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50 Cards in this Set

  • Front
  • Back
Air brakes use ____________ ___________ to make the brakes work.
compressed air
Air brakes are really three different braking systems:
-service brake
-parking brake
-emergency brake
The ____ ________ pumps air into the air storage tanks reservoirs
air compressor
The ________ controls when the air compressor will pump air into the air storage tanks.
When air tank pressure rises to the “cut-out” level (around ____ pounds per square inch or “psi”), the governor stops the compressor from pumping air.
When the tank pressure falls to the “cut-in” pressure (around _____ psi), the governor allows the compressor to start pumping again.
Compressed air usually has some _______ and some compressor oil in it which is bad for the air brake system. Be sure that you drain the air tanks completely.
Each air tank is equipped with a drain valve in the
bottom. There are two types:
Manual & automatic
Some air brake systems have an _________ __________ to put alcohol into the air system. This helps to reduce the risk of ice in air brake valves and other parts during cold weather.
alcohol evaporator
Check the alcohol container and fill up as necessary, every day during cold weather. __________ air tank drainage is still needed to get rid of water and oil.
A ________ _________ valve is installed in the first tank the air compressor pumps air to.
safety relief
The safety valve protects the tank and the rest of the system from too much __________. The valve is usually set to open at 150 psi.
You put on the brakes by pushing down the brake pedal. It is also called the ______ valve or _______ valve.
foot valve
treadle valve
Foundation brakes are used at each wheel. The most common type is the ______ _______ brake
s-cam drum
Brake drums are located on each end of the vehicle’s _________.
Too much ________ can make the brakes stop working.
Air pressure pushes the rod out, moving the slack adjuster, thus twisting the brake cam shaft. This turns the _________ so called because it is shaped like the letter “S”.
_________ brakes may have a single brake chamber, or two brake chambers, pushing wedges in at both ends of the brake shoes.
In air-operated disc brakes, air pressure acts on a brake chamber and slack adjuster, like s-cam brakes. But instead of the s-cam, a “________ __________” is used.
power screw
Wedge brakes and disc brakes are _______ common than s-cam brakes.
All air-braked vehicles have a ________ ________ connected to the air tank.
pressure gauge
A low air pressure warning signal is required on vehicles with air brakes. A warning signal you can see must come on before the air pressure in the tanks falls below ______ psi.
What device drops a mechanical arm into your view when the pressure in the system drops below 60 psi?
__________ valves were used to reduce the chance of the front wheels skidding on slippery surfaces.
________ wheel braking is good under all conditions
All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. They must be held on by ______________ force (because air pressure can eventually leak away).
In newer vehicles with air brakes, you put on the parking brakes using a ______________, yellow, push-pull control knob.
In some vehicles a control handle on the dash board may be used to apply the spring brakes gradually. This is called a ____________ ___________.
modulating valve
With duel parking contol valves when main air pressure is lost, the _________ brakes come on.
Most newer heavy-duty vehicles use ________ air brake systems for safety.
A dual air brake system has two separate air
brake systems which use a single set of brake controls. These are called:
Primary and Secondary
Before driving a vehicle with a dual air system, allow time for the air compressor to build up a minimum of _____ psi pressure in both the primary and secondary systems.
The warning light and buzzer should shut off when air pressure in both systems rises to a value set by the manufacturer. This value must be ___________ than 60 psi.
Park on level ground and chock the wheels to prevent the vehicle from moving. Turn off the _________ brakes so you can move the slack adjusters.
Brake drums (or discs) must not have cracks longer than ______ _______ the width of the friction area.
one half
When testing the air leakage rate the loss rate should be less than ______ psi in one minute for single vehicles and less than three psi in one minute for combination vehicles.
Chock the wheels, release the parking brakes when you have enough air pressure to do it, and shut the engine off. Step on and off the brake pedal to reduce the air tank pressure. What are you checking?
Spring brakes come on automatically
When the spring breaks come on automatically: The “________ _________” knob should pop out when the air
pressure falls to the manufacturer’s specification (usually in a range between 20-40 psi).
parking brake
When the engine is at operating rpm, the pressure should build from _____ to 100 psi within 45 seconds in dual air systems.
Pumping by the air compressor should start at
about 100 psi and stop at about ______ psi.
With this method, you apply the brakes as hard as you can without locking the wheels.
Controlled braking
Apply your brakes all the way. Release brakes when wheels lock up. As soon as the wheels start rolling, apply the brakes fully again.
Stab Breaking
Perception Distance + Reaction Distance + Brake Lag Distance + Effective Braking Distance =
Total Stopping Distance
At 55 mph for an average driver under good traction and brake conditions, the total stopping distance is over _____ feet.
Brakes can fade or fail from excessive _________ caused by using them too much and not relying on the engine braking effect.
Brake fade is also affected by _______________.
If your “safe” speed is 40 mph, you would not apply the brakes until your speed reaches 40 mph. You now apply the brakes hard enough to gradually reduce your speed to 35 mph and then release the brakes. What technique is this?
Proper braking technique
What should you do if your low air pressure warning comes on?
Stop & safely park your vehicle as soon as possible.
Any time you park, use the parking brakes,
except when the brakes are very _______ or ________.
hot or wet
If your vehicle does not have automatic air tank drains, drain your air tanks at the end of each ________ _______ to remove moisture and oil.
working day