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Dozers go hydrostatic.

By Daniel C. Brown

If you think a dozer is a dozer and they don’t change, think again. For one thing, North American dozers are making a decided shift to hydrostatic drive systems.

Recently, Caterpillar, Case, and Komatsu all have introduced new hydrostatic models. John Deere has sold hydrostatic dozers for 30-plus years, and today all of its models, from the 70-horsepower 450J up through the 335-horsepower 1050J, are hydrostatic machines.

Hydrostatic drive trains typically operate with dual hydraulic pump-and-motor sets that use one set to power each track independently. For example, Deere’s 1050J has two drive pumps and four drive motors that deliver power to the ground. Two drive motors are dedicated to each final drive, resulting in more steering power and more than 116,000 pounds of drawbar pull. Maneuverability is excellent: You can counter-rotate the tracks in power turns, and speeds are infinitely variable. There’s much less concern about shifting gears or being limited by the speeds you get in first, second, or third gear.
In February 2007, Caterpillar introduced the D6K, which comes standard with a hydrostatic drive train. Cat says hydrostatic drive on the D6K provides infinite speed selection from 0 to 6.2 miles per hour in forward and reverse.

And in June of last year, Komatsu introduced the D51EX-22 and D51PX-22 dozers—both 130-horsepower midsized models with Tier 3 engines. Both have hydrostatic drive systems with either variable or quick-shift speed control to help operators change speeds in fine- or rough-grading operations. Switching modes is as simple as pushing a button. When the variable speed selection is selected, travel speed is adjustable through a 20-increment speed range. Travel speed is controlled by using the shift buttons on the palm-command control system located on a joystick. The quick-shift speed selection enables the operator to select three predetermined speed settings to match job conditions.

Super Slant Nose
But Komatsu’s most visible change in this dozer is the new super slant nose coupled with a cab-forward design. “We slid the cab to the middle of the machine,” says Les Scott, senior product manager at Komatsu. “We took the radiator, oil cooler, and charge-air cooler, and put them in the rear of the machine. The engine is still in front.

“We were able to slant the hood dramatically downward, and the end result is the operator can completely see the back of the blade,” says Scott. “And he can see over the top of the blade. A novice operator can see ahead of the blade and be ready to react to a hill or bump ahead of the dozer. And a good operator can be exceptionally good. He can doze and final grade faster and be more productive with the machine.”

What’s more, Komatsu plans to broaden the cab-forward design to its D31, D37, and D39-sized machines being introduced during the first quarter of 2008.

In October 2006, Case introduced its new 118-horsepower 1150K Crawler Dozer with a hydrostatic transmission, a new cab design, a low-effort electronic blade control and high-performance hydraulics for blade speed, superior blade force and precise control. Case says the hydrostatic drive is the key to productivity on the 1150K dozer. Case components, the company says, are designed for the high horsepower needed to push the fullest blades, thus reducing the number of passes needed to move the material.

Earlier, Case introduced the 650K, the 750K, and the 850K—all with hydrostatic drive systems and single- lever control for optimum maneuverability and easy operation. The three models deliver from 75- to 96-net horsepower and have blade capacities ranging from 2.0 to 2.73 cubic yards. The hydrostatic pumps and motors were made larger on the 650K, 750K, and 850K to provide more power to each track. The cab is isolation-mounted to the frame to reduce vibration and provide smooth operation.
Case plans to move at least one larger dozer to hydrostatic drive. In late 2007, the company plans to install hydrostatic drive in its 140-horsepower-class 1650L model. Plus, Case will introduce Tier 3 engines in its 750L and 850L models in January 2008, says Jim Hughes, brand marketing manager for Case Construction Equipment.

On the four hydrostatic models—the 650K, 750K, 850K, and 1150K units—Case offers three speed modes—slow, normal, and fast travel speeds. That change will also occur on the 1650L. With the hydrostatic transmissions, one can do full-blade, full-power turns without raising the blade, says Hughes.

Hughes says the 1150K has a Tier 3–compliant engine with a common rail fuel injection system that supplies all cylinders equally with fuel for optimum firing and timing. Like all other Case K Series crawlers, the 1150K now has a tilting cab for easy serviceability.

GPS-Ready
The D6K, Caterpillar says, has been designed from the ground up to optimize performance through the use of Global Positioning System (GPS) grade controls. Every D6K is equipped standard with the electro-hydraulic control system, which eliminates the need to plumb an additional hydraulic control system to provide automatic blade-control capability. Cat AccuGrade technology is integrated into the machine to allow for simple and quick installations of the GPS and laser-based components.

Photo: Caterpillar

AccuGrade technology assists this Caterpillar dozer with its grading.

Cat says the AccuGrade Ready Option (ARO) provides true plug-and-play capability. The ARO also includes a control module for power masts for laser systems, robust electrical connections for the GPS or laser receivers, and a blade angle sensor. Machines equipped with the ARO have the most current GPS and Laser displays integrated into the dash panel. The display panel is hinged, allowing easy access to the electrical connector for the display and easy removal of the display without tools.

D6K machines, Caterpillar says, are compatible with AccuGrade Laser—single or dual 2D elevation control and AccuGrade GPS—single or dual 3D elevation control systems. The two-dimensional grade control systems are ideal for fine-grading of sites with flat surfaces, single slopes, and dual slopes, such as building pads and parking lots. The three-dimensional systems are ideal for complex 3D designs such as golf courses and roads with super-elevations (banked curves).

Deere offers similar GPS readiness. “We have an integrated grade control option on all dozers up through the 850J,” says Dan Drescher, product marketing manager. “By that we mean we have plug-and-play capability for both Trimble and Topcon systems. Either the John Deere dealer or the Trimble or Topcon distributor can mount their systems on our dozers in a matter of an hour or less.”

Drescher says without the plug-and-play option, GPS installation is a very involved process and would take a mechanic 12 to 18 hours to do.

Deere’s plug-and-play includes all the necessary internal wiring, the hydraulic valve, and mounting brackets for the monitor and sensors. “This is a factory option, and it carries a factory warranty,” says Drescher. “We can facilitate systems other than Trimble or Topcon, but not at the plug-and-play level.”

A Change at Komatsu
Les Scott says Komatsu has partnered with Topcon to offer a purpose-built hydraulic kit for a GPS system on its dozers. “Our system adopts the Topcon automated control system that controls the blade’s raise, lower, and tilt functions,” says Scott.

Komatsu realizes, however, that many customers have Trimble systems, and Trimble is not compatible with Topcon. “So we’re heading in the direction of having a dozer that is GPS-ready for either a Topcon or Trimble system,” says Scott. “We’ll provide the weldments and knockouts needed for either system. We’ll sell a Trimble or a Topcon kit. Scott says that change will occur early in 2008 on Komatsu’s D51 and D65 dozers.”

Operator Comfort
Caterpillar dozer officials say the D6K features seat-mounted electro-hydraulic controls. By mounting the controls to the seat, each control joystick (steering and implement) can be positioned independently fore and aft, and height-adjustable armrests provide a stable platform for operating the controls. The operator is now able to adjust the seat position without affecting the position of the controls. This arrangement provides an optimum seating position, with all controls falling readily at a hand or a foot.

Photo: John Deere

A joystick offers ease of operation and precise maneuverability for this operator.

The seat-mounted controls on the D6K provide optimum operator positioning for both foot- and hand-operated controls. The decelerator pedal has been combined with the brake pedal. And the operator can choose either engine or hydrostatic dynamic deceleration capability for precise control of travel speed and direction changes.

The D6K engine has been designed for quiet operation, and features several advances in sound reduction technology. The result is an engine that produces more horsepower with significantly reduced sound levels, says Caterpillar.

At Komatsu, Scott says, dozer cabs are attached to the frame with viscous mounts that act as little shock absorbers. The viscous cab mount is a small container with a spring and silicon oil inside. The viscous mounts, says Scott, provide very low noise levels in the cab and a very comfortable ride. In addition, Komatsu has air-suspension seats available as an option.

Komatsu’s ROPS (rollover protection system) cab structure is integrated into the cab, so that the operator does not have 6-inch posts to his right and left. The cab is solid glass around the front for improved visibility. Komatsu’s new dozers have a 7-inch color monitor to display various gauges and the operating condition of the machine, such as what gear the operator is using. “They’re easy to read at a glance,” says Scott. “You can make one gauge larger than another if you want to; we have pre-sets on our shift lever, and it tells you which one of those you’re using.”

Deere’s new 1050J crawler dozer features large access doors with easy entry and exit, a 15-degree angled seat, large adjustable armrests, standard leg cushions, suspended style decelerator, two footrests, and left and rear windows that open to keep the operator comfortable all day long. The Speed-in-Grip control lever features a shorter height and throw, which makes steering and forward/reverse travel even more intuitive and low effort. Speed selection is performed with an in-grip rocker switch, similar to other J-Series dozers. The dozer control lever also features shorter height and throw, with a button for optional blade pitch. A new front console mounted monitor system with backlit gauges and a high visibility screen provides visual and audible alerts to keep the operator well-informed of the machine’s operating status. Visibility to the blade is excellent.

Photo: Komatsu

Komatsu’s 130-horsepower D51EX features a hydrostatic drive train.

Deere says the 1050J is powered by a new, Tier 3–certified, 12-liter, six-cylinder engine with a wet sleeve design that provides 335 net horsepower at 1,600 rpm. The slow engine speed means longer engine life, low fuel consumption and extremely low noise levels. A deep oil pan assures full pressure lubrication on steep slopes. All essential maintenance points are grouped together on the right side of the engine, accessible through a hinged lockable door.

The Deere 1050J’s ease of operation and precise maneuverability are the direct result of its hydrostatic drive train, which is controlled by a single joystick. The drive train allows the dozer to deliver power turns under load, infinite speed control, power management, counter-rotation, dynamic braking and other productivity-boosting advantages. Maximum ground speed is controlled by a simple switch, and all available power is applied, regardless of the speed setting. Charge air cooling delivers greater power and longer component life. A five-fin-per-inch, heavy-duty radiator resists plugging and cleans easily, while the hydraulically driven fan reduces wear and adjustment of the drive belts.

Cat’s D6T
In addition to the D6K, Caterpillar also offers a D6T, which was introduced in February 2007 and has a planetary power-shift transmission. The company says the D6T offers superior maneuverability through the use of separate hydraulic pumps to supply power to steering and implements. The D6T also offers the Multi-Velocity Program, an innovative machine control system that provides the operator a selection of five speed ranges and automated speed control for productive performance in varying conditions.

Cat says the D6T powers the steering system with one hydraulic pump and the implement circuit with another pump. The result is quick and powerful steering performance that is independent of implement operation. The system also enhances blade response when using a machine control and guidance system.

The D6T retains the C9 engine with ACERT technology to meet exhaust emission standards, differential steering system, System One undercarriage, and the Accu-Grade grade control system. Cat says the System One undercarriage system has a cartridge that is factory assembled and sealed for life. This undercarriage system has proven to outperform sealed and lubricated track and heavy-duty track across a wide range of applications and operating conditions, says Caterpillar.

The D6T continues to be offered with several different undercarriage options for matching the machine to the job. The engine delivers 185 horsepower at the flywheel with standard undercarriage. For longer and wider undercarriages, the C9 engine delivers 200 horsepower.

Komatsu’s Komtrax Technology
As standard equipment on all of its Tier 3–compliant dozers, Komatsu offers its Komtrax system, which uses wireless technology to send machine operating information to a secure Web site. Data such as operating hours, location, cautions and maintenance alerts are relayed to the web application for analysis. The Komtrax fleet-monitoring system increases machine availability, reduces the risk of machine theft, allows for remote monitoring, and provides a wealth of other information to drive business productively.

“We provide five years of free connectivity,” says Komatsu’s Scott. When a customer enters the Komtrax Web site he can see his own machines. This will be standard on the D31, D37, and D39 machines when the Tier 3 models are introduced.

The dealer can tell if any machine experienced an error code the previous day, Scott continues. A dealer could know about a problem before the customer does. Most people use it for maintenance items, like when the next oil change is due and so forth. And now on the D155 you can use the Komtrax to tell actual fuel consumption. So it’s a way of managing your fleet without having the operator scribbling down some information on a piece of paper.

If you’re in the market for a dozer or two, check out some of these models at your local dealer. Especially if you’ve never experienced hydrostatic drive, ask for a demonstration of one. They’re productive machines, and easy to operate. In fact, never before has dozer operating been this enjoyable.

Daniel C. Brown owns TechniComm, a communications business.

GEC - February 2008

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