Abstract: A pump for chopping solid material in a liquid stream having a volute housing, a rotating cutter with at least one blade parallel to a rotational axis of the rotating cutter, an impeller arranged at an outer circumference of the rotating cutter, and a stationary cutter having at least one blade parallel to the rotational axis of the rotating cutter. The stationary cutter is concentric with the rotating cutter, and the stationary cutter, the rotating cutter and the impeller are all at least partially housed within the volute housing. Typically, the rotating cutter has a different number of blades than the stationary cutter. Optionally, the pump, further comprises an inspection cover that is removably attached to the pump, and has an opening large enough to remove the stationary cutter and the rotating cutter from the volute housing.

Abstract: A pump for chopping solid material in a liquid stream having a volute housing, a rotating cutter with at least one blade parallel to a rotational axis of the rotating cutter, an impeller arranged at an outer circumference of the rotating cutter, and a stationary cutter having at least one blade parallel to the rotational axis of the rotating cutter. The stationary cutter is concentric with the rotating cutter, and the stationary cutter, the rotating cutter and the impeller are all at least partially housed within the volute housing. Typically, the rotating cutter has a different number of blades than the stationary cutter. Optionally, the pump, further comprises an inspection cover that is removably attached to the pump, and has an opening large enough to remove the stationary cutter and the rotating cutter from the volute housing.

Abstract: A movable cover structure for a fixed ground area, such as a swimming pool cavity (4), has a platform (15) which is displaceable horizontally from a position where it covers the fixed ground area to a position where it is retracted clear of such area. Square section channels (10) are inset along the inner surfaces of opposed long vertical side walls of the cavity (4) and house guide tracks (11). Guide wheels (19) are provided along opposed long sides of the platform (15) and engage with the guide tracks (11). Movement of the platform (15) is effected by a motor (12a) driving toothed wheels (13) which engage with toothed racks (20) provided on the platform (15). In the retracted position the platform (15) is stowed beneath an adjacent horizontal flat floor surface (6) within an inner space (9) below the surface (6). Sensors are provided to detect the presence of persons in the swimming pool.

Abstract: Portable walls, in particular, walls for use in playing or practising ball games, for example Association Football (soccer) comprise: