Cold chain and railway track: what they have in common

1. Step 1. Cold chain — uses — Refrigerator. Refrigerators.
2. Step 2. Refrigerator — has part — Compressor. A compressor with an electric motor.
3. Step 3. Compressor — is part of — Air brake. A compressor pumps the air.
4. Step 4. Air brake — is part of — Diesel locomotive. Air brakes.
5. Step 5. Diesel locomotive — evolved from — Steam locomotive. It replaced the steam locomotive.
6. Step 6. Steam locomotive — uses — Railway track. It runs on rails.

Open Evothings