Abstract: Method and apparatus for controlling sucking of a material suspendible in air or liquid by means of a suction nozzle connected to a pump through a conduit and having a flow rate or solids concentration sensor connected to said conduit, the suction nozzle being supported via a supporting wire rope or like flexible support by a hoisting device which is carried by a device for moving the hoisting device and the nozzle along at least one horizontal axis at adjustable velocity, while the nozzle is vertically adjustably carried by the hoisting device, wherein the hoisting device for vertically adjusting the nozzle is controlled with a control device by signals from the flow rate or solids concentration sensor in such a way that said flow rate or solids concentration sensor is preset to supply a control signal to the hoisting device for raising or lowering the nozzle to thereby restore the flow rate or solids concentration quantity per unit time in the conduit when the flow rate or solids concentration quantity per