Abstract: A sludge vacuum trolley (14) propels a sludge vacuum manifold (12) along the bottom of a settling basin or tank along a track (16) attached to the bottom of the settling basin. The sludge vacuum trolley (14) incorporates two drive wheels (26,27) that selectively engage the track to propel the sludge vacuum system therealong. The drive wheels (26, 27) are actuated by respective pneumatic rotary actuators (24, 25) whose rotary output shafts are connected to either air clutches or roller clutches, which in turn, drive the drive wheels. Air-actuated clamping cylinders (32, 33) selectively engage or disengage the drive wheels (26, 27) from the track so that the drive wheels will frictionally engage the track, and that rotation of the drive wheels by respective pneumatic rotary actuators will propel the sludge vacuum trolley along the track.

Abstract: A self-supporting modular underdrain member for use in a liquid filtration system comprises a main body or housing including a pair of longitudinally extending inclined walls which may have a pair of generally triangular transverse walls connecting the inclined walls to one another, the inclined walls each being provided with a pair of longitudinally extending recesses and a plurality of orifices communicating with each of the recesses. A pair of flanges are connected to the inclined walls for attaching the underdrain body to a floor surface so that the inclined walls, any transverse walls and the floor surface define a cross-sectionally triangular underdrain chamber. Two pairs of elongate cover plates are attached to the inclined walls over the recesses to form in each of the inclined walls a pair of longitudinally extending plenums for the equalization of backwash air and water flow, each of the cover plates being provided with a plurality of spaced slots.