CDL Air Brakes Practice Test 1
What type of air do air brakes use?
Compressed air. Air brakes use compressed air for operation and are a safe way to stop large and heavy vehicles if maintained properly.
What are the three types of brake systems used in a commercial vehicle air brake system?
Service brake, parking brake, emergency brake. Anti-lock brakes are installed on many vehicles, but are an add-on component to the air brake system. Some brakes have hand controls, but this is not the name of one of the components of the air brake systems.
What is the name of the device that pumps air into the air storage tanks?
Air compressor. The air compressor pumps air into the air storage tanks/reservoirs. The governor controls when the air compressor will pump air into the air storage tanks. An alcohol evaporator puts alcohol into the air system to help reduce the risk of ice in cold weather. A safety valve protects the tank and system from too much pressure.
What is the alcohol evaporator's primary purpose?
Put alcohol into the air system. An alcohol evaporator puts alcohol into the air system to help reduce the risk of ice in cold weather.
What psi level is the safety relief valve set to open at?
150 psi. A safety relief valve is installed in the first tank that the air compressor pumps air into. A safety valve protects the tank and system from too much pressure by opening up at 150 psi.
Which of the following is the most common type of foundation brake?
S-cam drum brake. Wedge brakes and disc brakes are foundation brake types that are much less common than S-cam drum brakes. Anti-lock brakes are an add-on component to an air brake system to help reduce lockup.
Which of the following statements is true regarding front wheel braking?
Front wheel braking is good under all conditions. Testing has confirmed that front wheel braking will not cause skids, even on ice. If your vehicle is made before 1975, it may be equipped with a front brake limiting valve. You should set the valve in the "normal" position, regardless of driving conditions.
At what air pressure must the low air pressure warning signal come on?
60 psi. The warning light (or buzzer) must come on when the pressure falls below 60 psi.
Which of the following statements regarding spring brakes is true?
Spring brakes are held by mechanical force. Spring brakes use mechanical force to stop a vehicle and are designed to work if the air pressure becomes too low (under 45 psi).
Which of the following devices indicates how much pressure you have in your air tanks?
Supply pressure gauge. All vehicles with air brakes have a supply pressure gauge that indicates how much pressure is in the air tanks. The low air pressure warning signal will only indicate when you have low air pressure (below 60 psi). The application pressure gauge tells you how much pressure you are applying to the brakes. An ammeter is used to measure the amp usage of your electrical systems.
