Stopwatch crown button and elevator: what they have in common

1. Step 1. Stopwatch crown button — is part of — Stopwatch. A cam starts and resets the hand.
2. Step 2. Stopwatch — has part — Balance wheel. A balance wheel sets the pace.
3. Step 3. Balance wheel — has part — Spring. A spiral hairspring returns the balance.
4. Step 4. Spring — is part of — Elevator safety brake. Springs throw out the catches when the rope goes slack.
5. Step 5. Elevator safety brake — is part of — Elevator. Otis’s safety brakes.

Open Evothings