Road roller (sometimes called a roller-compactor, or just roller) is a compactor type engineering vehicle used to compact soil, gravel, concrete, or asphalt in the construction of roads and foundations. In some parts of the world, road rollers are still known colloquially as steam rollers, regardless of their method of propulsion. This typically only applies to the largest examples (used for road-making).Road rollers use the weight of the vehicle to compress the surface being rolled. Initial compaction of the substrate is done using a pneumatic-tyred roller, with two rows (front and back) of pneumatic tyres. The flexibility of the tyres, with a certain amount of vertical movement of the wheels, enables the roller to operate effectively on uneven ground. The finish is done using metal-drum rollers to ensure a smooth, even result. Rollers are also used in landfill compaction. Such compactors typically have knobbed ( sheep s-foot ) wheels, and do not achieve a smooth surface. The knobs aid in compression due to the smaller area contacting the ground.

 

Roller Types

Manual walk-behind

Powered walk-behind (electric or diesel/gas powered)

Trench roller (manual units or radio-frequency remote control)

Ride-on

Ride-on with knock-down bar

Ride-on articulating-swivel

Vibratory

Pneumatic-tyre

Tractor mounted and powered (this may be a one-off - see gallery picture below)

 

Drum types

Drums come in various widths: 24-to-84 inches

Single-drum sheeps/pad-foot (soil)

Single-drum smooth (asphalt)

Double-drum (duplex) sheeps/pad-foot (soil)

Double-drum (duplex) smooth (asphalt)

3-wheel cleat with bulldozing blade (landfills)

 

On some machines, the drums may be filled with water on site to achieve the desired weight. When empty, the lighter machine is easier and cheaper to transport between worksites.

Additional compaction may be achieved by vibrating the roller drums

Water lubrication may be provided to the drum surface to avoid hot asphalt (for example) sticking to the drum

Hydraulic transmission permits greater design flexibility (early examples were direct mechanical drive) and reduces the number of moving parts exposed to contamination.

Human-propelled rollers may only have a single roller drum

Self-propelled rollers may have two drums, mounted one in front of the other (format known as duplex ), or three rolls, or just one, with the back rollers replaced with treaded pneumatic tyres for increased traction.