Port, Crane & Terminal Equipment worked example

Spare Parts Buffer with daily critical spare consumption across the crane fleet of 600 units / day: a worked example in port, crane & terminal equipment

Here is what the math looks like when conditions slip. We hold every other input steady and drop daily critical spare consumption across the crane fleet to 600 units / day, then walk the calculation through step by step. Estimate spare parts buffer for port, crane and terminal equipment using production-ready inputs so teams can plan replenishment and safety stock using actual usage and lead time.

The inputs for this scenario

  • Daily critical spare consumption across the crane fleet: 600 units / day (the input this scenario stresses; the baseline uses 1,200)
  • Supplier replenishment lead time for the spare: 85 days (held at the documented default)
  • Safety stock multiplier for demand variability: 1.1 units (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Spare parts buffer cycle stock = spare parts buffer daily usage × spare parts buffer lead time.
  • Protected days of supply works out to 6.42 days at these inputs, and this is the headline figure for the scenario.
  • Unprotected days works out to 7.06 days at these inputs.
  • Inventory works out to 600 pieces at these inputs.
  • Daily usage works out to 85 pieces / day at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where daily critical spare consumption across the crane fleet sits at 1,200 units / day and the headline result is 12.83 days, this scenario comes in 50% below the baseline at 6.42 days.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to daily critical spare consumption across the crane fleet, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It assumes roughly constant daily usage; for lumpy, failure-driven demand on capital spares (a whole gearbox), a Poisson or criticality-based model is more appropriate than this linear buffer.

Results at a glance

  • Protected days of supply: 6.42 days (headline result)
  • Unprotected days: 7.06 days
  • Inventory: 600 pieces
  • Daily usage: 85 pieces / day

Run it with your numbers

  • To rerun this with your own numbers, open the live Spare Parts Buffer calculator, set daily critical spare consumption across the crane fleet to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.