Articulated dump truck (articulated hauler)

01

Size the hauler for payload, volume and ground

Rokbak, an articulated hauler maker, describes its RA30 as made for quarries, infrastructure and commercial construction sites, with independent front suspension as standard. Its published specifications for two models are shown below; weights are for EU Stage V versions. [1]

Editorial calculation: the RA30's payload is about 1.12 times its net weight (28,000 ÷ 24,911) and the RA40's about 1.17 times (38,000 ÷ 32,421). Rokbak states that its ground-pressure figures use the total contact area within the tyre contact ellipse. Wider 750/65 tyres lower the RA30's loaded rear ground pressure from 462 to 351 kPa.

Give the supplier the material and its loose density, the loading tool and bucket size, the haul distance, grades and ground conditions, the required payload and body volume, the tyre preference, the emission stage or tier required, the climate and altitude, telematics needs, and the dealer and parts support required at the site.

02

Check the drivetrain, braking and safety rules

Rokbak lists adaptive 8-speed shifting with selectable traction control. A transmission retarder combines with exhaust brakes and fully enclosed, oil-cooled multi-disc brakes. Its servicing features include ground-level test points, a fully tilting cab and an electrically raised hood. It states that its haulers are compatible with hydrotreated vegetable oil (HVO) fuel. [1]

In US mines, MSHA rule 30 CFR 56.14101 requires a service brake system “capable of stopping and holding the equipment with its typical load on the maximum grade it travels”, and parking brakes, where fitted, able to hold it there. Its Table M-1 sets maximum stopping distances by gross vehicle weight and speed. For example, at 20 mph it allows 119 ft for 70,000–140,000 lb and 133 ft for 140,000–250,000 lb. [3]

Editorial calculation: the RA30's gross weight of 52,638 kg is about 116,000 lb, which falls in the 70,000–140,000 lb row. The RA40's 70,339 kg is about 155,100 lb, which falls in the 140,000–250,000 lb row. 119 ft is about 36 m and 133 ft about 41 m.

On US construction sites, OSHA 29 CFR 1926.602 covers earthmoving equipment, including service brakes able to stop and hold the equipment fully loaded and the brake performance criteria for trucks and wagons in SAE J166. [4]

03

Understand the articulation and steering

Rokbak's brochure says the front and rear frames are all-welded steel fabrications. The frames articulate 45° to either side for steering on "two widely-spaced pivot pins in back-to-back sealed taper roller bearings", and a large cylindrical coupling with nylon bushings lets the frames oscillate relative to each other. Hydrostatic power steering uses two double-acting cylinders, with secondary steering pressure from a ground-driven pump. It lists SAE turning radii of 9,185 mm for the RA30 and 8,470 mm for the RA40. [2]

The brochure states that the body is all-welded from high-hardness steel (minimum 360 BHN, 1,000 MPa yield strength). The loaded body raises in 12 s on the RA30 and 12.5 s on the RA40. Brakes are oil-cooled multi-plate packs at each wheel, with independent front and rear circuits and a spring-applied, hydraulically released parking brake. Rear axles are linked by pivoting balance beams that share the load. [2]

04

Welded frames, steering cylinders, body, balance-beam axles and wet brakes

Rokbak's brochure supplies the frame, steering and brake rows; the 45° articulation and rear balance beams are as it describes them for the RA30 and RA40.

05

Rokbak RA30/RA40 figures and the MSHA brake rule as order fields

Rokbak's RA30 and RA40 supply the example values; the braking row is the MSHA performance requirement, not a maker figure.

06

Send the material, haul and site data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Material: [type; loose density]
Loading: [loader or excavator; bucket size]
Haul: [distance; grades; ground]
Truck: [payload; heaped capacity; tyres]
Emissions: [Stage V; Tier 4 Final; Tier 2]
Rules: [MSHA; OSHA; local]
Support: [dealer; parts; telematics]

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