In Depth: Komatsu’s new generation

When the EPA’s Tier 3 engine emissions requirements came due this year, Komatsu didn’t just drop in new powerplants and tweak the cup holders. It used the opportunity to engineer a new generation of machines, primarily dozers, loaders and excavators, that are more productive, use less fuel and keep operators safer and more comfortable.

Of the 43 new machines recently introduced we selected three – the D155AX-6 SigmaDozer, the PC220LC-8 excavator and the WA600-6 wheel loader – as being most representative of the new technology, and we visited Komatsu’s testing and training facility in Cartersville, Georgia, to try them out.

There we met with three of the company’s product managers and brought along Tony Rye, a veteran equipment technician, to run the machines and give us his feedback. Here’s an in-depth look at what we discovered.

354 horsepower
87,100 pounds
12.3 cubic-yard blade capacity

Save for the blade out front, there’s nothing particularly new about the components used in Komatsu’s SigmaDozer design. Bogies, pivot shafts, torque converters and differential-type steering mechanisms can be found in other types of machines, usually much smaller machines. But the combination of these components, the fact that they’re propelling a 40-ton bulldozer and the way the various systems use a computer “black box” or electronic control module to communicate with each other make for an altogether new and impressive experience from the operator’s seat.

The feeling is akin to stepping out of a rigid frame truck and into a sports car – except this sports car moves mountains. The ride is ultra-smooth (for a dozer) and the tracks stay firmly planted on the ground, boosting efficiency, productivity and fuel savings.

In operating the SigmaDozer, Rye used it to cut down material off a highwall and push it toward an excavator that was loading trucks. The soil coughed up plenty of large rocks, which would normally create a jarring ride, but in this instance proved to be a good test of the undercarriage and suspension. Despite the rocks, there was little lurching and shock transmitted to the cab. “I don’t know of any dozer I’ve operated that was as comfortable,” Rye says. “I didn’t have to strain against the seat belt to keep from coming out of the seat. If I had to make a living in a dozer, this one would be a comfortable choice,” he says.

Rye felt the bogie system added considerably to the smoothness of the ride. “On a rigid mount when you hit a rock, the whole weight of the machine comes down on that roller,” he says. “The bogies keep the load spread out fairly equally.”

The SigmaDozer’s Hydrostatic Steering System is similar to a differential steering mechanism, but with hydraulic power, which gives you infinitely variable power turns and counter-rotation capability. The steering system’s independent hydraulic pump does nothing as long as the dozer is moving in a straight line. “Once you start turning, the pump and motor speed up one track and slow down the other an equal amount,” says Chuck Murawski, product manager for crawler dozers.

While hydrostatic drives have evolved in recent years, becoming viable for larger and larger machines, there is still something reassuring about the metal-to-metal contact of mechanical drive systems, Rye says. The SigmaDozer’s hydrostatic steering, he says, is a great way to get the maneuverability and responsiveness of hydraulic drive with the bulletproof ruggedness of mechanical gears, he says.

Cutting into the high wall provided plenty of blade side loading, which Rye noted, on a conventional dozer would force one track to do most of the work while the other track spun. With the hydraulic steer, each track got as much power as it needed, making it easy to push this unbalanced load in a straight line.

Another way the SigmaDozer maximizes traction is with an automatic shift transmission and automatic torque converter lockup. An onboard computer selects the most efficient transmission gear and shifts up or down automatically. Automatic torque converter lockup gives you the benefits of a torque converter until it’s no longer needed and then takes the torque converter out of operation and reestablishes a direct drive linkage. There is a setting for manual shifting, but the automatic mode frees up the operator to concentrate on the blade and maximizes the efficient use of fuel and power, Murawski says.

“It surprised me, because I’m just not used to it coming on by itself,” Rye says of the torque converter lockup, “but it helped with the traction because it knew when to put the power to the ground.” The tendency operators have when shifting manually, Rye comments, is to wait until they have a maximum load and low rpms before shifting, which wastes power and fuel. “Most operators won’t be able to shift as efficiently as the computer,” he says.

A blade that piles it on
They may look like they were designed with Batman in mind, but the flaring V-shaped “wings” at the edges of the SigmaDozer’s blade aren’t there for style. They help the blade gather and hold more material by rolling soil toward the center and reducing spillage off the sides. The curve of the main section of the blade also lowers digging resistance enabling you to move greater amounts of material than dozers with similar horsepower ratings.

A tuned suspension
On the new K-bogie undercarriage the rollers are set up in three pairs of bogies which float over fairly large variations in the terrain without losing ground contact. An extra bottom roller brings the total length of track on the ground to 10 feet 9 inches. In addition to smoothing out the ride, the bogies reduce stress and wear on the pins and bushings, adding to undercarriage life.

Similar to the suspension on a car, the two sides of the undercarriage move up or down independent of each other. Both tracks are suspended by the equalizer bar that oscillates around a pivot point shaft located on the centerline of the machine.

The ecot3 engines: Tier 3 with a twist
Many of Komatsu’s new models with Tier 3 compliant “ecot3” engines have electronically controlled, hydraulically driven fans. These new fans turn only as fast as needed – the higher the temperature of the coolant and hydraulic oil, the faster the fan rotates. This frees up extra horsepower that would otherwise be wasted turning a fan belt at a constant speed. Plus, hydraulically driven fans can be set up to reverse airflow and blow out dirt and debris clogging the radiators. Noise levels are also decreased since rotational speed is only what is needed to maintain proper operating temperatures.

To improve combustion, the ecot3 engines employ high- pressure, common-rail systems that inject fuel at higher pressures – 26,000 psi versus 20,000 psi on prior designs. With high-precision electronic fuel injectors, clean fuel is mandatory, so Komatsu provides two fuel filters as standard – a 10-micron pre-filter with water separator and a 2-micron final filter.

Aluminum radiators are also a new feature. “We used to have brass tubes with steel fins. Now we’re using aluminum cores for better heat transfer,” Murawski says. On many models, the radiators, hydraulic coolers and the air-to-air aftercoolers are placed in vertical modules side by side to maximize cooling efficiency and provide easier separate access for cleaning and repairs. “In the past, you would have to take them all apart to get to the one in the middle,” Bangert says.

The cab of the future – today
The cabs on all three machines we looked at (and many more present and future Komatsu models) have several design changes.

First, rather than use a separate rollover protective structure, Komatsu builds the frames for some of their new cabs out of heavy-gauge plate and tubular-section steel. Building additional strength into the framework of the cab allows Komatsu to increase the glass area and eliminate posts that obscure visibility. It’s also something the company feels could be mandated in the future.

“What our new excavator cab design does is anticipate what we think OSHA may require in a year or two if they announce that rollover protective structures will be required for excavators,” says Carl Heggen, product manager, hydraulic excavators. “We believe the new cab offered today on the PC200LC-8, PC220LC-8 and PC270LC-8 will meet any future regulation in the United States, or with minimal changes, meet those regulations.”

The cab mounts also have evolved to a design that incorporates oil-filled rubber mounts with internal springs (see illustration). “They are similar to shocks or struts found on automobiles,” Heggen says. The result (in the case of the PC220LC-8) is an in-cab noise reduction from 73 to 70 decibels. “You’re now looking at sound levels comparable to a luxury automobile running down the interstate at 70 mph with the windows up,” he says.

By using all-electronic actuation in place of hydraulic proportional pressure control valves for the joystick and pedal controls, Komatsu’s engineers were able to eliminate a large bundle of hydraulic hoses that used to penetrate the cab floors, Murawski says. Now, there’s just a slender wiring harness and cab pressurization is 50 percent higher, which makes for more efficient climate control and less dust in the cab.

“Getting all the pilot lines out of the cab is a big deal,” Rye says. “You don’t have that 200-degree oil coming in through eight or 10 lines on each side of the seat.” As a technician Rye says he’s often seen cabs where the weight and heat of the hydraulic lines and the dirt buildup over time can cause the seats to jam or become difficult to adjust. “You’re lucky if you get some of them past warranty,” he says. “This will definitely help extend the life of the seats.”

Why test with a technician?
Experienced operators are usually good judges of a machine’s handling and performance. But what about judging the soundness of the design or the long-term costs and value of a machine? We felt a technician with a long history in the earthmoving and heavy equipment business would be best suited to answer these question. That’s why we chose Tony Rye, a career mechanic and technician, to evaluate the machines in this article. Tony started wrenching as a soldier fixing trucks in Vietnam. He has also worked as a mechanic for a GM dealership and as an equipment technician before retiring two years ago. He spends his time doing occasional earthmoving chores for friends and customers and working on (among his other machines) a vintage 1950’s era Allis-Chalmers bulldozer.

527 horsepower
118,385 pounds operating weight
8.4 cubic yard bucket

Like the SigmaDozer, the new wheel loader design, as exemplified by the WA600-6, has a lot of structural changes in addition to the new engine program.

Overall, the machine’s size has increased about 16 percent in weight, which allows the loading of a 70-ton dump truck, one whole class size larger, Bangert says. Eye level for the operator is about 12 inches higher than the previous model and the dump height is likewise higher. “When you dump your load into the truck there is no need to lift the bucket when you back up because you’re that much higher over the truck sides,” he says. “You can see to the center of the truck, hit your target a lot easier and do a better, quicker job of centering the load.”

The bucket geometry and size have been altered. “We paid extra attention to the bucket curvature so the material will roll and fill more easily – same as with the dozer blade – and the standard bucket is now 8.4 cubic yards,” Bangert says. The boom and bucket cylinders were also elevated for better digging geometry and to get them farther away from dirt and debris, Bangert says.

The WA600-6 uses Komatsu’s Advanced Joystick Steering System. “This system has direct tracking of your wrist action, as you move your wrist the front frame follows proportionately,” Bangert says. “When you steer all the way to the left it will start back to the right as soon as you nudge the joystick to the right. You’re not wasting a lot of effort or overcorrecting.”

A steering wheel, however, gives the operator something to hang onto, and to compensate for this, Komatsu designed the seat with adjustable arm rests that cradle the operator in a position that’s secure from jostling and requires low arm effort to manipulate the joystick.

Rye says he had seen a lot of the problems of oversteering that Bangert mentioned in earlier versions of this technology. “It was hard to keep them going in a straight line,” he says. But says Komatsu AJSS worked perfectly – better, with less effort and no less control than a steering wheel. And not having the wheel in front of the operator also helped with the visibility, he adds.

On the WA600-6 Komatsu designed a new powertrain with a large-capacity torque converter that increased the tractive effort 27 percent. To help control the increased tractive effort Komatsu used a modulation clutch similar to the one used in the WA1200-3. “The modulation clutch is a separate clutch pack placed between the engine and the torque converter,” Bangert says. “The clutch pack is a series of disks that will slip to reduce the power that is sent to the torque converter and reduce the tractive effort that is transmitted to the ground. By doing this you reduce the tire slippage.”

Controlling the modulation clutch is done through the variable traction control dial in the cab or through the left foot pedal. Either will change the tractive effort in first gear to prevent the wheels from slipping as you dig into a pile, allowing adjustment from 100 percent to 20 percent. The more you reduce the tractive effort the more the modulation clutch slips, reducing the power that is transmitted to the torque converter.

On his first time out, Rye says it took him about three buckets to get the variable traction control dialed in before he could grab a full bucket. But once he had it set right he was able to heap the bucket every time. Since traction changes from one site to the next, when it rains or when it’s dry, having the ability to change the machine in response is a big step forward, he says. Not only do you get full buckets every time, but you save on tire wear as well by not spinning them. “Some operators are going to spin them anyway,” Rye says. “But with this there’s no excuse. I’d like to see them make the traction control computerized and fully automatic, just like with the dozer,” he says.

The left foot pedal likewise reduces the tractive effort but then goes to a direct brake, Bangert says. Typically the left foot pedal will disconnect the transmission to allow for higher engine speeds to move the work equipment. The left foot pedal only controls the modulation clutch in all gears allowing you to control the machine’s speed when approaching a dump truck or hopper. “That way there is no jerking of the machine when shifting from forward to reverse and no bouncing or hard stops when dumping. Using the left pedal to control the machine’s speed allows for smooth transitions, making the machine more controllable and comfortable for the operator,” he says.

Additional operating finesse comes via the loader’s new Electronic Pilot Control levers for the work equipment and the Remote Position System. These let the operator preset different boom upper and lower kick out positions to match truck heights and other variables. There is also the ability to adjust the bucket return to dig angle from minus 5 degrees to plus 5 degrees. “You don’t have to worry about where that boom’s going to stop, and when you back away from dumping the boom and bucket are going to be in the set position allowing you to concentrate on where you’re going rather than repositioning the work equipment,” Bangert noted.

PC220LC-8 excavator
168 horsepower
54,309 to 54,926 pounds operating weight
0.76 to 1.85 cubic yard bucket

All of Komatsu’s excavators from the PC200 to the PC1250 models have been upgraded this year. The PC220LC-8 has received many improvements, says Heggen, including the new protective cabs with the viscous mounts (see sidebar on page 85).

The PC220LC-8 offers five selectable working modes, allowing the operator to match machine performance to the job at hand. Along with the Tier 3 engine improvements, power mode and economy mode have been tweaked to provide up to 10-percent fuel savings over the prior PC220LC-7, Heggen says. Power mode provides full engine and hydraulic power for production digging but is still easier on fuel than previous models. Economy mode cuts the engine and hydraulics about 15 percent to save on fuel, but still maintains near-P-mode production capacity. “If you’re doing medium- or light-duty work in E-mode, you won’t notice a production difference,” he says.

For lifting and craning concrete pipe and structures, traffic barriers and other heavy objects, there’s the lifting mode. “Lifting mode increases boom circuit pressure by about 7 percent for handling heavy lifting tasks. In addition, engine speed is reduced to slow attachment speed, providing increased control in craning applications,” Heggen says.

And there are breaker and attachment modes that allow the operator to dial in the flow needed for a particular attachment from the cab and save that setting for use later. “In the past, if you had a breaker with one hydraulic flow requirement and several other attachments with different flow needs, you were constantly shimming valve spools and opening your hydraulic system up to dirt and contamination,” Heggen says. “Now, with our breaker and attachment modes, the operator or service technician can go directly to the in-cab monitor panel, set the flow you want and save as ‘breaker number one.’ Once you’ve set it, you can install breaker number one months later and adjust the flow with a few keystrokes. Flow settings can be secured with password protection. It’s a huge time and cost savings for guys who use a lot of attachments and change them often.”

An automatic air conditioner/heater/defroster allows the operator to set cab temperature at a preset level and the system maintains that exact temperature all day.