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Load & Haul, Road Transport

Articles from HAUL TRUCKS (399 Articles), (PAID ONLY) ROAD TRUCKS (125 Articles), TYRES (67 Articles)











Notice the very tight turn and steep elevation of this haul road.
Notice the very tight turn and steep elevation of this haul road.

Keys to extending tyre life

While quarry operations do pay attention to preserving off-the-road tyres, it is little appreciated that the impact of road surfaces, water, inflation and more can influence tyre performance and wear life and in turn affect the bottom line.

We all know the importance of equipment management in minimising production interruptions related to maintenance downtime. How much attention does your operation pay to the management of its heavy equipment tyres? Not all tyre management, however, directly involves the tyres. Other factors in your operations can influence tyre performance and wear life.

Mine design, employee training, equipment modifications, servicing dealers and record keeping can also affect productivity and tyre performance. Take a look at these factors when putting together or evaluating your tyre management programs.

Consider an operation with 100-tonne haul trucks equipped with 27.00R49 tyres. Each truck’s tyres, purchased new, cost between $US38,000 ($AUD50,192) and $US44,000 ($AUD58,118). This is an asset you want to make last as long as possible. Many individuals within your organisation contribute to extending or diminishing tyre life.

Starting with quarry design engineers, considerations to take into account when designing the mine include grades, road crown, road surface, super elevations, and uphill and downhill loads. How do these design features affect the tyres?

Grades

Steep grades can cause tyre slippage resulting in increased tyre wear and slower trucks. They increase the amount of load transfer to the tyres and suspension components.

Load transfer onto front tyres in downhill hauls can cause overloading, resulting in increased tyre temperatures, which is a primary factor in poor tyre performance. Overly steep grades require operators to use multiple transmission shifts to make the climb. These shifts can cause additional shearing forces within tyres causing or increasing separations.

The recommended gradient is six per cent.

Road crown

A road crown is incorporated into haul road designs to disperse water off haul road surfaces, but care should be taken to ensure all tyres are evenly supported by the road surface. Surprisingly, people don’t realise just what an enemy water is to tyres. A wet tyre cuts eight to 10 times easier than a dry tyre.
Designers should also take into consideration the type of material used to build and maintain haul roads. Ideal materials compact more firmly and resist potholes. Some materials act like marbles, causing slippage of the tyres that can slow trucks (production) and cause tread cutting, chipping and premature wear.

Tyre manufacturers and their authorised dealers offer a number of services to identify design issues that affect tyre performance. Technical teams are capable of running real-time haul road analysis, targeting real-time critical forces affecting tyres in order to correlate haul road conditions to tyre life. Spotech (satellite performance optimisation technology) is one tool available to measure speed, latitudinal, longitudinal and vertical G-force accelerations by using internal accelerometers to generate data for analysis to ensure issues are addressed before they become irreparable problems.

Maintenance issues
 Ideally, haul roads should be the width of three trucks, allowing for easy passing on the roadway.
Ideally, haul roads should be the width of three trucks, allowing for easy passing on the roadway.

A majority of quarry operations do not have a tyre shop and dedicated maintenance staff to monitor tyre performance. In these situations, quarry operators rely upon OTR tyre dealers to provide service and track tyre performance. On average, a service call to remove and replace a haul truck tyre averages about four to five hours. This means your truck loses this amount of time, if not longer, away from production. Some questions to ask when assessing OTR tyre dealers include the following:

  • Where is the tyre shop in relationship to the quarry?
  • Does the tyre dealer have service trucks capable of safely handling OTR tyres?
  • Are the service truck technicians and salespersons appropriately certified?
  • What kind of OTR training do the technicians have?
  • Does the dealer have 24-hour service?
  • What kind of tyre tracking and record keeping does the dealer offer?
  • Does the dealer offer tyre pressure monitoring on a regular basis? Weekly is recommended.
  • Does the dealer have certified OTR sales representatives that can assess site conditions and make appropriate tyre recommendations suitable for your operations?

A servicing tyre dealer with well-trained and equipped sales and service personnel is an important asset to optimise your production and profit.

Employee training

Another key element of a great tyre management program is employee training and the establishment of best practices, including the following:

  • Training haul truck drivers to stay on the bench and avoid backing into debris will minimise rock cuts and sidewall damage.
  • Loader operators working the face should be vigilant in keeping the bench free of rock debris by cleaning between loads.
  • Centre loading of haul trucks is another important consideration as it minimises overloading of any one or pair of tyres.
  • Haul truck operators should avoid driving over rock spillage. A rock the size of a fist causes the most damage to equipment tyres.
  • Start-of-shift operator inspections should include inspection of the tyres and weekly pressure checks.
Haul roads

Haul road maintenance is another critical aspect of an operation’s tyre management program. Regular clearing of debris from haul roads is a must for tyre protection. Haul roads should be designed the width of three haul trucks. Narrow haul roads cause drivers to ride on or very close to the berm and can result in cuts and tyre damage. Consider also that mismanagement of haul roads can result in decreased production as trucks will slow down to minimise fatigue when roads are in poor condition.

Rock slots are another best practice in maintaining haul roads. When a motor grader is in the process of clearing rocks from the haul road, it frequently just pushes the rocks up against the berms. This results in two situations: the berm gets larger and the haul road gets narrower and/or rocks are still in the driving path of the trucks.

The next aspect of great tyre management programs is to consider the effect equipment modifications have on the tyres. The air inside is the single most important part of the tyre. It is the air that carries the load of the vehicle and its payload. The tyre itself is the vessel that holds the air. Tyres are designed to carry the quoted payloads and gross vehicle weight of the machine. Haul truck modifications such as the addition of sideboards to increase the payload or the addition of fuel tanks so trucks can run longer without stopping are great for increasing production, but at what cost? The addition of these items can increase the gross vehicle weight by hundreds of tonnes. Dealers make tyre recommendations based upon published gross vehicle weights and payloads. Savvy dealers will ask questions of the operations or maintenance managers prior to making tyre recommendations, but, ultimately, it is the responsibility of the operation to inform dealers of equipment modifications to avoid premature tyre removal resulting from overloading.

To wrap up this discussion, consider that some damaged OTR tyres can be repaired, so keep a scrap pile of slightly worn and repaired tyres on hand. While these tyres may not be suitable for your heaviest loads, you may get a little more life by rotating them to the front of haul trucks or the rear of loaders. Remember the best recommendation is to be proactive and prevent early or unexpected tyre removal and keep production rolling!

Article courtesy of BKT Tires Inc. This story first appeared in the January 2016 issue of Aggregates Manager (US) and reappears in Quarry with kind permission.











Isringhausen
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Wednesday, 21 August, 2019 9:35am
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