4-13. 6-NFR DISTRIBUTING VALVE (cont)
CLEANING, INSPECTION, AND REPAIR (cont)
Do not use metallic tools to clean chokes. The use of metallic tools will change
size of chokes, resulting in failure of brake valve system.
To avoid misplacement of chokes, remove and replace one choke plug at a time.
19. Clean, inspect, and repair choke plugs (53), (54), (55),
and (56) by the following:
Remove choke plug and place in dry-cleaning
Inspect choke plug passage for cleanliness. Use
compressed air and remove foreign matter.
Remove choke plug from dry-cleaning solvent and
dry with compressed air. Check that choke plug is
clean and unrestricted.
Lightly coat threads of choke plug with compound
consisting of one part graphite and two parts oil
20. Clean, inspect, and repair slide valve bushing by the following:
Check that slide valve bushing is not scratched or scored.
Use plug gage and check depth of seat.
If slide valve seat is scratched or scored, use a lapping compound and recondition.
Use marking pigment and gage blocks and inspect for low spots on bearing surface.
Remove burrs from slide valve seat
Use a depth gage and measure clearance groove. If it is less than 0.005 inch (0.13 mm) deep, use a hacksaw
blade and recut. Do not cut deeper than 0.020 inch (0.51 mm).