Grader

A grader, also commonly referred to as a road grader, motor grader, or simply a blade, is a form of heavy equipment with a long blade used to create a flat surface during grading. Although the earliest models were towed behind horses, and later tractors, most modern graders are self-propelled and thus technically "motor graders". Typical graders have three axles, with the steering wheels in front, followed by the grading blade or mouldboard, then a cab and engine atop tandem rear axles. Some graders also have front-wheel drives for improved performance. Some graders have optional rear attachments, such as a ripper, scarifier, or compactor. A blade forward of the front axle may also be added. For snowplowing and some dirt grading operations, a main blade extension can also be mounted. Capacities range from a blade width of 2.50 to 7.30 m (8 to 24 ft) and engines from 93–373 kW (125–500 hp). Certain graders can operate multiple attachments, or be designed for specialized tasks like underground mining. In civil engineering "rough grading" is performed by heavy equipment such as wheel tractor-scrapers and bulldozers. Graders are used to "finish grade", with the angle, tilt (or pitch), and height of their blade capable of being adjusted to a high level of precision. Graders are commonly used in the construction and maintenance of dirt and gravel roads. In constructing paved roads, they prepare a wide flat base course for the final road surface. Graders are also used to set native soil or gravel foundation pads to finish grade before the construction of large buildings. Graders can produce canted surfaces for drainage or safety. They may be used to produce drainage ditches with shallow V-shaped cross-sections on either side of highways. Steering is performed via a steering wheel, or a joystick capable of controlling both the angle and cant of the front wheels. Many models also allow frame articulation between the front and rear axles, which allows a smaller turning radius in addition to allowing the operator to adjust the articulation angle to aid in the efficiency of moving material.