There’s no better machine than the wheel tractor scraper to load large amounts of material in a short amount of time, maintains Jim Czuprynski, Caterpillar’s wheel tractor scraper commercial manager.
Demand for scrapers has dropped since the heyday of the interstate programs of the ’60s and ’70s, “but we believe the opportunity continues to grow due to the worldwide development of infrastructure,” Czuprynski says. “We have already seen scraper demand grow and believe it will continue for the next several years.”
So Caterpillar’s scraper team had several clear missions when upgrading the 657 from an E-Series to a G-Series machine. In addition to meeting engine emission requirements, the 657G needed to be comfortable to run, durable and – because scrapers last so long – compatible with the production capabilities of other scrapers in a contractor’s fleet. The largest in Cat’s eight-model scraper lineup, the 657G is used primarily in heavy and general construction, in addition to mining applications.
The new G-Series utilizes two Tier 3-compliant, ACERT six-cylinder engines, the C18 in the tractor and the C15 in the scraper. “Yet we still have comparable power with the E-Series,” says Dave Ellington, wheel tractor scraper marketing representative. The electronically integrated power train allows dual power capabilities – which lets the engines produce more power in higher gear ranges for improved gradeability and reduced cycle times – and 10 percent more power in the top speeds. “You can also electronically set your top gear if you don’t want the full range available to your operators,” Ellington says.
The G-Series Next Generation Modular Radiator has a nine-fin-per-inch spacing, which Cat estimates is 16 percent more efficient than its previous folded core radiator with its 33 fins per inch. This increased spacing between fins reduces clogging in severe applications, according to the company.
Some of the most obvious changes are in the cab, which offers more knee clearance and a Cat comfort seat that can be swiveled as much as 30 degrees to the right (this allows operators to comfortably look over their shoulders when filling the bowl), an implement joystick and redesigned gear selector. “Like other G-Series scrapers, the apron, bowl and ejector controls are now on one joystick,” Ellington says. To operate the bowl, move the joystick forward and back; control the ejector by moving the stick side to side; the apron is operated by the thumb rocker switch.
Service improvements include a centralized electrical service box, the ability to download fault codes for both the tractor and scraper in either location, and right-side access to a variety of components, including the air cleaner and pre-cleaner, engine oil check and fill, and engine oil and fuel filters.
“We expect the engine repair and overhaul costs on the G-Series to be 20 to 25 percent lower and the overall repair costs 8 to 12 percent less than the E-Series,” says Quentin Burt, wheel tractor scraper senior product service engineer.
The scraper can be equipped with either a standard bowl or an auger. A high-volume coal bowl will be available next year (see “657G introduction schedule”). The machine can either be push loaded by a D10 or D11 dozer, self loaded or loaded in a push-pull configuration.
In the field
Sukut Construction, Santa Ana, California, which received one of four field follow 657G units in the United States, offers a natural testing ground: the company owns 125 scrapers and usually rents another 75 scrapers during the summer. The $200-million-plus contractor specializes in mass excavation and grading, and also works in a variety of other applications, including landfills, roads and storm drainage systems.
Sukut put the field follow unit to work at its resort development project in Dana Point, California. There the company is site developing 118 custom single-family lots, a 90-room resort hotel, commercial space and five public parks – a project owned by Headlands Reserve. To date, Sukut has moved more than 1 million cubic yards of the total 3 million cubic yards of dirt on the job.
With so many scrapers in its fleet, Sukut was especially concerned with the compatibility of the G-Series machines with previous machines. “But it works well with them and doesn’t overpower them,” says Sukut operator Skip Northcott, a 26-year veteran with around 53,000 hours behind the controls, primarily with scrapers. “It will huff a load, though,” he says with a grin. “Just now, I had the power setting well below what it’s capable of. The power is available right from the start.”
Northcott admits the 657G’s joystick control took a little getting used to: “Since I’ve operated scrapers for so long, I was used to motions that didn’t require thought, so it took me a while to get comfortable with this.” What didn’t take any adjustment, he says, was the suspension seat and the jostle protection provided by the cab mounts.
Northcott did have some suggestions for Cat on the 657G: Get rid of the cup holder (“If an operator’s drinking coffee in a scraper cab then he’s not much of an operator,” he says) and move both the joystick control lever and gear selector forward.
All in all, though, Northcott appreciates the machine’s performance. “The hydraulics on it are as smooth as cutting butter,” he says.
Specs at a glance
Tractor engine: Cat C18 at 600/564 horsepower
Scraper engine: Cat C15 at 451/410 horsepower
Transmission: Eight forward/One reverse, powershift
Heaped capacity: 44 cubic yards
Rated load: 104,058 pounds
Maximum travel speed: 36 mph
Maximum cut depth: 16.7 inches
Maximum spread depth: 26.8 inches
Width of cut outside router bits: 12 feet, 7 inches
657G introduction schedule
First quarter 2006
- Wheel tractor
- Push-pull attachment
Fourth quarter 2006
- Wheel tractor-auger
- Auger scraper
Second quarter 2007
- Coal bowl scraper