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A grader, also commonly referred to as a road grader, a blade, a maintainer, or a motor grader, is a construction machine with a long blade used to create a flat surface during the grading process. Typical models have three axles, with the engine and cab situated above the rear axles at one end of the vehicle and a third axle at the front end of the vehicle, with the blade in between. In certain countries, for example in Finland, almost every grader is equipped with a second blade that is placed in front of the front axle. Some construction personnel refer to the entire machine as "the blade". Capacities range from a blade width of 2.50 to 7.30 m and engines from 93–373 kW (125–500 hp). Certain graders can operate multiple attachments, or be used for separate tasks like underground mining.
In civil engineering, the grader's purpose is to "finish grade" (to refine or set precisely). The "rough grading" is performed by heavy equipment or engineering vehicles such as scrapers and bulldozers.
Graders are commonly used in the construction and maintenance of dirt roads and gravel roads. In the construction of paved roads they are used to prepare the base course to create a wide flat surface upon which to place the asphalt. Graders are also used to set native soil foundation pads to finish grade prior to the construction of large buildings. Graders can produce inclined surfaces, to give cant (camber) to roads. In some countries they are used to produce drainage ditches with shallow V-shaped cross-sections on either side of highways.
A more recent innovation is the outfitting of graders with grade control technologies, such as those manufactured by Topcon Positioning Systems, Inc., Trimble Navigation, Leica Geosystems or Mikrofyn for precise grade control and (potentially) "stakeless" construction. Manufacturers such as Caterpillar have also begun integrating these technologies, like Cat Grade Control, into their machines so they're equipped out of the factory. ()
Early graders were drawn by people and draft animals. The era of motorization by traction engines, steam tractors, motor trucks, and tractors saw such towed graders grow in size and productivity. The first self-propelled grader was made in 1920 by the Russell Grader Manufacturing Company, which called it the Russell Motor Hi-Way Patrol. These early graders were created by adding the grader blade as an attachment to a generalist tractor unit. After purchasing the company in 1928, Caterpillar went on to truly integrate the tractor and grader into one design—at the same time replacing crawler tracks with wheels to yield the first rubber-tire self-propelled grader, the Caterpillar Auto Patrol, released in 1931.
In some locales such as Northern Europe, Canada, and places in the United States, graders are often used in municipal and residential snow removal. In scrubland and grassland areas of Australia and Africa, graders are often an essential piece of equipment on ranches, large farms, and plantations to make dirt tracks where the absence of rocks and trees means bulldozers are not required.
- Case Corporation
- Caterpillar Inc.
- Deere & Company
- Galion Iron Works
- Komatsu Limited
- LiuGong Construction Machinery, LLC.
- Mitsubishi Heavy Industries
- New Holland Machine Company
- Terex Corporation
- Volvo Construction Equipment
- Veekmas OY
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- Orlemann, Eric (2007). "The Caterpillar Century" (2nd ed.). Motorbooks International. p. 118. ISBN 978-0-7603-2961-0. Retrieved 7 March 2012.
- Video with technical development from graders
- photos/videos from different type of grader works
- A Road-Scraper That Cuts Through Snow, Popular Science monthly, February 1919, page 26, Scanned by Google Books: http://books.google.com/books?id=7igDAAAAMBAJ&pg=PA26
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