DMV Class B License Test: Air Brakes Endorsement Exam Graded A+

Excessive use of the service breaks results in overheating, which can lead to: a) Improper adjustment of the S-cam b) Increased contact between the brake drums and brake linings c) Expansion of the brake drums - ANSWER-c) Expansion of the brake drums If air pressure does NOT build up to normal within the correct amount of time: a) You should be ready to use your parking brake to help stop b) The alcohol container may be low c) Your air pressure may drop too low during driving - ANSWER-c) Your air pressure may drop too low during driving If you must make an emergency stop, you should brake so you: a) Use the hand brake before the brake pedal b) Use the full power of the brakes to lock them c) Can steer and your vehicle stays in a straight line - ANSWER-c) Can steer and your vehicle stays in a straight line 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 a) 5 b) 10 c) 15 - ANSWER-a) 5 Your bus or truck has a dual air brake system. If a low air pressure warning comes on only for one system, what should you do? a) Reduce your speed and drive to the nearest garage for repairs b) Reduce your speed and test the remaining system while driving c) Stop and safely park. Continue only after the system is fixed - ANSWER-c) Stop and safely park. Continue only after the system is fixed The driver must be able to see a warning before air pressure in the service tanks falls below ___ psi. a) 50 b) 60 c) 80 - ANSWER-b) 60 The parking or emergency brake on a heavy vehicle can only be held in position by something cannot leak away, like: a) Spring pressure b) Air pressure c) Hydraulic pressure - ANSWER-a) Spring pressure Before driving a truck or bus with a dual air brake system, the pressure in each system should be at least ___ psi. a) 80 b) 100 c) 120 - ANSWER-b) 100 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 - ANSWER-b) Service Controlled braking: a) Involves locking the wheels for short periods of time b) Is used to keep a vehicle in a straight line when braking c) Should only be used with hydraulic brakes - ANSWER-b) Is used to keep a vehicle in a straight line when braking Under normal conditions, to engage the parking brakes the driver must first: a) Turn off the engines only b) Let the air out of the air brake system c) Be sure that the air brake system is fully pressurized - ANSWER-b) Let the air out of the air brake system Total stopping distance for vehicles with air brakes is longer than that for vehicles with hydraulic brakes due to ___ distance. a) Brake lag b) Reaction c) Effective braking - ANSWER-a) Brake lag Some air brake systems have an alcohol evaporator. What may happen if you don't keep the unit filled with alcohol? a) The S-cam may not rotate back when you release the brake pedal b) Ice may form in the air storage tanks and cause the brakes to fail c) Ice may form on the brake drums and warp them - ANSWER-b) Ice may form in the air storage tanks and cause the brakes to fail Which of these is not a proper time to apply the parking brakes? a) When you will only be stopped for less than one hour b) When you are going to test the parking brake c) When you come down a steep grade and your brakes are very hot - ANSWER-c) When you are come down a steep grade and your brakes are very hot A truck with air brakes going 55 MPH would require a stopping distance of: a) Less than 100 feet b) 100-300 feet c) More than 300 feet - ANSWER-c) More than 300 feet If your vehicle has an alcohol evaporator, it is there to: a) Rid the wet tank of alcohol that condenses and sits at the bottom b) Eliminate the need for daily tank draining c) Reduce the risk of ice in air brake valves in cold weather - ANSWER-c) Reduce the risk of ice in air brake valves in cold weather The important thing to do when a low air pressure warning comes on is: a) Upshift and drive to a safe place b) Downshift and drive to a safe place c) Stop and safely park as soon as possible - ANSWER-b) Stop and safely park as soon as possible The application pressure gauge shows how much air pressure you: a) Have in the air tanks b) Have in the modulating control valve c) Are applying to the brakes - ANSWER-c) Are applying to the brakes What is emergency stab braking? a) Press hard on the brake pedal and apply full hand valve until you stop b) Use light steady pressure on the brake pedal c) Brake hard, release the brakes when the wheels lock, and reapply the brakes when the wheels start rolling - ANSWER-c) Brake hard, release the brakes when the wheels lock, and reapply the brakes when the wheels start rolling When you apply the brakes, the brake shoes/linings are pressed against the: a) Brake drum or disc b) Slack adjuster c) S-cam - ANSWER-a) Brake drum or disc The use of air brakes on a downgrade is only a supplement to the: a) Use of the spring brakes b) Use of the front brake limiting valve c) Braking effect of the engine - ANSWER-c) Braking effect of the engine Your truck has a properly functioning dual air brake system and minimum size air tanks. The air pressure should build from 85 to 100 psi within: a) 30 seconds b) 45 seconds c) 60 seconds - ANSWER-b) 45 seconds All air brake equipped vehicles have: a) An air supply pressure gauge b) An air use gauge c) A backup hydraulic system - ANSWER-a) An air supply pressure gauge If you must make an emergency stop, brake so you: a) Can steer while braking hard b) Use the hand brake first c) Can steer your vehicle in a straight line - ANSWER-c) Can steer your vehicle in a straight line The safety valve is usually set to reduce air pressure at ___ psi. a) 50 b) 100 c) 150 - ANSWER-c) 150 During normal driving, spring brakes are usually held back by: a) Bolts b) Spring pressure c) Air pressure - ANSWER-c) Air pressure In air brake vehicles, the parking brakes should be used: a) As little as possible b) To hold your speed when going downhill c) Any time the vehicle is parked - ANSWER-c) Any time the vehicle is parked The braking power of the spring brakes: a) Depends on the service breaks in adjustment b) Is not affected by the conditions of the service brakes c) Can only be tested by highly-trained brake service people - ANSWER-a) Depends on the service breaks in adjustment The brake pedal in an air brake system: a) Controls the speed of the air compressor b) Controls the air pressure applied to put on the brakes c) Is connected to slack adjusters by a series of rods and linkages - ANSWER-b) Controls the air pressure applied to put on the brakes The air loss rate for a straight truck or bus with the engine OFF and the brakes on should not be more than: a) 1 psi in one minute b) 2 psi in 45 seconds c) 3 psi in one minute - ANSWER-c) 3 psi in one minute Repeatedly pressing and releasing (fanning) the brake pedal may result in: a) The loss of brake air pressure b) A build up of brake air pressure