Which of the following are the two most common types of relating devices?

The most common types of relating devices in the context of elevator cab assembly and door operators are cable-related and mechanically linked systems.

Cable-related devices utilize cables to transmit force and control the movement of elevator components, which is essential for smooth operation and safety in both hydraulic and traction elevators. They are integral in acts such as opening and closing doors, as well as raising and lowering the cab itself.

Mechanically linked devices, on the other hand, involve a series of mechanical connections that facilitate the coordinated movement between different parts of the elevator system. This mechanical connection is critical for reliability and efficiency in the operation of the elevator, ensuring that all connected parts function in unison during operation.

These two types of relating devices are fundamental in elevator construction and functionality and are commonly encountered in various elevator designs, reinforcing why they are the most prevalent options in this field.