Elevator Overspeed Governor

An elevator overspeed governor is a critical mechanical safety device that monitors elevator car speed and triggers emergency braking if it exceeds safe limits, acting as the "first responder" to prevent free falls or uncontrolled descent. It is mandatory for all traction elevators (per EN 81 and ASME A17.1 standards) and works in tandem with safety tongs to safeguard passengers.

• Speed Monitoring: Continuously tracks the elevator's vertical speed via a rotating sheave connected to the car's suspension ropes.
• Overspeed Detection: Activates when the car's speed exceeds 115% of its rated speed (e.g., 1.15 m/s for a 1 m/s elevator) or during free fall.
• Emergency Trigger: Initiates two key actions: (1) cuts power to the elevator motor, and (2) activates safety tongs to clamp the car to guide rails.

The governor consists of a centrifugal mechanism with weighted levers attached to a rotating shaft. As the elevator speed increases, centrifugal force pushes the levers outward. When the speed reaches the overspeed threshold, the levers engage a trigger mechanism, which:

• Locks the governor's sheave, stopping the rope connected to the safety tongs.
• Pulls the tongs' activation cable, causing the tongs to grip the guide rails and halt the car.

• Precision Calibration: Adjusted to activate at exact speed thresholds (e.g., 1.15× rated speed) during installation.
• Durability: Made of corrosion-resistant steel, with sealed bearings to ensure smooth operation for 10+ years.
• Redundancy: Equipped with backup springs and locks to prevent failure during critical moments.

Mandatory for all traction elevators (residential, commercial, or industrial) and used in high-rise buildings, hospitals, airports, and shopping malls. It is also required for elevators in seismic zones, where sudden speed changes may occur due to structural movement.

In essence, the elevator overspeed governor is the "brain" of the elevator safety system, combining precision monitoring with rapid emergency response to protect lives and property.

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