The term road graders most commonly refers to a type of large construction machine used to level uneven ground, either to achieve a flat surface or a surface with a specific degree of incline, or cant. There are also smaller road grading machines that are a separate piece of machinery hitched to a tractor or other vehicle. A large steel blade is attached below the grader, and the angle, tilt and height of this blade can be adjusted to achieve the desired grading of a surface. Road graders can be used for various purposes, for example to prepare the base of a new highway for paving, to construct and maintain gravel and dirt roads, to level the soil for building sites and to remove snow. These machines are also known as graders, motor graders, blades and maintainers.
In construction, the purpose of road graders is usually to finish the rough grading done by other heavy machinery that is not capable of the same precision, such as a scraper or bulldozer. The grader's adjustable blade allows for precise leveling of a surface, and this can be used to create a perfectly level area, for example for the construction of a large building. A grader can also be used to give a surface, often a road surface, a specific cant or cross slope to achieve better runoff from the surface once it is paved. Other common uses for road graders are to maintain gravel and dirt roads by eliminating uneven surfaces, such as potholes and wash-boarding.
The blade of a road grader can vary in size, usually between 8 and 24 feet (2.5 and 7.3 m). Some road graders, for example those used for clearing snow, can be fitted with two blades to increase efficiency. Engines also vary in size from 125 to 500 horsepower. Some road graders incorporate GPS technology, allowing for greater control and precision when it comes to determining the length of road or the area of soil that is to be leveled by the machinery.
Large road graders are most commonly used for road and highway construction and maintenance, site preparation in construction, snow removal, and in underground mining. The smaller graders, that are hooked up to another vehicle for use, are more commonly used to make and maintain dirt and gravel roads, and for smaller construction projects like making driveways and parking lots. Several companies manufacture road graders, including Caterpillar, Volvo Construction Equipment, Komatsu and Liu Gong.