paddles or other suitable means for further lifting the swept material in the preferred embodiment base member 8 and upper members 15 17 have the same outside diameter and the distance between walls 4 and 5 is slightly larger than this diameter each member 8 15 17 is supported by a shaft whose axis is ordinarily horizontal or parallel to the surface to be swept i e normal to the direction of side walls 6 7 the shafts themselves are parallel to each other and turn in bearings 18 19 member 17 fixed to walls 6 and 7 of body 1 fig2 the axes of rotation of each rotating member are preferably arranged on a single line parallel to the front and back walls and essentially median therebetween each member preferably turns in the same direction counter clockwise when viewing the device moving forward from left to right with identical or preferably different speeds increasing from bottom to top a motor not shown actuates the shaft 20 of the uppermost member 17 pulleys 21 22 are respectively fixed to the shaft 20 of member 17 and to the shaft 23 of member 16 and are connected by driving belt 24 this arrangement serves to actuate member 16 similar arrangements actuate members 15 and 8 and by means of different size pulleys shown schematically the members can be made to rotate at different speeds with the base member 8 rotating at the slowest speed the lower.