Pre-Operational Inspection, Preventive Maintenance, and Component Care
What the exam tests
This domain covers the daily walkaround, scheduled service, wear-item diagnosis, and the paperwork that proves the work was done.
Core rules and concepts
- Walkaround before every shift: fluids and leaks under the machine, cracked or chafed hoses, scored cylinder rods, loose or missing pins and retainers, cutting edge and teeth, track or tyre condition, ROPS and FOPS damage, seat belt, fire extinguisher charge, lights, horn, backup alarm, mirrors and decals.
- Fluid checks per the OEM: engine oil on level ground, coolant only when cold, hydraulic oil at operating temperature on the sight glass, final drives at the plug level, and the water separator drained daily.
- Scheduled service is interval-based: greasing (often every 10 h for pins and bushings), engine oil and filters, air cleaner element checked against the restriction indicator, fuel filters, hydraulic return filter, and annual or 2,000 h items. Use the OEM fluid specification, not whatever is on the shelf.
- Track tension: measure sag per the manual. Too tight wears sprockets, idlers and bushings; too loose lets the track jump the sprocket.
- Oil and coolant sampling catch wear metals and contamination before failure.
- Defect handling: tag out, record it on the inspection form, report to the supervisor, and do not operate a machine with a safety defect.
Worked example
A track on a 20-tonne excavator shows excessive sag and the sprocket teeth are hooked. Reasoning: adjust tension to the OEM specification only after confirming the adjuster and relief valve are not the cause, then measure the sprocket against the wear-limit gauge. Hooking means the sprocket is near end of life; continued running accelerates chain and bushing wear, so schedule replacement and monitor. Record the measurement so the next shift and the shop see the trend.
Traps that cost marks
- Opening a hot cooling system.
- Greasing without wiping the fitting, pushing grit into the pin.
- Ignoring a small leak that becomes a blown hose under load.
- Signing off an inspection you did not perform.
- Mixing hydraulic oil grades or topping up with the wrong product.