Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/777939
AGGREGATES MANAGER / February 2017 39 I s bigger always better? When it comes to articulated haulers, the industry certainly seems to be moving in that direction. While 30- to 40-ton-capacity haulers still make up the major- ity of the market, many manufacturers have rolled out 45-ton trucks in the last few years, and 2016 gave way to the largest yet — the 60-ton A60H from Volvo. While these capacity increases can boost production numbers, and ultimately reduce cost per ton, there are many more factors at play that must be evaluated by a fl eet manager to ensure the site is able to reap the rewards of a larger machine. An articulated hauler is only as effective as its supporting machines — the excavators, loaders, and crushers. Evolving site conditions can also factor into proper fl eet sizing. What once was the perfect combination of machines may not be in the future as haul routes or crushing sites change. Thus, properly sizing a hauler requires looking at the site and the fl eet holistically, and continuing to monitor fl eet utilization over time. Fortunately, many equipment dealers and OEMs offer a range of technologies and services that can make this an easier process than ever before. Site simulation One of the best ways to gain a holistic view of the operation is to conduct an analysis via site simulation software — a process typically completed with the help of an equipment dealer and/or OEM. The process begins by gathering all necessary data points on jobsite conditions. The following will outline, step-by-step, the actual data from a site simulation conducted by Volvo Construction Equipment and a local dealer for a Virginia limestone quarry owner who was evaluating whether four 60-ton articulated haulers would pose effi ciencies over fi ve 43-ton articulated haulers. Step 1: Jobsite conditions The fi rst step is completed with the help of a handheld GPS device that records and logs site information along the haul route — including haul distances, curves in the haul road, and road gradients — factors that all affect cycle times. This data is then imported as a GPX fi le into a site simulation software program. In the example below, the haul route is 7,286 feet from loading point to dumping site. Once GPS data is imported, the fl eet manager works hand-in-hand with the OEM or dealer to input a number of jobsite-specifi c factors, including material information, such as bank density, swell factor, loose density, and the estimated average percentage of bucket fi ll. The software also allows for selection from several categories of ground conditions in order to calculate rolling resis- tance of the equipment — a key factor in estimating cycle times and fuel effi ciency levels. Step 2: Operating hours Next, annual working hours (per machine) are estimated by taking into consideration total sched- uled shifts per year, average shift duration (minus non-operating delay per shift), and then sub- tracting estimated scheduled maintenance. In this instance, the quarry owner estimated 95 percent machine availability, which amounts to 240 8-hour shifts (or 1,824 operating hours) per machine, per year. Step 3: Equipment specifi cations After incorporating GPS information and manually entering jobsite factors, the team then inputs equipment model information, including number of machines, model numbers, and bucket size(s). The software will automatically pull the necessary equipment specifi cations in order to run a pro- duction simulation. The team can then run reports with various combinations of equipment models Material Bank Density (pound/ cubic yard) Swell Factor Loose Density (pound/ cubic yard) Bucket Fill Factor (%) Excavation Class Limestone- blasted 4,960 1.35 3,100 95 Class 4 A combination of mine conditions, operating parameters, and equipment options should be analyzed to determine the most cost-effective equipment options.