Grading and Graders Doing Their Level Best
"I'd rather have used a dozer for this small job, but we don't have one," comments Peter Taylor, after just finishing the grading for an additional, small parking lot at a Miami hospital. Taylor is a peripatetic construction worker who has grading experience with contractors in the southeastern United States. A big, old motor grader did the grading, with help from loaders for the tighter corners. The problem with the grader was that its hydraulics was now unreliable, its maneuverability inadequate, and its use of power insufficient for the best and fastest results. "The controls on newer machines make such a difference, too-for accuracy as well as speed," adds Taylor. "I personally don't like trying to grade with a motor grader on small jobs. This one is too big to maneuver easily, and I'd prefer a small dozer."
Dozers can perform the initial grading at many sites.
Asking manufacturers and contractors about gradingequipment proved to be very interesting. "What kind of grading?" was the most common reaction to our initial request for opinions and advice about this vital, basic aspect of site preparation. The consensus was that grading is the technique that reduces uneven ground to levels that are flat or sloped correctly for building. Good drainage was a goal mentioned frequently. For road construction, the motor grader has been the most popular, and municipalities and counties use graders for the many thousands of miles of gravel roads and alleys in the US. But not all grading is for road construction or maintenance. Almost every construction project or site preparation requires some grading, and the machines used depend on the precision specified. The first grading at a site in northern California for new houses involved removing a few acres from the top of a hill and using the spoil to form the stable ground for the new structures about a half mile away. For accuracy at this site, the graders were fitted with a Trimble Navigation machine guidance system. This system allows a contractor to have a stakeless environment at a site, eliminating downtime while surveyors are staking and significantly reducing rework. Trimble (Sunnyvale, CA) and Caterpillar (Peoria, IL) are two of several companies that have worked together to develop better grading techniques that involve machine guidance, taking advantage of a daylight-readable display in the cab to show the operator what has been done correctly and what still needs to be done. "We keep the dozers running all the time with minimal supervision," states engineer Erik storm, who monitors dozer operations for Glenrock Coal Company (Glenrock, WY), where accuracy and productivity have equal importance. "We don't even stake the ground because our operators can tell in their machines where to make the next cut." Radio communication of global positioning system information with the office virtually turns the dozer or grader into an automatic surveyor as it moves around the site.
Grading is an essential part of road maintenance.
Spectra Precision in Dayton, OH, makes the Blade-Pro control system for motor graders and says that its use can help cut the cost of fine grading by reducing conventional grading time as much as 50%. With Blade-Pro, both sides of the blade correct simultaneously, eliminating that wobbly movement called "duck walking," and there is no jerky response when starting the grader forward or shifting gears. Control of the system is mostly by push button, while the LCD and LED grade lamps are automatically adjusted according to ambient conditions. The functions that the operator can select include remote slope and elevation offsets (good for vertical curves, multiple layers of material, or slope transitions), slope alert to warn the operator if the cross-slope was not cut to tolerance, and selectable slope units that display slope as a percentage slope or rise over run. The latter function can easily match the units specified on the blueprints. The instruments for grading from such companies as Trimble, Spectra Precision, and Topcon (Paramus, NJ) are sophisticated and accurate. They have also been welcomed by operators as simple to operate and understand. One experienced grader operator remarks, "I used to enjoy my work, but with this system, I love it!" Accuracy in grading is especially important when the specifications call for "special graded aggregate" because payment for such work is usually based on tons or cubic yards actually placed and includes compensation for all materials, equipment and labor (including fine grading and trimming), and all the other incidental costs needed to complete the work according to the engineer's opinion. Time taken and materials used are critical to profitability. Today's instruments can help.
Today's designs aim for good visibility for grader operators.
Most contractors say the size of the site to be graded is important. "We have used skid-steer loaders with grading attachments, and it worked perfectly, but not for jobs where the grading was deeper than, say, a foot," observes an experienced worker for Al Aldinger Construction in Dawson County, MT. "For some of our jobs-and you might not believe this in this day and age-we have finished with grading by hand. Grading the small forecourt for a car dealership was the site for that elementary grading technique. Our machines could not achieve the desired finish."
With the right attachments, skid-steer loaders can grade.
The reduction of rework is a benefit that all contractors appreciate. What disappointed the young worker mentioned above (whose company didn't own a small dozer) was that he found himself spending far more time maneuvering the motor grader than he felt was necessary. Using a machine of the right size and grading with first-time accuracy were mentioned by several contractors as critical aspects of completing a job in good time with no wastage. This was a consideration when John Deere developed its H-Series dozer line (the 450H, 550H, and 650H). "All dozers push dirt," says David Werning, director of international operations for Deere Construction Equipment in Moline, IL. "If you want one that also has the finesse for finish work, the H-Series is the answer." These dozers have a center of gravity engineered to provide a balance and stability that will improve grading ability, as well as single-lever steering and direction control for smooth steering and pinpoint maneuverability, even with heavy-blade loads. The three-pitch adjustable blade offers a pitch of 52º, 56º, and 60º (with several lengths of blade also available). Full-power turns, unlimited counterrotation, infinite speed control, and automatic load sensing can all contribute to improved mobility and maneuverability. In a demonstration for our reporters, the double-bevel cutting edge of the Deere 450H penetrated easily and the curvature of the moldboard seemed to shake off even sticky material.
Large graders need space but they are the most accurate.
For larger jobs, the GD750A-1 is a motor grader from Komatsu America in Vernon Hills, IL, that weighs 42,000 lb. It has four-wheel drive and an articulated frame, with moldboard geometry enabling the operator to position the blade 90º to the right or left. "One of this machine's key features is the torque converter with lock-up direct drive," notes Jimmy Slavens, vice president of marketing for Komatsu. It allows the operator to run the machine smoothly by using only a brake pedal. "This function will assist, among other things, in the ease of fine grading because the operator will be able to better concentrate on moving the blade." As with most of today's construction equipment, good visibility for the operator has been addressed by manufacturers. Being able to see the blade, front tire, tandem tires, and rear ripper from both the front and side windshields is a benefit of Komatsu's GD750A-1.
"Rebuildability" is one of the benefits described by Caterpillar regarding its H-Series of seven motor graders (with weights from 27,600 to 36,460 lb.). Motor graders do not last forever, but many owners (especially, perhaps, those funded by the public) have requested machines that are rebuildable. For improved performance, the H-Series can do in one pass what might have taken two or more passes with the G-Series. As aware as all contractors are of the importance of operator skill in grading, Caterpillar concentrated on making the control of the graders as straightforward as possible, with the machine taking the responsibility for some functions of precision that could only be previously managed by the most skilled operators. A perceived shortage of skilled operators is a nationwide problem for owners of motor graders.
Graders look cumbersome but produce precise results.
Deere says that there has been great interest from owners of rental companies in its new series of dozers, presumably for use by those contractors who need a grading dozer only now and then. Motor graders and dozers are available at Cat rental outlets too. General contractor Irving Mitchell, who specializes in local residential and commercial work, observes that with grading equipment rental, "You must know what kind of time you will save and what profit you will make if you are considering renting equipment for a specific project. Those companies that can estimate accurately all the costs of a larger-than-usual job can often make excellent profits, but smaller contracting companies should be cautious. It's as easy to make a big loss as it is to make a big profit on some of these large jobs." Some general contractors are still wary of undertaking projects beyond their normal capabilities, but others say that the only way to grow the business is to meet more challenges. The grading segment of a larger project can be a key factor in profit or loss. Renting the appropriate grading equipment can make sense for the contractor who has a job requiring equipment he does not own (and that he might not need again for a long time). Counter clerks at rental stores say they are seldom asked for motor graders, but small dozers are gaining popularity as a rental item. For turning loaders and excavators into precision grading machines, our observation is that owners tend to purchase attachments for grading work rather than rent them.
Champion 700 Series grader doing road-finish work.
Champion has recently introduced the Series VI in response to extensive customer surveys with impressive improvements in hydraulic response, maneuverability, and blade mobility. "The customer and operator are the most important part of the grading operation and machine design," says Ron Huibers of Volvo Construction Equipment North America, which manufactures Champion graders. Its new Series VI includes 23 models ranging from 80 to 235 hp and is the fourth generation of graders in the past 10 years. It features an All Wheel Drive System and the only hydrostatic front-drive option that allows the operator to select two-, four-, or six-wheel drive. With only the front wheels engaged, the grader can finish grade a radius of 1.5 ft. at 0 to 2 mph. "This is accomplished by disengaging the tandem drive, which eliminates the tendency to push the grader straight forward," explains Huibers. "This puts power where it is most effective for fine grading and allows the moldboard to be navigated around the tightest corners without the rear wheel 'scuffing' the final grade."
Champion 700 Series grader with ripper.
"On the go" is a phrase mentioned frequently during discussions of the functions of grading equipment. "Not having to stop frequently keeps machine and operator progressing smoothly and productively," notes Richard Schwartz, owner of a contracting company that manages projects in North Dakota, Wyoming, and Montana, where fast, efficient work is especially important because of the shorter work season. The three models of the H-Series of crawler dozers from Deere offer a counterrotation usable at any speed and helpful for fast repositioning of the blade on-the-go and overcoming corner-loaded side drafts. The operator need not shift into neutral to avoid stalling or limit the machine's use to good ground conditions. "Good ground conditions? What are they?" ask contractors and operators who work year-round. On the Deere H-Series dozers, the operator sets the ground-speed lever to the maximum speed desired, and as loads change, the drive train responds to power up and down. On level ground or a 2:1 slope, the driver does not need to cross-clutch or ride a brake because the machine will not freewheel (as a dozer equipped with a torque converter might do).
DC80 dozer tracks have the ability to counterrotate for precise maneuvering.
New Holland North America in New Holland, PA, also has dozers with counterrotation: the DC70, the DC80, and the DC100. These are smaller models designed to give low operating costs and easy servicing. Low-ground pressure versions of dozers offer superior flotation for work on weaker ground. In practice, this means in some states that the contractor can enjoy a longer grading season. New Holland offers eight models, with operating weights from 14,300 to 40,800 lb. and blade capacities from 1.7 to 7.4 yd.3 The company markets motor graders, too, and makes all-wheel drive available "for really demanding applications." Setting the blades on New Holland graders is designed to be practical and easy because the power to the blade rams is always maintained regardless of engine speed or hydraulic pressure. Pitch range for the blade is 5º backward to 40º forward. Hyundai Construction Equipment in Elk Grove, IL, markets the H70 for smaller dozing and grading work, with 72 flywheel hp. "As a world-leading ship builder and steel fabricator and the only industry supplier that manufactures all of the products we sell, Hyundai is better able to control both quality and price," asserts Bob King for Hyundai. The H70 is another machine available in a low-ground-pressure version.
Small graders handle parking lots well. Operator skill plays an important role in Grading.
Users everywhere have acclaimed the advantages of hydrostatic drive, including the fact that the diesel engine is never overloaded. All of Liebherr Construction Company's (Newport News, VA) crawler dozers have hydrostatic drive to allow them to maneuver with both tracks powered and without shifting gears. Liebherr dozers require little room for turning, are able to vary their travel speed without gears, and can carry out steer movements with both tracks powered. They also counterrotate on the spot. A joystick lever controls all driving and steering functions. In talking with contractors, we noticed that it isn't so much the power of the grading machine that concerns operators; the ability to get around on the site and move in all directions is more of a necessity for fast and accurate completion of the job. The controls play an important role in this, a fact recognized by all manufacturers in their newer designs. Today's controls are easy to use, conveniently placed, and require little effort. Komatsu makes some huge dozers, such as the D575A with its 1,150 hp and a blade capacity of 90 yd.3, but the D155Ax-5 comes at the lower end of the range. "It includes many of the features found throughout the Komatsu dozer line," says Ed Warner, Komatsu's US crawler dozer product manager. "It has a hydrostatic steering system, a dual hydraulic pump system, a resilient equalized undercarriage, proportional pressure controls, and our human-first engineering principles." The dozer operator has received good attention from Komatsu and other manufacturers recognizing that ease and comfort of operation can boost productivity significantly. In the past, the frustrations of discomfort and unresponsive controls caused inefficiency and waste in grading jobs, but almost all the operators of grading equipment we met affirm that today's machines are much easier to run and that their own productivity has increased as a result.
Author's Bio: Paul Hull is a frequent contributor to Forester Media publications.