Road roller

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Zettelmeyer diesel road roller

Steam-powered roller

A Road roller (sometimes called a roller-compactor, or just roller) is an engineering vehicle used to compact soil, gravel, concrete, or asphalt in the construction of roads and foundations.

In many 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).

This article concentrates on non- steam-powered rollers.

1 History
2 Uses
3 Configurations
4 Manufacturers
5 In fiction
6 See also

[edit] History

The first road rollers were horse-drawn, and were probably just borrowed farm implements (see roller (agricultural tool)).

Main article: steamroller

Since the effectiveness of a roller depends to a large extent on its weight, self-powered vehicles replaced horse-drawn rollers from the mid 1800's. The first such vehicles were steam rollers, and, in the UK, these remained in commercial service until the early 1970's.

As internal combustion engine technology improved during the 20th century, petrol- and diesel-powered rollers gradually replaced their steam-powered counterparts, and virtually all road rollers in commercial use now use diesel power.

[edit] Uses

Road rollers work by using the weight of the vehicle to compress the surface being rolled. Initial compaction of the substrate is done using a pneumatic-tyred roller, where instead of the single- or double-drum is replace by two rows (front and back) of pneumatically filled 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 knobbly ('sheeps-pad') wheels and do not attempt to achieve a smooth surface, merely a squashed one.

[edit] Configurations

The roller can be a simple drum with a handle that can be operated by one man, and weighs 100 pounds, all the way up to a massive ride-on road roller weighing 21 short tons (44,000 lb or 20 tonnes) and costing more than $150,000 US dollars. A landfill units can weigh 59 short tons (54 tonnes). On some machines the drums may be filled with water.

[edit] 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-tyred

Powered walk-behind	Ride-on with articulating-swivel (small machine)	Ride-on with articulating-swivel (large machine)	Dynapac CC232
Pneumatic roller for initial compaction

[edit] 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)

[edit] Variations and features

On some machines, the drums may be filled with water on site to achieve the desired vehicle weight. When not filled, 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 the dust and filth associated with construction sites
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

[edit] Manufacturers

Bomag [1]
Case CE
Caterpillar
CMI-Terex [2][3]
Dynapac [4]
Galion
Hamm
HYPAC [5]
Ingersoll Rand
Multiquip/Rammax [6]
Stone Equipment [7]
SuperPac [8]
Vibromax [9] [10]

[edit] In fiction

George the Steamroller is a character from The Railway Series children's books written by the Rev. W. Awdry.
Bob the Builder has a green, diesel-powered road roller in his team by the name of Roley.