| 摘要 |
Apparatus for intermittently directing one or more streams of water across the inner surface of a swimming pool structure for cleaning the surface. A cylindrical retractable nozzle head actuated by fluid pressure moves to an active, extended position to expose nozzle passages therein when water under pressure is applied thereto. The nozzle passages are formed in diametrically and symmetrically disposed thickened wall regions of the nozzle head to provide a nozzle head that is balanced about its longitudinal axis. In certain embodiments of the invention, a pair of nozzle passages are formed in the thickened regions and some or all of the passages have destructible membranes blocking communication with the interior of the nozzle head, which membranes may be selectively drilled out at the time of installation of the apparatus. The nozzle head, which is preferably molded from plastic material, may contain a weight member for additional balance and to assist in retraction of the head to its inactive position.
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