Professional Courses
Industry-relevant training in Business, Technology, and Design to help professionals and graduates upskill for real-world careers.
Categories
Interactive Games
Fun, engaging games to boost memory, math fluency, typing speed, and English skills—perfect for learners of all ages.
Typing
Memory
Math
English Adventures
Knowledge
Enroll to start learning
You’ve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Understanding Rimpull and Its Importance
Unlock Audio Lesson
Today, we're going to discuss rimpull. Can anyone tell me what rimpull means?
Is it the pulling force that a wheel can exert on the ground?
Exactly! Rimpull is the force available at the wheels to do work. Remember, it is primarily determined by two factors: the coefficient of traction and the weight on the powered wheels.
What’s the coefficient of traction?
Great question! The coefficient of traction indicates how well the wheels grip the surface. A higher coefficient means better grip!
How does weight factor into this?
The more weight on the driving wheels, the more rimpull we can generate. Hence, knowing how much of the total weight rests on the drive wheels is vital! It leads us to calculate usable rimpull more accurately.
To remember this, think of 'RIMPULL' - 'R' for Resistance, 'I' for Input weight, 'M' for Maximum force that can be generated. This acronym will help you relate weight and traction back to usable power.
So if we have more traction, we can do more work with the same vehicle?
Yes, that's correct! Let's move on to how we calculate this, including the influences of the environment and the specifics of the load.
Calculating Maximum Usable Rimpull
Unlock Audio Lesson
Now, we will calculate maximum usable rimpull. Can anyone tell me the formula?
It's the coefficient of traction times the weight on the powered running gear, right?
Correct! Let's apply it now. For a scraper with a gross weight of 76,000 kg and a coefficient of traction of 0.7, what would the maximum usable rimpull be?
So, 0.7 times half of 76,000 kg would be what, 26,600 kg?
Exactly! Now this value represents the maximum rimpull available. But there's more; we need to consider rolling resistance, which is 2% of the gross weight. Can someone calculate that?
That would be 0.02 times 76,000 kg, which is 1,520 kg.
Great! Why is this figure important?
It shows how much pulling force we need to overcome just to keep the scraper moving!
Precisely! Remember to always subtract resistances from your rimpull to get your effective pulling capacity.
Altitude and Efficiency Adjustments
Unlock Audio Lesson
Let's talk about altitude effects now. How does altitude impact a machine's performance?
Doesn't it reduce air pressure, making combustion less efficient?
Absolutely! Particularly for combustion engines. At 600 meters, we need to adjust the rimpull further. Can anyone tell me how we would do this?
We would reduce it by 3% for every 300 meters above 300 meters.
Correct! So how would we calculate the deduction at 600 meters?
For the first 300 meters there's no deduction, but for the next 300, the deduction would be 3% of the maximum rimpull! So, that's 3% of 26,600 kg.
Great work! This accounts for the reduction of effective rimpull. Remember, lower efficiency from altitude means we must closely manage power outputs.
To help you remember: ALTITUDE - 'A' for Air pressure, 'L' for Lower performance, 'T' for Tolerate reductions, 'I' for Impact on rimpull, 'T' for Temperature, 'U' for Usage, 'D' for Deduction needed, 'E' for Efficiency decrease.
Practical Application of Rimpull Calculations
Unlock Audio Lesson
Now that we understand the theory, let’s see it in practice. How do we determine rimpull in different gears?
We use the horsepower formula, factoring in gear speed, right?
Yes! The formula is Rimpull = 273.6 x HP x Efficiency / Speed. Let’s calculate for the first gear at 6 km/h with 500 HP and 80% efficiency.
That gives us 18,240 kg as the supplied rimpull!
Exactly! And after altitude adjustment, what would our available rimpull be?
It would be 17,692.8 kg after subtracting 547.2 kg for altitude.
Right! And how does this help us in operational decisions?
We can determine if we have enough power to move up inclines based on our rimpull!
Exactly! Remember, always compare supplied rimpull against the required to avoid slippage.
Selecting Optimal Gear Conditions
Unlock Audio Lesson
Finally, let's reflect on how we select gears. What are the criteria we should consider?
We need to make sure the available rimpull meets the required rimpull for moving uphill.
Good! Can anyone illustrate this using the values we've calculated?
In the top gear, the available rimpull is less than required, so we cannot use it on inclines.
But first and third gears would work because their rimpull exceeds requirements.
Exactly right! Your choice of gear should always hinge on operational conditions. Remember: GEAR - 'G' for Grip, 'E' for Efficiency, 'A' for Adjustment to rimpull, 'R' for Resistance handling.
In summary, to optimize our rimpull calculations, always consider weight, traction, altitude impacts, and gear selection to enhance productivity.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
In this section, the focus is on determining the maximum usable rimpull for scrapers, emphasizing the roles of coefficients of traction, weight distribution, resistance factors like rolling resistance, and adjusting for altitude. Practical examples demonstrate production estimates based on different configurations.
Detailed
Calculating Maximum Usable Rimpull
This section covers essential calculations to estimate the maximum usable rimpull for scrapers, which is crucial for understanding their operational efficiency.
Key Points:
- Definitions: The maximum usable rimpull determines how much force a scraper can exert at its wheels to do work, heavily influenced by the coefficient of traction between the wheels and the ground.
- Weight Distribution: The gross weight of the machine, including its payload, influences the amount of force available. For this context, the weight distribution is noted, with 50% of the total weight resting on the drive wheels.
- Resistance Factors: It's essential to factor in rolling resistance (2% of the gross weight in this case) and gradient resistance, which affects the overall rimpull performance.
- Altitude Corrections: A deduction of rimpull occurs when altitudes exceed 300 meters, as reduced air density impacts engine efficiency. The section explains how to adjust calculations for equipment operating at 600 meters.
- Practical Examples: Example calculations are provided for determining usable rimpull in various gears, clarifying when a machine is suitable for climbing grades or operating efficiently.
The knowledge gained here allows operators to make informed decisions on equipment usage based on calculated rimpull, enhancing productivity while reducing downtime.
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Understanding Usable Rimpull
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
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. 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.
Detailed Explanation
In this chunk, we discuss the economic implications of using fewer scrapers than needed, specifically five scrapers. When the number of scrapers is less than the ideal balance, it creates a situation where scrapers become a bottleneck in the production process. The critical role of the scrapers means that the pusher must wait for them to complete their work before it can follow through with its tasks. This relationship highlights the importance of matching the numbers of scrapers and pushers appropriately for efficient workflow.
Examples & Analogies
Imagine a restaurant kitchen where there are only two chefs (scrapers) to prepare food, but there are four waiters (pushers) ready to serve. The waiters will remain idle if the chefs cannot keep up with food preparation. This scenario emphasizes the need for an optimal balance of chefs to waiters, just as equipment in construction needs to be balanced.
Calculating Production with 5 Scrapers
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, now, let us see the productivity in 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
Here, we outline the steps to calculate the production of scrapers. The volume per load for each scraper is given, specifically at 19.82 bank cubic meters. To determine hourly production with five scrapers, we use the formula provided to multiply the number of scrapers by the volume per load, adjusted for cycle time and machine efficiency. The result yields a productivity rate measured in bank cubic meters per hour.
Examples & Analogies
Think of it like filling water balloons. If each balloon holds 19.82 liters and you have five friends filling them (the scrapers), the total volume filled in an hour will depend on how long each takes to fill a balloon (cycle time) and how efficiently they work together. This ensures that within an hour, you can achieve a specific total.
Analyzing Production Efficiency
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
We need the unit production cost in terms of cost per bank meter cube. That is why we have to estimate the production also in the bank cubic meter.
Detailed Explanation
This portion emphasizes the importance of understanding the cost of production. By calculating the total production volume and related costs, you derive the cost per bank cubic meter. This is vital for evaluating the economic feasibility of using the scrapers, enabling decision-makers to balance productivity against expenses.
Examples & Analogies
Consider a bakery assessing its cost of making pastries. If each pastry costs $2 to make, and they produce 100 pastries, they need to know how much each pastry contributes to their overall expenses to ensure they can sell them for a profit.
Efficiency Comparison Between Scrapers
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Based on productivity if I select obviously I have to go for 6 number of scrapers per pusher, because 5 scrapers is giving you 636.89, 6 scrapers is giving you 723.36 bank cubic meters per hour.
Detailed Explanation
In this part, we compare the outcomes of using five scrapers against six scrapers, highlighting productivity differences. Six scrapers increase production significantly, thus making it a more efficient choice for high-demand scenarios.
Examples & Analogies
Imagine you're assembling furniture. If you have five friends helping you, it takes longer compared to when you have six. With six, tasks are completed faster, just like how adding more scrapers can lead to higher productivity.
Calculating Unit Production Costs
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Let us now estimate the cost. How to calculate the unit production cost? Total unit cost of production for combination.
Detailed Explanation
To calculate unit production costs, you aggregate the total operational costs (such as costs per hour for machines) and divide it by the total production output. This calculation helps in determining which setup is more economically viable by comparing the costs directly with the produced volume.
Examples & Analogies
Think of running a lemonade stand. If you spend $20 on ingredients and make 40 cups of lemonade, your cost per cup is $0.50. Understanding this helps you set a price that covers costs and ensures profit.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Coefficient of Traction: Determines the stickiness of the wheels to the ground surface, impacting rimpull.
-
Usable Rimpull: The actual pulling force available after considering discount factors like altitude and resistance.
-
Rolling and Gradient Resistance: Forces that must be overcome by the rimpull to move effective loads uphill.
-
Weight Distribution: Influences how much weight affects traction and rimpull effectively.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
If a scraper has a gross weight of 76,000 kg and a coefficient of traction of 0.7, the maximum usable rimpull would be 26,600 kg.
-
With a 2% rolling resistance, the resistance force is 1,520 kg, which impacts the effective rimpull available for pulling loads.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
-
Rimpull high, wheels won't slip, grip the ground and let them rip!
📖 Fascinating Stories
-
Imagine a scraper at a construction site trying to move uphill, every bit of traction counts. Just as a climber relies on their grip to ascend a slope, the scraper needs effective rimpull to haul its loads.
🧠 Other Memory Gems
-
Remember ALTITUDE - A for Air pressure, L for Loss in efficiency, T for Terrain impacts, U for Underfoot changes, D for Deduction needed, E for Efficient operation adjustments.
🎯 Super Acronyms
RIMPULL = R for Resistance, I for Input weight, M for maximum force.
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Rimpull
Definition:
The pulling force exerted by the wheels of a scraper on the ground.
-
Term: Coefficient of Traction
Definition:
A measure of how much grip a wheel can exert against a surface.
-
Term: Rolling Resistance
Definition:
The resistive force that acts against the motion of a vehicle due to the contact between its wheels and the surface.
-
Term: Gradient Resistance
Definition:
The force required to overcome the incline when moving uphill.
-
Term: Gross Weight
Definition:
The total weight of the machine plus its payload.
-
Term: Altitude Correction
Definition:
Adjustments made to performance calculations based on operating altitude.
-
Term: Horsepower (HP)
Definition:
A unit of measurement for power that indicates the capability of an engine.