Mechanical Systems & Equipment Maintenance Flashcards

A technician notices a bright, polished contact band on only one side of a V-belt in a drive system. This indicates:

Answer: Sheave grooves are misaligned

One-sided contact wear indicates sheave misalignment, causing the belt to run against only one groove wall.

The purpose of a torque limiter (slip clutch) in a power transmission system is to:

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.

When performing a precision shaft alignment using dial indicators, a reading that changes as the shaft is rotated indicates:

Answer: Shaft runout or coupling eccentricity

A varying dial indicator reading during shaft rotation indicates shaft runout, bent shaft, or an eccentric coupling hub.

Which type of preventive maintenance task is MOST effective at detecting early-stage bearing failure?

Answer: Vibration analysis using an accelerometer

Vibration analysis detects bearing defect frequencies (BPFO, BPFI, BSF) long before failure becomes visible or audible.

What is the recommended action when a technician discovers 'soft foot' during a machinery alignment procedure?

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.

A piston rod seal in a hydraulic cylinder is leaking externally. Before replacing the seal, the technician should inspect the rod for:

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.

Which lubrication property describes a grease's resistance to being displaced from the bearing by centrifugal force or heavy loads?

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.