It's been a quiet year for the rigid-body, quarry-class haul truck sector — but not without a few interesting developments from major suppliers Caterpillar, Komatsu and Terex. However, most OEM activity has been concentrated at either end of the truck-size spectrum, with new models of articulated dump trucks (ADTs) up to 50-ton capacity introduced to the market, accompanied by technological innovations in the larger, mining-class, rigid-truck category that could possibly filter down to the mid-sized and smaller truck ranges in the not-so-distant future.

Articulated Answers for Heavier Hauling

• John Deere's 250D, 300D, 350D and 400D ADTs have been enhanced to increase productivity and uptime, including updates to the transmission, operator station improvements, electrical enhancements and a new engine in the 250D and 300D.

  The 350D and 400D ADTs are powered by a turbocharged and intercooled Mercedes Benz OM501LA 12-liter V6 diesel that meets EPA Tier-3 emissions standards. According to the company, the compact engine allows these trucks to offer a best-in-class approach angle. The 250D and 300D also feature a Tier 3-certified diesel, in this case a 24-valve John Deere 6090 PowerTech Plus I6. Engine displacement has increased from 8.1 to 9 liters. The transmission, updated in all four models, offers improved shift quality and clutch control. The 250D and 300D cooling system also provides greater transmission cooling capacity.

  Cab features include a fully adjustable air-suspension seat, more sound insulation and a high-capacity air conditioner. A new monitor provides increased diagnostic capability, and a new sealed switch module with centralized controls eliminates several rocker switches, a retarder lever and mechanical heating and ventilation controls. A relocated electrical center provides easy access to fuses, relays and controllers. Only four relays remain in the electrical center.

  A driveline assist feature automates some repetitive tasks during dumping. It shifts the transmission to neutral, applies the parking brake and takes the engine to maximum speed when the dump body lever is in the full dump position. Once the maximum dump angle is reached, the engine returns to low idle travel.

  A new electrohydraulic tip control allows the operator to set maximum dump-body tip height and specify either soft or hard stops at the end of dump-body travel. According to a Deere spokesman, “Sticky material applications may require mechanical hard stops to minimize carry-back, but for other applications that don't require hard stops, the electrohydraulically controlled soft stop reduces machine structural loads and improves operator comfort.”

  

• Volvo CE, which claims top spot in the rankings of ADT suppliers, introduced a series of ADTs at bauma 2007, starting with its top-of-the-line A35E and A40E, both of which are now available with full suspension (FS) and automatic leveling. The A40E will be powered by Volvo's 16-liter engine with 12% more power (rated at 470 hp) and 19% more torque than its predecessor. The A35E uses Volvo's 12-liter engine. Volvo CE also will sell any E-series models without the full-suspension option; the company will offer the FS option only on its two largest models until it gauges market demand for the feature on the smaller E-Series ADTs. Overall, the seven models in the series offer capacities from 25 to 40 metric tons.

  The A35E, A35E FS, A40E and A40E FS all feature a new, fully automatic, nine-speed adaptive transmission. According to the company, driveline shafts, planetary gears and bearings have been reinforced to cope with the higher torque produced by the larger engines. An optimized gear shifting pattern offers better overlap of ratios to give constant power transfer. These models also have new frames, axles and a new drop box with longitudinal differential and 100% lockup to reduce power loss and improve traction and fuel efficiency. The larger models are fitted with more powerful exhaust brakes and retarders. Volvo says the cooling system has been improved to the point where extra cooling capacity is not required in hot climates.

  The trucks' FS designation refers to the installation of hydraulic cylinders at all wheel positions, replacing conventional rubber bushings. The FS system continually monitors the truck load and ground conditions and adjusts the suspension to suit prevailing conditions. Volvo CE claims the system allows a fully loaded truck to travel at speeds up to 35 mph while “floating” over rough surfaces, thus reducing stress on components and allowing operators to work much longer without being fatigued by vibration and jostling.

  The A35E will feature new wet disc brakes for better stopping power, and the A40E is fitted with a new body designed for easier loading and more efficient dumping into hoppers or over berms. Options for both the FS-equipped and conventional models include a bolt-on light-materials kit that increases truck body volume when hauling low-density materials; over- and under-hung tailgate options; and heavy-duty wear plates.

  For the time being, Volvo CE seems content to concede the 50-ton-payload ADT class to Moxy. As the company indicated during bauma, 50-ton trucks are most properly matched with 100-ton-class excavators, and Volvo CE's largest current model is the 70-ton EC700B LC. However, Volvo CE President Tony Helsham said that the company is not opposed to building larger hydraulic excavators, but did not offer any timeline for development and introduction of bigger units.



• Komatsu's newest ADT model is the HM400-2, featuring a hydropneumatic front and rear suspension, two-stage lift cylinders, wet multi-disc brakes, speed retarder and a maintenance-free oscillating hitch. Its 438-hp SAA6D140E-5 turbocharged, after-cooled diesel engine meets EPA Tier 3-emission regulations. The truck body has a heaped capacity of 29.2 cubic yards and a loading height of 9 feet 9 inches.

  For convenient maintenance, the HM400-2 is designed with fewer grease points — made possible by incorporating more rubber bushings — along with easier access to filters and longer intervals between oil changes. The cab can be tilted 32 degrees rearward to allow easier access when servicing the engine and transmission.



• Terex Equipment's TA27 ADT now features a Tier 3-compliant Cummins QSM-series diesel rated at 365 gross hp and 1,234 feet-pounds of torque, driving an automatic transmission with manual over-ride and rotational pressure compensation (RPC) for smoother, faster shifting. The TA27 also has automatic slip differentials in each axle for superior traction. Filtering and grease points are centrally located from the ground for quick and easy servicing. The tilt-up cab provides easy access to the transmission and other components. The operator's cab employs flat glass sections for inexpensive replacement and less distortion.

  Capable of carrying 15.5 cubic meters of heaped material, the TA27's dump body is designed with a dual-sloped tail chute and tapered side rails for quick material ejection. With a maximum payload of 25 tons, the truck weighs 48,280 pounds.

Rigid Haulers Upgraded

• Caterpillar's 770 and 772F rigid-body haul trucks are designed for applications in the 40-ton and 50-ton payload classes, respectively. Introduction of these units, both of which feature a new engine and radiator, enhanced transmission and brakes, and a new cab and operator station, allows Cat to discontinue its existing 769 and 771 models.

  The 770 is powered by Cat's C15 engine, which produces 476 net hp; while the 772F has a C18 engine rated at 535 net hp. According to the company, both engines meet EPA Tier-3 and EU Stage-IIIa requirements and deliver improved fuel economy compared with the previous engine used in this size class. Engine service interval for each truck is 500 hours — twice that of previous truck models. Cat's QuickEvac on-board engine oil evacuation and pre-lube system, now standard equipment on these trucks, reduces oil-change labor time by 50%.

  On both models, a seven-speed power-shift transmission is integrated with new transmission chassis-control electronics for improved performance, while a new differential design reportedly extends durability. Automatic retarder control (ARC) is now standard to protect the engine from overspeeding, improve fuel efficiency and provide better overall control of the truck. In addition to ARC, the compression brake option offers a 35% increase in retarding speed capabilities.

  Vital machine information is available to the operator or technician through Cat Messenger, which provides real-time and stored machine performance and diagnostic data through an LCD display in the cab. With the optional truck payload management system (TPMS) attachment, Messenger also shows payload state, payload weight, loaded travel time, loaded travel distance and accumulated weight. TPMS now has second-gear weighing capability and 2,400-cycle storage for data analysis.

  Caterpillar offers dual-slope and flat-floor body systems with three steel-liner packages and two rubber-liner packages on the 770 and 772. Five body-liner systems for the 770 and 772 enable customers to configure the trucks for a specific application.

• The introduction of Komatsu America's 40-ton-capacity HD325-7 and 45-ton HD405-7 rigid body trucks in 2006 filled out the company's quarry-class range of -7 series haulers, joining the larger 61-ton HD465-7, 69-ton HD605-7 and 100-ton 785-7. Both the HD325-7 and HD405-7 are powered by Komatsu SAA6D140E-5 turbocharged, after-cooled diesel engines that generate maximum net output of 498 hp. The HD465-7 and HD605-7 both feature a SAA6D170E-5 turbocharged, air-to-air, after-cooled diesel engine that provides 715 net hp and meets both EPA Tier-3 and EU stage-IIIA emission standards — as does the smaller engine used in the HD325-7 and HD405-7.

• Terex Equipment continues to offer a broad line of quarry-class trucks starting with the rigid body TR35 and extending up to the TR100. The TR70, a popular model in the quarry-truck class, is powered by a Detroit Diesel 12V2000 rated at 760 gross hp and 2,400 feet-pounds of torque, coupled to an Allison transmission equipped with integral retarder, wheel-spin sensor, downshift inhibitor and reverse lockout. The TR70's frame actually is designed to 85-ton capacity for reliability and long life; a five-year, 20,000-hour frame warranty is standard. The heavy-duty body, fabricated with a Hardox 450 abrasion-resistant steel floor, provides 70- to 75-ton allowable payload capacity. With full payload, the TR70 weighs 105,140 pounds.

• Moxy Engineering, the Norway-based manufacturer of six-wheel-drive articulated dump trucks, is preparing to launch its new flagship model MT51, set for production in the second half of 2007 and billed as the industry's biggest ADT. Although no photos and only preliminary specifications for the new model were available at presstime, the MT51, according to information posted on the company's Web site, employs Moxy's usual full-time 6 x 6 drive and is powered by a 510-hp Cummins QSX15 six-cylinder, turbocharged and air-to-air intercooled diesel that complies with EPA Tier 3 and EU Stage IIIA emissions standards. With a 50-ton payload, the vehicle will weigh a total of 85.5 tons; body capacity is 30 cubic yard level, 37 cubic yards heaped.

Moxy lists key benefits of the newly designed truck as:

• Improved safety due to better visibility from a new cab and bonnet design;
• Higher load capacity and lower unladen weight than competing truck models;
• Ground-level servicing capability, with centralized service points and intelligent design;
• Improved comfort and ride with the new cab and an independent nitrogen front suspension;
• Better performance, beginning with improved traction from the rear freeswinging tandems and a 15-liter Cummins diesel, plus reliability from more than 30 years of ADT design experience.

Future Features?

In the larger mining-class haulers of 100-ton payload and more, several recent developments and technical innovations make for interesting “what if?” speculation: could some new features and capabilities of the larger haulers eventually filter down to the smaller truck sizes? Alternating current (AC) drive systems are receiving more attention than ever, with Caterpillar having announced that it will exhibit a new line of AC-drive trucks possibly by autumn 2008. More recently, Siemens Group Industrial Solutions and Services and Komatsu formed an alliance to jointly develop advanced AC drive systems for mining trucks, aimed at achieving higher power-to-payload ratios.

With little fanfare, Cat also developed an Extra Quiet (XQ) version of its 240-ton 793D mechanical-drive mine hauler, designed to reduce exterior noise — mostly from engine cooling fans — during operation. The success of Cat's engineers in reducing its noise emissions leads logically to this question: If it can be done for a large truck, why couldn't it be applied in an economical fashion to the smaller truck models commonly used in quarries worldwide?

And in perhaps the most radical departure from conventional off-highway truck design, Liebherr introduced its TI 274 pre-production hauler at bauma. The AC-drive, 320-ton-capacity TI 274 features a two-rear-axle system, with two wheels on each independent axle, and each of the four wheels powered by its own electric motor. The advantages: more traction, with the built-in axle oscillation keeping the maximum amount of tire surface on the ground at all times; more stability, with the wide stance of the two-rear-axle arrangement resulting in wider support structure than allowed by conventional designs; and more economy, with the four-wheel arrangement reducing the strain on each individual tire.

With its 320-ton payload, the TI 274 isn't the top heavy hauler; Liebherr's TI 282B and Cat's 797B battle each other for that ranking with payload ratings in the 400-ton range. But those two are about to be joined by another; Terex announced at bauma that it is moving forward on its MT6300 rigid hauler, which also will be in the 400-ton class.