Coaster brake and tunnelling shield: what they have in common

1. Step 1. Coaster brake — is a kind of — Bicycle brake. A brake.
2. Step 2. Bicycle brake — has part — Brake pad. Pads.
3. Step 3. Brake pad — is part of — Brake caliper. Pads.
4. Step 4. Brake caliper — has part — Piston. Pistons.
5. Step 5. Piston — is part of — Hydraulic cylinder. The piston is moved by liquid.
6. Step 6. Hydraulic cylinder — is used in — Tunnelling shield. The shield was pushed forward by jacks.

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