Maintenance, Troubleshooting, and Equipment Reliability
Core concepts
Reliability is built on preventive and predictive maintenance: lubrication schedules, vibration analysis, thermography, oil analysis, and alignment checks. Know the difference between preventive (scheduled), predictive (condition-based), and corrective (after failure) maintenance, and why predictive is preferred for critical assets.
Troubleshooting follows a systematic method: define the symptom, gather data, form a hypothesis, test, and verify. Common scenarios: pump vibration (misalignment, imbalance, cavitation, bearing wear), blower overheating (filter, oil, belt, bearing), clarifier torque alarm (solids overload), and odor complaints (septicity, sulfide). Root-cause analysis tools include the 5 Whys and fishbone diagrams. Keep a maintenance management system (CMMS) with work orders, parts inventory, and asset history.
Traps
Questions often suggest "replace the part" when the correct answer is to diagnose first. Another trap: confusing vibration frequency signatures - imbalance at 1× running speed, misalignment often at 2×, bearing defects at high frequency. Watch for lockout/tagout questions where the correct answer is to verify zero energy state, not just flip a breaker.
Worked example / rule of thumb
A blower trips on high temperature. Rule of thumb: check inlet filter differential pressure first (cheapest, most common cause), then oil level and cooler, then belt tension, then bearings. Never reset and restart repeatedly without finding the cause - repeated trips damage bearings and seals.