STAIRCASE ON CONCEALMENT BOLTS Russian patent published in 2020 - IPC E04F11/02 

FIELD: construction.

SUBSTANCE: invention relates to construction, in particular to the design of stairs, and is intended for creation of cantilever ladders of various shape and parameters and comprising several prefabricated modular elements. Technical result is achieved by the fact that a ladder on concealed bolts includes fastening of steps of ladder using spacer tube from profile pressed from aluminium alloys system "KRAUSS" Ø40 mm with possibility of installation of pin screwed into upper screw on glue with right external thread into upper step with right internal thread pitch of 1.5 mm, with possibility of preliminary screwing in lower screw on glue with left external thread of lower stage with inner, also left-hand thread of high nut-adapter with left external thread, in which there is a possibility of screwing the pin with a lower end, for which the right-hand thread with a smaller pitch of 1.25 mm, wherein it is possible to rotate the pin through the internal slot due to the pin, which is preliminary screwed in through the spacer tube, which in turn is rotatable with a special key, wherein it is possible to tighten two stages by pin due to thread pitch difference at its ends through pin providing inner coupling between spacer tube and pin itself.

EFFECT: proposed design of latent bolt allows to tighten steps of ladder from inside spacer pipe due to rotation of pin, which is transmitted through pin, previously screwed through spacer pipe, thereby achieving effect of complete absence of upper and lower nuts as bearing elements, which gives ease and aesthetic appearance.

1 cl, 9 dwg