Rigid-Frame Haulers Make Smooth Operators

By Lynn Landberg, Senior Editor | September 28, 2010


Komatsu HD785
With an automatic, powershift transmission and electronic shift control, this Komatsu HD785 can work under tough conditions, yet maintain efficiency and ease operator fatigue.
Hauler Image
A hauler matched in size with an excavator as a package can make mass-excavation projects both efficient and productive.



Average base price of a mechanical-drive, rigid-frame hauler. The average base price of an electric-drive hauler is approximately $1.6 million. Rigid-frame haulers have extreme variations in size, which greatly affects the cost of a unit. Mechanical-drive hauler models used to compute the average price range are from $300,000 to $1.1 million.*


Number of rigid-frame haulers offered by manufacturers represented in the Buying File. This includes both mechanical- and electric-drive units.


Average hourly combined ownership and repair expenses for mechanical-drive haulers. For electric-drive units, the hourly cost is $448, owing to their size. The argument is made that electric drives on larger haulers actually are more efficient and cost-effective than mechanical drives. These figures take into account downtime for service and other functions.*


Rigid-frame haulers, the workhorses on large earthmoving sites and mining operations, have gotten larger over the years to the point where they can carry in excess of 300 tons. Designing a hauler to carry these extreme payloads used to require massive components that were not particularly efficient and added a huge amount of weight to the machine. As such, the size that a hauler could attain was limited by practical considerations such as efficiency, maneuverability and safety.

With improvements to frame designs, drive trains, suspensions and operator controls, manufacturers have been able to increase the hauler's capacity while improving its performance and handling.

The largest haulers are used in mining operations and have little application on today's scaled-down construction sites. Most of the large mining trucks have electric drives, while the "smaller" haulers used in construction have mechanical drives. In the past, the shear size of the mechanical-drive components on larger haulers favored electric drives. But mechanical drives have now reached a point in their development where they can be used on some of the largest haulers, although proponents of electric drives will argue that electric drives on large mining trucks are more efficient and cost effective.

Mechanical drives for big haulers

At least one manufacturer, Caterpillar, would argue differently. Cat offers a full line of mechanical-drive trucks, including its largest, the 380-ton capacity 797B mining hauler. Each of Cat's haulers features the Integrated Power Train, which includes an Electronic Unit Injection (EUI) engine with electronic control module and Electronic Programmable Transmission Control.

Along with the 797B, new additions to the Cat line include the 773E and 775E, both suited to construction applications with payload capacities of 60 and 70 tons, respectively. Both haulers feature the Cat 3412E diesel engine equipped with hydraulic electronic unit injectors. Replacing the D-Series model, the 773E has a capacity increase of about 3 percent and increase in gross horsepower of 4.1 percent, now rated at 710 horsepower. The engine and mechanical drive train of each hauler are electronically controlled, and components are electronically linked for integrated operation. The electronic systems monitor and control machine functions to reduce wear, increase performance and aid maintenance planning and diagnostics.

Euclid-Hitachi offers a full line of haulers with both mechanical and electric drive, ranging in capacities from 40 to 300 tons. The largest mechanical drive unit is the EH1700, with a 1,200-hp engine. This is coupled to a planetary type, fully automatic shift transmission with an integral converter and automatic lock-up shifting in all ranges.

The hauler is equipped with wet disc brakes located on the rear axle. The brakes provide service braking, secondary braking and retarding. Separate pedals activate the service braking and retarding functions so the operator can keep both hands on the steering wheel.

The front suspension system has an independent trailing arm for each front wheel, with the struts containing energy-absorbing gas. The trailing arm front suspension absorbs haul-road irregularities, minimizing suspension-induced frame twisting while providing independent tire action. In the rear, the suspension has a cast axle housing with a parallel link mounting and an A-frame top member for a more stabilized ride and lower overall frame stress.

Innovative axles

To give some of its big haulers (two over 300 tons capacity) a smooth and safe ride, Liebherr has come up with an innovative rear-axle system. In fact, the rear axle actually is two axles—one for each of the wheel pairs. Each axle oscillates around its own suspension pivot. When the hauler runs over a bump or obstacle, it will affect only one wheel pair without influencing the other one. Even on the involved wheel pair, both tires will keep carrying the same load practically all of the time, avoiding the problem of tire overloading. The body pivot suspension of these haulers also has a wider stance, which makes for a more stable load distribution and decreased wallowing on rougher roads.

With lines of both mechanical-drive and electric-drive haulers, Komatsu has units for both the construction industry and mining. Two of the newest offerings are the 61-ton HD465-7 and the 69-ton HD605-7, a quarry version of the HD465-7. The HD465-7 replaces the HD465-5. A Tier II-compliant Komatsu SAA6D170E-3 turbocharged engine generates 715 horsepower. The haulers also come with the Komatsu Advanced Transmission with Optimum Modulation Control System (K-Atomic), designed to provide smoother shifting, improved operator comfort and a longer life cycle for drive-train components.

At 72-tons capacity, the TR70 is the largest of Terex's haulers fitting into the construction category. This mechanical-drive unit has dual retardation, using the oil-cooled disc brakes or transmission retarder. The automatic, electronically controlled Soft-Shift transmission has six forward speeds up to 35.5 mph. The Unit Rig division of Terex produces electric-drive mining haulers ranging from 120 to 360 tons.

Rimpull's three rigid-frame models range from capacities of 98 to 150 tons. The company also offers a number of specialty trucks, remanufactured and recertified equipment, and OEM components. The chassis of the haulers are of box beam construction that incorporates five torque tubes, a frame stabilizer/superstructure support, and integral front bumper. The engine turbos can be accessed through a door in the center deck. Radiator cover and grill removal is accomplished by removing two bolts for radiator accessibility.

Basic Specifications
Company/Model GVW (lbs.) Payload (tons) Drive E — Elec. M — Mech. Max. Fwd. Speed (mph)
Specifications shown here are based on the Construction Equipment Specifications Guide and manufacturer literature and are given here for comparison only. Specifications are subject to change and manufacturers or their distributors should be contacted for the most current information.
771D 163,100 44 M 35
773E 219,000 60 M 41.1
775E 239,000 70 M 41.1
775D 235,000 69 M 41
777D 355,000 100 M 38
785C 550,000 150 M 34
789C 700,000 195 M 34
793C 830,000 240 M 34
797B 1,230,000 360 M 40
EH 600 125,467 35.9 M 35.4
EH 650 137,919 40 M 39.1
EH 700 163,139 42.5 M 47.2
EH 750 163,000 43 M 47
EH 1000 224,000 66 M 45.1
EH 1100 224,000 60 M 45
EH 1600 354,086 98.9 M 36.4
EH 1700 375,000 108.4 M 40.1
EH 3000 615,000 173 E 34
EH 3500 715,000 213.1 E 34.4
EH 4000 850,800 251.4 E 30.3
EH 4500 960,000 281.6 E 34
EH4500 AOS 1,034,295 301.5 E 36.4
HD325-6 159,020 44 M 43.5
HD465-5 211,860 61 M 43.5
HD605-5 235,190 67 M 43.5
HD785-5 367,000 100 M 40.2
HD1500-5 550,000 164 M 36
630E 650,000 190 E 31.7
730E 715,000 205 E 34.6
830E 850,650 255 E 30.3
930E-2 1,100,000 320 E 40
T 252 715,000 200 E 32
T 262 815,000 240 E 32
T 272 974,000 320 E 40
T 282 1,248,000 400 E 40
R2749 345,900 98 M 39
R3051 412,000 115 M 39
R3351 499,300 150 M 39
TR100 351,280 100 M 29.6
TR35 121,260 35 M 34.5
TR40 155,850 40 M 36
TR45 167,780 45 M 37
TR60 210,940 60 M 35
TR70 248,330 72 M 35

Manufacturer Websites
Caterpillar - www.cat.com Hitachi - www.hitachiconstruction.com
Komatsu - www.komatsuamerica.com Liebherr - www.liebherr.com
Rimpull - www.rimpull.com Terex - www.terex.com
*Source: "Contractors' Equipment Cost Guide," published by Equipment Watch; telephone 800/669-3282.