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Interactive Audio Lesson
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Introduction to Cycle Time Components
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Today, we are going to explore the concept of cycle time in scrapers and its components. Can anyone tell me what cycle time includes?
Does it include loading and dumping times?
Exactly! The formula for cycle time combines Load Time (LT), Haul Time (HT), Dump Time (DT), Return Time (RT), Spotting Time (ST), Turn Time (TT), and ADBT. ADBT stands for Acceleration, Deceleration, and Braking Time.
What makes fixed time different from variable time?
Good question! Fixed time is independent of travel distance while variable time, which includes haul and return times, is heavily dependent on the distance traveled and speed of the machine.
And how does the machine speed get affected?
Machine speed can be influenced by several factors including underfoot conditions and equipment types. It is crucial to optimize this for efficiency!
In summary, understanding fixed and variable times can help in planning operations better to enhance productivity.
Loading Time and Load Growth Curve
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Let’s discuss loading time! Loading time remains fairly consistent for different scraper sizes. Can anyone guess why?
Is it because they are usually assisted with pusher loaders?
Exactly! Now, have you heard of the load growth curve? It’s an important principle in loading scrapers.
What does it show?
It shows that loading beyond a certain point—typically more than 85% of the scraper bowl—can decrease production due to increased resistance.
So we should avoid overfilling to stay efficient?
Exactly! Always aim for optimum loading time by referring to the load growth curve. This aids in maintaining operational efficiency.
Remember, optimizing loading time is critical for improving overall scraper productivity.
Hauling and Route Maintenance
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Now let’s talk about haul and return times. Does anyone remember the factors affecting these times?
It’s mostly about distance and speed, right?
Correct! Additionally, maintaining the haul route can significantly reduce these times. Why do you think that is important?
It probably helps avoid wear and tear on the machine and increases speed!
Exactly! An effectively maintained haul route minimizes resistance and improves overall productivity. What factors might influence route maintenance?
Weather conditions could make it tougher to maintain!
Right! The effort invested in maintaining these routes pays off in terms of reduced cycle time and cost.
Remember, keeping a clean and clear haul route is key to effective scraper operation.
Dump Time and Safety Practices
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Let’s shift our focus to dump time. So, what can you tell me influences dump time?
I think it varies based on the size of the scraper and type of material?
Great point! Additionally, site constraints and congestion at dump sites can further impact dump times.
What’s the safest way to dump?
The safest practice is to dump before turning, especially when loaded. This reduces risk during operations.
So, what is the average turning time affected by?
The average turning time is typically higher in cut areas because of congestion and equipment involvement. Always prioritize safety!
In summary, understanding the implications of dump time enhances both productivity and operational safety.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
The section elaborates on cycle time calculations for scrapers, detailing fixed and variable time components such as loading, hauling, dumping, and turning times. It also emphasizes the importance of proper maintenance of haul routes, the effects of loading methods, and optimizing production by understanding the dynamics of dump time and load growth curve.
Detailed
Dump Time: Detailed Overview
In the context of scrapers, the cycle time is a critical measure that incorporates various durations, represented mathematically as:
Cycle Time Equation
Cycle time = LT + HT + DT + RT + ST + TT + ADBT
Where:
- LT: Load Time
- HT: Haul Time
- DT: Dump Time
- RT: Return Time
- ST: Spotting Time
- TT: Turn Time
- ADBT: Acceleration, Deceleration, and Braking Time
Components of Cycle Time
The cycle time can be divided into fixed and variable components.
- Fixed Time: Includes loading, dumping, turning, accelerating, and decelerating, which do not depend on travel distance.
- Variable Time: Primarily consists of haul and return times, which are influenced significantly by travel distance and machine speed.
Loading Time
Loading time is notably consistent across different scraper sizes and is often supported by pusher loaders. Key points to note include:
- The average loading time for a pusher-loaded scraper is around 0.8 minutes for common earth.
- There's a load growth curve where loading beyond 85% leads to diminishing returns in productivity due to material resistance.
Haul and Dump Time
Hauling and return times vary based on site conditions, maintenance of haul routes, and machinery speed. Proper maintenance reduces cycle time and improves productivity.
- Dump time varies based on scraper size, material consistency, and site constraints.
- Operative safety practices dictate the most effective dump method considering project layout.
Conclusion
Understanding these components enables effective planning and optimization of construction operations, ensuring timely project execution and cost efficiency.
Audio Book
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Understanding Cycle Time
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Cycle time = LT + HT + DT + RT + ST + TT + ADBT (Where, LT-Load, HT-Haul, DT-dump, RT-Return, ST-Spot, TT-Turn, ADBT- Acceleration, Deceleration and braking)
Detailed Explanation
Cycle time is the total time taken to complete one full operational cycle of a scraper. It encompasses several components: Load Time (LT), Haul Time (HT), Dump Time (DT), Return Time (RT), Spotting Time (ST), Turn Time (TT), and the time taken for Acceleration, Deceleration, and Braking (ADBT). Each component contributes to the overall efficiency and productivity of the machine, and understanding these components helps in optimizing the operational process.
Examples & Analogies
Imagine running a race where you have to complete several tasks: warming up (Acceleration), running (Haul), stopping to catch your breath (Dump), returning to start (Return), and taking turns (Turn). Just like a racer must consider each phase to improve their total time, operators must consider each phase of the cycle to enhance the scraper's efficiency.
Fixed and Variable Time Components
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So, basically you can split the cycle time into 2 parts. One is fixed time, other one is variable time. Fixed in the sense this part of the cycle time does not depend upon your travel distance. So, that is called as fixed time, say your loading, dumping, turning, your accelerating, decelerating. All these things comes under the fixed time. The other one is a variable time, your haul and return is a variable time because it is significantly dependent on your travel distance.
Detailed Explanation
Cycle time is broken into two parts: fixed time and variable time. Fixed time does not change based on how far or fast the scraper travels; it includes tasks like loading, dumping, and turning. Variable time, however, is affected by the distance traveled and the speed of the machine. For instance, hauling material over longer distances will require more time than shorter distances, reflecting the variable nature of this component.
Examples & Analogies
Think of a trip you take: no matter where you go, the time you spend packing your bags and getting ready (fixed time) remains the same. However, the trip duration (variable time) changes based on how far your destination is. Similarly, the fixed and variable times of a scraper's operation help in estimating its overall efficiency.
Loading Time Consistency
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So, basically the loading time of the scraper is fairly consistent irrespective of the scraper size. ... average load time for the pusher loaded scraper in common earth. Say for example this typical values given for common earth it is 0.8 minute.
Detailed Explanation
The loading time for scrapers remains relatively stable regardless of their size. It is largely dependent on the assistance provided by a pusher. Typically, for standard earth materials, the average loading time is recorded at about 0.8 minutes. This consistency allows operators to rely on manufacturer data to predict performance efficiently.
Examples & Analogies
Consider a fast-food restaurant: whether you are ordering a small meal or a large feast, the time taken to prepare your order (loading time) doesn’t differ much if the kitchen is efficient, just like loading time is somewhat constant for scrapers aided by pushers.
The Load Growth Curve
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Another important concept which we need to know is about the load growth curve for scraper loading. ... the loading rate will start reducing, that is why we have to draw this kind of load growth curves and you have to find the optimum loading time.
Detailed Explanation
The load growth curve illustrates how loading a scraper to its maximum capacity does not necessarily maximize production; in fact, loading beyond a certain point reduces the loading rate. This phenomenon, referred to as diminishing returns, emphasizes the importance of identifying optimal loading time for efficiency.
Examples & Analogies
Imagine a cereal box: initially, you can easily refill it (fast loading), but as it gets fuller, spilling occurs, making refills slower (reducing loading rate). Like finding the right portion size for your cereal, finding the optimal loading amount for a scraper can significantly impact productivity.
Haul and Return Time
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So, the next important component of the cycle time of the scraper is your haul and return time, ... you have to determine the speed of the machine in every section independently.
Detailed Explanation
Haul and return time, a variable component of cycle time, is determined by distance and speed. Different conditions in the haul route can affect the efficiency. It's essential to maintain the haul route even through actions like watering to reduce dust and enhance visibility, which collectively can lower cycle time and boost productivity.
Examples & Analogies
Think of an athlete training on a track: if the track is well-maintained, they can run faster (less haul time) compared to running on a rough terrain where they may trip (longer return time). Just like the athlete needs a good track to maintain speed, scrapers need well-kept haul routes to minimize cycle time.
Dumping Time Factors
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So, the next important thing which we are going to see as a component of your cycle time is your dump time. ... this is the best way dump before turning...
Detailed Explanation
Dump time varies based on the scraper's size, the material being dumped, and site constraints like congestion. Efficient dumping is critical; dumping before turning is safer and quicker than doing so while loaded. Understanding these dynamics aids in planning operations to minimize dump time.
Examples & Analogies
Consider a truck unloading cargo: unloading while parked safely (dumping before turning) is quicker and reduces accidents compared to unloading while trying to maneuver (turning while loaded). Just like a truck needs to unload properly, scrapers require efficient dumping processes to maximize productivity.
Estimation of Cycle Time
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So, far we have discussed about the cycle time of the scraper. ... to reduce your unit production cost.
Detailed Explanation
After reviewing all components of the cycle time, we understand that the fixed and variable times collectively influence productivity and cost. The fixed section consists of loading, dumping, and turning times, while the variable section encompasses haul and return times. Together, effective management of these factors can enhance efficiency and lower costs.
Examples & Analogies
Think of planning a road trip where you must consider gas stops (fixed time) and variable traffic conditions (variable time). By estimating these elements correctly, you can save money and make your trip smoother. Similarly, understanding the cycle time allows for enhanced production planning in scraper operations.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
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Fixed Time: Components that do not depend on travel distance, including load, dump, and turn times.
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Variable Time: Components that depend on distance and speed, including haul and return times.
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Load Growth Curve: The phenomenon where loading rate decreases after a certain threshold, affecting production.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
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If a scraper has an average loading time of 0.8 minutes but exceeds 85% of bowl capacity during loading, the loading rate may drop significantly.
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Proper maintenance of haul roads can reduce travel time, thereby improving the machine's productivity.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
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Loading time is a steady climb, overloading gives us less time.
📖 Fascinating Stories
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Imagine a baker who has a tray. If too much dough fills it, some won't blend in—they only cause trouble and make the baking murky.
🧠 Other Memory Gems
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To remember the cycle time components, think 'L-D-H-R-S-T-T-A' for Load, Dump, Haul, Return, Spot, Turn, and then Acceleration.
🎯 Super Acronyms
CYCLE for remembering
- C: for Components
- Y: for Yield
- C: for Capacity
- L: for Load time
- E: for Efficiency.
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
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Term: Cycle Time
Definition:
The total time taken for a scraper to complete one full operation cycle, including various time components.
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Term: Load Time (LT)
Definition:
The time taken to load materials into the scraper.
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Term: Dump Time (DT)
Definition:
The time taken to dump materials from the scraper.
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Term: Haul Time (HT)
Definition:
The time taken to transport materials from the loading site to the dumping site.
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Term: Fixed Time
Definition:
The portion of cycle time that is independent of travel distance.
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Term: Variable Time
Definition:
The portion of cycle time that depends on travel distance.
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Term: Load Growth Curve
Definition:
A graphical representation showing the relationship between loading time and the percentage of payload.