| 摘要 |
A pool cover sheet has beaded edges guided in side edge guides along the pool. The cover sheet is wound onto and pulled from a spool mounted on a motor driven shaft. The cover sheet is pulled by the spool by cords traveling along the side edge guides with cords being wound onto and from cord drums. The velocity of the cover sheet travel is attempted to be matched to the cover sheet velocity by means frustoconical drums having tapered surfaces onto which the cords are wound and unwound. To attempt to equalize the tension in the cords as well as in the cover sheet, the spools and drums are driven through opposed torsion springs from a common main shaft. The tension in the respective sides of the sheet or in the respective cords may be adjusted to take up any slack found to occur. A traversing cord handling carriage moves in timed relationship to the velocity of the cord travel and lays the cord onto or takes it from the tapered drum surface at a velocity matched to velocity of the cord traveling in the side edge guides or at the front of the cover sheet. |
