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A short class with Sarah and her students. The other ways are under More.
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Today, we will start learning about cycle time in scrapers. Can anyone tell me what components make up the cycle time?
Isn't it loading and unloading time?
Good start! Cycle time actually includes loading time, dumping time, as well as haul and return time.
So, how do these times relate to each other?
Excellent question! We divide cycle time into fixed and variable components. Fixed times like loading, dumping, and turning do not depend on travel distance, while variable times, like haul and return, vary based on distance and speed.
How does the speed of the machine affect them?
The speed is influenced by project conditions and can change the haul and return time significantly. Maintaining the haul route is essential to improve speed and decrease cycle time!
That sounds important! What can reduce those times?
Maintaining a good haul route and avoiding overloading are critical strategies to enhance efficiency.
In summary, understanding these components can significantly improve the productivity of scrapers. Make sure to differentiate between fixed and variable times!
Today, let’s discuss overloading scrapers. What do you think happens when we try to load them beyond capacity?
Maybe it slows them down?
Exactly! The load growth curve illustrates that as you overfill the bowl, loading rates drop due to resistance. Thus, for maximum efficiency, you should load to an optimal capacity.
How do we find that optimal capacity?
Good question! Manufacturers usually provide optimal load times. The load growth curve helps visualize how much should be loaded for maximum efficiency.
So, we should never fill the scraper completely?
Correct! Aim for the optimal loading percentage, around 85%, to maintain efficiency. Remember the 'law of diminishing returns' here!
In summary, overloading can significantly reduce productivity. Use load growth curves to guide your loading practices!
Can anyone tell me how we can reduce cycle time in scrapers?
Maybe by speeding up the haul time?
Exactly! One way to speed up haul time is by maintaining the haul road. What do you think we should do?
We can keep it smooth and avoid dust!
Yes! Using graders and sprinklers to maintain moisture helps reduce resistance and speeds up travel times.
How does that help with productivity?
A well-maintained route enhances speed, thereby reducing cycle time and improving productivity.
To summarize, diligent haul route maintenance has a huge impact on cycle time and overall scraper productivity. Remember it helps your bottom line!
What other component affects cycle time significantly?
Is it dump time?
Correct! Dump time varies with scraper size and material type. What do you think are the implications of that?
A bigger scraper would take longer to dump?
Yes, and materials also impact the time. Loose materials will be quicker to dump than cohesive ones. What else affects dump time?
I think space limitations in the dumping area could slow it down too.
Exactly! Congestion in the dumping area can lead to delays. It’s crucial to assess the site layout before working with scrapers.
In conclusion, understanding dump time's contributing factors assists in optimizing scraper operations effectively.
Lastly, let’s dive into turning times. Why do you think turning time is essential?
It could affect how quickly we can get back to hauling.
Yes, and it can also affect safety. Turning in a loaded state can be dangerous. What do we prefer?
To dump before turning for safety?
Exactly! Moreover, turn times differ between fill and cut areas, due to the congestion in cuts. Always aim to turn safely and efficiently.
In summary, understanding turning times is crucial for both efficiency and safety in scraper operations!
Encompasses all operational phases of scrapers.
Understanding how each component contributes to overall cycle time.
Impact of optimal loading practices on scraper productivity.
Critical for reducing operational delays and improving efficiency.
Variations leading to changes in operational practices.
Turn and churn, load correctly, not too fast, to maximize the work and make our profits last!
Imagine a farmer loading a cart. If he overloads, the cart won't move quickly. Similarly, scrapers need to know when enough is enough for maximum efficiency.
Remember 'Fewer Haul Times Bring Efficient Shifts': F=Fixed time, H=Haul time, T=Turn time, B=Bring, E=Efficient, S=Scraper.
STAD (Speed, Turn, ADBT, Dump) helps remember the four crucial concepts to improve scraper cycle times.
Term
What are fixed components of cycle time?
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Term
Define variable components of cycle time.
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The total time taken to complete one full cycle of operations involving loading, hauling, dumping, and returning.
The time taken to transport material from the loading area to the dumping area.
The time required for the scraper to unload the material it carries.
The time required for a scraper to make turns during operation.
The portion of cycle time that does not depend on travel distance.
The portion of cycle time that is affected by travel distance and speed of operation.
A graph showing the relationship between loading time and the percentage of payload, illustrating diminishing returns after a certain capacity.
Acceleration, Deceleration, and Braking Time, part of the fixed time in cycle calculations.
This section discusses the cycle time of scrapers and its various components, emphasizing the significance of optimizing loading, hauling, dumping, and turning times.
In this section, the cycle time of scrapers is broken down into fixed and variable components, including loading, dumping, turning, and haul times. The discussion covers how to maximize efficiency and reduce cycle time through optimal loading strategies and route maintenance.
The cycle time of a scraper encompasses several components that contribute to its overall operational efficiency. It is given by the formula:
Cycle Time = LT + HT + DT + RT + ST + TT + ADBT
Where:
The cycle time can be categorized into:
Understanding these components will aid in enhancing scraper productivity and reducing overall operational costs.