CDL Air Brakes Test Flashcards
Air brakes use
A. hot air
B. cold air
C. compressed air
D. decompressed air
C. compressed air
Air brake systems are three braking systems combined. They are
A. emergency, service, hand.
B. emergency, parking, service.
C. parking, service, hand.
D. None of the above
B. emergency, parking, service.
Which of the following pumps air into the air storage tanks?
A. Safety valve
B. Air compressor
C. Governor
D. Reservoir
B. Air compressor
The main purpose of the alcohol evaporator is to
A. put alcohol in gas tanks
B. remove alcohol from the compressor
C. remove alcohol form the storage tank
D. put the alcohol in the air system
D. put the alcohol in the air sysem
A safety relief valve is installed in the first tank the air compressor pumps air to. The valve is usually set to open at what psi level?
A. 130
B. 140
C. 150
D. 160
C. 150
The most common foundation brake is the
A. wedge brake
B. S-cam drum brake
C. disc brake
D. front brake
B. S-cam drum brake
The brake system that applies and releases the brakes when the driver uses the brake pedal is the ____ brake system.
A. emergency
B. service
C. parking
D. trailer
B. service
The low air-pressure warning light must come on before the air pressure in the tanks falls below what psi level?
A. 30
B. 40
C. 50
D. 60
D. 60
Spring brakes do which of the following?
A. They use air pressure to stop the vehicle
B. They will not work if all the air leaks out of the air brake system
C. They are held by mechanical force
D. They will come on fully at 50 psi
C. They are held by mechanical force
Which of the following tells you how much pressure there is in the air tanks?
A. Stop-light switch
B. Application pressure gauge
C. Supply pressure gauge
D. Low-air-pressure warning signal
C. Supply pressure gauge
Why, on long downhill grades, do experts recommend using a low gear and light steady pressure instead of on-again, off-again braking?
A. Air usage is less with lightly steady pressure
B. Brake linings do not heat up as much
C. You can keep vehicle speed constant in a low gear with light steady pressure
D. All of the above
D. All of the above
The braking power of spring brakes depend on
A. proper adjustment
B. how far the modulating control lever (if present) is moved
C. traction
D. All of the above
D. All of the above
Most newer heavy-duty vehicles use dual air brake systems for safety. A dual air brake system has
A. two seperate air brake systems and two sets of brake controls
B. two seperate air brake systems and a single set of brake controls
C. one air brake system and two sets of brake control
D. one air brake system and one brake control
B. two seperate air brake systems and a single set of brake controls
Foundation brakes are used
A. only in emergencies
B. when parking
C. at each wheel
D. at each axle
C. at each wheel
During walkaround inspections of your vehicle, which parts of the air brake system shoud be checked?
A. Manual slack adjusters on S-cam brakes
B. Brake drums or discs
C. Air hoses connected to brake chambers
D. All of the above
D. All of the above
During the walkaround inspection, if a slack adjuster moves slightly more than an inch where the push rod attaches to it, then
A. it has the perfect amount of slack
B. it probably needs adjustment
C. the brakes will stop the vehicle very suddenly
D. it will pass roadside inspection
B. it probably needs adjustment
You have a fully-charged air system (125 psi). Ater turning off the engine and releasing the service brake, what are the maximum leakage reates per minute for both single and combination vehicles?
A. 2 psi for single, 3 psi for combination
B. 3 psi for both
C. 4 psi for both
D. 4 psi for single, 5 psi for combination
A. 2 psi for single, 3 psi for combination
In checking that the spring brakes come on automatically, you should not
A. pull the parking brake control knob
B. chock the wheels
C. step on and off the brake pedal
D. shut the engine off
A. pull the parking brake control knob
Which of the following is a proper technique in using controlled braking?
A. Putting the brakes on very hard to lock the wheels
B. Releasing the brakes if you need to make large steering adjustments
C. Pressing harder on the brakes when you feel the wheels sliding
D. Turning the steering wheel while braking
B. Releasing the brakes if you need to make large steering adjustments
Total stopping distance for air brakes is longer than that for hydraulic brakes due to ____ distance.
A. perceptive
B. reaction
C. brake lag
D. None of the above
C. brake lag
You are driving a vehicle at 55 mph on dry pavement under good traction and brake conditions. What is the approximate total stopping distance needed to bring your vehicle to a complete stop?
A. Two-and-a-half-times the length of the vehicle
B. Half the length of a football field
C. Just over the lenghth of a football field
D. The length of the vehicle plus 20 feet
C. Just over the length of a football field
What should you do if the low-air-pressure warning comes on?
A. Use stab braking until you stop
B. Drive to the nearest rest area
C. Nothing; the vehicle will stop automatically
D. Stop your vehicle as quickly as possible and safely park it
D. Stop your vehicle as quickly as possible and safely park it
If your truck or bus has dual parking control valves, you can use pressure from a seperate tank to:
A. balance the service brake system when you are parked
B. release the spring emergency/parking brakes to move a short distance
C. brake harder if the main tank is getting low
D. keep on about your business
B. release the spring emergency/parking brakes to move a short distance
When braking on downgrades,
A. go slow enough so that a light, steady use of the brakes keeps you from speeding up
B. brake hard, then let up to cool brakes
C. coast downhill, then apply the brakes hard
D. use stab braking until wheels lock, then release
A. go slow enough so that a light, steady use of brakes keeps you from speeding up
