FLSmidth's Dorr-Oliver® CableTorq® or SwingLift thickeners and clarifiers have streamlined rake arms, pulled by cables, connected to a torque (or drive) arm that travels above the sludge. The rake arms are attached to a special double-axis hinge. The arms are able to rise automatically when heavy sludge concentrations occur. But because of the unique hinge, the arms continue to operate in two planes keeping the rake blades in perfect position for most efficient raking and solids removal. CableTorq Machines automatically rides out high torque loads and keeps on raking.