Figure 10-39.-Entering the cut.Figure 10-40.—Loading the bowl.Figure 10-41.-Loaded bowl.The scraper work cycle has four phases ofoperation: loading, hauling, spreading or unloading,and returning to the cut.LoadingWhen loading, enter the cut with the ejectorpositioned at the rear of the bowl, open the apron enoughto allow material to enter the bowl (normally 4 to 8inches above the leading edge of the bowl), and thenlower the bowl to cut a depth of 1 to 1 1/2 inches. Thegear that the transmission is engaged in depends on thenature of the material being cut. For light, loosematerial, a relatively high gear can be used. For heavycompacted material, a low gear is used; however, toobtain a full load, you should use a lower gear, even inloose material. As the scraper proceeds through the cut,the material is loosened by the scraper cutting edges andforced into the bowl by the forward motion of thescraper (fig. 10-39).NOTE: Avoid spinning the scraper tires during cutoperations. Spinning the tires is nonproductive andcauses expensive premature wear of the tires,differential, and transmission.The material entering the bowl boils back against theejector and forward against the apron (fig. 10-40). Whenthe bowl is filled to capacity (commonly know as heaped),close the apron, and at the same time, raise the bowl 1 or2 inches above the ground (fig. 10-41). On scrapersequipped with diverter valves in the apron hoist system,the bowl automatically starts raising, while the aproncontrol lever is held in the lower position. After the scraperis fully loaded and the bowl is raised, continue to travel outof the cut with the scraper bowl at a height that spreads outthe material that piles in front of the cutting edges.The push cat supplies extra power to the scraperduring loading operations. When a push cat is used, itshould be positioned about 45 degrees off the lane to be cut.The scraper should start loading before the push cat makesa smooth contact with the rear push block (fig. 10-42).Figure 10-42.-Push block.10-21
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