Patent ID: 8708025

Claim:
A device for covering a substantially rectangular surface having two mutually opposite and parallel longitudinal sides and two mutually opposite transverse sides being substantially normal to the two longitudinal sides, the sides defining a perimeter with four corners, the device comprising: a cover having longitudinal edges; a drum having a longitudinal axis and being configured to wind up or unwind said cover; and a longitudinal-translation mechanism on which said drum is mounted for rotation about said longitudinal axis, said longitudinal-translation mechanism including: a) rails positioned along the two longitudinal sides of the perimeter of the surface to be covered; b) two flexible belts each including first and second ends and each extending from a first one of the corners to a second one of the corners along a respective one of the longitudinal sides of the perimeter of the surface to be covered, said belts being fixed only at each of said ends at a respective point of attachment to a respective one of the first and second corners; (c) a carriage overhanging the surface to be covered, extending substantially parallel to the transverse sides and supporting said drum, said carriage having ends each including: (i) a drive wheel having a rotation axis parallel to said longitudinal axis of said drum; and (ii) at least two casters resting on and being directly adjacent the surface to be covered and configured to allow for longitudinal translational movement of said carriage, said at least two casters being mounted on each respective side of said drive wheel and together with said drive wheel constituting a triangle with said drive wheel forming a vertex of said triangle; d) each of said flexible belts including side sections each disposed between a respective one of said points of attachment and a respective one of said casters and a central section disposed between said at least two casters, said side sections each being pressed against a respective one of the longitudinal sides of the periphery of the surface to be covered and said central section of each of said belts running over a respective one of said drive wheels without slipping; and e) at least one roller configured to continuously guide and insert each of said longitudinal edges of said cover into a respective one of said rails upon said cover being gradually unwound from said drum and to reversibly jam said edges in said rails due to action of said belts.