TABLE OF CONTENTS The grader, motor grader, or motor patrol, is a machine used principally in shaping and finishing, rather than in digging or transporting. It is available in sizes ranging from 35 to over 600 horsepower, in a variety of constructions.
Except for a few light models that are rear-mounted tractor accessories, a grader consists of a wide, controllable blade (moldboard) mounted at the center of a long-wheelbase, rubber-tire prime mover. The blade is usually held at an angle to travel direction. It will cut, fill, and sidecast. These functions can be performed separately or at the same time, in any combination.
A grader may be used as a prime mover or carrier for a number of accessories. These include snowplows and side wings, belt loaders, arm-mounted clearing tools, bank slopers, trailer drags, and disc harrows, in addition to scarifiers or rippers.
The typical grader works for more than 15 years. The average machine is rebuilt twice. The first time is for the transmission after about 8,500 hours of use, whereas the engine should not need an overhaul until 12,000 to 14,000 hours of service.
Most heavy graders are tandem drive units of the type shown in Fig. 19.1 . The diesel engine, with 125 to 275 horsepower, is mounted at the rear, and drives four single wheels in tandem pairs through gears and chains. The frame connection to the front axle is long and high, to allow space for carrying and manipulating the moldboards or...
