The screen conveyor for root crop harvesters comprises an endless screen belt conveyor, which consists of at least two conveyor belts and transverse conveying rods fastened to the conveyor belts and rotates about deflection rollers, which are rotatably mounted in a housing and of which at least one group can be driven by a driving mechanism by coaxially disposed deflection rollers. For this purpose, at least one adjuster is provided, which can be shifted into position against the working half of the screen conveyor belt and specifies a changing course for the working half of the conveyor belt by forming a step.