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.
Introduction to Rolling Resistance
Unlock Audio Lesson
Today, we’re going to discuss rolling resistance, which is the resistance a tire encounters while rolling on a surface. Can anyone explain why this concept is important in construction?
It helps to determine how much power we need for our machinery, right?
Exactly! Rolling resistance influences the power requirements, which directly impacts the cost and efficiency of our operations. Let’s break this down further.
Factors Affecting Rolling Resistance
Unlock Audio Lesson
What are some factors that we think might affect rolling resistance?
I think the type of surface plays a big role.
And the condition of that surface! Well-maintained roads would have less resistance.
Exactly! We have hard surfaces like concrete which are better than soft surfaces like earth. Surface maintenance is crucial too, as it affects resistance.
Impact of Tire Design on Rolling Resistance
Unlock Audio Lesson
Now, let's talk about tire design. How might tires affect rolling resistance?
A wider tire would be better for soft surfaces.
And narrow tires with high pressure help on hard surfaces to reduce the contact area.
Correct! The right tire design is crucial for minimizing rolling resistance effectively.
Calculating Tractive Effort
Unlock Audio Lesson
Let’s work through a calculation. Suppose a vehicle’s rolling resistance is 70 kg per ton on a certain road. If it weighs 20 tons, how would you find the tractive effort required?
We would multiply 70 kg by the total weight!
Exactly! So, 70 kg multiplied by 20 tons gives us a total tractive effort. This tells us how much force we need to keep the vehicle moving.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
Rolling resistance is defined as the resistance encountered by wheels as they move over a surface and varies with the type and condition of the surface. This section elaborates on how factors like surface type, tire design, and maintenance affect the overall performance of earthmoving equipment, ultimately influencing operational efficiency and costs.
Detailed
Factors Affecting Rolling Resistance
Rolling resistance is a crucial parameter in earthmoving operations, representing the resistance encountered by wheels as they roll over a surface. The resistance encountered can vary significantly based on several key factors, including the type of surface (e.g., concrete versus earthen), the condition of the surface, and the design of the tires themselves. In order to optimize equipment efficiency and minimize costs, it’s essential to understand these influences.
Key Factors Influencing Rolling Resistance
- Type of Surface: Rolling resistance differs across various surfaces. For instance, concrete roads generally have lower rolling resistance when compared to earthen roads, where conditions can lead to higher resistance due to soft ground.
- Surface Condition and Maintenance: The performance of earthen roads can enhance if they are well-compacted and maintained, suggesting the importance of regular maintenance to minimize resistance.
- Tire Design: The dimensions and pressure of the tires also play a significant role. For harder surfaces, narrow treads and high tire pressure help minimize contact area and hence resistance; however, for softer surfaces, broader treads and lower pressure are preferable to prevent sinking into the material.
- Overall Impact: Proper understanding of these factors is vital as they affect the power required to overcome resistance, influencing the operating costs and efficiency of earthmoving operations.
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Understanding Rolling Resistance
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Rolling resistance is nothing but what is the resistance offered by the hauled route to the wheel which is rolling over the particular surface.
Detailed Explanation
Rolling resistance refers to the force that opposes the motion of a wheel as it rolls over a surface. This force is influenced by the type of surface the wheel is on. For instance, rolling resistance will be different when moving on concrete compared to loose soil. The main idea here is that whenever equipment moves, it doesn't face just air friction; the surface itself pushes back against the wheels, slowing them down.
Examples & Analogies
Think of riding a bicycle on different surfaces. When you ride on a smooth road (like concrete), it's easier to pedal because there's less resistance. However, if you go onto a sandy beach, pedaling becomes much harder because the sand pushes against your tires, making it more challenging to move forward. This difference in resistance is similar to rolling resistance on various surfaces.
Factors Influencing Rolling Resistance
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Resistance to the motion of equipment on a level surface is called as rolling resistance. It varies with the type of the hauled route.
Detailed Explanation
The rolling resistance is not uniform; it changes based on the type of surface. For example, a hard surface like asphalt creates less resistance than a soft, uneven surface like an unpaved road. Additionally, well-maintained surfaces tend to have lower resistance compared to those that are poorly maintained. Therefore, understanding the nature of the surface is crucial in estimating how much power will be required for equipment to move efficiently.
Examples & Analogies
Imagine how a car drives on a new, well-maintained highway versus a bumpy dirt road. On the highway, it glides smoothly, using less fuel and energy. But, on the dirt road, the car has to work harder to keep moving, which is similar to how rolling resistance differs between hard and soft surfaces.
Maintaining Haul Roads
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Depending upon how you maintain it and prepare the earthen roads, it can even give you a better performance equivalent to hard roads.
Detailed Explanation
The condition of the hauled route significantly impacts rolling resistance. Proper maintenance can create conditions that lower resistance, making it similar to that of hard roads. For instance, regular compaction and ensuring optimal moisture content can keep earthen roads firm and reduce how much the tires sink, thereby reducing resistance during movement.
Examples & Analogies
Consider a garden path. If you keep it clear, firm, and dry, it's easy to walk on, similar to a paved sidewalk. However, if it’s overgrown with grass or muddy, walking will take more effort. The same goes for the machines – well-maintained routes reduce resistance and effort needed to operate.
Impact of Machine Mounting
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, mounting in the sense, it can be either a wheel mounted or it can be a track-mounted.
Detailed Explanation
The type of mounting (wheels vs. tracks) also plays a role in rolling resistance. Wheel-mounted machines generally perform better on hard surfaces, while track-mounted machines (like bulldozers) distribute weight more effectively over weaker surfaces, reducing penetration resistance.
Examples & Analogies
Imagine walking on a frozen lake in high heels versus in snowshoes. The snowshoes are designed to spread out your weight and prevent you from sinking, just as track-mounted equipment spreads out its weight. In contrast, heels put more pressure on a small area, making you sink more - the same principle applies to equipment on different surfaces.
Calculating Rolling Resistance
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
So, rolling resistance is expressed in kilograms of tractive effort or pounds of resistance required to move each ton of the vehicle weight over a level surface of the specified type.
Detailed Explanation
Rolling resistance is typically quantified in terms of 'tractive effort', which can be expressed in kilograms or pounds. This represents how much force is required to move a vehicle across a certain surface. By understanding how much power is necessary to overcome these resistances, operators can choose the appropriate machinery that can manage that level of effort.
Examples & Analogies
When planning a road trip, you consider the fuel your vehicle needs based on how much resistance the road will provide. Just like fuel economy decreases on steep hills or bumpy roads, rolling resistance tells us how much energy our machines will consume as they navigate different surfaces.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Rolling Resistance: The resistance that affects the power needed for earthmoving operations based on surface interaction.
-
Surface Type: Different surfaces (hard vs. soft) significantly affect the level of rolling resistance encountered.
-
Tire Design: The design characteristics of tires, including width and inflation, can influence rolling resistance and vehicle performance.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
A bulldozer on a well-maintained concrete surface will experience less rolling resistance compared to the same equipment on an unpaved earthen road.
-
For a construction vehicle weighing 20 tons, if the rolling resistance on a gravel road is calculated to be 70 kg per ton, the total tractive effort required to maintain movement will be 1400 kg.
-
Using wider tires with lower inflation on soft soil can prevent them from sinking, thereby reducing rolling resistance.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
-
On hard roads, narrow tires ride, / With high pressure they glide.
📖 Fascinating Stories
-
Imagine a bulldozer on a rocky road; narrow tires help it glide smoothly, whereas on a muddy path, the same tires get stuck—showing us how tire type matters.
🧠 Other Memory Gems
-
Remember the phrase 'STP' - Surface type, Tire design, Maintenance, helps you recall the factors affecting rolling resistance.
🎯 Super Acronyms
Use the acronym 'RES' to remember
- R: for Rolling resistance
- E: for Efficiency
- S: for Surface types.
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Rolling Resistance
Definition:
The resistance encountered by wheels as they move over a surface, affecting the power required for machinery.
-
Term: Tractive Effort
Definition:
The force needed to move a vehicle over a surface, typically influenced by rolling resistance and surface condition.
-
Term: Surface Resistance
Definition:
The resistance due to the contact between the wheel and the travel surface.
-
Term: Penetration Resistance
Definition:
The resistance experienced when a tire sinks into a softer surface.