EARTH, SAND-CLAY, AND GEAVEL EOADS. 



21 



USE OF GRADING MACHINE. 



The grading machine illustrated in figure 11 is of the general 

 design commonly followed in machines of this type. The heavy 

 blade, which is 7 or 8 feet long and provided with a steel cutting edge, 

 may be adjusted to any desired vertical or horizontal angle by means 

 of hand wheels arranged conveniently about the operator's platform. 

 Some of the best makes of grading machines are provided with attach- 

 ments for such purposes as shifting the frame back and forth on the 

 rear axle so as to adjust the blade to a desired position with reference 

 to the wheel tracks, or to lean the wheels at an angle with the vertical 

 and thus lessen the tendency of the machine to slide over a bank, or to 



Pig. 11. — Grading machine. 



cut the rear wheels at an angle with the frame in order to overcome 

 the tendency to slide when the blade is loaded. Most of the better 

 makes of such machines are now constructed so the blade may be 

 reversed entirely and the convex surface used for smoothing a road 

 surface after it has been graded approximately to the required cross 

 section. Machines of this type are made in different sizes and weights 

 and cost from about $175 to $300 f. o. b. factory. The heavier sizes 

 are best adapted for construction work and the lighter ones for main- 

 tenance. 



A modified form of grading machine consists of a blade similar to 

 that of the machine just described, which is supported by a simple 

 frame on only two wheels. The 2- wheeled machine usually weighs 

 only about one-fourth as much as the 4-wheeled type and costs con- 

 siderably less, but the 4-wheeled type generally is to be preferred on 

 account of its greater stability and also because it can be adjusted to 

 meet a much wider range of conditions. In the following description 



