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OPERATING STRATEGIES Paying Attention to Load Balance and Road Repairs for Haulage Cost Reduction By Vivien Hui New technology and tools can be used to monitor and analyze hauling conditions. The production and cost benefits asso- ciated with having correct load balance on haul trucks and improving haul-road conditions are difficult to quantify on paper and therefore a lot of mines do not make it a part of their standard operating procedure/best practice—but it is a relatively easy change to make to yield lower cycle time, higher produc- tion and lower costs. The goal is to cre- ate an environment where the truck is operating as close to design parameters as possible. In this article, we will only focus on the design parameters of road conditions and load balance and how to utilize technology to monitor, analyze and improve these parameters. My experience with open-pit haulage has been with Caterpillar mechanical- drive 240-ton trucks (793x) so this arti- cle will use the Caterpillar line of prod- ucts in the examples of technology. However, the same best-practice strate- gies should apply to other brands of haul trucks and if your truck isn't cur- rently equipped with the technologies mentioned in this article, third-party technologies are available. First, let's look at the "perfect" envi- ronment for haul trucks—the environ- ment that spec sheets are based on, for the most part. 144 E&MJ; • JUNE 2012 1. Truck weight when loaded should be distributed as follows: • 1/3 of weight to front axle • 2/3 of weight to rear axle • 1/2 of weight to the right side • 1/2 of weight to the left side 2. Truck is traveling at 0% rolling re- sistance. The smoother the road, the lower the rolling resistance value. Zero percent is impossible to achieve in the real world; in general, 1% is great, 2% is average. A high rolling resistance causes reduced rimpull and reduced acceleration and there- fore, longer cycle times and lower productivity. 3. Truck box is optimally sized, based on density of material to optimize payload. 4. Payload (Gross Vehicle Weight (GVW) minus Empty Vehicle Weight (EVW) equals Maximum Payload) follows the 10/10/20 rule; often misunderstood, the rule means no more than 10% of loads may exceed 10% above target payload and no loads may exceed 20% above target payload. Based on the "perfect" environment described above, this means that any- time you deviate from the conditions, the truck is performing at a level slight- ly less than its potential. Translated into production/savings, it means that the changes you make to ensure proper payload weight/distribution and well- maintained haul roads will enable the following: •Faster cycle times → increase productivity. •Extended drive train, suspension, frame and tire life (See p. 145) → lower operating cost and increased machine availability. •Reduced fuel consumption → lower operating cost. •Reduce operator fatigue → promotes safety. •Increased haul road maintenance → maximize support equipment utilization. Use It, Improve It The information above begs two questions: 1. What technology tools can be used to help monitor and analyze the conditions? 2. How do we improve conditions to better reflect design parameters? To answer the questions, I will first introduce a tool, then explain how this tool can help in each of the four oper- ating conditions of the "perfect" envi- ronment. Caterpillar has designed a system called Road Analysis Control www.e-mj.com