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A short class with Sarah and her students. The other ways are under More.
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Today, we're going to discuss why the position of the truck in relation to the excavator is critical for productivity. Can anyone tell me what happens when the truck is placed too far away?
The cycle time increases because the angle of swing is larger.
Exactly! When the angle of swing increases, what do you think happens to productivity?
It decreases because it takes longer to load the truck.
Great! To summarize, an ideal position is at a 90-degree angle to minimize the angle of swing, thus maintaining productivity. Remember the mnemonic 'SIMPLE' - Swing Angle Influences Machine Productivity Levels Everyday.
Let's move on to the height of cut. What do we mean when we say the optimum height of cut should align with the actual height?
If the actual height of cut is much lower or higher than the optimum, we need to adjust productivity with correction factors.
Correct! And can someone explain how we calculate these correction factors?
We find the percentage of actual height divided by the optimum height and apply that to our productivity estimates.
Exactly! Remember the acronym 'FIND' - Factor In Necessary Dimensions, to help you recall the importance of using correction factors.
Now, let's talk about haul unit exchange time. What does this term mean, and why is it significant?
It refers to the time it takes for a loaded truck to leave and a new empty truck to arrive, which can slow down operations if it's too long.
Exactly! Long exchange times can lead to increased cycle times. What can we do to minimize this time?
We can balance the number of trucks and shovels to ensure there’s always a truck ready for loading.
Perfect! Just remember to keep your operations organized. Use the mnemonic 'TACKLE' - Trucks And Cutters Keep Loading Efficiently.
Can anyone tell me how we determine the optimum height of cut for different materials?
It often depends on the type of material – harder materials require higher optimum heights.
That’s right! With well-blasted rock, we typically choose around 50% of the maximum digging height. Let’s remember this with 'HALF' - Harder Adjustment Lessens Flexibility in height.
The time taken for a round trip of loading and dumping.
Directly affects cycle time; should ideally be 90 degrees.
Important for productivity; must be minimized.
Necessary adjustments to maintain accurate productivity estimates.
Derives from the maximum height allowed for efficient operation.
If a truck is positioned at a 90-degree angle to an excavator, the angle of swing is minimal, resulting in a cycle time of 24 seconds, which is optimal for productivity.
In a project where the actual height of cut is 60% of the optimum height, a correction factor of 0.91 must be applied to the productivity calculation.
Swing it right, swing it tight, 90 degrees keeps us bright!
Once was a shovel at a racetrack, where it loaded trucks quickly at 90-degrees, while others trying at 135 never won a race!
SIMPLE - Swing Angle Influences Machine Productivity Levels Everyday.
FIND - Factor In Necessary Dimensions for optimal height and swing.
Term
Angle of Swing
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Term
Correction Factors
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Term
Haul Unit Exchange Time
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The horizontal angle between the digging and dumping positions of the bucket.
The time required for a loaded truck to leave and for a new truck to take its position for loading.
The ideal height at which material should be cut to maximize productivity.
Adjustments made to productivity estimates based on the actual height of cut and swing angle.
The total time taken for a shovel to complete one loading and dumping operation.
This section discusses the impact of truck positioning and swing angles on cycle time and productivity when using front shovels.
The section elaborates on how the placement of trucks in relation to excavators affects the cycle time and, therefore, the productivity of shovels. It highlights the importance of maintaining optimal swing angles and heights of cut, and considers key factors like truck spotting clearance and haul unit exchange time.
In this section, we explore the relationship between cycle time and productivity when operating front shovels. A key factor is the positioning of the truck relative to the excavator, ideally at a 90-degree angle, to minimize the angle of swing and thus reduce cycle time. The angle of swing is defined as the horizontal angle between the loading and dumping positions, and increasing this angle leads to longer cycle times and decreased productivity. Furthermore, the actual height of cut should align with the optimum height to maintain productivity levels, while correction factors must be applied if project conditions deviate from these ideal parameters. Consideration is also given to truck spotting clearance and haul unit exchange time, both of which influence overall productivity. Finally, we demonstrate how to estimate shovel productivity based on these factors.