Preventive Maintenance, Inspection, and Equipment Servicing
What this domain tests
Scheduled service intervals, oil sampling programs, inspection routines, fluid and filter selection, record keeping, and putting a machine into or out of storage - the area where careless habits cause the most expensive failures.
Core rules
- Intervals are condition-based, not just hour-based. Severe duty (dust, heat, high idle time, short cycles) shortens oil, filter, and coolant intervals. Follow the manufacturer's schedule for the application, not a single blanket number.
- Sampling: draw oil at operating temperature from a live, mid-stream point after the machine has run; a cold or drain-point sample reads wrong. Trend results against the previous sample for the same unit; a single report without history is weak evidence.
- Filters: cut the element open on a scheduled basis and inspect for metal, clutch material, or dirt. That inspection often finds a failure before a gauge does.
- Daily walkaround: fluid levels and leaks, tire or track condition, belt and hose condition, guards, lights, backup alarm, fire extinguisher, and attachment pins. Record defects and correct them before the machine goes back to work.
- Servicing: correct fluid specification and cleanliness matter more than brand. Torque drain plugs and wheel nuts to spec; re-torque wheel nuts after the specified interval on newly installed wheels.
- Storage: full fuel tanks to limit condensation, batteries on maintainers, cylinders retracted where possible, and seals protected. Return to service with a full inspection, not just a start.
Worked example
A 500-hour service is due on a wheel loader in a quarry. Because of the dust and the high idle time, the schedule calls for shorter air filter inspection and oil sampling intervals. The correct action is to service to the severe-duty interval, take the oil sample before draining, and cut the oil filter open - not simply to reset the hour meter and change oil.
Traps
- Taking oil samples from the drain plug after the oil has cooled.
- Resetting a service reminder without performing the inspection items.
- Ignoring a rising trend in wear metals because the value is still inside the flag limits.