Air Brakes

Question 1

Air Brakes have (3) different breaking systems….

Answer 1

1. Service Brake 2. Parking Brake 3. Emergency Brake

Question 2

Service Brake

Answer 2

Applies and releases the brakes when you use the brake pedal during normal driving.

Question 3

Parking Brake

Answer 3

applies and releases when you use the parking brake control.

Question 4

Emergency Brake

Answer 4

uses the parts of the service and parking break systems to stop the vehicle in a brake system failure

Question 5

Air Compressor

Answer 5

pumps air into the air storage tanks. connected to the engine via gears or a v-belt. may be air cooled or cooled or cooled by engine cooling system.

Question 6

Air Compressor Governer

Answer 6

controls when the air compressor will pump air into the air storage tanks. Will stop at 125 psi and will kick in at 100 psi.

Question 7

Air Storage Tanks

Answer 7

used to hold compressed air, size varies among vehicles. Tanks hold enough air to stop vehicle multiple times even if the compressor stops working.

Question 8

Air Tank Drains

Answer 8

should be drained at the end of every working day to avoid the water and oil that sit in the tanks from freezing up. 1. Manually operated by turning a quarter turn or by pulling a cable 2. Automatic, will auto drain tanks at end of day or have built in electronic heating devices.

Question 9

Alcohol Evaporator

Answer 9

put into air tank drains to help prevent ice from forming inside reservoir.

Question 10

Safety Valve

Answer 10

installed in the first tank the air compressor pumps to. Protects the tank and the rest of the system from too much pressure.

Question 11

Brake Pedal

Answer 11

also called, Foot valve or Treadle valve

Question 12

Foundation Brakes

Answer 12

used at each wheel, most common type is S-cam drum brake. See figure 5.2 for info on Drum Brake

Question 13

Wedge Brakes

Answer 13

brake chamber push rod pushes a wedge directly between the end of two brake shoes. May have a single break chamber or a double brake chamber. May be self adjusting or require manual adjustment.

Question 14

Disc Brakes

Answer 14

instead of the s­ cam, a “power screw” is used. The pressure of the brake chamber on the slack adjuster turns the power screw. The power screw clamps the disc or rotor between the brake lining pads of a caliper, similar to a large c-clamp.

Question 15

Low Air Pressure Warning “Wig Wag”

Answer 15

signal warning that appears before the tank drops to and below 60 PSI, light is red.

Question 16

Parking Brake Control

Answer 16

allows the driver to let air out of the spring brakes. A leak in the air brake system will cause the spring brakes to activate.

Question 17

Tractor Protection Valve

Answer 17

provides air supply, closes automatically if the air supply drops while driving.

Question 18

Anti Lock Braking Systems (ABS)

Answer 18

Required by vehicles built on or after March 1, 1998. Keep wheels from locking. Yellow malfunction lamp to tell you if there not working properly, left side front or rear.

Question 19

Dual Air Brakes

Answer 19

Have to separate air brake systems…using a single set of controls. Before driving both the primary and secondary systems need to have pressure built up to a minimum of 100 psi.

Question 20

Slack Adjusters

Answer 20

Should not be able to be moved more than 1 inch, any vehicle built after 1994, has automatic slack adjusters .

Question 21

Brake Lag

Answer 21

the time required for the brakes to work after the brake pedal is pushed.