leakage test, the maximum leakage rate for a single vehicle with air
brakes is
3 psi in one minute
During a static leakage test, the maximum leakage rate for a double combination
vehicle is:
3 psi in one minute.
During a static leakage test, the maximum leakage rate for a triple combination vehicle
with air brakes is ____ in a minute
5 ps
During a static leakage test, the maximum leakage rate for a single vehicle with air
brakes is ____ in one minute.
2 psi
While driving, spring brakes are generally held in place by
Air pressure.
The emergency brake system uses:
Parts of both the parking and service brake systems.
A modulating control valve can control the
Spring brakes.
During a walk-around inspection, ensure there are no cracks on the brake drums that
are more than ____ of the width of the friction area.
One hal
The air pressure in a dual air brake system should build from 85 to 100 psi within:
45 seconds.
In cold weather, an alcohol evaporator should be checked and filled:
Every day.
Applying the brake pedal causes air pressure to activate an electric switch and:
Turn on the brake lights.
A one-way check valve:
Prevents air from escaping if the air compressor has a leak.
An air compressor governor will stop the compressor from pumping air once the air
tanks have an air pressure level of:
125 psi
While driving downhill, you should brake until you reach a speed that is ____ below
your safe speed, then release the brake pedal
5 mph
When you need to stop in an emergency, you should:
Stop in a way that keeps your vehicle in a straight line.
If braking at a speed of 55 mph while driving on dry pavement, the brake lag can add
____ to your vehicle’s total stopping distance
32 feet
An air brake-equipped vehicle traveling at a speed of 55 mph under ideal driving
conditions will need approximately ____ to come to a complete stop
450 feet
