Abstract: Apparatus for periodically drawing accumulated sludge (12) from a settlement tank (10) includes a hydraulically powered ram type positive displacement pump (14), operation thereof being controlled automatically in a timed or other sequence in response to signals derived from a pressure transducer (34), conveniently in the hydraulic supply line (24), said signals being a function of the pressure exerted by the pump ram (22) in operation and hence the density or other properties of the material being handled by the pump, a higher pressure showing the presence of sludge and a lower pressure its absence.

Abstract: Dosing apparatus for adding a metered quantity of liquid additive to slurry or other flowable material handled by a ram-type positive displacement main pump (10) includes a positive displacement metering pump (32) whose outlet (44) connects into a material carrying portion of the main pump e.g. its inlet (22). The metering pump is driven by a rocking lever (48) connecting it to the main pump ram (14) through adjustment means comprising a lead screw (62) along an arm (50) of the lever for selectively shifting a slide block (68) linked to the metering pump piston rod (42); the slide block being secured against movement on the lever arm once adjustment has been effected by clamping means (74).