TM 10-6640-233-10 Table 2-12. Operator Preventive Maintenance Checks and Services (cont.) B - Before A - After M - Monthly D - During W - Weekly B D A W M 15 Air Compressor a.   Check for loose mounting Mounting bolts loose bolts. or missing. b.   Check crankcase oil level. Low oil level. c.   Check intake for obstruc- Intake is obstructed. tions. d.   Check air filter for Clogged or dirty fil- obstructions. ter. e.   Listen for rattles, knocks, Vibration or unusual squeaks, or hums that may noise occurs. indicate trouble in air compressor or motor. f.    Observe motor for indica- Motor overheats. tion of overheating and smoke. 16 Air Tank and a.   Check for loose mounting Missing bolts. System Piping bolts. b.   Inspect for leaks, leaky Air leaks or defective valves, or inoperative valves. valves. c.   Drain air tank as required. 17 Vacuum Pump a.   Check for loose mounting Mounting bolts miss- bolts. ing. b.   Check crankcase oil level. Low oil level. c.    Listen for rattles, knocks, Vibration or unusual squeaks, or hums that may noise occurs. indicate trouble in air compressor or motor. d.   Observe motor for indica- Motor overheats. tion of overheating and smoke. INTERVAL ITEM NO. ITEM TO BE INSPECTED Equipment is Not Ready/ Available Procedures Check for and have repaired or adjusted as necessary. 2-21