Wood pulp and railway track: what they have in common

1. Step 1. Wood pulp — is used in — Paper machine. The raw material.
2. Step 2. Paper machine — works like — Conveyor belt. Fourdrinier’s endless wire mesh moves like a conveyor belt, forming the web of paper.
3. Step 3. Conveyor belt — is part of — Tunnel boring machine. Spoil is removed by a conveyor.
4. Step 4. Tunnel boring machine — evolved from — Tunnelling shield. A development of the tunnelling shield.
5. Step 5. Tunnelling shield — is used in — Metro. Metro tunnels were built with shields.
6. Step 6. Metro — uses — Railway track. It runs on rails.

Open Evothings