Amazon Maintenance Technician Preventive Maintenance & Lubrication 2 — Questions and Answers
Question 1: Which technique uses infrared thermography during PM inspections to identify problems in electrical panels?
- Vibration analysis
- Ultrasonic testing
- Thermal imaging (Correct answer)
- Oil analysis
Correct answer: Thermal imaging
Thermal imaging cameras detect abnormal heat signatures in electrical connections, identifying loose connections or overloaded components before failure.
Question 2: What is the correct procedure when mixing two different grease types during a PM?
- Mix them freely — all greases are compatible
- Avoid mixing; if switching, purge old grease completely before applying the new type (Correct answer)
- Add a solvent to blend them
- Apply the new grease on top of the old without purging
Correct answer: Avoid mixing; if switching, purge old grease completely before applying the new type
Different grease thickener systems (lithium, calcium, polyurea) can be chemically incompatible, causing softening or hardening that leads to bearing failure.
Question 3: What is the purpose of vibration analysis in a predictive/preventive maintenance program for motors?
- Measure the motor's electrical resistance
- Detect imbalance, misalignment, bearing wear, or looseness before catastrophic failure (Correct answer)
- Verify motor speed under load
- Check insulation breakdown voltage
Correct answer: Detect imbalance, misalignment, bearing wear, or looseness before catastrophic failure
Vibration signatures identify mechanical faults such as unbalance, misalignment, and bearing defects, allowing scheduled repair before unplanned breakdown.
Question 4: A conveyor drive chain shows elongation (stretch) during a PM inspection. What action should be taken?
- Add more lubricant to compensate
- Measure elongation against manufacturer's wear limit; replace if it exceeds 3% elongation (Correct answer)
- Increase chain tension to correct for stretch
- Continue operation until visible link failure
Correct answer: Measure elongation against manufacturer's wear limit; replace if it exceeds 3% elongation
Chain elongation of 3% or more indicates significant pin and bushing wear; continued use risks sprocket damage and sudden chain failure.
Question 5: What is the primary difference between time-based and condition-based maintenance strategies?
- Time-based replaces parts on a fixed schedule; condition-based replaces them when monitoring data indicates degradation (Correct answer)
- Time-based costs more; condition-based is always cheaper
- Condition-based requires more labor hours than time-based
- There is no practical difference between them
Correct answer: Time-based replaces parts on a fixed schedule; condition-based replaces them when monitoring data indicates degradation
Time-based PM replaces parts at fixed intervals regardless of condition; condition-based maintenance (CBM) uses real-time data to trigger maintenance only when needed.
Question 6: When torquing fasteners during reassembly after PM work, why is a torque wrench required instead of hand-tightening?
- Hand-tightening is faster but uses more lubricant
- Torque wrenches prevent over-tightening that can strip threads or under-tightening that causes loosening and vibration fatigue (Correct answer)
- Torque wrenches are required only for hydraulic fittings
- Hand-tightening provides more consistent clamping force
Correct answer: Torque wrenches prevent over-tightening that can strip threads or under-tightening that causes loosening and vibration fatigue
Proper torque ensures correct clamping load; over-tightening can yield fasteners and under-tightening allows joints to loosen under vibration.
Amazon Maintenance Technician Preventive Maintenance & Lubrication 2
Which technique uses infrared thermography during PM inspections to identify problems in electrical panels?