Which safety mechanism activates the emergency brakes on an elevator?

Which safety mechanism activates the emergency brakes on an elevator?

• A. Governor
• B. Mechanical brake
• C. Rope tension switch
• D. Door interlock

Answer: (A)

The key idea is that an elevator’s safety system uses a speed-sensing device to trigger brakes. The governor continuously monitors the car’s speed, and when overspeed is detected, it activates the safety mechanism that moments the emergency braking system—usually by engaging the safeties along the guide rails to clamp and stop the car. The actual braking action comes from the mechanical brake, but it is the governor’s safety trigger that commands it in an emergency. Rope tension switches and door interlocks serve other protective roles: rope tension switches guard against rope slack or failure, and door interlocks prevent doors from opening while the car moves. Neither is meant to trigger the emergency brakes, so the governor is the mechanism specifically designed to activate them in an overspeed situation.

The key idea is that an elevator’s safety system uses a speed-sensing device to trigger brakes. The governor continuously monitors the car’s speed, and when overspeed is detected, it activates the safety mechanism that moments the emergency braking system—usually by engaging the safeties along the guide rails to clamp and stop the car. The actual braking action comes from the mechanical brake, but it is the governor’s safety trigger that commands it in an emergency.

Rope tension switches and door interlocks serve other protective roles: rope tension switches guard against rope slack or failure, and door interlocks prevent doors from opening while the car moves. Neither is meant to trigger the emergency brakes, so the governor is the mechanism specifically designed to activate them in an overspeed situation.