Abstract: In one aspect, there is provided a wear plate for use in combination with a centrifugal pump and impeller. The wear plate has a wear surface defined by a substantially flat surface, a truncated conic section, and/or a curvilinear solid of revolution formed by revolving an area bounded by a curve around a center axis of the wear plate, wherein a notch or recess is provided. The notch or recess extends in a first direction perpendicular to a predetermined direction of rotation of an impeller and a second direction crossing against a direction of rotation of the impeller.

Abstract: A four-way air directional valve assembly is disclosed in combination with apparatus employed for pneumatically generating waves in a wave pool having a plurality of wave generating chambers arranged side-by-side and extending across the width of a pool at one end thereof. Each of these wave chambers has a below the water passageway in communication with the pool and a sealed portion located above the normal water level of the pool. Each chamber has an inlet-outlet passageway above the water level with the passageway serving in one mode as an inlet for directing forced air into the wave chamber and in a second mode as an outlet for exhausting air therefrom.

Abstract: A slide structure for sleds for human occupancy is disclosed, and is designed to have human occupant sleds sliding down into a body of water. The slide structure has a support framework on which a plastic sheet material is provided and a water supply means supplies only a thin film of water to the upper surface of the plastic sheet material. This conserves power and water, yet the thin film provides a very low coefficient of friction, so that the sleds attain a high speed for a quiet, fast, smooth, and more exciting ride, yet with reduced wear on both the slide and sleds.