When you’re considering the purchase of a new articulated dump truck (ADT), you need confidence the investment you’re making will help you achieve your business goals.
You want to know your ADT can quickly and efficiently haul high volumes of material — over rugged terrain — for long distances at the lowest possible cost of ownership.
Industry experts say that’s not too much to ask.
Today’s ADTs provide more power, productivity and stability, resulting in shorter haul cycles than previous generations. They also offer a number of off-road performance advantages over rigid frame trucks in most mining and quarry applications, according to Aaron Kleingartner, marketing manager for Doosan Infracore North America.
Due to their articulated design, ADTs are able to withstand even the earliest stages of mine site preparation and excavation. They may be operated in areas where there are no roads or poorly maintained pathways. Generally, ADTs are most preferable and profitable to move materials over distances as great as 3 km, with volumes as large as 27 cubic metres, when the ground is soft, slippery or hilly.
Since an ADT’s capabilities are different from other pieces of hauling equipment, it’s important that models be compatible with the specific tasks being performed.
“The first step is to identify the tasks the mine needs to perform, and then determine what ADT design is best for those jobs. If the tasks are routine and regular, owners will most likely purchase the ADTs,” Kleingartner said. “If the tasks are performed only on a periodic basis, it may be more advantageous to rent them as needed. You’ll also want to pair them with properly sized loading equipment for the best results, and find dedicated dealer support to help you sustain its performance and decrease ownership costs.”
Kleingartner offers the following five factors to consider when specifying an ADT to perform mining and quarry work.
1. Match machine to task
ADTs are commonly tasked with removing overburden — such as surface rocks and soil — in the early stages of a mine’s development. Other common chores include cleaning out holding ponds, hauling ore to crushers and hoppers and stockpiling metals and aggregate. Articulated trucks are available in 25 tonne to 40 tonne class sizes and can carry up to 46-tonne payloads.
Since an ADT’s body is its revenue generator, size and payload are critical specifications and involve several more factors. Therefore, accurately estimating productivity before purchasing for a particular task in mining environments needs to be specific and comprehensive.
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“It may be necessary to measure the haul roads and accurately calculate gradients to arrive at sound production estimates. The hardest estimation can be rolling resistance, as it is subjective and can change quickly,” Kleingartner said.
For greater productivity with all tasks, some ADT manufacturers offer body designs that enhance the stability of the machine during transport. For better dumping performance on ground, over banks and into hoppers, some trucks are engineered with lower centres of gravity for faster dumping rates. Since ADTs perform well in 800 metre to 3 km applications, look for advanced transmission systems and other component advantages that contribute to reduce fuel consumption.
On longer hauls, possible overheating of transmissions, cooling systems and tires must be considered, which may result in necessary cooling down periods. This may slow production, so manufacturers should be consulted for recommendations on a particular application.
Other task-related issues that should be considered are whether tailgates will be an advantage or a disadvantage for your operation. For instance, large boulders or stumps can contact the tailgate during dumping and cause safety concerns.
Also, determine early in the process if your ADT will need a body liner to minimize impact damage from loading larger rock or if materials are abrasive and will cause shorter body life. Body liners are generally steel, but can be plastic or polyethylene if very sticky materials are hauled. Other options in cold climates can include heated bodies and cold weather engine starting aids.
In heavy metal mines such as iron or lead ore, overloading of ADTs can easily occur and will shorten the life of components, so understand and abide by weight limitations for best results. On-board weighing systems may be a good investment if each load can’t be weighed on a site’s truck scale.
2. Partner with the right loading equipment
One of the primary goals of any ADT owner is to accomplish tasks and reduce haul cycles for maximum efficiency. One of the best ways to achieve these results is to match an ADT to its loading equipment, so that neither the loader operator nor the ADT operator will have long waits between loads. More than 95 per cent of ADTs are loaded by excavators, while large wheel loaders, conveyor belts or hoppers are used in many mining or quarry operations.
For most material hauling sites with good production, the industry consensus is that it typically takes between six and 10 passes to fill an average ADT with an excavator and four to six passes with a wheel loader. For maximum production, the number of passes to load should be between three and five.
“Many of the largest ADTs available are similar in size to the smallest rigid frame truck commonly used in mining, so it’s easy to mismatch equipment,” Kleingartner said.
3. Identify jobsite restrictions
Are there any width, height or maneuverability restrictions that may impact an ADT’s ability to fully perform? Loading under a hopper, for example, will usually mean there are width and height restrictions and some larger ADTs may not physically fit in the space.
Built for maximum maneuverability, ADTs are designed to adapt to uneven terrain due to a hinge connecting the cab to the body, which allows the truck to flex. This feature also assists in keeping all six wheels in constant contact with the ground while travelling over loose or compacted soil, banks, material pilings or rocks common in mining or quarry jobsites.
Due to their massive size, mining and quarry projects can involve long drives on congested haul roads and operations in confined staging and dump areas. Select an ADT with a tight turning radius, which can help decrease the time it takes for operators to position the trucks for loading and unloading.
4. Choose ADT tires carefully
“Tires are always a concern in quarries and mines because of the risk of sidewall damage and lower tread life due to operation on hard packed surfaces,” Kleingartner said. “So, choose tires carefully to minimize costs.”
The right tires contribute significantly to an ADT’s tractive force, which is determined by the tread design, remaining tread life and tire inflation, along with the ground conditions at the site.
One of the most important tire decisions is whether to use E3 or E4 tires. The most common ADT tires are two star E3 radial tires. However, E4 tires offer better sidewall protection for sites that have sharp rocks and may serve as an upgrade in those environments. Hard packed roads cause shorter life for all tires, but individual tire manufacturers can inform users about which rubber compounds will provide longer life.
5. Extend ADT life with dealer support
Finally, make sure you understand all of your ownership costs and the expected lifetime of ADT components, as they may be different from equipment you currently own. Since ADTs are used off-road and are subject to severe duty, component lifetimes may be different than typical mining equipment. This is why educated and dependable product support is critical. Before purchasing an ADT, choose a dealer that has product specialization and trained mechanics, offers great response times and has good parts stock.
“I would advise sitting down with an ADT dealer and having a discussion about the type of work you’ll be performing, required scheduled maintenance, a preventive maintenance program and major component rebuilding,” Kleingartner said. “The cost of downtime is usually the most expensive component of any maintenance or repair, so it must be minimized.”
When properly evaluated and matched to the type of work you’re performing, the return on an ADT investment will be proven in daily performance, lower ownership costs and longer life.