Air Brakes 5

A device which can reduce brake lag on vehicles with air brakes is:

• The quick release valve

• Front wheel limiting valve

• Tractor protection valve

• The relay valve

A straight truck or bus air brake system should not leak at a rate of more than _____ within one minute with the engine off, brakes released, service brakes released.

• One psi

• Two psi

• Three psi

• Four psi

Air storage tank should hold enough air to allow several brake applications even when the air compressor stops working.

• True

• False

All airbrake vehicles have an air dryer and an alcohol evaporator.

• True

• False

Applying the service brakes when the spring brakes are on will cause:

• Compounding pressure and could damage the brakes

• Controlling pressure and could make the brakes out of adjustment

• Impounding pressure and could cause the compressor to fail

• Confounding pressure and could cause brake lag

Brake drums or discs must:

• A. Not have cracks

• B. Not have cracks longer than 1/2 the friction area

• C. Be free of oil and grease

• Both B and C are correct

Brake failure:

• Often lead to trailer breakaway

• Are most often caused by road hazards

• Are most often caused by brake fade

• Are the leading mechanical cause of accidents

Break lag is caused by:

• The time it takes for air to flow through the system

• The time it takes for the compressor to build air pressure

• The time it takes for the brake chamber to compress

• The time it takes for the slack adjuster to turn the camshaft

Dual air brake system supply air to the trailer through:

• The primary system

• The secondary system

• The emergency system

• Both the primary and secondary system

During normal driving, the parking and emergency brakes are held back by:

• Air pressure

• Spring pressure

• Hydraulic pressure

• Centrifugal force