Components In An Air Brake System

Front 1

Compressor

Back 1

Used to compress site for the brake system

Front 2

Reservoir

Back 2

Stores a volume of compressed air for the system

Front 3

Foot valve

Back 3

Regulates the flow of compressed air from the reservoir when it is needed for braking

Front 4

Brake chambers and slack adjusters

Back 4

Transfers the force exerted by compressed air to mechanical linkages. Slack adjuster is also used for brake adjustment.

Front 5

Brake linings and drums

Back 5

Create the friction necessary to stop the wheels.

Front 6

Governor

Back 6

Controls the minimum and maximum air pressure in the systems; minimum pressure is approx. 20 PSI below max

Front 7

Safety Value

Back 7

Protects the systems from over-pressurizing if the governor fails to unload the compressor.

Front 8

Wedge-type brake

Back 8

Not readily adjustable, most are self-adjusting

Front 9

One-way check valve

Back 9

Allows air to flow in on direction only, used to isolate reservoirs from each other.

Front 10

Air gauge

Back 10

Tells how much air pressure there is in the system, also can be used to tell the amount of air application to the brake chamber.

Front 11

Low-pressure warning

Back 11

Used to warn the driver of low air pressure by a visual or audible warning set to activate at 60 PSI

Front 12

Stop light switch

Back 12

Air-operated electrical switch which turns on the brake lights when a brake application is made.

Front 13

Quick release valve

Back 13

Used to release air pressure faster

Front 14

Relay valve

Back 14

Applies and releases brakes faster; reduces brake lag

Front 15

Front wheel limiting valve

Back 15

Limits the braking power of the front brakes by 50% when the control valve is in the slippery position

Front 16

Control valve

Back 16

Controls the action of the front wheel limiting valve

Front 17

Automatic front wheel limiting valves

Back 17

Modulates the limiting of the front brakes stops limiting the front brakes at approximately 60 PSI

Front 18

Spring brakes

Back 18

Mechanical parking brakes, also can be used as an emergency brake when you have a loss of air in the system

Front 19

Park control valve

Back 19

Applies and releases parking brake

Front 20

Dual control valve

Back 20

Allows you to use an emergency release tank to release

Front 21

Caging bolt

Back 21

Allows you to release your spring brakes in an emergency without the use of air pressure

Front 22

Hand valve

Back 22

Allows you to control the trailer brakes separately from the tractor, makes it possible to use trailer brakes only

Front 23

Two-way check valve

Back 23

Allows air to be directed through one delivery pipe from either of two sources:

1) Allows control of the trailer brakes by the use of the hand valve or foot valve.

2) Allows blended air supply pressure taken from the primary and secondary reservoirs.

3) Allows blended service air pressure taken from the primary and secondary foot valves.

4) Can be used as an anti-compound device in the spring brakes.

Front 24

Tractor protection system

Back 24

Prevents total loss of air from the tractor if the trailer breaks away from the tractor, or if connection lines between the tractor and trailer become separated or ruptured. The system consists of the tractor protection valve and the trailer supply valve.

Front 25

Tractor protection valve

Back 25

Protects the tractor air supply.

Front 26

Trailer supply valve

Back 26

Supplies air to the trailer reservoir

Front 27

Relay emergency valve

Back 27

The relay part of the valve applies and releases the trailer brakes faster, the emergency part of the valve directs trailer reservoir pressure to the trailer brake, causing an emergency application of trailer brakes when the trailer breaks away or if connection lines area separated or ruptured, or if the driver closes the trailer supply valve.

Front 28

Dual foot valve

Back 28

Two foot valves in one (a primary and secondary foot valve)

Front 29

Spring brake modulator valve

Back 29

If you have a primary circuit failure only, it allows you to use controlled spring pressure to help stop the vehicle

Front 30

Dump valve

Back 30

If the relay type tractor protection system does not work immediately the dump valve will make the system work at 60 PSI on an L75 system

Front 31

T.A.S.K. valve

Back 31

On dual air trailer, supplies air to both reservoirs, and applies and releases spring brakes and dynamites spring brakes in trailer in an emergency