Pushing forward

Rethinking dozer power systems yields higher efficiency, lower emissions

Dozers Article October 31, 2001
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The bulldozer market is almost holding steady through the economic slowdown of this year, according to two of the major partici


The bulldozer market is almost holding steady through the economic slowdown of this year, according to two of the major participants.


Caterpillar Inc., for one, expected this year to be worse than last year and tried to prepare. The result is that Cat has not had any layoffs, Tim Lemons, Cat’s sales and marketing consultant for heavy industries, told ROADS & BRIDGES. Lemons said the company has avoided the problem of excess inventory that some other U.S. manufacturers have suffered from.


"I would say that we have been doing a very diligent job of managing our inventory to meet the demand," Lemons said. "We work extremely well with our distribution system, which is our dealers, in trying to make sure that we have an adequate amount of equipment to meet all the sales requirements and conversely not have them stacked up with too much inventory so there’s more because of the cost associated with that."


Ed Warner, dozer product manager for Komatsu, told ROADS & BRIDGES, "Our sales have remained about equal to last year. Our sales have slowed down a little bit but not to the degree that the market is down."


Warner said the main factor at work in the dozer market was the downturn in the general economy, but he thought that the rise of independent equipment rental houses also contributed: "I think that two or three years ago, when third-party rental companies built up a big rental fleet, they actually over-inventoried. Now they have brought in some management people who realize that they need to restructure the way that they’re running their business and maybe instead of 50 dozers or 50 excavators or whatever in inventory they only need 20."


Caterpillar and Komatsu have both recently done some major redesigning of their dozers.


Peoria, Ill.-based Caterpillar introduced the D8R Series II in January. The 310-hp machine features a brand new electronically monitored and controlled engine instead of the previous mechanical engine. The result is an increase in efficiency, measured in cubic yards of material moved per gallon of fuel burned.


"On the D8, this has been about a 15% improvement [in efficiency] with the Series II over the old D8," Rick Watts told ROADS & BRIDGES. Watts is senior marketing representative for the track-type tractors division of Caterpillar, with responsibility for the D6R, D7R and D8R dozers. "Fuel consumption actually dropped close to 11% with the electronic engine of the Series II versus the mechanical of the old D8R. And that was with a 5 hp increase."


"The big thing with electronics is you can inject the fuel at the right time, depending on the rpm," explained Bill Nordsiek, senior project engineer of performance applications for the D6 and D11 dozers. "With the old mechanical system it was set at a certain ratio. They can figure out exactly when to inject that fuel and how much."


The new electronic engine also operates under higher fuel injection pressure, which atomizes the fuel into finer particles. The fuel burns more cleanly and completely, and less soot and other residue goes out the exhaust and into the oil system, so the interval for changing the oil in the D8R has gone from 250 hr to 500 hr.


The D8R Series II now meets Tier II exhaust emission standards and also the demanding European sound regulations. Cab sound levels have been reduced to 79 dB.


The D8R Series II has an operating weight of 83,500 lb and a 310-hp engine. It is available with a semi-universal or a universal blade.


Another recent introduction from Cat is the D6R XW, which stands for "extra wide." The track gauge of the XW is intermediate between that of the XL and the low ground pressure (LGP) versions. The XW was originally developed as a custom product but was so popular that Cat made it a standard feature.


Watts stated: "So many of the customers were moving all the way up to an LGP tractor to get into some softer underfoot conditions—to start a little earlier in the year and work a little later in the year—when they truly didn’t need the full benefits of an LGP and the value really wasn’t there for the customer."


The D6R XW uses the D6R XL as a base and widens the track gauge from 74 in. to 80 in. The 8% wider gauge allows using wider track shoes to reduce ground pressure and boost flotation.


To your dozer, stat!


It may sound like the name of a business convention or a military preparedness condition, but Komstat is really the name of the new dozer technology from Komatsu America International Co., Vernon Hills, Ill. The D39 was the first Komstat model to be introduced in spring of this year, available in the D39EX-21 and the D39PX-21 versions.


"Komstat" stands for the "Komatsu hydrostatic" system redesigned from the ground up. It combines Komatsu’s electronics and hydraulics into an operator-friendly dozer with three distinct gear ranges.


With Komstat, power is distributed to the tracks independently for easy turning. The outside track moves faster, and the inside track moves slower. The minimum turning radius is 11 ft 6 in. for the EX version and 12 ft 2 in. for the PX version.


The EX machine has a weight of 18,191 lb; the PX has a weight of 19,030 lb. Both machines are powered by a 95-hp Komatsu engine. They carry blades with capacities of 2.52 cu yd (EX) and 2.69 cu yd (PX).


The EX is available with a standard-length undercarriage, while the PX features a longer, wider undercarriage for improved flotation and lower ground pressure for increased versatility. The track gauge is 65 in. for the EX and 70 in. for the PX.


More power, new name


Power and productivity features abound on the latest dozer from John Deere, and the division has a new name. John Deere Construction Equipment Co. is now known as John Deere Construction & Forestry Co., but it is still headquartered in Moline, Ill. The new name reflects the division’s increased status in the forestry harvesting equipment industry after its acquisition last year of Timberjack, a leading forestry equipment maker.


The new dozer, the 1050C, is Deere’s most powerful dozer ever at 324 hp. The 1050C is driven by a single-lever-controlled hydrostatic transmission that delivers power turns, counterrotation and automatic load sensing.


The operator in the 1050C has independent control of each track: during a turn, the inside track slows down while the speed of the outside track remains constant. An electronic system called AutoTrac monitors the speed of the independently driven final drives. If they are not operating at the same speed, AutoTrac makes adjustments to maintain straight tracking in forward or reverse and minimizes the need for steering corrections.


Advanced technology


The latest bulldozers from New Holland Construction, Carol Stream, Ill., combine advanced technology with operator comfort and ease of servicing, according to the company.


The engine in both the 140-hp DC150 and the 180-hp DC180 is matched to a torque converter and powershift transmission featuring automatic kick-down and automatic shifting to speed the loading and return cycles.


The DC150 has an operating weight of 32,090 lb and a blade capacity of 4.12 cu yd with a standard VPAT (six-way) blade. The DC180 has an operating weight of 44,500 lb and a blade capacity of 7.35 cu yd with a standard semi-U blade.


Quiet running


Brand new earmuffs—of a sort—have been installed on the PR 752 Litronic crawler dozer from Liebherr Construction Equipment Co., Newport News, Va. In order to obtain the lowest noise levels in the operator’s cab, sound protection measures were undertaken from the design stage. They resulted in noise levels of 80 dB at the operator’s ear, making the machine into what Liebherr called a "silent tractor."


The PR 752 is the most muscular of Liebherr’s crawler dozer offerings, sporting a turbocharged, intercooled Liebherr diesel engine that generates 330 hp.


Little powerhouse


The C85D Mini Crawler from Rayco Manufacturing Inc., Wooster, Ohio, is designed to work in areas not accessible to ordinary machines. Rayco equipped the C85D Mini Crawler with an 83-hp engine, an 80-in.-wide blade with six-way movement, joystick controls and cab-forward design in an 82,000-lb package.


The Mini Crawler can be transported on most trailers behind a 3/4-ton pickup.


The case for redesign


The latest dozers from Case Corp., Racine, Wis., are the H Series, a group of five machines introduced in the summer of 2000. They range from 67 to 119 hp, and feature a redesigned transmission and Case’s exclusive PowerTurn system. PowerTurn provides full power to either track during a turn.


Case made significant modifications to previous models to arrive at the H Series. One modification that came out of customer evaluations was a narrower dashboard and a sloped hood to give a better view of the blade.


Other modifications include a quieter cab and lower control lever effort.


An "L" of a dozer


The DD80(L) dozer was introduced in September 1999 by Daewoo Heavy Industries Corp., Suwanee, Ga. It incorporates many features designed to improve performance over the previous model. The 90-hp dozer weighs in at 17,000 lb in a package 13 ft 8 in. long and 8 ft 10 in. wide including the blade.


To ensure efficient performance and smooth operation, an electronic control system adjusts the variable-displacement hydraulic pump and motors that drive the DD80(L) to produce the ideal speed and horsepower output for the working conditions.


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