Filter Clogged Too much oil in gear case or drive cover. Too low operating speed Clogged filter or silencer Excessive pressure differential
Clean or replace filter. Reduce oil level. See filling Procedure.
Worn impeller clearances Overheating of bearings or gears
Inadequate lubrication
Increase blower speed. Remove cause of obstruction. Reduce pressure differential across the blower and accessories (silencers). Restore clearances.
Coupling misalignment Excessive belt tension
Check type and viscosity of oil , and grease in drive end bearings (when applicable). Check oil level. If incorrect, drain and refill with clean oil of recommended grade. Make sure grease is not excessive. Check inlet vacuum and discharge pressure, and compare these figure with predicted operating conditions. Check carefully. Realign if questionable. Readjust for correct tension.
Impeller end or tip drag
Insufficient assembled clearances Case or frame distortion Excessive operating pressure Excessive operating temperature
Correct clearances Check mounting and pipe strain Remove cause Remove cause
Knocking
Unit out of time. Distortion due to improper mounting or pipe strains. Excessive pressure differential or discharge temperature too high
Retime Check mounting alignment and relieve pipe trains. Reduce to manufacturer's recommended pressure. Examine relief valve, re-set if necessary. Replace timing gears See Section III New bearings. Check bearing fit in headplate.
Excessive lubrication
Excessive pressure rise
Worn gears Worn bearings Worn bearing fit Vibration
Misalignment Impellers rubbing
Worn bearings / gears Structural Unbalanced or rubbing impellers
Loss of oil
Abnormal noise
Readjust for correct tension. Inspect outside of cylinder and headplates for high temperature areas, then check for impeller contacts at these points. Check gear backlash and condition of bearings, and replace as indicated. Correct and make proper leveling. Scale or process material may build up on casing and impellers, or inside impellers. Remove build-up to restore original clearances and impeller balance.
Headplate, gear case or drive cover vents plugged. Worn seal.
