In a two-speed, horizontal sliding entrance, the door panels are known as?

In a two-speed, horizontal sliding entrance, the door panels are commonly referred to as lead and lag doors. The lead door is the one that initiates the movement and opens first, allowing access into or out of the elevator. The lag door follows the lead door's motion but remains slightly behind, closing or opening in tandem with the lead panel to ensure a smooth operation and maintain safety standards.

Understanding the function of these terms is critical, particularly because the lead and lag configuration directly influences the efficiency and speed of the entrance operation. In this context, referring to the doors as fast and slow does not accurately convey their roles in the mechanism, as both doors operate simultaneously to achieve the entrance's intended function. Likewise, primary and secondary or outer and inner do not align with the technical terminology used in the elevator installation industry, which specifically distinguishes the operational roles of the panels.