TM 5-4930-218-14
Table 5-1. Direct Support and General Support Troubleshooting--Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
GREASE DISPENSER-continued
2. DISPENSER FAILS TO DELIVER GREASE WHEN TRIGGER IS OPERATED.
Step 1. Check trigger adjustment.
Adjust trigger (para 6-12).
Step 2. Check flow adjusting screw.
Turn trigger knurled screw counterclockwise to increase flow (para 6-12).
AIR COMPRESSOR
1. COMPRESSOR FAILS TO PUMP RATED PRESSURE OR VOLUME.
Step 1. Check for faulty intake of exhaust valves.
Repair or replace faulty valves (para 7-5).
Step 2. Check for worn piston rings, which prevent sufficient compression.
Replace defective rings (para 7-8).
Step 3. Check for faulty unloader mechanism holding open intake valve.
Free or adjust unloader mechanism (para 7-3).
2 COMPRESSOR OVERHEATS.
Step 1. Check for defective crankshaft bearings.
Replace defective bearings (para 7-9).
Step 2. Check for defective rod bearings.
Replace defective rod bearings (para 7-8).
Step 3. Check for exhaust valve stuck closed.
Free, repair, or replace exhaust valve (para 7-5).
3. COMPRESSOR VIBRATES EXCESSIVELY.
Step 1. Check for flywheel misalinement.
Remove, clean, and reinstall flywheel. Replace if vibration continues (para 7-2).
Step 2.
Check for stuck valve.
Clean, repair, or replace valve (para 7-5).
Step 3. Check for defective crankshaft bearings.
Replace defective bearings (para 7-9).
Check for defective rod bearings.
Step 4.
Replace defective rod bearings (para 7-8).
Step 5. Carbon buildup on piston or in cylinder interferes with piston travel.
Disassemble piston and clean out carbon deposit (para 7-8).
BRAKE RELAY VALVE
1. RELAY VALVE FAILS TO BRAKE VEHICLE WHEN ACTUATED BY TOWING VEHICLE.
Step 1. Check for ruptured diaphragm.
Disassemble valve and replace diaphragm (para 8-2).
Step 2. Check for sticking plunger or valve.
Disassemble relay valve. Clean and free parts (para 8-2).
2. TRAILER AIR RESERVOIRS LOSE AIR THROUGH BRAKE RELAY VALVE.
Step 1. Check for faulty check valve spring.
Disassemble as necessary to replace check valve spring (para 8-2).
Step 2. Check for faulty inlet valve spring which should keep inlet valve closed.
Disassemble as necessary to replace inlet valve spring or inlet valve (para 8-2).
Step 3. Check for faulty preformed packings around piston.
Disassemble as necessary to replace preformed packings (para 8-2).
Step 4. Check for faulty preformed packing around check valve plug.
Remove plug and replace packing (para 8-2).
AXLE ASSEMBLY
1. TRAILER TIRES WEAR UNEVENLY.
Inspect axle tube for bent condition.
Step 1.
Straighten axle tube or replace axle assembly (para 9-6 through 9-8).
Step 2. Inspect for misalined frame.
Straighten frame (para 9-10 through 9-12).
2. EXCESS PLAY OF AXLE TUBE IN BEARINGS.
Step 1. Check for excessively worn split bearings.
Remove axle and replace split bearings (para 9-10 through 9-12).
LANDING GEAR
1. LANDING GEAR WILL NOT EXTEND OR RETRACT.
Step 1. Shaft screw, inner tube, or outer tube is bent and binding.
Disassemble landing gear as necessary to replace defective parts (para 9-2 through 9-4).
5-3
