Road-Building Machinery

If the maximum amount of earth is to be placed upon the road at once, it is wise to roll each successive layer with as heavy a roller as is available or as the team can draw, as otherwise traffic will con solidate only the surface, and the bottom of the grade will long remain soft and spongy.

The scraping grader is usually drawn by four or six horses, depending upon their size, and the character and condition of the soil. One man can operate the machine, and one or two men are required to drive.

A traction engine is sometimes used; and it is a better power, since it gives a steady draft and does not need to stop to rest. At certain seasons of the year, the traction engine is the cheaper power, and at other times horses are the cheaper, depending upon the re quirements of horses for farm work and the demands for the trac tion engine in threshing and shelling.

The cost of building an ordinary prairie road with this machine is about $30 to $40 per mile, with a width of 30 or 35 feet and a crown of 6 inches above the natural surface. The first is the cost when there is a stiff sod, and the second when there is none. A second 6 inches may be added for about $30 per mile.

If the ground is very dry and hard, another team and driver will be required, and the above prices may be nearly doubled.

Elevating

Grader. The best known form of the elevating grader is shown in Fig. 35. It consists of a frame resting upon four wheels, from which is suspended a plow and a frame carrying a wide traveling belt. The carrier is built in sections and its height is adjustable. The larger carrier will deliver earth 14, 17, 19, or 22 feet horizontally and 8 feet vertically from the plow; while the smaller size delivers 14 and 17 feet horizontally and 7 feet vertically. The smaller machine is designed for highway work. The plow loosens the soil and throws it upon the traveling inclined belt, which delivers it upon the embankment direct or into wagons.

This is an exceedingly effective machine for building open ditches, earth embankments, or filling wagons. By changing the length of the carrier and by properly distributing the earth, the machine will build either a broad low embankment from a narrow deep cutting, or a narrow high embankment from a broad shallow cutting; or the machine will excavate a deep narrow ditch with flat spoil banks, or a shallow ditch with narrow spoil banks.. This machine is espe cially adapted to building earth roads in a prairie country, for which purpose it has been very largely used.

The large machine is usually propelled by twelve horses—eight in front and four behind,—and the smaller by eight in front. Often a traction engine is cheaper than horses. One man can operate the machine; and at least two men, and usually three, are required to drive the larger machine, but usually two drive the smaller one.

The factory price of the smaller machine is $1,200.

The large machine is guaranteed to place 1,000 cubic yards of earth in an embankment in 10 hours, or to load 600 cubic yards into wagons in the same time. The small machine will grade a quarter of a mile of ordinary prairie road per day, with a width of 25 to 30 feet and a crown of 12 inches at the center, at a cost of $11 to $14, or at the rate of, say, $45 to $60 per mile.

Recently there have appeared upon the market two forms of elevating graders consisting of a plow, carrier, and traction engine combined. So far as known these are still in the experimental stage.

Operating the Elerating Grader.

To build a new road of the sections shown in Fig. 9 and 10, page S5, first mark by stakes a line 10 feet on *each side of the center of the proposed road. With the machine arranged to carry 17 feet, drive along the left hand row of stakes and back on the other side of the road in the same way. The streams of earth as delivered will overlap 5 or 6 feet. Start the machine on the second round with the right-hand forward wheel in the furrow of the previous round, and complete the round. A harrow should follow the machine to break up the sod and level the bank. Continue to make rounds until the ditches are as wide as desired.

Commence the second plowing by bringing the left-hand wheel of the machine to the left-hand edge of the first furrow cut, which brings the plow one furrow to the left of the point of commencing the first plowing, and keep this relative position while making this round. Make the second round with the right-hand forward wheel in the furrow of the previous round; and continue to make rounds until the outside of the ditch is reached again. For the best results a harrow and roller—the heavier the better—should follow the grader during the second and subsequent rounds. Sec Fig. 36, page 112.

When the second plowing has been completed, the grade will be high and narrow; and therefore the carrier should be shortened to 14 feet. Then start the machine so that the plow will take a furrow from the center of the ditch, and continue the third plowing, as described above for the first and second, to the outside of the ditch. For the fourth plowing take a couple of furrows from the outside of the excavation to deepen the ditch.

The final result should be about as in Fig. 9, page 85. Most operators, however, leave a berm at the inside edge of the ditch (see Fig. 36), which is undesirable since it interferes with the opera tion of the scraping grader in maintaining the road.

For loading wagons, the carrier is arranged to deliver at 17 or 19 feet horizontally from the machine, the wagons are driven so that the earth falls from the carrier into the wagon, and both move at the same speed until the wagon is loaded; and then the grader slows down while the loaded wagon drives out and an empty one drives in. In a public test at Denver, Colorado, in 1890, 55 dump wagons were loaded in 22 minutes, or at the rate of 150 wagons per hour.* Common wagons with dump boards are not so easily loaded as the usual dump wagon, since they are narrower and longer. It is customary to estimate three dump wagons for the first 100 feet of haul, and an additional wagon for each 100 feet thereafter.