Sept/Oct 2008

Innovation Page

Design changes for today’s haul trucks

By M. Parsons

Beasts of burden pull payloads to the dump.

The origins of today’s rigid frame haul trucks predate the advent of mechanical power. In the horse-and-buggy days, payloads were deposited into a hinged dump box and pulled to the dump area by a beast of burden. The driver’s job was to guide the animal and cart to and from the load and dump locations and assist in turning the beast and cart around for loading and dumping.

Engines of thousands of horsepower with automatically controlled transmissions have replaced the beast of burden. The development of larger tires, wheels and axles, and the use of camera and sensor systems to see with have all allowed payloads to grow to hundreds of tonnes. A new generation of autonomous haulage vehicles is evolving with design concerns such as the location and mounting of the necessary telemetry and communication antenna arrays.

Today’s haul trucks are still designed around a beast pulling a payload with a driver guiding the way. The haulage cycle these large trucks follow is in part a throw-back to an earlier time. The vehicle backs into its loading position, travels to the dump area, where it turns around and dumps its load, and then travels back to the loading area, where it again turns around and starts over.

Changing the haul cycle is the idea behind the design of the patented Vector Neutral Truck, which is designed around a payload, not a power plant and driver. Positioning the engine and operator midway between the axles and steering the axles equally and opposite to each other creates a situation where both ends of the truck are the same. From the controls, the driver has an equal view of travel in both directions without having to change orientation. Because vehicle performance is the same in both directions, it is insensitive to direction or, in other words, “vector neutral.” There is, therefore, no need to turn the truck around for loading or dumping.

There are undisputable advantages, in terms of time and distance, that result from eliminating the turn-around and back-up parts of the haul cycle. This change in the haul cycle results in less steering and brake actuations, less wear on the drive train, less scrub and wear on tires, no need for maintaining turn-around areas, and ease in adapting remote and automatic control of the vehicle.

Vector Neutral trucks with 400-ton and 60-ton capacities have the same power plants as conventional trucks of the same capacity: 2,700 horsepower for the 400-ton truck and 650 horsepower for the 60-ton truck. The engine is mounted mid-ship in the main frame, driving two axles through a mechanical transmission or electric wheel motor. Each axle has four tires, which carry half the total vehicle weight, regardless of whether the truck is loaded or empty.

Conventional suspension members are fixed to an excavator-type slew bearing that allows rotation of the axle and suspension about a vertical centreline to steer the truck. The driver sits facing perpendicular to the line of travel and watches a multiple-screen display that is fed by multiple redundant cameras to produce a virtual view of the vehicle’s travel path.

Mining companies today are seriously evaluating their future haul truck options and the Vector Neutral Truck might provide the next technology innovation for more efficient operation.

Mike Parsons is a mechanical design consultant in Sudbury, supplying services since 1994 to customers in the mining, construction, utility and agricultural industries. Mike is now promoting his patented Vector Neutral Truck while enjoying the natural allure of northern Ontario life.

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