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Air Brake
| Question | Answer |
|---|---|
| When is it OK to leave your truck unattended without applying the parking brakes and choking the wheels? | Never |
| The stop light switch_______ | Turns on your brake lights to warn drivers behind you. |
| It is not safe to drive a vehicle that has brake drums with cracks longer than_______ of the width of the friction area. | 1/2 |
| To test air service brakes you should________. | Brake firmly while slowly moving forward. |
| If air pressure is not built up within the correct amount of time, then ___________? | Your air pressure may drop to a low point while driving, requiring an emergency stop. |
| The safety valve reduces pressure at _________ psi? | 150 |
| Why should you drain water from compressed air tanks? | Water can freeze in cold weather and cause brake failure. |
| If your vehicle has an alcohol evaporator, everyday during cold weather you should _________. | Check and fill the alcohol level |
| The air loss rate for a straight truck or bus with the engine off and the brakes on should not be worn more than ________. | 3 psi in one minute |
| The driver should be able to see a low pressure warning which comes on before pressure in the service air tanks falls below ________ psi? | 60 |
| The air brake lag distance at 55 MPH on dry pavement adds about ____ feet: | 32 |
| If 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 in ____ seconds: | 45 |
| 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. While moving forward, apply the brakes firmly using the brake pedal |
| Excessive use of the service brakes results in overheating which can lead to: | Expansion of the brake drums |
| The safety valve is set to automatically reduce tank pressure at what psi? | 150 |
| If you must make an emergency stop, you should brake so you __________. | Can steer and so your vehicle stays in a straight line |
| Your truck or bus has a dual air brake system. If a low air pressure warning comes on for only one system, what should you do? | Stop right away and safely park. Continue only after the system is fixed. |
| The brake pedal in an air brake system: | Control the air pressure applied to put on the brakes. |
| All air brake equipped vehicles have _________. | A supply pressure gauge |
| With air brake vehicles, the parking brakes should be used _____________. | Whenever you leave the vehicle unattended |
| A straight truck or bus air brake system should not leak at a rate of more than ___ psi per minute with the engine off and brakes released: | 2 |
| To check the free play of manual slack adjusters on S cam brakes, you should park on: | Level ground, chock the wheels and release the brakes |
| The use of brakes on a long and steep downgrade under normal conditions is only a supplement to: | The braking effect of the engine |
| The most important thing to do when a low air pressure warning comes on is ________? | Stop and safely park as soon as possible |
| The parking or emergency brake on a heavy vehicle can only be held on position by something that cannot leak away, like ____? | Spring pressure |
| Repeatedly partially releasing and pressing the brake pedal may result in _____? | A loss of brake air pressure |
| The brake system that applies and release the brakes when the driver uses the brake pedal is the __________ brake system. | Service |
| A slack adjusters free play needs to be adjusted if it is more than about ________ how many inches when you pull hard on it? | 1 inch |
| An air brake system is fully charged at what psi? | 125 |
| When brakes are applied, the brake shoes will press against the ______? | Brake drum or disc |
| The safety valve discharges automatically at the pressure of _________? | 150 |
| Emergency stab braking is ________? | Press on the brake pedal as hard as you can, release the brakes when the wheels lock, put on the brakes again when the wheels start rolling |
| Modern air brake systems combine three different systems. They are the service, the parking and the ___________ brakes. | Emergency |
| If you do not have automatic tank drains, how often should you drain the oil and water from the bottom of compressed air storage tanks? | At the end of each day of driving |
| The proper use of brakes on a long, steep grade after selecting a proper gear is to brake until your speed is about ___ mph below the posted safe speed, then release your brakes: | 5 |
| In ideal conditions, a truck or bus with air brakes going at 55 mph would require a stopping distance of: | More than 300 feet |
| The application pressure gauge shows how much air pressure you: | Are applying to the brakes |
| Some air brake systems have an alcohol evaporator. What may happen if you don’t keep the proper level of alcohol in its container? | Ice may form in the air storage tank and cause brake failure |
| Which of these is NOT a proper time to apply the parking brakes | a) If you are going to use the parking brakes you need to make sure that they will hold the weight of the vehicle b) If the brakes are very hot |
| The most common type of foundation brake found on heavy vehicles is the: | S-cam drum |
| Excessive heat caused by using your brakes too often can also cause: | Brakes to fade or fail |
| The supply pressure gauge shows how much air pressure: | Is in the air tanks |
| If you are going down a steep downgrade and you have reached a speed of 40 mph, you would apply the service brake until your speed has dropped to below ___ mph: | 35 |
| Your truck has a dual air system and one of the systems loses its pressure. What will happen? | Either the front or back brakes will not be fully operational |
| Parking or emergency brakes on trucks and buses can legally be held on by ___ pressure: | Spring pressure |
| The S-cam: | Forces the brake shoes against the inside of the brake drum |
| Under normal conditions, in order to engage the parking brakes, the driver: | Lets the air out of the brake system |
| Total stopping distance for air brakes is longer than for hydraulic brakes due to ___ distance: | Brake lag |
| During normal driving, spring brakes are usually held back by: | Air pressure |
| The air compressor stops pumping air at what psi? | 125 |
| The braking power of the spring brakes: | Depends on the service brakes being in adjustment |
| Your brakes are fading when: | You have to push harder on the brake pedal to control your speed on downgrades |
| If your vehicle has an alcohol evaporator, it is there to: | Reduce the risk of icing in air brake valves in cold weather |
| The air compressor governor controls: | When air is pumped into the air tanks |
| Air braking takes more time than hydraulic braking because: | Air takes more time to flow through the lines than hydraulic fluid |
| What can legally hold a parking or emergency brake in position for a truck, truck tractor, or bus? | Spring pressure |
| If the air compressor should develop a leak, what keeps the air in the tanks? | The one-way check valve |
| If your truck or bus has dual parking control valves, you can use pressure from a separate tank to: | Release the spring brakes to move a short distance |
| The spring brakes used on the chambers in a straight truck will bring you to a stop when air pressure drops below ___ psi. | 20 to 45 psi (typically 20 to 30 psi). |
Created by:
kok777
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