Scraper Spacing Efficiently

Scrapers should be teamed by their speed whenever possible. The fastest scrapers should be assigned to one section of a job, while the slower ones are on another. They should use different haul roads if possible.

NOTE: No scraper can travel faster than the scraper ahead of it. Passing only increases the chances of accidents.

Scraper operators can help in traffic control by speeding up to close along gap and slowing down when too close. Efficient spacing supports the optimum use of the push cat. When unloading and lagging far behind the next scraper, spread the load at the beginning of a

Figure 10-48.-Cut and spread sequence.

fill. When traveling too close to the next scraper, spread the load at the far end of the fall.

NOTE: Keep the scraper bowl as close to the ground as possible to lower its center of gravity and to keep it upright.

Spreading

Techniques for scraper spreading operations are as follows:

l Spread the first load at the start of the fill.

l Travel with subsequent loads over the previous fill, provided lifts are small.

. Make each following spread start at the end of the previous layer.

. Finish spreading in one full length before starting a new lane, so rollers can begin compaction.

. Route the scrapers to compact the fill. Overlapping the scraper tire tracks aids in the compaction of the entire area and reduces the compaction time necessary with a roller.

l Spread in the highest gear permitted by the condition of the fill area terrain.

NOTE: Slowly discharging loads at low speed slows down production and cycle time.

l Do not waste time on the fill. As soon as the load is spread, get the scraper back on the haul road and return to the cut. Plan your exit from the fill to avoid soft ground and detours around trees and other obstacles.

. As shown in figure 10-49, make the fill high on the outside edge. This prevents the scraper from sliding over the outside edge and helps in maintaining accurate slopes to desired heights. When the fill is not made in this manner, the scraper tends to work away from the edge of the fill, making it hard to maintain the correct slope. In inclement weather, build the low center up for drainage.

SCRAPER SAFETY

Safety precautions that apply to scrapers are as follows:

. Never operate a scraper at speeds that are unsafe.

. Always wear seat belts. Uneven terrain can cause a violent tilt of the scraper, causing possible personal injury by throwing you off or against the steering wheel if NOT secured in the operator's seat.

Figure 10-49.-Proper placement of fill material.

. Block up the scraper bowl and apron before performing any work on the cutting edges of the scraper.

. Keep the operator's cab clear of debris, grease, oil, and mud which can cause the operator to slip or fall.

. Never kick the scraper out of gear when going downhill. The increased speed will make control of the scraper very difficult.

Keep the scraper in gear at all times and use the cutting edge to control the speed

When the brakes fail to hold the load, lower and drag the scraper bowl.

l When securing the scraper, ensure the apron is closed and the bowl on the ground.

l Do NOT spread when turning.

l When working on slopes, always turn uphill.

. Do NOT drop the bowl suddenly; ease the cutting edge onto the ground.

. Load and spread when going downgrade, whenever possible.

. When constructing a fill, keep the outside edge high and the center low to prevent the scraper from sliding over the edge.

l When the scraper begins to fall off the fill, steer downhill, drop the bowl, and rapidly accelerate to maximum rpm. Do NOT attempt to turn the scraper back up the slope. Do NOT stop the forward motion of the scraper when there is any danger of the unit tipping over.

. Wear any required personal protective equipment, such as hard hats and steel toe safety shoes.