From fine grading to pushing material
Motor graders are used for a variety of construction, mining and road building applications, in particular for applications requiring precision to within a fraction of an inch. Removing a surface layer of asphalt or snow from a roadway or angling a road base to a precise degree of slope to create a path for water drainage are all fine grading tasks best left to motor graders and their experienced operators. If heavy equipment were knives, a motor grader would be a carving knife used by a skilled craftsman with years of experience.
Motor graders resemble long and lean bulldozers, except the blade (also referred to as the moldboard) attaches to the frame from a circle-mount in the middle of the machine and the engine sits behind the cab. The engine was originally placed in front of the cab until it was discovered to block too much of the operator's view of the blade.1
A motor grader blade has a greater range of motion than a bulldozer. An operator can move the blade up, down or sideways to move material outside of the wheel tracks (extremely useful for pulling ditches) and also can change the blade's pitch.
What really differentiates the motor grader from the bulldozer is that the wheel lean is not used so much for turning the machine, but to keep the machine pulling straight during fine grading work.3 But much like a bulldozer, motor graders are used for less precise ground levelling and material removal operations.
The first motor grader: Adams's "Little Wonder"
The first grader was developed by J.D. Adams in 1885. But Adams only started producing motor graders for road construction and maintenance in 1890, when he established J.D. Adams & Company.2 Adams' original grader was a horse-drawn, fixed-angle blade set on two wooden wheels called the "Little Wonder." Adams effectively retired his original grader design in 1896 when production of the Road King, an all-steel four-wheeled grader with an 8-foot blade, began. The blade unit still needed a tractor unit to pull it - just like the Caterpillar D2 pulling a Road King in this video:
First self-propelled grader
It wasn't until 1919 that Russell Grader Manufacturing Company modified an Allis Chalmers tractor and developed the first self-propelled grader.4 Caterpillar bought Russell Grader Manufacturing Company in 1928 after experiencing initial success with marrying its crawler tractors with Russell Grader Manufacturing's Patrol No. 4 and Patrol No. 6 graders.4 Check out a 1929 Russell motor grader in operation in this video:
In 1931 Caterpillar created the first rubber-wheeled grader in which the drive train and grader were designed as one unit.5 These new Caterpillar motor graders officially ended the days of two-man grader operation: one operator for the tractor unit and one operator for the grader unit.
Other grader manufacturers
John Deere introduced the world's first articulated-frame motor grader in 1967.6 By the time Volvo motor graders entered the market in 2001, John Deere motor graders had been in production for over 30 years. Like Caterpillar, Volvo bought and built upon an early pioneer in the motor grader industry: Champion Road Machinery, formerly known as American Road Machinery Co. from 1889 to 1915 and the Dominion Road Machinery Co. from 1915 to 1977.7
Mammoth motor graders
The largest grader ever built was by Acco, an Italian company, in the 1980s. The machine was powered by a rear 1,000 hp engine and a front 700 hp engine.8 It was built in preparation for a project in Libya that ended before it ever began.9 The 33-foot blade was kept on track by the grader's 12 tires.8
Caterpillar's 24M motor grader, designed for maintaining mining roads for heavy haul dump trucks, holds the title for the largest motor grader in production. Its blade measures 24 feet across.10
With integrated cross slope functions, joystick controls for up to two moldboards and motor grader attachments, one-touch-button-articulation-return-to-center control, cameras and tapered cabs, modern motor graders seem to take their cues from a fighter jet's cockpit rather than its Indianapolis, IN rural beginnings.
Find late model and used motor graders from Caterpillar, John Deere, Champion, Volvo and more in upcoming Ritchie Bros. unreserved auctions.