SCRAPERS

Scrapers are designed for self-loading, hauling, and spreading material on long-haul earthmoving operations. Scrapers are most efficient when operated in light and medium materials that are nearly free of roots, stumps, and boulders. Heavy or consolidated materials require ripper-equipped dozers to rip open the surface and assist loading operations by pushing the scraper through the cut to achieve maximum loading. The dozer pushing the scraper is referred to as a push cat.

Scrapers are built with open tops to make them suitable for loading by crane clam shell, conveyor, or front-end loader. The types of scrapers used in the NCF are equipped with either a single engine or twin engine (fig. 10-33). On twin-engine scrapers, the one engine in the front is used to pull, and the one in the rear is used to push.

Another type of scraper used in the NCF is the paddle wheel scraper (fig. 10-34), also called the

Figure 10-33.-Scraper.

Figure _10-34.-Paddle wheel scraper.

Figure 10-35.-Scraper nomenclature.

elevating scraper or self- loading scraper. This scraper, on most projects, requires no push cat for loading and is ideal for small- to medium-size earthmoving jobs. The scraper loads its pan from the top by means of a paddle wheel elevator after the material has been cut by the cutting edge. Material is not forced to the top as on other scrapers. The loaded material can also be unloaded by the paddle wheels, giving the operator more control of the desired depth of fill.

A variety of scrapers are used in the NCF. Each operator is responsible for reading the operator's manual to obtain detailed information about each make and model.