A sliding door system in which two or more door panels move at different speeds on a common header, opening a wider clear passage than a single-panel door of the same pocket depth.
Full Definition
Telescopic (multi-speed) sliding doors are used when the available wall pocket depth is insufficient for a single-panel door of the required clear opening width. In a two-speed telescopic arrangement, the leading panel travels at twice the speed of the trailing panel, both driven by a synchronised belt or rope drive from a single door operator motor. Three-speed telescopic doors achieve even greater clear width from a shallower pocket. EN 81-20 requires that all door panels reach the fully open position within the opening time and that maximum kinetic energy during closing does not exceed 10 J (or 4 J for the reduced-energy re-opening). Interlocks must engage only when all panels of the landing door are within 10 mm of their fully closed position. Telescopic doors are standard on freight elevators and hospital (bed) elevators where 1,100–1,600 mm clear opening widths are required.
