SCRAPER COMPONENTS

The scraper is made in two sections: the tractor and the scraper. The tractor contains the engine, the drive train and wheels, the hydraulic pumps, and the operator's cab. The tractor is connected to the scraper by a vertical kingpin swivel connection usually in two parts with upper and lower pins. When you are steering, this connection permits turns of 85 to 90 degrees to each side of the center line of the scraper. There is also a longitudinal horizontal hinge that permits the two sections to tip independently from side to side.

The gooseneck of the scraper arches up to allow space for the tractor wheels to roll under it on turns. The

Figure 10-36.-Scraper bowl, apron, and ejector.

gooseneck then widens into a very massive crossbeam becoming a pair of side arms extending backward to the trunnion fastenings on the sides of the scraper bowl.

The gooseneck carries the steering cylinders, the lift cylinder and lever arm for the apron, and a pair of hoist cylinders for the bowl. Scraper nomenclature is shown in figure 10-35.

A scraper has three basic operating parts: the bowl, the apron, and the ejector.

Bowl

The bowl (fig. 10-36, view A) is a box with rigid sides, with the apron as a movable front, and the ejector as a movable back. The forward edge of the bowl is fitted with cutting edges. The cutting edges are made of wear-resistant steel and are bolted to the bottom of the bowl. The three main cutting edges areas follows:

1. The straight cutting edge is the most efficient for smooth finish grading.

2. The curved cutting edge penetrates more than the straight edge.

3. The three-piece cutting edge has the center piece positioned ahead of the two side pieces for deeper penetration. The center piece is referred to as the stinger (fig. 10-37).

The bottom front sides of the bowl usually have bolted-on wear plates called side cutters. The side cutters normally receive less wear than the cutting edges.

NOTE: Cutting edges that are worn or damaged should be replaced to prevent wear of the scraper bowl.

Apron

The apron (fig. 10-36, view B) forms the forward section and a variable amount of the bottom of the bowl assembly. When closed it rests at the cutting edges. The apron is hydraulically controlled by a lever in the _{operator's cab.} When the apron is lifted, it moves upward and forward far enough to leave the whole front of the bowl open.

Ejector

The ejector is the rear wall of the bowl (fig. 10-36, view C). The most common ejector is hydraulically controlled and moves forward horizontally, forcing the load out of the bowl. It is supported by rollers riding on the floor and on tracks welded to the sides of the bowl.

Figure 10-37.-Scraper cutting edges.