Motor graders have traditionally been the domain of only the most experienced equipment operators. The complexity of the controls and the finesse required to maintain precise grades have often necessitated an extensive learning curve — in some cases, years of regular use.
Most manufacturers are striving to reduce this learning curve via increased automation of machine functions. This automation can be largely attributed to advances in electronics — a byproduct of emissions control technology.
"Every engine manufacturer had to figure out a way to make their engines burn cleaner, yet still be very productive, capable engines," notes Howard Woolard, motor grader commercial manager, Caterpillar Motor Grader Product Group. "It stirred the creativity that led to electronic engine controls."
Electronic engine controls were initially introduced with Tier II designs. They not only delivered emissions compliance, they provided improved overall power management. "It allowed us to electronically control the engines and change the characteristics of how the engines performed based on what the customer was trying to do with the machine," says Woolard.
The electronics have since been married to other machine systems, serving as the "building blocks" for greater automation of key motor grader functions.
Mating electronics with hydraulics
Electronically-controlled hydraulic valves have enabled load-sensing hydraulics to become almost a "given" on today's motor graders.
"In LeeBoy models, this gives the operator better blade control through more accurate metering of cylinders," says Keith Lee, research and development at LeeBoy. "For the operator, the 'feel' while grading is better and blade movement is more constant and precise."
Electronic control of hydraulics has also produced improvements in all-wheel-drive systems. For example, both Volvo and Deere use a two-pump configuration to provide independent control of hydraulic flow to each front wheel hydrostatic motor.
Caterpillar also offers this feature on its M-Series models. "The dedicated pumps help us to control flow to the front wheels more than ever before," says Wade Porter, marketing supervisor, Caterpillar Motor Grader Product Group. "We've dramatically increased the overall torque by 52%, which has really helped us in terms of the tractive effort with the six-wheel drive."
It has also led to a hydrostatic-only mode (transmission neutralized) for the all-wheel-drive system. "This allows us to essentially dial down and precisely control our ground speed in certain applications, like cul de sac work where you already have your curb set and you don't want to damage it, for instance," says Porter. "Being able to dial that machine down below 1 mph and be able to just creep along for precision control is really essential."
Volvo includes an enhanced "Creep Mode" on its G900 Series motor graders, as well. When operating at speeds below 2.5 mph, this mode enables the operator to grade using only the hydrostatic front-wheel drive, while the rear tandems roll freely to minimize scuffing and rework. The result is smoother starts and stops and more precise passes.
A patent-pending automated steering compensation system is also featured on Caterpillar's M-Series. "Through the communication between the electronic control modules, we are automatically turning the outside tire 21% faster than the inside tire when we are in a six-wheel power turn," Porter explains. "That helps out in loose underfoot conditions where you really need your all-wheel-drive system working for you." It also cuts the turning radius by as much as 15 ft.
Electronics have played a significant role in recent enhancements to grader transmissions.
"We have an electronic shift management system for the transmission, for example," says Ed Samera, vice president, North America Heavy Products, Terex Construction Americas. "The operator can just put it in forward or reverse and it will shift multiple gears without having to do anything else. That is controlled electronically, coupled with the electronics of the engine to optimize fuel and meet emission requirements."