A compactor roller, sometimes known as a roller compactor, a steam roller, or an asphalt roller, is a piece of heavy machinery used to compact fine particulate material or asphalt to create a flat surface or to rid the material of void pockets. Two general types of compactor roller models exist: single roller models and double roller models. A single roller model will feature one large steel drum and a set of rear wheels or tracks for propelling the machine forward; a double roller model will feature two large steel rolling drums and no rubberized wheels for propulsion.
The single drum compactor roller is useful if the machine will be used to help grade uneven surfaces of soil or dirt. The rubber wheels or tracks will help the machine keep traction and overcome some obstacles, but the single steel drum will be quite heavy and may be prevented from rolling over obstacles anyway. The soil the machine is meant to compact will generally need to be graded beforehand using a full-size grader machine. The compactor roller can then flatten the soil or particulate matter using static force created by the weight and motion of the roller.
A double drum compactor roller will not feature rubber wheels or tracks, which means the two steel drums will be responsible for propelling the machine forward. These steel drums may not have exceptional traction on many surfaces, so this type of compactor roller is often used on asphalt or other tacky materials. The two drums are useful for creating a flat, smooth surface with no tire or track divots. The machine is not exceptionally maneuverable, especially if it is not an articulated machine that pivots at its center. An articulated machine will have a shorter turning radius and will be more maneuverable, while fixed body designs will have a wider turning radius.
The drum or drums will be mounted on an axle that is supported by a heavy-duty frame. The machine will generally move very slowly to ensure all materials are evenly compacted and all voids within the materials are eliminated. The machine may need to make several passes over the same material, depending on how much air or moisture is present within that material. An operator will usually sit in a cab above the roller or rollers for better viewing capabilities; the seat within that cab may swivel so the operator can safely operate the machine in either direction without turning the vehicle around entirely.