Some sculptors never see the day of attending a famous art museum to see their work on display. Then there are others who get as far as the curb in front of that famous art museumputting the finishing touches on a road grade using a 41,000-lb motor grader.
"The operator of a motor grader is highly prized because it requires somebody with a particular set of skills," George Smith, commericial manager for the motor grader product group at Caterpillar, told ROADS & BRIDGES. "You have to be able to visualize like a sculptor does when he walks up to a block of marble what that finish product is going to look like."
The motor grader is the shaping tool of the roadbuilding project, it shapes the grade and cuts it to a particular form. Because the job demands such precision, the goal at Caterpillar has been "keeping the operator effective," according to Smith.
"Theres an improved focus on operator ability to run the machine, to increase their confidence level through better visibility and through better predictable hydraulics."
Now manufacturers are looking into ways to cope with new emission levels which will be handed out by the Environmental Protection Agency in 2003. The stricter standards could mark the debut of electronically controlled engines and electronic injection equipment.
"It will bring a sophistication to the machine that doesnt exist today," said Smith.
Several manufacturers today are building machines to the customers demands. Caterpillar opened its ears five years ago with the introduction of the H-Series120H, 12H, 140H, 135H, 143H, 163H and 160Hmotor graders.
According to the Peoria-based company, "H-Series motor graders are designed to get the most out of an operator in a machine thats engineered to produce more, is easier to operate and creates an environment that is quiet and comfortable."
The machines come with a Caterpillar-built transmission, which is electronically controlled for easy shifting, and closely spaced gears in the working range increase grading speed in most applications.
Adding variable horsepower has increased rimpull above third gear, and the electronic control system encourages operators to use the full potential of the engine/transmission system.
A wheel base 6 in. longer than the G-Series model gives a steeper blading angle for more efficient material rolling.
In the operators station a repositioned moldboard, a redesigned blade linkage, increased glass area, an angled rear cab window and a tapered rear hood has improved visibility.
Caterpillars Proportional, Priority, Pressure-Compensated hydraulic system provides "more efficient hydraulic flow proportioning." Better pump flow proportioning means consistent implement speeds with no interruptions, regardless of how many controls are used simultaneously.
"I think our customers liked what we did and have kept us in the leadership position that we enjoyed with the G-Series," said Smith. "Like our G-Series, its very reliable, and thats important."
Volvo Construction Equipment Group has just started to scrape the surface with the Champion Series VI, which is the newest line of motor graders ranging from 9,420 lb to 42,740 lb.
At the top of the list of features is the Moveable Blade Control System, which allows the operator to position the blade on either side of the grader at any angle up to 90û for bank sloping and to a 21û downward angle for ditching. Volvo also claims the Series VI offers "the industrys longest blade reach outside the tire profile. You can cut a 2:1 bank slope with the moldboard completely outside of the tire profile." The blade lift system can lower the blade to 33 in. to provide a deep cut below ground.
All-wheel drive, available on models 716A VHP through the 736A VHP, is another new innovation. The system provides even distribution of power through independent variable displacement pumps and high torque motors to each front wheel. Speed sensors on each front wheel control relative front-to-rear wheel speeds, and the main all-wheel drive control gives the operator 16 levels of aggression to the front wheel drive, "ensuring the right match of power to any job without excessive wheel slip or spin," according to the company.
The operator can use the system in two-, four- and six-wheel drive modes, and Champions Creep Mode allows one to disengage the rear drive and pull the grader at low precision grading speeds using hydrostatic front wheel drive only.
The Series VI also offers 360û visibility, short throw hydraulic controls and a fully adjustable pedestal.
The PowerShift Plus direct drive countershaft transmission has charged new life into the motor graders at John Deere, Moline, Ill.
Dubbed as the most significant improvement to the C-Series670CH, 672CH, 770CH, 772CH, 670C and 770Cthe electronically controlled transmission "delivers smooth shifts between eight forward and eight reverse gears," according to Deere. Travel speeds are identical in forward and reverse, and drawbar pull is nearly the same in both directions, providing enough power for backing up inclines and getting out of trouble spots. Gear ratios are closely matched to working conditions.
The machines have a 6-cylinder Powertech turbo-charged diesel engine which comply with new EPA emission standards. All C-Series graders, except the 670C, are equipped with a waste-gate turbocharger that delivers high torque and "superior" lugging ability, and provides improved performance at lower rpm settings and at higher altitudes.
To prevent cross contamination, a closed-center hydraulic system has its own separtate oil lubrication, filtration and cooling system.
The 670CH (140/155 hp), 672CH (150/160 hp), 770CH (155/170/185 hp) and the 772CH (170/185/200 hp or 185/205 hp when all-wheel drive is engaged) are variable horsepower graders.
Weighing in at 42,000 lb
The GD750A-1 motor grader just recently entered the ring for Komatsu, Vernon Hills, Ill.
The new 42,000-lb four-wheel drive machine features an "articulated frame and a moldboard geometry" that enables the operator to position the blade 90û to the right or left. It has a cutting depth of 27 in., a maximum lift above ground of 16.5 in. and a blade tip range of 46û forward and 7.5û backward.
Powered by a 225-hp, turbo-charged Cummins M11-C diesel engine, the GD750A-1 has a full powershift transmission with integral free wheeling stator type torque converter and lock-up.
The motor grader comes with eight forward and four reverse speeds, and by multiplying engine torque and delivering it to the power train when needed, torque converters decrease the need for shifting and increase tractive effort, according to the manufacturer.
A load-sensing hydraulic with variable displacement system is another highlight of the model, which is equipped with an electronic self-diagnostic system.
Keeping the blade in line for three new motor graders from New Holland, Carol Stream, Ill., is a load-sensing hydraulic system. The innovation controls the blade while working, ensuring the blade maintains a level contact with the ground and reacts quickly to changes in resistance to maintain grading accuracy. The feature is available on machines in the 12-, 13- and 14-ft blade range.
The blade pitch range is from 5û backward to 40û forward and the bank cutting angle, left to right, is 90û.
Putting the RG140 in motion is a New Holland 7.5-liter Genesis diesel engine, while the RG170 and RG200 models are powered by an 8.3-liter Cummins diesel.
A direct drive Power Shift transmission has modulated shift under load and provides eight forward and four reverse speeds. Gears are selected by a single "bump type" lever that is pushed forward or pulled back to change up or down the transmission.
The Huber M-850-C Maintainer compact grader features a new engine, braking system and hydrostatic transmission and is designed for grading jobs from base to finish work, as well as spreading asphalt, stone, fill dirt and other materials.
A product of Huber Construction Equipment, Iberia, Ohio, the grader receives its kick from a Cummins 4B3.9 diesel engine that generates 80 hp at 2500 rpm.
A Linde hydrostatic transmission permits the operator to accelerate, brake and shift to forward or reverse with a single lever for a faster, smoother operation, according to Huber.