The wheel tractor scrapers excel in materials that require a high horsepower-to-weight ratio. "If we have some very hard clay that we are trying to move, the tractor scraper exerts about 85 psi of ground pressure to the tires," says Knoblauch. So we can get the horsepower to the ground."
Towed scrapers are not capable of producing this kind of ground pressure. You dont want to try to hog material with a towed scraper or your operational costs will go through the roof, claims Knoblauch. The ag tractors used in these applications also run 10 to 12 mph slower down the road, something to consider if you need to move a lot of material in a short time on a long haul road.
Jerry Foster Land Grading, Dexter, MO, has been in the land grading business for 40 years. He uses three rigs: two Case IH STX 450 tractors, each pulling two Reynolds scrapers (a 17 yd. on the front and a 16 yd. on the back), and a Case IH STX 375 pulling two 14-yd. Reynolds scrapers.
These units usually work in light clay, gumbo and sandy loam conditions. There is also some sand. "Of course, in some soils it works better, but all around they do real well," says Foster.
Haul distances vary from less than a quarter to half a mile. "Most of the time it is a quarter mile or less," says Foster.
This setup has proven very durable and efficient for Jerry Foster Land Grading. "The price and the maintenance, for what we do, they just work in our application," says Foster. Each rig costs approximately $317,000, which includes $195,000 for the tractor, $102,000 for the train of pull scrapers and $20,000 for laser equipment on the scrapers. This is less than the investment required for a wheel tractor scraper. "The upkeep and maintenance would be less, too," says Foster. "You dont have to have something pushing you. You can fill both buckets and it is just more efficient."
Equipment disposal is also greatly simplified with the pull-type scraper arrangement. "There is a bigger demand when you get rid of them because there are farmers who want a bucket to use around the farm," says Foster. "You can just sell the tractor separate. You have so many places to go with it."
Sevig Construction, Cedar Rapids, IA, performs residential and commercial site development work. Its fleet of equipment includes six pull-type scrapers. "We pull them in tandems, but of course you can pull a single if you want to," says Gordon Sevig, owner/president. "We have three 15-yd. Ashland scrapers and two 18-yd. Ashland scrapers. Then I have a Caterpillar 70, which is about a 14- or 15-yd. scraper."
The Caterpillar 70 is a four-wheel scraper while the Ashland scrapers are two-wheel drawbar hitch models. The Cat 70 is pulled behind one of the Ashland scrapers. These tandem setups are pulled by a Case IH 375 Quadtrac, a Case IH 425 Quadtrac and a Cat Challenger, which are all rubber-tracked tractors. Added together, these scrapers allow Sevig to move 66 yds. per pass. "To make a tandem scraper practical, you need to have a little space," says Sevig. "It takes a little while to load two of them. It takes some distance to get two of them loaded correctly."
When Sevig encounters a confined space, he simply unhooks one of the scrapers. "Right now, we are pulling just a single behind one of the tractors because we are in kind of a confined area," he notes. "The drawbar-hitch tandems can also be backed into tight spaces."
Sevig sticks with short hauls. "A quarter of a mile would be the maximum," he says. He claims he has never needed a truck. When conditions are too soft for scraper operations, he top loads them with an excavator. "If you load 36 yds. in the two 18-yd. scrapers, it takes a pretty big truck to match that."
One scraper rig is equipped with Trimble GPS. "It is accurate to within 1/10th ft. on a project," says Sevig. This keeps all of the scrapers on the job productive. "I have seen guys run around half empty because they didnt know where they were going or what they were going to do," says Sevig. "So they thought they were doing something if they just took half a load."
With GPS in the lead scraper and business band radios in all scrapers, productivity has been maximized. "The main operator can pretty much keep the other guys loaded and tell them where to unload all of the time," says Sevig.