They look pretty much the same as they did 20 or 30 years ago, and more than a few of them are actually that old and still working. But motor graders have improved significantly over the years in areas that aren't immediately visible. Climb into a grader's cab and you're confronted with a bewildering array of levers. In an age where so many machines have simplified controls down to joysticks, buttons and switches, the motor grader keeps an "industry standard" set of controls that have endured relatively unchanged over the years. Why? Because motor-grader operators like it that way. Considered among the most skillful of all heavy-equipment operators, those who take the grader's controls prefer to keep the feel of the machine, much as automobile aficionados prefer manual shifts to automatic shifts.
But where those controls take the operator from there is the story. More horsepower, improved drive trains, and pumped-up hydraulics all contribute to added precision and production of the motor grader. A look at the latest offerings from grader manufacturers tells you why.
Case continues to expand its equipment line with the introduction of three motor graders. Ranging from 140 to 205 horsepower, the 800 Series features a one-piece, non-metallic sloping hood for excellent visibility and a streamlined design with many hoses covered for protection from the elements. Instead of swing-out engine-access doors, the Case graders have a flip-up hood and flip-down panels along the bottom of the hood.
A single-drive-gear motor turns the circle up to 360 degrees. The motor is mounted on the outside of the circle, reducing stress on the teeth of the circle and preventing debris or dirt from spilling onto the motor or into the drive-gear teeth.
In the cab, the operator has industry-standard controls, closed-center load-sensing hydraulics and 85 square feet of floor-to-ceiling glass. The powershift direct-drive transmission provides eight forward speeds and four reverse speeds. An inching pedal gives the operator a fine creep control for finish grading.
New from Volvo is the B-Series, comprised of five tandem-drive models and two all-wheel-drive models. All models are equipped with variable horsepower systems, which provide the correct power to the drive wheels for every application. A large variable displacement hydraulic pump allows the operator to reduce first gear ground speed by operating a lower rpm and retaining full hydraulic control, permitting precise moldboard positioning to match the grade requirement.
Volvo's largest grader in the line is the G746B, weighing 38,250 pounds and with 243 horsepower. This all-wheel-drive machine develops 30,259 pounds of blade pull. In the cab, the operator works with the Contronic Monitoring System, which monitors various machine functions. Performance information can be downloaded for maintenance diagnostic purposes.
Electronically controlled engine
The newest motor graders from Caterpillar are the 140H, 160H and 14H, with operating weights of 32,358 pounds, 34,560 pounds and 41,465 pounds, respectively. The machines are powered by Cat's electronically controlled 3176 ETA engine. The 140H and 160H offer the optional VHP Plus arrangement, which provides more horsepower in seventh and eighth gears. The three models have been re-engineered to reduce maintenance time, and fluid-change intervals have been extended.
The operator's compartment also has been redesigned for improved sightlines to the work area and enhanced operator comfort. Electronic throttle control is designed to make throttle operation easier and more precise, with the Electronic Clutch Pressure Control delivering optimized inching modulation and smooth, consistent shifting.
Komatsu's Laterra motor-grader line features a dual-mode transmission that allows the operator to move from torque converter to direct drive mode by a flip of a switch. The direct drive mode provides plenty of speed and, when used in conjunction with the inching pedal, gives operators the feel that they're used to. The torque converter mode can be used for slow speed control and power without stalling out under load. Blade geometry features a true 90-degree bankslope position, which makes for easy blade maneuvering while providing impressive reach and ground clearance.
Having been producing motor graders since 1949, New Holland now offers five machines from 76 to 205 horsepower. These latest graders have rear axles equipped with the automatically applied Super Max-Trac differential, which reduces slippage, eliminates tire scuffing and allows the machine to track. The Super Max-Trac also transmits up to 65 percent torque to the axle for great traction. In addition, some models offer unlock/lock differentials.
All new models feature New Holland's rollaway moldboard, which lowers the apex of the blade and keeps material from building up in front of the blade, reducing the amount of power and fuel needed to complete the job.
Another long-time manufacturer of motor graders, John Deere, started sales of its newest series machines in January 2002 and includes six models. Upgrades include improving internal components on the direct-drive transmission, increasing overall efficiency, and allowing the transmission to run cooler. The front wheels are powered by a dual path hydrostatic drive system with an independent pump and motor for each wheel. The inching pedal has been redesigned to give the operator more control when fine grading and working around obstacles. Those improvements, plus the integrated monitoring that's part of the horsepower-management system, results in all six wheels pulling the tractor smoothly. Finally, there's a new higher torque circle drive motor that improves performance when repositioning the blade under load.
| Websites | ||
| Case: www.casece.com |
Caterpillar: www.cat.com |
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| John Deere: www.johndeere.com |
Komatsu: www.komatsuamerica.com |
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| New Holland: www.newhollandconstruction.com |
Volvo: www.volvoce.com |
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