ITMC Mechanical Systems & Equipment Maintenance 5 — Questions and Answers
Question 1: A technician notices a bright, polished contact band on only one side of a V-belt in a drive system. This indicates:
- Normal belt wear from proper tension
- Belt is over-tensioned
- Sheave grooves are misaligned (Correct answer)
- Belt is under-tensioned
Correct answer: Sheave grooves are misaligned
One-sided contact wear indicates sheave misalignment, causing the belt to run against only one groove wall.
Question 2: The purpose of a torque limiter (slip clutch) in a power transmission system is to:
- Increase the torque output of the drive motor
- Disconnect the drive when torque exceeds a preset limit to protect equipment (Correct answer)
- Maintain constant speed under varying loads
- Reduce vibration between driver and driven equipment
Correct answer: Disconnect the drive when torque exceeds a preset limit to protect equipment
A torque limiter slips or disconnects when transmitted torque exceeds its set point, protecting downstream components from overload damage.
Question 3: When performing a precision shaft alignment using dial indicators, a reading that changes as the shaft is rotated indicates:
- Soft foot condition
- Shaft runout or coupling eccentricity (Correct answer)
- Correct alignment
- Bearing preload error
Correct answer: Shaft runout or coupling eccentricity
A varying dial indicator reading during shaft rotation indicates shaft runout, bent shaft, or an eccentric coupling hub.
Question 4: Which type of preventive maintenance task is MOST effective at detecting early-stage bearing failure?
- Visual inspection of the bearing housing
- Vibration analysis using an accelerometer (Correct answer)
- Checking lubricant level in the reservoir
- Measuring shaft rotational speed
Correct answer: Vibration analysis using an accelerometer
Vibration analysis detects bearing defect frequencies (BPFO, BPFI, BSF) long before failure becomes visible or audible.
Question 5: What is the recommended action when a technician discovers 'soft foot' during a machinery alignment procedure?
- Proceed with alignment and compensate with shims under the coupling
- Correct the soft foot condition by shimming the affected machine foot before aligning (Correct answer)
- Tighten all hold-down bolts as tightly as possible
- Ignore it if misalignment readings are within tolerance
Correct answer: Correct the soft foot condition by shimming the affected machine foot before aligning
Soft foot must be corrected before alignment because it causes the machine frame to distort when bolts are tightened, invalidating alignment readings.
Question 6: A piston rod seal in a hydraulic cylinder is leaking externally. Before replacing the seal, the technician should inspect the rod for:
- Correct rod diameter
- Scoring, pitting, or surface roughness that would damage the new seal (Correct answer)
- Rod end thread condition
- Piston ring wear
Correct answer: Scoring, pitting, or surface roughness that would damage the new seal
Surface defects on the rod will cut or abrade a new seal immediately, causing it to fail prematurely.
Question 7: Which lubrication property describes a grease's resistance to being displaced from the bearing by centrifugal force or heavy loads?
- Viscosity index
- NLGI consistency grade (Correct answer)
- Dropping point
- Flash point
Correct answer: NLGI consistency grade
The NLGI (National Lubricating Grease Institute) consistency grade indicates grease stiffness; higher grades resist displacement better in high-speed or heavy-load applications.
ITMC Mechanical Systems & Equipment Maintenance 5
A technician notices a bright, polished contact band on only one side of a V-belt in a drive system.
This indicates: