Pull scraper systems provide unmatched flexibility. “The beauty of a pull scraper system is that capacities can be adjusted by adding or subtracting scrapers from the prime mover to suit each individual project or set of conditions,” says Mark Oliver, John Deere product marketing manager, scraper systems.
This versatility has made pull scrapers popular, but selection and setup determine success. “Pairing of the tractor and scraper(s) is the most critical step,” says Oliver. “The relationships between scraper size, quantity, horsepower and ground conditions are key.”
There is an art to sizing pull scrapers. “The more volume that can be moved per load, the more you minimize repetitive trips,” says Kelly Goossen, sales manager, K-Tec Earthmovers. K-Tec takes a unique approach by offering single scrapers with a capacity of 25 to 54 cu. yds.
Ideally, you want a scraper that provides the lowest overall cost per yard for the specific job. “Factors driving the cost per yard include load carrying capability, time to load and overall cycle time, as well as fuel consumption or operating costs,” notes Walt Baty, Bult Enterprises.
Another tangible factor is versatility and the resulting utilization. “On many jobs, there are areas where using a scraper results in the lowest cost per yard. In other areas, it is more economical to top load a truck,” says Baty. “If a scraper can be top loaded, it may not be necessary to bring in additional equipment to achieve the overall lowest cost per yard.”
Both John Deere and Case IH offer scraper system productivity calculators on their websites to help compare the costs of different earthmoving solutions. This can help you identify the ideal size and quantity of scrapers to minimize the costs per cubic yard.
Dump vs. ejection scraper
Soil type is the most important factor when choosing between a dump or ejector scraper. “If your jobsite requires moving loose topsoil or land leveling, a wide format, dump-style scraper is preferred over a narrower cut ejector scraper [which is used primarily to move bulky material like clay],” says Randy Rust, president, Ashland Industries.
Dump scrapers are less costly than ejector scrapers and they can unload faster. “But ejector scrapers unload more evenly than dump scrapers,” says Rust. “This can be a benefit to meet compaction standards.”
Dump scrapers may also present problems when unloading if the material is wet or sticky.
“As material that cannot be dumped builds up in the bowl, the load carrying capacity is reduced,” says Baty. “The ejector scraper always has the ability to positively eject, or push out of the bowl, all of the loaded material. The speed of the ejector can also be adjusted to provide better control of the spreading operation at the fill site. Consistent depth of material when being spread is a benefit during the compaction process.”
Ejector scrapers do offer the ability to work in all soil conditions. “Ejector scraper design allows loading of light or heavy material, and the fast ejector scrapers are considered all-in-one scrapers,” says Goossen.
But dump scrapers can really shine in sand. “A Deere carry-all scraper approaches the cut with a slightly different angle than an ejector, making its performance in dry, loose materials superior,” Oliver asserts. “Because the carry-all relies on gravity for dumping, its cycle times are typically faster than an ejector. Its aggressive approach and front pivot design give the ejector faster blade response than a carry-all.”
Also take note of the blade configuration. “Certain blade configurations such as drop centers and teeth are better in tougher soils, while straight blades work better in sand,” says Oliver.
Tires or Tracks?
Soil type also influences the choice between wheels or tracks. “Selecting the right tires or tracks for the conditions and following the manufacturer’s recommendations for wheel slip will lead to better performance and lower costs,” says Oliver.