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Interactive Audio Lesson
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Understanding Cycle Time
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Today, we are going to explore cycle time for scrapers. Can anyone tell me what cycle time comprises?
Is it about the time taken for different operations of the scraper?
Exactly! It's the total time needed to complete a specific operation. It includes loading time, hauling time, and more. Let's break down these components. We use the formula: Cycle Time = LT + HT + DT + RT + ST + TT + ADBT.
What does ADBT stand for?
Good question! ADBT stands for Acceleration, Deceleration, and Braking. Memory aid: Think of it as the 'Speed Management' part of your operations.
So, are all these parts essential for calculating the cycle time?
Correct! Each part affects the overall cycle time and productivity.
Do we have a way to categorize these components?
Certainly! We categorize them into fixed and variable times. Fixed times do not change with distance, while variable times do. For example, haul and return times depend on the distance traveled.
To summarize, we've discussed that cycle time represents various operational phases, and understanding it helps improve machine efficiency.
Loading Time
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Let’s discuss loading time. What influences this timing?
Is it based on how big the scraper is?
Size does play a role but generally, loading time is consistent across scrapers. When assisted by a pusher, the loading time stays relatively stable regardless of size.
What about the maximum capacity? Does that impact the loading rate?
Yes, actually it does! You might think loading to the maximum capacity is best, but studies show that it often leads to decreased production due to increased resistance, known as the law of diminishing returns. Remember: optimum loading is key!
So, where can we get the actual loading times?
Typically, you can find that information from the equipment manufacturer or relevant handbooks.
In short, the optimal loading practices can greatly affect the cycle time positively.
Haul and Return Time
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Let's now move on to haul and return time. How does this part work?
I assume it varies with distance?
Yes! This is the variable part of the cycle time. The time taken to haul and return heavily depends on the distance and the speed of the machine treated on site and terrain conditions.
Do we need to maintain the haul routes?
Absolutely! Proper haul route maintenance decreases resistance and enhances speed, improving productivity. Remember, maintain your routes, and you maintain your efficiency.
What if different sections have different resistances?
That's important too! You need to analyze every section independently as different conditions affect speeds.
In summary, haul and return times vary and maintenance is crucial for optimizing these times.
Dump and Turn Time
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Let's discuss dump time — what factors affect it?
I believe it depends on the scraper size and the type of material?
Correct! Larger scrapers take more time to dump, and the type of material affects dumping efficiency too.
What about site conditions?
Environmental constraints play a role as well. If the area is congested, wait times can increase, affecting overall dump time.
And what about turn time?
Good question! Turn time is influenced by congestion too, particularly in cut areas where more equipment is present. Typically, it takes longer in the cut area compared to the fill area.
To summarize, the conditions at the dump site and how scrapers turn in different zones significantly affect timing.
Balancing Scrapers and Pushers
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Finally, let's discuss the role of pushers in cycle time optimization.
How exactly do pushers help with cycle time?
Pushers assist during the loading phase, which can significantly reduce loading times for the scrapers. But we need to ensure that we balance the number of pushers with scrapers. Can anyone guess why?
So one doesn’t wait for the other?
Exactly! Wait times elongate the cycle time and cost. Hence, it is vital to optimize their usage during operations.
What kind of cycle time does a pusher have?
The pusher's cycle time is shorter since its primary job is during the loading phase. This means understanding both roles is crucial for efficiency.
In conclusion, balancing pushers and scrapers is essential for optimized operation and reduced production costs.
Introduction & Overview
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Quick Overview
Standard
The section provides an in-depth look at how to estimate cycle time using the formula and the role of each component in the cycle, including loading, hauling, returning, dumping, turning, and ADBT (Acceleration, Deceleration, and Braking), while also delving into the significance of optimal loading practices.
Detailed
Estimation of Cycle Time
The cycle time for scrapers can be articulated through the formula:
Cycle Time = LT + HT + DT + RT + ST + TT + ADBT
(where LT = Load Time, HT = Haul Time, DT = Dump Time, RT = Return Time, ST = Spot time, TT = Turn time, ADBT = Acceleration, Deceleration, and Braking).
In the context of a scraper, the cycle time is composed of various time components. The fixed time comprises loading, dumping, turning, and acceleration/deceleration, which are independent of travel distance. Conversely, the variable time is contingent upon the hauling and return distances, heavily reliant on the speed of the machine influenced by project conditions.
Loading time remains consistent regardless of scraper size, typically derived from manufacturer specifications. However, unexpected findings suggest loading scrapers to maximum capacity diminishes loading efficiency due to material resistance.
The section also emphasizes the importance of maintaining haul routes to optimize hauling speeds. Factors contributing to dump time include scraper size, material type, and constraints at the dump site, while the turn time is influenced by site congestion. Overall, understanding these components is critical for accurately estimating and enhancing productivity.
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)
So, cycle time of a scraper, it is nothing but load time, hauling time, dumping time, return time, spotting because most of the conventional scrapers are pusher loader scrapers. So, it has to spot the pusher, that spotting time is also included then turning, then ADBT that means the time needed for increasing your speed or decreasing the speed, time needed for applying the brakes. So, all this manure comes under this ADBT acceleration deceleration and the braking.
Detailed Explanation
Cycle time refers to the total time taken for one complete operation of a scraper, which includes various components: Load time (LT), Haul time (HT), Dump time (DT), Return time (RT), Spotting time (ST), Turn time (TT), and Acceleration, Deceleration, and Braking time (ADBT). Each of these processes contributes to the overall cycle time and needs to be measured for effective project management and productivity analysis.
Examples & Analogies
Imagine a bus that has to pick up passengers (Load time), drive to a destination (Haul time), drop off the passengers (Dump time), return to the starting point (Return time), park (Spotting), and maneuver at the pick-up point (Turn time). Just like each step takes time for the bus, each component of cycle time is crucial for a scraper's operation.
Fixed and Variable Time
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So, basically you can split the cycle time into 2 parts. One is fixed time, the 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 come under the fixed time. So, it is not dependent upon the distance travelled. 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 can be divided into two categories: fixed time and variable time. Fixed time is constant and includes tasks like loading, dumping, turning, and maneuvering, regardless of how far the machine travels. On the other hand, variable time, such as hauling and returning, changes based on the distance travelled, which means it can vary depending on factors such as machine speed and project conditions.
Examples & Analogies
Think of fixed time like a standard delivery fee for a pizza, which remains the same no matter where you live. Variable time is like the distance fee for the pizza; if you live far away, you pay more, just like hauling and return times depend on how far the scraper needs to go.
Loading Time
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So, the loading time of the scraper is fairly consistent irrespective of the scraper size. So, commonly we can say that we are going to assist this scraper with the help of a pusher according to the size of the scraper the compatible size of the pusher you have to select and we are going to supplement the loading power. The average load time for the pusher-loaded scraper in common earth is 0.8 minutes.
Detailed Explanation
The loading time for scrapers is largely consistent regardless of the scraper size, largely due to the assistance provided by a pusher. This means whether you're using a large or small scraper, the average loading time remains near 0.8 minutes when handling common earth. It's important to choose a pusher that is compatible with the scraper size to optimize productivity.
Examples & Analogies
It’s like using a smaller or bigger grocery cart to carry groceries. Regardless of the cart size, it takes about the same time to fill it up because you have someone helping you get the items from the shelf to the cart, similar to how a pusher helps load the scraper.
Load Growth Curve and Diminishing Returns
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Another important concept which we need to know is about the load growth curve for scraper loading. So, we commonly believed that when we load this scraper when we fill the bowl of the scraper to the maximum capacity we are going to maximize a production. So, this is what is a common belief... So, do not try to load the scraper to its maximum capacity. The incoming earth encounters greater resistance as the quantity of earth in the bowl increases resulting in a reduction in rate of loading.
Detailed Explanation
The load growth curve illustrates that while many believe that fully loading a scraper maximizes production, this is not necessarily true. Studies show that once a scraper reaches about 85% capacity, resistance from already loaded material slows the rate at which new material can enter, leading to diminishing returns in loading efficiency. Thus, optimal loading should be below maximum capacity.
Examples & Analogies
Imagine trying to stuff too many clothes into a suitcase. Initially, it’s easy to put in clothes, but as the suitcase fills, it becomes harder to add more. Eventually, you can only fit a little more, wasting your time and effort - just like a scraper that reaches full capacity and struggles to load more efficiently.
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, as I told you it is a variable time, it is going to depend upon your travel distance and the speed of your machine. So, haul and return time depends upon the distance and the travel speed.
Detailed Explanation
The haul and return time is a variable component of cycle time, influenced by the distance the scraper must travel and the speed it can achieve given the project's conditions. Because the speed often varies considerably between loaded and unloaded conditions, it is essential to efficiently maintain the haul route to optimize travel speed and consequently reduce overall cycle time.
Examples & Analogies
Consider a truck driving to deliver goods. If the route is bumpy and long, the driver will take longer to reach the destination. However, if the road is smooth and well-maintained, the truck can travel faster, demonstrating how maintaining a clear path significantly affects the delivery time.
Maintaining the Haul Route
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It is economical to maintain the haul route. So, whatever efforts, whatever money you spend for maintaining your haul road, it is going to give you good return by saving your cycle time, by increasing your productivity and thereby reduce your unit production cost.
Detailed Explanation
Investing in the maintenance of the haul route is cost-effective because it reduces cycle time, enhances productivity, and lowers overall production costs. Efforts might include using graders, sprinkling water to control dust, and ensuring the route is clear of obstructions. Proper maintenance leads to smoother operations, which contributes to better productivity for machines like scrapers.
Examples & Analogies
Think of it like taking care of your driveway. If you regularly maintain it, you can drive your car quickly and smoothly. If it’s filled with potholes, it will take much longer to traverse, and you may even damage your vehicle. Similarly, a well-maintained haul route helps scrapers work more efficiently.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
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Cycle Time: The total duration of all operations.
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Fixed Time: Time components that remain unchanged with distance.
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Variable Time: Components that vary depending on conditions and distances.
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Load Time: The time needed to load materials into the scraper.
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Dump Time: Duration necessary to unload materials.
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Hauling Time: The time spent transporting materials from one area to another.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
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Example of Cycle Time Calculation: If LT = 0.8 min, HT = 3 min, DT = 1 min, RT = 2 min, ST = 0.5 min, TT = 0.2 min, then Cycle Time = 7.5 min.
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Load growth curve showing diminishing returns when filling a scraper beyond 85% capacity, leading to reduced efficiency.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
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In the cycle of scrape, don’t overload; it slows the pace, take it slow to unleash the load.
📖 Fascinating Stories
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Imagine a scraper trying to fill its bowl with sand. As the bowl fills, it becomes harder for the sand to enter, slowing down the process. Just like that, less is sometimes more in productivity.
🧠 Other Memory Gems
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Remember 'FLAT DRB': Fixed Load Acceleration Time, Dump Return, fixed times aggregate, hauling's the variable part.
🎯 Super Acronyms
Use 'CHARTS' to remember the cycle
- Cycle Time = Haul + Return + Spot + Turn + Dump + Load.
Flash Cards
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Glossary of Terms
Review the Definitions for terms.
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Term: Cycle Time
Definition:
The total time taken to complete a specific operational task in construction machinery.
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Term: Fixed Time
Definition:
Components of cycle time that do not change with travel distance.
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Term: Variable Time
Definition:
Components of cycle time that vary based on travel distance or conditions.
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Term: ADBT
Definition:
Acceleration, Deceleration, and Braking time, which is part of cycle time measurement.
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Term: Load Growth Curve
Definition:
A graphical representation showing how loading rates change with increasing volume of material.
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Term: Haul Route
Definition:
The path along which materials are transported on a construction site.