Dillenger is now investigating a Trimble GPS system for the pull scraper systems.
Maintaining tight tolerances
Louisiana-based Quad M Investors LLP uses a Topcon laser system with its John Deere pull scrapers. The scrapers are pulled by two John Deere 9420 scraper tractors, in addition to two John Deere 8520 and 9370 tractors. The operators have five to six years experience running the pull scrapers. "The same guys run the same tractors every day," says Mark Frey.
Project sizes vary. In Baton Rouge, one job is 750,000 yds., and the company just picked up a job for 110,000 yds. It has also tackled 1/2-million-yd. jobs where the scrapers were top loaded.
On the bigger sites, the range of the higher-power Topcon laser system is a benefit. It has a range of 1,000 to 1,200 ft. on each side of the laser, or roughly 2,400 ft.
Many of the projects completed by Quad M Investors had to meet tolerances of about three hundredths. This is one reason the company chose the laser system vs. GPS. "We had the opportunity to go to the total GPS, but there was still too much discrepancy from the time you start until nightfall came," says Frey. "You had to continually go back to the benches and check the accuracy.
"With a laser, we continue to have accuracy throughout the day," he states. "If you check the transmitter while you are setting up and everything is within specs - within a hundredth on each axis - you can tolerate that. You will not have any problems."
To further enhance accuracy, scrapers used for finish work have fixed blades. "We run the ejectors to do all of the finishing work," says Frey. "The bulk hauling is done with the carry-all scrapers. Those scrapers will definitely get off grade after about half a dump."
So the 18-cu.-yd. John Deere 1812 carry-all scrapers are pulled in tandem for bulk cutting and filling, and the ejector scrapers, with a 14-ft. cutting width, are pulled as singles for finish grade work. The final grade is accomplished with an automatic grade control system.
Quad M Investors purchased the scrapers in 2001 and the units have proven very durable. "Both the carry-alls and ejectors at this point have somewhere around 9,000 hours on them. We have only had one cylinder fail, and that was on an ejector cylinder that I changed this past year," says Frey. "I am not going to trade them in. There is nothing wrong with them. As far as wear and tear, they are good scrapers."