Air Brakes 21-40

The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than:

• 3 psi in one minute

• 1 psi in 30 seconds

• 2 psi in 45 seconds

The driver must be able to see a low air pressure warning which comes on before pressure in the service air tanks fall below

• 80

• 50

• 60

The braking power of the spring brakes

• is not affected by the condition of the service brakes

• Depends on the service brakes being in adjustment

• Increases when the service brakes are hot

The air brake lag distance at 55 mph on dry pavement add about ___ feet.

• 32

• 12

• 52

Total stopping distance for air brakes is longer than that for hydraulic brakes due to ___ distance

• Effective Braking

• Reaction

• Brake lag

It is accepted that too much heat caused by using your brakes too ofeten can also cause

• Modulated control valve to wear out

• Brake to fade or fail

• Brake linings to split up

Repeatedly partially increasing and pressing the brake pedal may result in:

• A buildup of brake air pressure

• No change of brake air pressure

• A loss of brake pressure

The brake system that applies and releases the brakes when the driver uses the brake pedal is the ___ Brake system

• Parking

• Service

• Emergency

A slack adjuster's free play needs to be adjusted if it is more than about ___ When you pull hard on it

• 1/4 inch

• 1/2 inch

• 1 inch

An air brake system is fully charged at what psi?

• 75

• 100

• 125