Elevator

A box on ropes, balanced by a counterweight. The motor doesn't lift the car. It only tips the balance.

• Steel ropes run over a grooved traction sheave. Friction in the grooves moves the car. Nothing winds up.
• The counterweight equals the car plus half its rated load. The motor only moves the difference. An empty car going up even makes power.
• The brake is spring-applied. Power holds it open. It clamps at every floor and whenever power fails.
• The governor spins with the car. If the car ever overspeeds, it grabs its rope, which pulls the safety gear wedges onto the rails.
• The door motor rides on the car. A vane drags the landing doors along, so they open only where the car is.