The air brake valves include the following:
| • | Automatic control valves |
Air valves are pneumatic controls that route compressed air through
hoses and lines to or from the air brake components. Air valves control the
following:
| • | Spring brake chamber assemblies |
| • | Trailer service air lines |
All air valves have air passages and internal moving parts. These moving
parts direct the compressed air to the desired location. Each valve has the
following components:
| • | At least one supply port to allow air to enter the valve |
| • | One delivery port to allow air to exit the valve |
Some valves have a control port that allows an air pressure source to
control air flow through the valve. An exhaust port allows air to vent to
the atmosphere. Some valves have special function control ports such as balance
or reservoir ports. Refer to these valves for more discussion of the special
ports.
Air brake valves operate either manually or automatically. Manual valves
require the driver to move a knob, handle, or pedal in order to work the valve.
Automatic valves use control ports or internal regulating parts in order to
work.
