Attitude indicator and tunnelling shield: what they have in common

1. Step 1. Attitude indicator — is part of — Cockpit. An attitude indicator.
2. Step 2. Cockpit — is part of — Aeroplane. A cockpit.
3. Step 3. Aeroplane — has part — Landing gear. Landing gear.
4. Step 4. Landing gear — includes — Retractable landing gear. Landing gear.
5. Step 5. Retractable landing gear — has part — Hydraulic cylinder. Retraction cylinders.
6. Step 6. Hydraulic cylinder — is used in — Tunnelling shield. The shield was pushed forward by jacks.

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