Application Tips: Motor graders
| June 12, 2007 |
Since you’ll probably hang onto a motor grader for 10 to 15 years, get a good handle on the average size of your jobs and how much dirt you’ll be moving before making a purchase.
If your projects are usually along the lines of one-acre parking lots, a small, 80- to 150-horsepower grader will work, says Mark Bolick, service manager for LeeBoy. Driveways, landscaping and road maintenance are also good applications for small motor graders. And if your work primarily involves these types of jobs, a small grader will give you the added advantages of better maneuverability and easier transport compared to a larger machine, says Bryan Abernathy, vice president of sales and marketing, Champion Motor Graders.
You also need to take ground conditions in your area into account before purchasing, says Gary Atkinson, product manager, motor graders, Volvo Construction Equipment. Some situations require extreme blade down pressure while others benefit from lower ground-bearing pressure. As a result, ground conditions affect the selection of the machine itself, attachments, tire sizes and type, as well as optional accessories. “For instance, extremely rocky conditions may dictate the use of a heavier machine,” Atkinson says. And high-impact loads can take an early toll on pins, bearings and basic structures, making options such as blade lift and side shift accumulators wise investments.
Maurice Nesbitt, John Deere’s motor grader product consultant for North America, says six-wheel-drive graders, which have been around for 25 years, are a well-kept secret. “Most contractors assume because they’ve always had tandem-drive graders, that’s all they need,” he says. While a six-wheel-drive motor grader costs about 15 percent more than a tandem-drive unit, Nesbitt says it can increase productivity up to 30 percent.
He says many contractors think they would only need six-wheel drive in mud or snow, but the extra drive wheels can boost productivity in all applications – from site development to fine grading. In the past, one complaint about six-wheel-drive graders was that a lot of front-end horsepower was wasted due to inefficient drive axles. But Nesbitt says the efficiency of the front-wheel drive has been greatly improved in recent years and that’s not the case anymore.
Because a motor grader is a complex machine to operate, this task usually falls to the most experienced person on a job. Abernathy says he sees a lot of company owners still serving as the grader operator.
With few experienced motor grader operators left, more construction companies are using laser and GPS systems because they make precise operation easier for younger operators. Bolick says 8 or 9 percent of contractors are using GPS systems on their motor graders, compared to less than 1 percent a few years ago. Another reason for using automatic grade control systems is the tight tolerances engineers are putting in jobs today.
As a result of the lack of skilled operators, Nesbitt says contractors are relegating graders to finish work, using dozers instead for rough work. Consequently, there are fewer training opportunities for new operators. “It’s a circular problem,” Nesbitt says.
The small, aging pool of motor grader operators highlights the labor issue the entire construction industry is facing. Few training schools teach equipment operation, and schools don’t look at the profession as a high-skills trade, Abernathy says.
That’s despite the fact that operating earthmoving equipment today often requires someone to be both skilled at running machines and knowledgeable in technology as a result of increasing reliance on GPS and laser guidance systems. In the future, Abernathy thinks contractors may have engineers come to the jobsite and set up high-tech grade control systems on machines such as motor graders, and then have someone else operate them.
Currently, though, there aren’t many shortcuts to good motor grader operation. “There aren’t really any tricks to operating a grader other than experience,” Bolick says.
That being said, here are a few tips that can help you or your operators avoid some of the most common mistakes:
Don’t try to move too much material too fast. Because motor graders are traction limited, they can only push so much before the drive wheels behind the blade spin, digging holes in what should be the finished path. “An operator who can slow down a little bit and understand what’s going on is just so much more productive,” Abernathy says.
Use less rpm. This can help you conserve fuel while maintaining productivity. Operators sometimes think they need to run the grader at high rpm when they can operate at medium rpm, do the same amount of work and use half the fuel.
Don’t pitch the moldboard too far forward. The inexperienced operator does this to see the cutting edge, but over time it blunts the edge. So when he has to cut a hard surface, the cutting edge isn’t sharp enough. You should have the top of the blade only slightly forward of the cutting edge; this gives you good rolling action. Then when you have to cut, you pitch the blade forward.
Here are some of the ways motor graders have changed during the past two years.
- Volvo’s Atkinson says hydraulically driven engine cooling fans now maximize system cooling performance in hot weather while allowing for lower fan speeds when cooling demands are reduced. This saves fuel, reduces noise and puts more power to the ground.
- With the advent of EPA Tier 2 and Tier 3 emissions requirements, engines reject dramatically more heat to the machine’s cooling system than they used to, Atkinson says. You should pay close attention to maintaining your grader’s cooling system to avoid overheating and possible costly damage.
- Champion’s Abernathy says customers asked for better versatility, so this year the company designed a new front axle that turns sharper. Champion also began using bigger blades this year.
- Deere has a new event-based shifting feature that monitors numerous inputs from the machine and tailors shifts to the specific job. It creates a smoother shift and allows shifting without the clutch – which is beneficial for older operators with bad knees. In addition, automatic grade control systems, which tend to overreact to the transmission jerk in a shift, don’t detect shifts initiated by an event-based shifting system, Nesbitt says.