San Francisco’s iconic cable cars are hoisted uphill by 35-year-old wheels called “sheaves,” which pull massive steel cables at 9.5 miles per hour. Now, those 25 underground sheaves will be rebuilt ...

A gear close gearA gear is a mechanical part with teeth that interlock with another gear or belt to transfer motion and power while changing speed, or direction in a mechanical system. is a special ...

Emergency pull-wire switches have become established as "extended emergency-stop" buttons, especially along conveyor belts: one pull on the wire, and the relevant part of the machine comes to a safe ...