Road-Building Machinery

In addition to the type of grader shown in Fig. 24, 25, and 34, pages 102 and 109, there is on the market a cheaper and lighter machine which differs from the forms shown chiefly in having wooden wheels and frame, and less elaborate adjusting devices.

All of the forms referred to above have four wheels, but there are also upon the market several varieties consisting of a blade carried by only two wheels. As this form of machine is more suit able for use in maintenance than in construction, its consideration will be deferred to Art. 2, Maintenance (see § 200).

Still another form of scraping grader is shown in Fig. 62, page 219. It is primarily a land-leveling machine. It differs essentially from scraping graders in having a digging or plowing apparatus in front of the scraping blade, and in having adjustable aprons at each end of the blade that may be employed to prevent the earth from sliding off at the end of the blade. The scraping blade is adjustable in both the vertical and the horizontal plane. The price is *125 f. o. b. factory.

Operating the Scraping Grader.

To build a road with the scraping grader, first plow a light furrow with the point of the blade, where the outside of the ditch is to be (see Fig. 26, page 104). To make the blade penetrate hard or stony ground, elevate the rear end considerably and use only the point. On the second round, with the front and rear wheels in line (see Fig. 27), drive the team so that the point of the blade will follow the furrow made the first round, plowing a full furrow with the advance end of the blade, and dropping the rear end somewhat lower than before. The third time round, move over toward the middle of the road the earth pre viously plowed. In moving the earth toward the center of the road, elevate the rear end of the blade to allow the earth to distribute under it, so as to build the road at the side of the proper crown before filling the center (see Fig. 28); and if the machine slides side wise instead of pushing the ridge of earth toward the center, either slue the whole rear end of the machine toward the center, or move one hind wheel or the whole rear axle laterally until the rear wheel bears against the bottom of the unplowed bank at the ditch—ac cording to the construction of the machine (see Fig. 28 and 33, page 108). If the newest form of scraping grader (Fig. 34, page 109) is employed, there will be no tendency to slip. Finally, return to

the ditch and plow it out deeper, moving the earth over toward the middle whenever as much is plowed as the machine can move at once. Repeat this until the ditches are of the proper depth, and the road as full and round as required.

A ridge should not be left in the middle of the road. Usually a skilful handling of the machine will prevent the formation of such a ridge by elevating the rear end of the scraping blade, thus allowing the earth to loose out under it as the center of the road is approached. If the road is very rough, it may not be possible to fill all the ruts without forming a ridge in the center of the road at sonic places.

If the ridge is formed, it can be flatted down by setting the blade square across the road and allowing the earth to flow under it; and with most machines the center ridge can be leveled down by re versing the blade and using the back of it. ' If the ground where a road is to be constructed is covered with weeds and grass, it should be cleared by burning or by mowing and raking. With sod ground the best road can be obtained by first cutting the sod as thin as possible and moving it to the center of the road, and then going back to the ditch and continuing the grading as described above. To cut a thin slice of sod, the scraper blade should be as sharp as possible. When the ground to be moved is covered with sod or weeds, some operators make the first cut on the inside of the ditch and at each successive round cut a little farther out, thus distributing the sod through the earth forming the road way. This requires too much cutting with the unsharpened end of the blade, and is therefore not as good as the method described above.

It is best not to put more than 4 to 6 inches of loose earth into the road at one working, as that is all that can be thoroughly packed by traffic. If a greater amount is thrown up at one time, the bottom of the grade will remain soft and cause the road to cut into deep ruts as soon as the top has become thoroughly soaked by rain. As far as possible the grading should be done early in the summer, giving ample time for the loose earth to settle and pack before the fall rains. If worked in the fall, there should never be more than 4 inches of loose earth put upon the road at one working.