doorway and a bent down section 14 34 such an embodiment is in itself known the illustrated door is provided with an in itself basically known weight compensation mechanism 15 comprising helical tension springs and associated cords in this particular embodiment a single spring parallels each horizontal section of track the spring is secured to the wall of the building and toward the door to a deflection pulley a cord extends around each pulley and is attached at one end to the lower edge of the uppermost panel and at the other to a fixed point specifically to a component of the doorcase the illustrated embodiment has a tension spring system against each outward facing side of horizontal sections 12 and 14 and accordingly occupies practically no space above or below the tracks very little space is occupied at each side because the helical tension spring systems comprise several parallel helical spring modules 16 the number depending on how heavy the door is and on the risk of breakage each spring module in turn comprises two coaxial or nested individual helical tension springs with the coils of inner spring 17 winding opposite those of its associated outer spring 18 and along the same axis viewed at a right angle to that axis accordingly the coils of each spring cross those of the other spring at an acute angle as will be particularly evident from fig3 a.