Electric Elevator Equipment and Components
Core traction components
The exam expects you to identify the traction machine, motor, brake, driving sheave, ropes, counterweight, governor, car safeties, guides, buffers, door operator, and interlocks. Geared machines use a worm gear or helical gear; gearless machines couple the sheave directly to the motor. Roping may be 1:1 or 2:1. The governor trips a safety if the car overspeeds, and the safety grips the guide rails. Buffers absorb kinetic energy at the pit: spring, elastomeric, or oil. Door interlocks prove the car door and hoistway door are closed and locked before the car can run.
Worked example
A car is rated 350 fpm. The governor must trip at not less than 115% and not more than 140% of rated speed. 115% × 350 = 402.5 fpm; 140% × 350 = 490 fpm. Therefore the governor tripping speed must fall between 402.5 and 490 fpm. If a test shows 395 fpm, the governor trips too low and does not meet the minimum; if it shows 500 fpm, it trips too high.
Traps that cost marks
Do not confuse governor tripping speed with car rated speed. Do not assume every elevator has a counterweight or a governor; hydraulic and ropeless designs differ. Do not overlook that safeties are type-specific and must match the guide rail and speed. Remember that door interlocks are part of the electrical safety chain, not merely a door-closing convenience.