Abstract: Within an agricultural vehicle for harvesting root crops, such as potatoes, a frame is suspended and has its bottom formed by a screen conveyor, its front end carrying a set of plows preceded by pilot wheels which ride respective furrow slices and control the elevation of the frame. The suspension for the frame comprises a pair of cables, one of them extending transversely over two rollers and engaging the rear of the frame at opposite ends while the other rises from a forward part of the frame and is hydraulically tensionable for raising or lowering same. The frame is limited for movement both longitudinally and transversely with reference to the vehicle body, its mobility in any direction being restricted by a pair of rearwardly projecting lateral guide rollers confined between vertical tracks and horizontal abutments; one of these guide rollers has a trapezoidal profile coacting with a similarly shaped track surface while the other guide roller is substantially cylindrical.