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Interactive Audio Lesson
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Understanding Cycle Time
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Today, we will talk about cycle time which is essential for estimating bulldozer productivity. Cycle time consists of fixed and variable components. Can anyone explain what fixed time is?
Is it the time taken for actions that don't change regardless of conditions?
Exactly! Fixed time includes tasks like maneuvering, which can be influenced by the type of transmission—manual or automatic. Student_2, do you remember how these might differ?
Yes! Manual gear changes take longer than automatic ones.
Great! So, let's relate this to productivity. Why do you think understanding cycle time is vital for project bidding?
Because it helps in calculating how much work can be done in a specified time!
Absolutely! Remember, this leads us to estimate productivity accurately. Let's summarize key takeaways: cycle time is split into fixed and variable—fixed time is steady while variable time changes with haul distance and speed.
Calculating Haul and Push Times
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Now, let’s elaborate on variable time! What affects push time and backtrack time?
It depends on haul distance and the speed of the bulldozer, right?
Exactly! The greater the haul distance, the longer the push and backtrack times. Student_1, how do we determine the speed?
From the performance chart based on project resistance!
Correct! Remember to consider total rolling resistance and grade resistance. Why are these factors so crucial?
They affect how fast the bulldozer can push the material!
Exactly, well put! To summarize, the speed derived from performance charts directly influences our estimate of push and backtrack time, which is critical for productivity calculations.
Job Efficiency and Production Curves
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Next, let’s discuss job efficiency. Why can't a bulldozer work the full hour?
Because it might only operate for a part of that hour, due to breaks or project conditions!
Exactly! Job efficiency can vary greatly, so we need to account for it in productivity estimates. What about production curves? Student_4, how do we use them?
We refer to the curves for specific models to find productivity based on dozing distance!
Perfect! Remember, those curves assume ideal conditions, so correction factors are necessary under different conditions. Let's summarize today; we discussed job efficiency's importance and how to utilize production curves effectively.
Application of Correction Factors
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Now, let’s explore correction factors. Why must we apply them?
Because real site conditions can differ from the standard conditions used to create production curves!
Absolutely! Factors like operator skill and material type affect productivity. Student_2, can you give an example of how material type affects it?
If the material is tough, it would take longer to push, reducing productivity!
Right! Also, visibility impacts how effectively the bulldozer can operate. Summarizing, always apply correction factors to cater to actual project conditions to enhance the accuracy of productivity estimates.
Calculating Unit Cost of Production
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Finally, let’s wrap up with cost estimation based on productivity. Why do we calculate unit cost of production?
To understand how much each unit costs during bidding for projects!
Exactly! It’s calculated by dividing the hourly cost of using the machine by the productivity in loose cubic meters. What do we need to know to arrive at the hourly cost?
We need to consider ownership and operating costs!
That’s right! Always take all associated costs into account. In summary, productivity is tied directly to our cost estimates and forms a key component in successful project bidding.
Introduction & Overview
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Quick Overview
Standard
The section outlines how to estimate the productivity of a bulldozer by breaking down its cycle time into fixed and variable components. Factors like haul distance, material type, job efficiency, and operator skill are critical to accurately derive productivity in loose cubic meters per hour. It also introduces methods such as performance charts and thumb rules for simplified estimation.
Detailed
In this section, the productivity estimation of a bulldozer is explored by examining how different elements contribute to cycle time, which impacts overall productivity. Cycle time is divided into fixed time (e.g., maneuvering time) and variable time (e.g., push and backtrack time), with the latter being dependent on haul distance and speed. Performance charts are highlighted as a tool for determining speed based on project conditions like total resistance. The measurement of productivity is expressed in loose cubic meters per hour, emphasizing the importance of job efficiency and material properties in this context. The section also delineates the significance of correction factors when project conditions differ from assumed standard practices, providing a nuanced approach to estimating machine productivity effectively. Additionally, alternative methods such as thumb rules and production curves from manufacturer handbooks are discussed, supporting various estimation strategies.
Audio Book
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Understanding Cycle Time
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So, this cutting and pushing will go together. So, the time required to push, backtrack and maneuver into position, so that is called as a cycle time of the bulldozer.
Detailed Explanation
Cycle time refers to the total time a bulldozer takes to complete one full operation cycle, which includes cutting the earth, pushing it to a designated spot, dumping it, and then returning to the starting position. Each part of this process contributes to the overall cycle time. The cycle time is critical as it helps estimate how efficiently the bulldozer is operating.
Examples & Analogies
Think of the bulldozer as a chef preparing a meal. The cycle time would be similar to the time it takes from when the chef starts chopping vegetables, cooking them, serving the dish, and then cleaning up before starting the next meal. Just like every step in the cooking process takes time, every step in the bulldozer's operation adds to the total cycle time.
Variable vs Fixed Time
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So, we call this as fixed time, this is fixed time and this one is variable time, your push and backtrack it is called this variable time, why do we call this push time and backtrack time as variable time?
Detailed Explanation
In the context of bulldozer operations, fixed time refers to the time it takes for maneuvers (like changing gears), which is relatively constant. In contrast, variable time refers to the push and backtrack times, which can change based on factors like haul distance and the speed of the bulldozer. The further the distance or the slower the speed, the longer these variable times will be.
Examples & Analogies
Imagine driving a car on a long road trip. The time it takes to shift gears (fixed time) remains relatively the same regardless of distance. However, the time spent driving to your destination varies based on traffic conditions and how far away you are (variable time). Thus, in both cases, you have a predictable part and a part that changes.
Calculating Push Time and Backtrack Time
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To know the push time and the backtrack time, I need to know the travel distance or the dozing distance or the haul distance.
Detailed Explanation
To calculate the push time (the time taken to move the bulldozer forward) and backtrack time (the time taken to return to start position), you first need to know certain distances, specifically the dozing distance or haul distance. The longer the distance, the longer the push and backtrack times will be.
Examples & Analogies
Think of pushing a shopping cart. If your grocery store requires you to push the cart from one end of the store to the other far down aisle, it will take longer than if the distance is just a few feet away. Thus, just as knowing the distance affects your time in the store, it similarly affects the bulldozer's operation.
Determining Speed Using Performance Chart
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So, you very well know how to determine the speed. So, in the earlier lecture, I discussed about how to determine the speed from the performance chart.
Detailed Explanation
The speed of the bulldozer can be determined from a performance chart, which presents data on speed versus total resistance. This chart helps operators find the optimal speed based on the specific project conditions and terrain. Knowledge of the speed is crucial as it directly impacts the cycle time and productivity.
Examples & Analogies
Imagine running a race; knowing your average speed can help you understand how long it will take you to finish the race. Similarly, by using the performance chart, operators can estimate how quickly they can complete their work, akin to planning your strategy to finish the race effectively.
Understanding Maneuver Time
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So, now let us see what is this maneuver time? So, already I told you maneuver time is nothing, but the time needed for changing your speed accelerating, changing the gears, or reducing the speed.
Detailed Explanation
Maneuver time involves the adjustments made while operating the bulldozer, like changing gears or modulating speed. This time can vary significantly depending on whether the bulldozer uses direct transmission (manual gear changes) or automatic options like torque converters. The less time spent on these adjustments, the more efficient the operation.
Examples & Analogies
Consider a cyclist who has to change gears frequently while riding up and down hills. If the cyclist has an automatic gear system that adjusts seamlessly, they can focus on pedaling faster rather than shifting gears, much like how bulldozers with automatic systems can operate more efficiently.
Estimating Productivity in Loose Cubic Meters
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Now let us see how to estimate the productivity of the bulldozer. So, we are going to estimate the productivity a lose meter cube per hour.
Detailed Explanation
Productivity of a bulldozer is calculated in terms of loose cubic meters moved per hour. This is obtained by dividing the blade load (amount of material the bulldozer can move in one cycle) by the total cycle time, which includes all components of time discussed earlier. It is crucial to specify whether the volume is measured in a loose state or bank state to avoid confusion.
Examples & Analogies
Imagine a construction worker moving sand with a wheelbarrow. If they need to know how much sand they can transport in an hour, they would assess how much fits in the wheelbarrow (blade load) and how often they can make trips (cycle time). Similarly, measuring bulldozer productivity relies on these simple principles.
Calculating Unit Cost of Production
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Now, to calculate the unit cost associated with every activity, unit cost of earthmoving operation. So, for that you need to know unit cost is nothing but cost per loose meter cube.
Detailed Explanation
The unit cost of production is calculated by dividing the total cost of operating the bulldozer (including ownership and operational costs) by the productivity measured in loose cubic meters. This calculation is vital for budgeting and for determining bids during contracting work.
Examples & Analogies
This is similar to calculating the cost of producing a specific product in a factory. If a factory has to calculate how much each product costs to produce, they would take their total production costs and divide it by the number of products made, just like how we calculate unit costs for bulldozer operations.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
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Cycle Time: Total time for a bulldozer operation including fixed and variable times.
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Fixed Time: Constant time aspects of cycle time, such as maneuvering.
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Variable Time: Time that varies with conditions like haul distance and speed.
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Job Efficiency: Actual working time divided by total available time.
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Production Curve: A visual representation of productivity against dozing distance.
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 bulldozer has a blade load of 2 cubic meters and cycle time of 10 minutes including all time components, its productivity in loose cubic meters per hour would be calculated as 2 cubic meters divided by (10/60) hours, resulting in 12 cubic meters per hour.
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When estimating a bulldozer's productivity operating on a slope, the correction factor may adjust values from production curves, if it's less or greater than one depending on whether the project is uphill or downhill.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
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To push or to pull, the bulldozer needs to know, cycle time and job skill make the productivity flow!
📖 Fascinating Stories
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Imagine a bulldozer at work, diligently pushing dirt across a slope. Its speed doubles as it goes downhill, while it struggles uphill. This tale reminds us of how terrain influences productivity.
🧠 Other Memory Gems
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PUSH: Performance, Utilization, Speed, Haul - Remembering the key to estimating bulldozer productivity!
🎯 Super Acronyms
CYCLE
- Constant (fixed) and Yielding (variable) Cycle time Lead to Estimating productivity.
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 bulldozer to perform a complete operation cycle, including pushing, backtracking, and maneuvering.
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Term: Fixed Time
Definition:
The portion of cycle time that remains constant regardless of project conditions, typically related to maneuvering tasks.
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Term: Variable Time
Definition:
The portion of cycle time that changes based on haul distance and speed.
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Term: Job Efficiency
Definition:
The actual operational time of the bulldozer expressed as a percentage of total available time.
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Term: Production Curve
Definition:
Graphical representation that shows the relationship between dozing distance and productivity for different models of bulldozers.
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Term: Correction Factor
Definition:
Multiplier applied to ideal production estimates to adjust for differing project conditions.
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Term: Blade Capacity
Definition:
The maximum volume of material that a bulldozer's blade can hold during a single push.