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Machine Matters

Cover Story/Machine Matters: Dynamic duo

July 02, 2008 |

Pairing a pull-behind scraper and scraper hauler – specifically designed for the task – is teamwork at its best. Pull-behind scrapers work well in light stripping applications with no severe grades or where the material weighs less than 3,000 pounds per bank cubic foot and has no rocks or debris. According to Scott Knoblauch, senior consultant with Caterpillar, if you are working in soft or very poor underfoot conditions, pull-behind scrapers have much higher flotation than self-propelled scrapers.

The haul distance on a job has been a factor in determining whether to use a self-propelled scraper or a pull-behind scraper. Generally, the self-propelled scrapers could travel faster over long distances (usually over a mile) but could carry only one load. Pull-behind scrapers could be linked up to three to a train and carry a greater total of material, but their less powerful towing tractors were slower than the self-propelled machines. Today, purpose-built scraper haulers are combining more pull power and faster speeds to let contractors move more cubic yards of material at efficient speeds.

Since fuel consumption has become a machine decision factor, one advantage of pull-behind scrapers is that they usually require only one diesel-powered engine to move them. Robin Pett, president of UED, which distributes Bell scraper tractors in North America, says the Bell unit uses a scant 13 gallons per hour of fuel, making it less expensive to run than similar capacity self-propelled scrapers that can burn approximately 25 gallons per hour. Keep in mind, however, that you still need to take the cost per yard of material moved. This cost-per-yard figure takes into account operating, maintenance and purchase costs.

The powers that be
While pull-behind scraper manufacturers strive to design scraper equipment that works well with most haulers, and scraper hauler manufacturers build construction-grade haulers, Randy Rust at Ashland Industries says both machines must work well together. Matching the scraper hauler to the scraper will maximize production, decrease down time and provide the lowest cost per yard over the long run.

Regular-duty ag tractors with enough horsepower can be used to tow a pull-behind scraper but they aren’t built to pull heavy material or multiple scrapers through rocky or wet conditions, “A standard ag tractor doesn’t have the proper gear mechanisms,” says Danny Dumey, president of Double D Manufacturing. “If they get into soft conditions, they run out of power and can’t get the job done.” So equipment manufacturers are building construction-grade scraper haulers that take the best from the manufacturers’ power unit lineups.