The model lineup for most manufacturers with a broad range of crawler dozers includes a “mid-range” of machines having horsepower ratings from around 130 to the mid-200s, with next smaller models usually dropping down to 100 horsepower or so, and the next largest models generally topping 300 horsepower. This mid-range category is arbitrary, of course, but it does represent the bulk of industry sales, the widest diversity of application potential, and probably more than its share of innovation, especially in drive-train and grade-control technology.
Surveying the market
Caterpillar’s Dave Cusac, global product application specialist for track-type tractors, identifies what many manufacturers consider the best-selling segment of the mid-range:
“Although some manufacturers might consider the mid-range classification to include models from 130 to more than 300 horsepower, the highest volume of machines in this category is in the 150 to 215 horsepower range.”
Cost of Ownership
Size class (hp) Avg. purchase price Hourly rate* 105-129 $188,948 $77.29 130-159 $251,093 $92.91 160-189 $306,362 $109.53 190-259 $445,124 $148.43 260-359 $614,593 $203.72 *Hourly rate represents the monthly ownership costs divided by 176, plus operating cost. Unit prices used in this calculation: diesel fuel, $3.98 per gallon; mechanic’s wage, $49.8 per hour; and money costs, 2.125 percent.
Source: EquipmentWatch.com
Mid-range models are the workhorses of the crawler dozer fleet, and given their varied capabilities, these machines are placed in a diversity of applications. John Bauer, brand marketing manager, Case Construction Equipment, uses the company’s three-model mid-range line to illustrate the capabilities of these tractor sizes:
“Machines the size of the 127-horsepower 1150M work extensively in nonresidential—road and bridge construction, for example—but also crossover into residential building. For machines with around 150-horsepower, such as the 1650M, nonresidential, roads and bridges are still important markets, but you begin to see expansion into larger jobs—oil and gas development and land clearing, for instance. Larger models, such as the 214-horsepower 2050M, cover those markets, but also see use in aggregate and mining operations, overburden clearing, and pushing material to wheel loaders and excavators.”
Liebherr’s Robert Klima, product manager crawler tractors, would classify “mid-range” a bit more narrowly, as models with 115 to 205 horsepower, but says that machines in this range still see a wide scope of work, ranging from standard earthmoving to coal, woodchip and landfill applications.
Mark Oliver, product marketing manager for crawler dozers, John Deere Construction & Forestry, adds that tractors in the John Deere 850K class (187 or 205 horsepower depending on blade type) are developing a market niche based on application versatility.
“This size has found a sweet spot in the market,” says Oliver, “because users have discovered that these models typically are available with the most track configurations and most blade configurations. It’s probably the most flexible machine out there in today’s market.”
Although most buyers are savvy about what they need in a crawler dozer, says Anthony Lovero, product marketing manager, dozers, for Komatsu America, a review of the basics is always beneficial:
“Most of the time, customers know what size machine they need,” says Lovero. “If they’re looking for advice, though, it always comes down to this basic question: In what application will the machine spend most of its time? Once the customer identifies that key issue, then we as a manufacturer can give guidance about optimum horsepower, track configuration and blade configuration.”
John Deere’s Oliver adds that “buyers are definitely becoming more aware of the economics of matching machines to their most common job types. It’s a matter of deciding where the purchased machine will get the best utilization and where it makes sense to rent.”
Case’s Bauer reminds buyers, however, that when the dozer is working with other machines in a material-flow process, careful attention to machine size is essential:
“The dozer often works upstream of other processes, so matching it to other equipment is critical,” says Bauer. “For instance, if a dozer is pushing material to a wheel loader, you don’t want it undersized and leaving the loader idling and trucks or hoppers waiting.”
Buying a crawler dozer that is right for a particular operation also involves considering transportability of larger machines in terms of weight and width restrictions, says Liebherr’s Klima. One way manufacturers assist buyers in this regard is by offering “foldable” power angle/tilt (PAT) blades that have pivoting end sections that reduce overall blade width.
And, says John Deere’s Oliver, the person in the seat dare not be forgotten: “Operators still have a lot of influence over dozer purchases,” he says. “Given the long experience and expertise of most dozer operators, owners want to be sure that operators are going to be happy.”
Drive-train configurations
Drive-train philosophies differ among mid-range-dozer manufacturers. John Deere, Liebherr, and Case, with its new M Series models, use dual-path hydrostatic drive systems for all models, employing a separate hydraulic pump and motor for each side of the tractor. Benefits cited include eliminating the torque converter and power-shift transmission, infinitely variable speeds, fast response to changes in load, and maintaining power to both tracks during turns of any degree.
Komatsu uses dual-path hydrostatic drive in its 130-horsepower D51 and 168-horsepower D61, but employs the company’s planetary power-shift Torqflow transmission and a hydrostatic steering system in the larger D65 and D85, having 205 and 264 horsepower, respectively. The planetary steering system in the larger tractors has a separate hydraulic pump/motor control system to provide variable-radius, full-power turns.
Caterpillar uses a hydrostatic system for its 130-horsepower D6K2 and a mechanical drive train for the 150-horsepower D6N and 207-horsepower D6T. A “torque divider” sends power to a planetary power-shift transmission by splitting input 70 percent through a converter and 30 percent through a direct-drive shaft. The design, says Caterpillar, results in “greater driveline efficiency and higher torque multiplication.” A joystick-controlled differential steering system allows full power to both tracks during turns.
The Cat D7E, on the other hand, uses a 235-horsepower diesel to drive an electrical generator that sends electrical power to an inverter and then to the tractor’s propulsion module, which houses two large electric motors, geared together, that drive a conventional differential steering system. Smooth, step-less power and significant fuel savings result, says Caterpillar.
The Dressta TD-14M, TD-15M and TD-20M, with 160-, 190- and 240-horsepower Cummins engines, respectively, have a 3F/3R countershaft power-shift transmission and a modular two-speed steering system with planetary gear sets controlled by multi-disc hydraulic brake packs. The three-speed transmission working through the two-speed steering system provides six speeds forward and reverse for greater control of speed/torque requirements, says the company, and the steering system’s ability to effect a 30-percent speed differential between the tracks allows for gradual, full-power turns.
Blades and undercarriage
Although not universally true, most dozers at the lower end of the mid-range category are fitted with inside-mounted PAT blades, while larger machines generally use outside-mounted straight and semi-U blades, some with proprietary designs aimed at improving the way the blade accumulates and carries the load. In the interest of expanded versatility, however, the PAT blade is now more frequently being offered on larger models.
“Several years ago, Komatsu made a PAT blade available for the D65,” says the company’s Lovero, “which means customers can use it for both mass excavating and fine grading—versatility that was not available in the past. At the end of the day, machine users must weigh productivity against overall versatility and the possibility of needing fewer dozers on site.”
(The PAT blade usually is mounted with a “C” frame secured under the tractor and having a front trunnion that allows the blade to angle and tilt hydraulically. Semi-U and straight blades are connected to the tractor with push beams secured with trunnion mountings to the outside of the track frames.)
“The PAT blade gives added ability to get a fine grade, because there’s more control of blade position,” says John Deere’s Oliver. “An outside mount somewhat restricts blade movement when grading.”
Blade types often are paired with specific undercarriage designs, which can vary in gauge (the width between track-chain centers) and length, depending on the primary application of the machine. Generally, too, a wide selection of track shoes is available to match the undercarriage to the machine’s typical operating situations, whether to provide high flotation in soft underfoot conditions, optimum performance in high-impact or rocky conditions, or to work efficiently in materials that tend to pack, such as mud, snow or extremely sandy soil.
Most dozers leave the factory with sealed-and-lubricated track chains that maintain lubrication between pins and bushings to retard internal wear. As long as seals remain viable, these systems work well. Premium undercarriages available from some manufacturers are designed, essentially, to address external wear on the bushing, basically by either allowing the bushing to rotate as it engages the sprocket (reducing sliding action between the two) or by using special hardened bushings—or both.
The consensus of opinion seems to be that these premium undercarriages are most effective when the tractor works consistently in highly abrasive conditions and that a careful cost/benefit analysis is in order before choosing an optional system over a standard configuration.
Telematics and machine control
“The customer’s appetite for technology is going through an evolutionary phase,” says Caterpillar’s Cusac. “What this means is that now more than ever customers are realizing the value in fleet-management features and automated machine-control systems.”
Standard on many mid-range dozers are telematics systems that remotely report machine location, fault codes and operating parameters—often including fuel use, machine hours, working versus idling time, and in some instances, forward versus reverse travel, which might be important for crawler dozer owners wanting to reduce undercarriage wear by limiting reverse travel. This data typically is available through the manufacture’s secure website.
“Telematics systems provide considerable benefit for all types of contractors,” says Case’s Bauer, “including idle-time reduction, improved maintenance through remote monitoring, improved equipment utilization, and improved equipment security.”
John Deere’s Oliver offers an observation about buyer reaction to innovative features available with today’s dozers: “Any time technology is involved, there’s a pattern to acceptance, with ‘early adopters’ buying in with little hesitation, and then the rest of the market catching up. The industry is, however, starting to see automated grade control becoming more important to buyers of crawler dozers.”
Komatsu’s Lovero is of like opinion: “There might be some customers who are hesitant to adopt new technology, and others who simply don’t like electronics. Machine control, however, has been around for some time now, and it’s becoming increasingly difficult for machine buyers to look past the benefits and relatively short payback periods on the investment in this technology.”
