3.1 - Rimpull Sufficient Analysis
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Introduction to Scraper Economics
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Today, we'll explore the economics of scrapers in operation. Can anyone explain why knowing the number of scrapers is critical?
Is it because fewer scrapers can lead to more idle time for pushers?
Exactly! When scrapers are limited, production is controlled by their availability. The pushers will wait while scrapers are busy. This balance is essential for maximizing efficiency.
So if we have excess scrapers, does that mean production is controlled by the pusher?
Correct! When there are more scrapers than needed, they end up waiting, and the focus shifts to the pusher's cycle time.
Remember when calculating efficiency, we use the formula: Efficiency = (Volume per load × Number of scrapers) / (Cycle time × Job efficiency). Anyone recall what efficiency means?
It's how effectively the scrapers or pushers use their operational time!
Great job! Understanding this concept lays the groundwork for analyzing productivity.
Calculating Production Efficiency
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Let's calculate production efficiency for five scrapers. If the bowl volume is 19.82 cubic meters and the cycle time is 7.78 minutes, what do we do?
We would plug these values into the formula you mentioned earlier.
Exactly! Following the calculations, we would find that production per hour would equal 636.89 cubic meters. But what if we switch to six scrapers?
The production would increase, right? We’ll find higher efficiency than with five scrapers.
Absolutely! This highlights how productivity improves with the right configuration.
It's essential to balance scrapers and pushers. Can anyone summarize why that’s crucial?
To reduce idle time and maximize total production!
Well said! Balancing ensures that neither scrapers nor pushers are waiting on each other unnecessarily.
Understanding Rimpull and its Importance
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Let's dive into the rimpull. Who remembers what rimpull actually refers to?
It's the tractive force at the contact point between the wheel and the ground, right?
Correct! Now, if we know our rimpull is determined by the coefficient of traction and the weight on the drive wheels, how can altitude affect it?
I think higher altitude reduces engine power, which can lower the rimpull.
You're absolutely right! The altitude correction can reduce rimpull by 3% for every 300 meters above sea level, affecting overall efficiency.
Now, let's summarize why it's crucial to assess rimpull when planning operations.
If we don't, we might not have enough force to move the load, leading to slippage.
Exactly! Understanding and calculating rimpull ensures we can effectively manage scraper operations.
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
The section provides a detailed examination of how the number of scrapers affects production rates and costs associated with their use. It explains the calculation of scrapers' productivity based on rimpull and identifies optimal combinations for maximizing efficiency while considering costs.
Detailed
In this section, we analyze the economics surrounding the use of scrapers, specifically how the number of scrapers in operation influences productivity. When fewer scrapers than the required balanced amount are used, productivity is limited by the scrapers themselves, as they control production due to scarcity, causing pushers to wait idly. The section illustrates how to calculate scraper productivity using formulas involving bowl volume, cycle time, and job efficiency. Conversely, when more scrapers than necessary are available, production is determined by the pusher's cycle time, demonstrating the critical differences in operational efficiency based on scraper quantity. The section also discusses the costs of production per bank cubic meter, comparing scenarios with five and six scrapers to identify optimal combinations for maintaining cost-effectiveness in operations. Ultimately, it emphasizes the importance of analyzing rimpull—the effective force that scrapers can exert—under various operational conditions to ensure that they have sufficient force to handle the load without slippage.
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Introduction to Rimpull Analysis
Chapter 1 of 9
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Chapter Content
Now let us consider the economics of going for 5 scrapers. So, 5 in the sense you are going to use lesser than what is needed, you are assuming 5 that means you are going to use the number of scrapers lesser than what is needed.
Detailed Explanation
In this introduction, the text discusses the scenario of using fewer than the optimal number of scrapers needed for a task. By only using 5 scrapers, one is limiting their efficiency since there are not enough scrapers to keep up with the required workload. This sets the stage for a deeper exploration into the production capabilities and the associated economics of the operation.
Examples & Analogies
Consider a pizza restaurant that can serve 100 pizzas in an hour, but they only have two ovens instead of three. Even though they have the capacity to bake more, the limited number of ovens means they can't meet the demand during busy hours, affecting their overall sales.
Impact of Scraper Availability
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Chapter Content
So, when the number of scrapers are lesser than the balanced number so obviously scrapers are more critical, but a pusher will have the ideal time. Your pusher will wait for the scraper. So, unless a scraper is available you cannot complete the job.
Detailed Explanation
Here, it is explained that when there are too few scrapers, the operation is limited by the scraper's availability. The pusher, which helps move materials, ends up having idle time because it cannot proceed until the scraper has finished its work. This bottleneck highlights the importance of balancing the number of machines used in operation to ensure efficiency.
Examples & Analogies
Think of a relay race where one runner is significantly slower than the others. The faster runners will have to wait for the slower runner to catch up before they can pass the baton, ultimately slowing down the entire team's performance.
Calculating Production for 5 Scrapers
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So, now, let us see the productivity this case of n equal to 5 scrapers. How to estimate the production of this scraper? The volume of your bowl volume per load, you know the value of 19.82 bank cubic meter.
Detailed Explanation
This segment introduces calculations for estimating the productivity of the 5 scrapers. It is noted that each bowl load has a volume of 19.82 bank cubic meters, which will be used in calculations to determine the overall production. The effective production rate will depend on the number of scrapers, the cycle time of each scraper, and the operational efficiency.
Examples & Analogies
Imagine filling a bucket with water. If each bucket can hold 10 liters, and you have 5 buckets, the total amount of water you can carry in one trip is 50 liters. Similarly, the number of scrapers directly influences the total volume of material that can be moved.
Production Calculation Methodology
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Production (Scraper controlling) min Efficiency, hr = × number of scrapers × vol. per load Cycle time of scraper, min 50 min/hr = ×5 ×19.82 bcm = 636.89 bcm/hr.
Detailed Explanation
This segment outlines the formula for calculating scraper production. By multiplying the number of scrapers by the volume per load and dividing by the cycle time, the total production in bank cubic meters per hour is derived. The efficiency factor of 50 minutes of operating time is taken into account to provide a realistic estimate.
Examples & Analogies
Imagine a team of workers assembling toys. If each worker can assemble 5 toys in an hour, and there are 10 workers, the total output is 50 toys an hour. This formula calculates productivity just like that team.
Comparing Different Scenarios of Scraper Numbers
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If n is greater than the balance number that means you are going to use more number of scrapers, then what is indicated by the balance number. In this case, scrapers will have the ideal time. Scrapers are not critical. So, the scraper will be waiting for the pusher.
Detailed Explanation
This chunk examines what happens when more scrapers are used than the optimal number. In this case, the scrapers are underutilized while the pusher becomes the limiting factor. The production efficiency shifts, and understanding this balance is essential for optimizing operations.
Examples & Analogies
In a school band, if there are too many drummers and not enough flutists, the drummers may end up playing less than they could because they are waiting for the flutists to catch up with the performance schedule.
Estimating Production with More Scrapers
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In this case, how to estimate the production? Efficiency, min/hr Production (Pusher controlling) = × vol. per load Cycle time of pusher, min.
Detailed Explanation
This portion focuses on the scenario where scrapers outnumber the required amount. The production calculation method shifts focus to the pusher instead, where the efficiency of the pusher's cycle time controls the overall production rate. The formula involves volume per load and the pusher's cycle time.
Examples & Analogies
If you have a large group of runners at a track, but only one person has the baton to run with, the speed at which they can finish the race will depend on how fast that one person can run, despite the many waiting.
Unit Production Cost Estimation
Chapter 7 of 9
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Let us now estimate the cost. How to calculate the unit production cost? Total unit cost of production for combination = Cost of Push tractor with operator + Cost of scrapper with operator × number of scrapers / Job production.
Detailed Explanation
In this section, the calculation for unit production cost is introduced. This involves summing the costs associated with both the pusher and the scrapers, then dividing by the total job production. This helps to understand the cost effectiveness of the operation.
Examples & Analogies
Think of it like preparing a meal. You calculate the total cost of ingredients and divide it by the number of meals you can serve to determine the cost per meal.
Choosing Optimal Scraper and Pusher Combination
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So, if you are more concerned about productivity, if you have a very tight deadline, you have to finish the project faster. In that case people prefer to go for the combination which gives you higher productivity...
Detailed Explanation
This part discusses the decision-making process regarding the choice between using more scrapers for higher productivity versus considering the cost implications. Organizations often have to balance between the two based on project deadlines and budget constraints.
Examples & Analogies
This is akin to choosing between hiring more workers to complete a task quickly or keeping fewer workers to save on payroll expenses, depending on the urgency of the project.
Conclusion on Rimpull Sufficiency
Chapter 9 of 9
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Chapter Content
The conclusion is the rimpull sufficient for the different gears first gear, second gear and third gear, only for the top gear it is not sufficient.
Detailed Explanation
The conclusion summarizes the findings of the rimpull sufficiency across various gear settings. It indicates when the rimpull can manage to pull the scraper load effectively and when it cannot, particularly highlighting the limitations present in the top gear due to higher resistance.
Examples & Analogies
It's like driving a car up a steep hill; in lower gears, you can accelerate, but in higher gears, you struggle to gain speed or may even stall out completely.
Key Concepts
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Scraper productivity is influenced by the number of scrapers and the efficiency of pushers.
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Rimpull is critical for moving loads efficiently without causing slippage.
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Cycle time is essential for calculating overall operational efficiency.
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Cost per bank cubic meter is vital for evaluating economic feasibility.
Examples & Applications
If five scrapers can produce 636.89 bank cubic meters per hour, then six scrapers should produce more due to better efficiency.
At an altitude of 600 meters, applying a 3% reduction in rimpull ensures that scraper operations are adequately evaluated against operational needs.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
Scrapers in a line, five or six, watch the cycles, learn the tricks.
Stories
Imagine a busy construction site where scrapers, much like chefs in a bustling kitchen, must gather ingredients (loads) quickly to prepare the meal (completed work), balancing their numbers for optimal output, just as chefs rely on their sous-chefs to keep the kitchen running smoothly.
Memory Tools
SCRAP - Scraper Count Reduces Advertising Pusher idle time: Helps remember how scraper quantities affect operations.
Acronyms
CAT - Coefficient, Altitude, Traction
Key factors in determining scraper effectiveness.
Flash Cards
Glossary
- Rimpull
The tractive force generated by a scraper at the wheel-ground contact that can be used to move loads.
- Coefficient of Traction
A measure of the friction between the scrapers' wheels and the ground, determining effective force application.
- Cycle Time
The time taken to complete a cycle of operations, including loading, hauling, and dumping.
- Job Efficiency
The effective working time a machine operates compared to total time available.
- Balanced Number of Scrapers
The optimal number of scrapers needed to achieve maximum production without causing delays for either scrapers or pushers.
Reference links
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