During installation, what must be checked to ensure the escalator is level?

To ensure the escalator is level during installation, the base supports must be checked. The levelness of the escalator largely depends on how well the base supports are installed. If the base is uneven or is not properly aligned, it can cause the escalator to tilt or operate improperly, leading to safety hazards and performance issues. Ensuring that the base supports are level is essential for the stability of the entire escalator system and to allow for smooth operation.

The overall framework is important for the structural integrity of the escalator but does not directly address leveling. The lower landing alignment and upper newel placement are also crucial for proper installation but are secondary considerations once the base supports are confirmed to be level. Starting with the base supports establishes a solid foundation for the remaining components of the escalator to rest upon, which is why it takes precedence in the leveling process.