Patent ID: 8646225

Claim:
An underground shelter having a front wall, a back wall, two opposing side walls, a bottom and a top defining a substantially rectangular box with an opening defined in the top, a flat lid adapted to cover the opening, a roller means for alternately rolling the lid to expose or close a portion of the opening defined in the top, the improvement comprising: a. the lid divided into two portions and adapted to be substantially flush with a surrounding ground level in a closed position having i. a first lid portion remaining stationary over a first portion of the opening and beginning at the back wall, ii. a second lid portion which moves relative to the first lid portion and, in the closed position, begins at the front wall, iii. a dividing space defined between the first and second lid portions when the first and second lid portions are in the closed position, and iv. each lid portion having an upper surface lying in a same plane and not offset from one another vertically; b. the roller means comprising i. at least one linear track positioned near the opening defined in the top, ii. at least one upper track roller disposed between the second lid portion and each track, each upper track roller rollingly supporting the lid as the lid moves relative to the track; c. at least one ramp defined in the first lid portion adjacent to the dividing space, and out of line with the track, and adapted to elevate a leading edge roller moving relative to the ramp from a lower level to a higher level, the higher level allowing the second lid portion to pass over the first lid portion; d. at least one of the leading edge rollers engaging the at least one ramp, each leading edge roller adapted to rollingly engage a surface to support a leading edge of the second lid portion as the second lid portion passes up and over the first lid portion; e. a latch means releasably engaging the moveable second lid portion into a fixed closed position; f. a lid retainer means for keeping the second lid portion in position against a lifting force created by a differential pressure between an inside of the shelter and an outside atmosphere during a storm event; and g. access means for allowing at least one person to enter or leave the shelter.