Maintenance due dates

Use a meter that measures the intended activity

Running hours, powered-on hours, and loaded operating hours are not always equivalent. Match the meter and interval to the equipment's service instructions. Check the last-service date and meter together; an incorrect baseline carries through to every subsequent due estimate.

Treat forecast dates as estimates

An hours-based date changes when actual weekly use changes. The calendar limit still applies independently. This tool is a planning worksheet, not a background monitoring or notification system. Recheck it when usage changes and follow the equipment manufacturer's service requirements.

Comparing calendar and runtime triggers

If service is required every 180 days or 500 running hours, either condition can make it due. Adding the calendar interval to the last-service date gives one threshold; adding 500 hours to the last-service meter gives the other. A machine used infrequently can reach the calendar threshold first, while a heavily used machine can reach the runtime threshold first.

The forecast date for remaining runtime depends on the entered weekly use. If use doubles, the remaining hours are consumed in roughly half the forecast time under the same steady-use assumption. Recalculate after a schedule change rather than treating the earlier forecast as a fixed appointment. Keep meter rollover, replacement, and units in mind when recording service baselines. An hour interval from the equipment instructions should be applied to the specified kind of operating time. This worksheet does not collect machine telemetry or send reminders in the background; it organizes the dates and readings entered so the next required action can be planned.

Formula

Calendar due = last service date + calendar interval. Runtime due meter = last service meter + hour interval. The earlier trigger governs.