What is the main purpose of an overspeed governor?

To detect when the lift car's speed exceeds a safe limit and to mechanically trip the safety gear, which then stops the car by clamping onto the guide rails.

At what speed range should the governor for a 1.0 m/s lift trip?

It must trip at a speed between 1.15 m/s (115% of rated speed) and 1.25 m/s (calculated as 1 + 0.25/1), as per Clause 4.

Is an electrical switch required on the governor?

Yes, an overspeed switch must be provided on the governor to cut power to the motor and apply the brake before or at the moment the governor trips mechanically (Clause 5.4).

What tests are required for an overspeed governor?

The standard mandates type tests by the manufacturer to certify the design and routine tests on-site during commissioning and periodic inspections to verify the tripping speed and function (Clause 6).

IS 14669

: 1999

Overspeed Governors for Lifts

CurrentSpecializedSpecificationMEP · Lifts, Escalators and Mechanical Handling

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This standard specifies the requirements for the design, construction, and testing of overspeed governors used in electric and hydraulic lifts. It details critical safety parameters like tripping speeds, constructional integrity, rope specifications, and testing procedures to ensure the governor can reliably activate the safety gear in an overspeed event.

Specifies the requirements for overspeed governors used in lifts to activate the safety gear.

Quick Reference Values

Minimum tripping speed115% of rated speed

Maximum tripping speed (v rated > 1 m/s)v_rated + 0.25 / v_rated (in m/s)

Maximum tripping speed (v rated <= 1 m/s)1.5 m/s

Minimum governor rope diameter6 mm

Minimum tensioning force in governor rope300 N

Minimum sheave to rope diameter ratio30

Key Formulas

v_trip_min = 1.15 * v_rated — Minimum tripping speed

v_trip_max = v_rated + 0.25 / v_rated — Maximum tripping speed for rated speed > 1 m/s

Practical Notes

The tripping speed is a critical setting that must be verified and sealed during commissioning and periodic inspections.

Ensure the governor rope is correctly tensioned and free from excessive wear, as low tension or a worn rope can cause slippage and failure to trip.

The type of governor (e.g., pendulum, centrifugal) must be compatible with the type of safety gear (instantaneous or progressive) it is designed to operate.