FREE Air Brake MCQ Questions and Answers


What kind of gradient should you park on in order to check the manual slack adjusters of the S-CAM brakes for free play?

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When a low air pressure warning appears, the most crucial action is to stop and park safely as soon as you can.

Between what two pressures should reservoir pressure be maintained?

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Air brake system specifications are outlined in the National Safety Code and other laws. A vehicle must run between 80 psi (552 kPa) to 135 psi (930 kPa) of pressure. 105 psi (724 kPa) to 135 psi is the operating pressure range for the majority of late-model vehicles with air brake systems; the governor cut-in pressure is 20 psi (138 kPa) below the maximum pressure.

Typically, an emergency release tank features a "dead man" switch—a switch that requires holding in order to operate. This air tank can be used to release the spring brakes and move the car to safety if the air brake system completely loses pressure.
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What is the emergency release tank's intended use?

What is the lowest pressure at which the governor should trigger the compressor to resume its pumping phase?

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The lowest pressure at which an air brake system can safely function is 80 psi (552 kPa). The spring brakes will engage when the system's pressure falls below 80 psi. This criterion, to put it sarcastically, was set for Luddites who still drive their 1956 Peterbilt. The governor of the majority of late-model trucks—that is, any vehicle manufactured within the previous forty years—will return the compressor to the loading stage well before 100 psi (690 kPa).

When the air system reaches operational pressure, what does the compressor do?

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When the reservoirs reach their maximum operational pressure, which is around 125 PSI, the governor switches the compressor into an unloading phase. The compressor re-engages when the pressure drops to around 20 PSI below the maximum operational pressure.

What type of pressure holds the parking or emergency brakes on trucks and buses in place?

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On trucks and buses, spring pressure can hold on to the parking or emergency brakes.

What is a parking brake with a DD3 safety actuator?

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These parking brakes are a good substitute for the big, heavy spring and service brake chambers on buses and other vehicles with little ground clearance. The locking mechanism that cages and holds the push-rod in the applied position when the parking brakes are engaged replaces the massive coil spring that normally applies the brakes.

Which three fundamental brake types are there?

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The term "foundation brake" refers to the portion of the air brake system that actually has the ability to stop the vehicle. A foundation brake can also be referred to as a wedge brake, disc brake, or drum brake. Drum brakes are the most common, and the brake shoes, brake chamber, slack adjuster,

When conducting a build-up test on the compressor, what pressure do you start at?

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The driver checks the compressor's ability to build a specified volume of air in a predetermined amount of time. The compressor in British Columbia needs to build air at a high idle pressure of 50 psi (345 kPa) to 90 psi (620 kPa) in 3 minutes. The vehicle is considered "out of service" if the test results indicate that the compressor is malfunctioning.

Air loss shouldn't be more than when performing an air leak test in a single unit at maximum air pressure.

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The vehicle is permitted to lose 3 psi (21 kPa) on a single unit during a one-minute leak test. Following the first pressure drop that applies the service brakes, the allowed air loss is calculated.

How much force is applied to the push rod in a type 30 brake chamber when a 40 PSI brake application is made?

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The amount of pressure on the push rod in this instance is 1200 PSI because the area of the braking chamber (type 30 = 30 square inches) is multiplied by the application pressure being provided.

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