Crane (ancient) and boiler: what they have in common

1. Step 1. Crane (ancient) — has part — Block and tackle. The crane lifted loads with a block and tackle.
2. Step 2. Block and tackle — is part of — Drilling rig. The block and tackle lifts the drill string.
3. Step 3. Drilling rig — has part — Diesel engine. The drive.
4. Step 4. Diesel engine — is part of — Excavator. The drive is a diesel.
5. Step 5. Excavator — has part — Boiler. The first excavators were steam-powered.

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