Glossary
Governor
A speed-sensing safety device mounted at the top of the hoistway that triggers the car safety mechanism if the elevator exceeds a preset overspeed threshold.
The governor is a critical safety component in traction elevators. It consists of a rotating flyweight mechanism connected to the car by a separate governor rope that loops from the governor at the top of the hoistway, down to a tension sheave in the pit, and back up. As the car moves, the governor rope turns the flyweight assembly at a speed proportional to the car's travel speed.
If the car speed exceeds approximately 115 percent of rated speed (the exact threshold is set by code), centrifugal force pushes the flyweights outward far enough to engage a jaw mechanism that grips the governor rope. The now-stationary rope pulls a linkage on the car frame that activates the safety device — a pair of wedge-shaped clamps that grip the guide rails and bring the car to a controlled stop. Governors are tested periodically (typically annually) by tripping them at reduced speed to verify they engage correctly.