is carried out using the mold board blade 27 as the motor grader advances the disks 11 are engaged by the surface of the shoulder cutting a swath of approximately 32 inches and moving the gravel and newly mulched material inwards i e towards the center of the road the amount by which the cut material is moved laterally inwardly will vary according to the orientation of the disk gang 11 to the fore and aft direction and also according to the speed of advance in the forward direction the faster the speed the further the cut material will be displaced laterally preferably these conditions are set so that the newly mulched material is moved laterally by from 12 to 16 inches during this operation the disks are of course turned by interaction with this material the disks turning in the clockwise sense as viewed from the rear end of the shaft 12 the material cut by the disk gang is turned and mulched and left to dry so that on a subsequent pass of the grader over the same path the previously cut and now dried material is displaced inwardly by a further 12 to 16 inches so that the outermost 12 to 16 inches of the swath is swept clean on subsequent passes the entire 32 inch swath will be swept clean effectively retrieving surface gravel from the shoulder of the.