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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 dive into the cycle time components of a scraper. Can anyone tell me what some of these components might be?
Maybe loading time? I think there's also dumping time?
Great! Yes, loading time and dumping time are part of it. We also include haul time, return time and the time spent turning. These can be divided into fixed and variable time components. What's the difference between fixed and variable time?
Fixed time doesn’t change with the distance traveled, right?
Exactly! Fixed time includes loading, dumping, and turning. Variable time, on the other hand, is influenced by the distance traveled and it includes haul and return time. Can anyone explain why that’s important?
Because it helps us optimize our operations and reduce costs by understanding what affects the cycle time?
Exactly right! It’s all about maximizing efficiency. Let's move on to how we can visualize this with the load growth curve.
Let’s talk about the load growth curve. What do you think happens when we load the scraper to maximum capacity?
I think it should increase production, right?
That's a common belief! However, studies show that it reduces production after a certain point. Why do you think that might be?
Is it because the material being added bumps against the loaded material?
Exactly! After the bowl is about 85% full, the incoming material faces resistance, leading to diminishing returns. We need to understand this to find the optimal loading time.
How do we find that optimal point?
We can draw the load growth curve and analyze the data to see how loading efficiency changes. In summary, loading beyond optimal levels wastes time and effort.
Next, let’s examine how maintaining the haul route impacts cycle time. Why is this an important aspect?
If the haul route is not maintained well, it might increase resistance, right?
Absolutely! Poor conditions can slow down the scraper’s speed and increase cycle time. What could we do to improve the haul route?
We could use graders or bulldozers to maintain the route and sprinkle water to control dust!
Exactly! Those actions reduce drag, increase speed, and ultimately improve productivity. Let’s remember that maintaining the haul route is an economical way to optimize output.
Total operational time for scrapers, covering loading, dumping, and return.
Demonstrates diminishing returns on loading efficiency when scrapers are overloaded.
Components of cycle time that either remain constant or change with distance.
Scrape it right, load it right, keep it light to avoid the fight.
Imagine a busy construction site where a scraper is trying to carry too much dirt. Every time it overloads, it struggles and slows down, while the operator realizes they are wasting time. The lesson is learned: less is more at the load's core.
FLIGHT: F for Fixed time, including Loading, Dumping, Turning; while L for Variable time includes Haul and Return.
LOAD: L for Loading time, O for Overloading issues, A for Analysis of cycle time, D for Dumping efficiency.
Term
What is load growth curve?
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Term
What aspects make up cycle time?
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The total time taken for one complete loading and unloading operation of a scraper.
The time taken to load materials into the scraper.
The time taken to transport materials from a loading site to the dump site.
The time taken to unload materials from the scraper.
The time taken for the scraper to return to the loading site after unloading.
A graph showing the relationship between loading time and the percentage of payload, illustrating diminishing returns on loading efficiency.
Cycle time components that remain constant, independent of travel distance.
Cycle time components that depend on distance traveled.
This section discusses the cycle time components of a scraper and introduces the concept of the load growth curve, emphasizing the importance of not maximizing payloads beyond optimal levels.
The load growth curve section explains cycle time components such as load time, haul time, dump time, and return time, highlighting the fixed and variable time aspects. It introduces the load growth curve's significance in determining the optimal loading time for scrapers and cautions against overloading, which leads to diminishing returns on productivity.
The load growth curve conceptually illustrates the relationship between loading time and payload percentage in operation. It provides insights into how scrapers function and their cycle times, broken down into components such as load time, haul time, dump time, and return time. The total cycle time consists of fixed and variable components, where fixed time encompasses loading, dumping, and turning, while variable time refers to haul and return based on distance traveled.
An important principle is identified in the load growth curve, challenging the belief that filling the scraper to maximum capacity increases production. Research shows diminishing returns occur once the scraper bowl exceeds around 85% full, as the incoming material encounters resistance from pre-existing material. Understanding this can help optimize loading strategies and avoid wasted effort. The subsequent parts of the section also discuss haul routes, their maintenance, and the significance of optimizing cycle times of scrapers and pushers in light of project conditions.