4-22 AIR SYSTEM - Continued
4-22.4 Relay Valve.
This task covers
Shop Equipment, Automotive
22, Appendix E Pipe Sealant
Maintenance and Repair,
Main Engine Shutdown (see para. 2-10)
APU Shutdown (see para. 2-12)
Batteries Disconnected (see para. 4-24)
All Air Tanks Drained
Death or serious injury could occur if compressed air is directed against the skin. Always
drain all air tanks via the draincocks prior to maintaining the relay valve.
This valve is installed on the frame cross member above the rear axle.
Tag and disconnect air lines A, B, C, D and E
from relay valve
Remove locknuts and remove relay valve from
Remove all pipe fittings from relay valve ports.
Make a sketch that indicates which fittings fit
Install pipe fittings in relay valve ports using
sketch as a guide. Coat all threads with pipe
sealant (item 22, Appendix E) prior to installation.
Install relay valve on truck using locknuts
Install air lines to valve ports. Be sure the air lines are connected the same as noted in step 1 of
Reconnect the batteries and start the truck main engine