Elevators demand rigorous inspectors and maintenance to ensure their continued operation and safety.
The tracks or guard rails position the car and also provide a surface for the operation of safety clamps, which prevent car runaways or freefalls. Vertical travel motor power is provided by either a hydraulic plunger or motor-driven cables or wire ropes. Wire rope units are either traction or winding drum hoist machine types. Both use counterweights to reduce the amount of driving power required for lifting or lowering. Controllers for all elevators perform the same basic functions, including closing doors, controlling travel speed to the desired landing, opening doors and repeating the sequence as required.