Productivity considerations are:

Loading methods, Truck/shovel pass match, and Gaps between theoretical and actual tons per hour,

o Skilled truck and shovel operators. o Shovels properly “trucked.”

There are four primary loading methods: single side, double side, drive-by and

modified drive-by. There can be significant productivity differences depending

on which method is used and how well it conforms to site conditions and fleet

configuration. Each loading method has specific advantages and disadvantages,

but as the chart indicates, the modified drive-by method (illustrated in the

diagram above) offers the highest potential production rate of all the methods, if

the proper site conditions and necessary operator skills are available.

For prospective or even current customers that are unsure about which method

would yield the best results, given a specific site’s fleet configuration, terrain,

worker experience and other variables, Cat can help in estimating potential

productivity, said Klingel. Its senior application engineers have developed an

elaborate spreadsheet that takes into account a wide range of loading-related

factors and produces an accurate estimate of shovel/truck loading productivity

per year for various loading scenarios. Based on input data such as shovel

model, truck type and capacity, loading method and dipper capacity, the

“Theoretical Production Estimate” spreadsheet supplies an appraisal of

maximum annual production capacity for different combinations of the input

items. A simplified summary of its results is shown in the chart below.