Frequently Asked Questions — Elevator Overspeed Governors
How does an overspeed governor work?
The overspeed governor consists of a centrifugally-operated sheave mounted in the machine room or hoistway, connected to the car-mounted safety gear via a continuous governor rope. As the car speed increases, the centrifugal flyweights in the governor sheave rotate outward, increasing the friction force on the rope. At the trip speed, a mechanical latch engages, clamping the governor rope — the rope tension then pulls the safety gear linkage, engaging the gear jaws against the guide rails and bringing the car to a controlled stop.
What is the trip speed of an overspeed governor?
EN 81-20 specifies that the governor trip speed must be at least 115% of the rated car speed for the car-side governor, and at least 110% for the counterweight-side governor (if fitted). The maximum permissible trip speed depends on the type of safety gear — progressive gears allow higher trip speeds than instantaneous gears. Trip speed is set and sealed at the factory and must be verified at commissioning and at each periodic inspection.
How often should governors be inspected and recalibrated?
EN 81-20 and TS EN 13015 require overspeed governor testing at initial commissioning, after any modification to the suspension or safety system, and as part of the mandatory periodic inspection programme. In Turkey, full governor trip speed testing is typically performed every 5 years by an authorized inspection body. The governor rope tension device must also be inspected at each maintenance visit to confirm correct rope tension and freedom of movement of the governor sheave.
Can an overspeed governor be replaced without replacing the safety gear?
Yes, provided the replacement governor is calibrated to a trip speed compatible with the installed safety gear type and rated speed. The governor rope engagement force (the pull force applied to the safety gear linkage at trip) must match the safety gear's activation force requirement. Turkish suppliers on elevator.tr can assist with governor-safety gear compatibility verification and supply matched replacement sets for modernization projects.