GUARD 2975874 - Caterpillar

Purge Procedure
When opening the drain valve, wear protective gloves, protective face shield, protective clothing and protective shoes.Pressurized air could cause debris to be blown and result in personal injury.
Note: The following procedure illustrates the release of the air pressure in both the starting and service brake air system as well as the parking and secondary brake air system.
Install the wheel chocks. Refer to Disassembly and Assembly, "Wheel Chock (Front and Rear) - Remove and Install".
Illustration 1 g00535521
Illustration 2 g00620763
Purge the air pressure in tank (1) by pulling handle (2) in order to open control valve (3) .Note: Control valve (3) is located below tank (1) .
After the air pressure has been purged from tank (1), release handle (2) in order to close control valve (3) .
Illustration 3 g00535524
Illustration 4 g00535525
Purge the air pressure in tank (4) by turning handle (5) clockwise in order to open drain valve (6) .Note: Drain valve (6) is located on the right side of the cab.
After the air pressure has been purged from tank (4), turn handle (5) counterclockwise in order to close control valve (6) .
Charge the air pressure in the air tank. Refer to Operation and Maintenance Manual, "Starting with an External Air Supply" for the correct procedure.
Remove the wheel chocks. Refer to Disassembly and Assembly, "Wheel Chock (Front and Rear) - Remove and Install".