BOMwiki is the free bill-of-materials encyclopedia. Every product is exploded into the parts it is built from, down to individual screws, bearings, and cells. Excavator. A hydraulic crawler excavator: diesel-powered, hydrostatic, with boom-arm-bucket work equipment on a tracked undercarriage. Its bill of materials rolls up to 639 parts across 7 top-level assemblies, each explorable down to ...