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Interactive Audio Lesson
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Understanding Cycle Time
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Today, we are going to delve into the concept of cycle time in bulldozer operations. Can anyone tell me what cycle time consists of?
Isn't it the time it takes for the bulldozer to complete one full operation?
Exactly! Cycle time includes all the time spent cutting, pushing, and maneuvering. Cycle time is composed of both fixed and variable components. Can anyone give an example of fixed time?
Changing gears or accelerating would be part of the fixed time, right?
Correct! Those operations don’t change much regardless of the haul distance. Now, what about variable time?
Uh, isn't that influenced by how far the bulldozer has to push the earth?
Yes! Excellent point. The push and backtrack times are variable and depend on the haul distance, which is crucial for estimating the cycle time.
So, we need to measure those distances accurately?
Absolutely. Without accurate measurements, our entire productivity calculations would be off. To sum it up, cycle time is critical for planning and efficiency in bulldozer operations.
Estimating Productivity
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Let’s move on to estimating productivity! Who can explain how productivity is computed?
Is it the blade load divided by the cycle time?
Exactly! The formula is productivity equals blade load divided by cycle time. Now, what factors influence blade load?
The capacity of the bulldozer’s blade and the type of material being moved?
Very well put! This capacity can usually be provided by the manufacturer or measured in the field, but remember to specify the material state. Why is this important?
Because moving material in its bank state differs from its loosen state?
Correct! It’s essential to have these distinctions in mind when estimating production. Can anyone list factors that could impact our cycle time?
Haul distance and speed come to mind, right?
Absolutely! Factors like terrain conditions can also impact machine efficiency. Great job summing that up!
Influence of Operational Conditions
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Now, let's talk about job efficiency and operational conditions. What is job efficiency?
It’s the actual working time of the machine in an hour?
Yes! It often won’t be 60 minutes because of downtime. How do we account for that in our productivity calculations?
We multiply our productivity by a job efficiency factor?
Correct! Can anyone give me an example of how terrain can impact productivity?
If it’s muddy, it slows down the bulldozer, reducing productivity, while a downhill might increase it!
Exactly! Thus, we must apply correction factors based on the specific job site conditions. Well done, everyone!
Correction Factors and Their Importance
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Let’s examine correction factors. Why do we apply correction factors to productivity estimates?
To account for variables that differ from ideal conditions?
Correct! Can anyone suggest what variables might require these adjustments?
Like the operator's skill level or the type of material?
Yes, precisely! For instance, a poor operator or very tough material will reduce efficiency. What other factors can affect our productivity?
Slopes or visibility conditions can change how well we conduct operations!
Great! Visibility issues will indeed impact how much work can be done, and all these must be factored in to ensure accurate productivity estimates.
Practical Estimation of Cost
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Finally, let's talk about estimating costs. What is the importance of flexibility in productivity estimates?
It helps in making realistic bids for contracts, right?
Exactly! You need accuracy for successful bidding. How do we find the unit cost of production?
It’s the hourly cost divided by hourly productivity.
Spot on! Remember that the hourly cost should include all related expenses like labor and machine ownership. Once you calculate this, what’s the next step?
Use the cost to create bids that can help us earn a profit!
Right! And that’s the crux of our discussions on productivity and costs today. Great work, everyone!
Introduction & Overview
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Quick Overview
Standard
The section discusses the elements of cycle time associated with bulldozer operations, including cutting, pushing, and maneuvering. It also examines the impact of haul distance and operational conditions on productivity, featuring methodologies for estimating machine performance and efficiency.
Detailed
Detailed Summary
In this section, we explore the critical components of cycle time for bulldozer operations, defining cycle time as the sum of processing activities such as cutting, pushing, and maneuvering. Cycle time has both fixed and variable components: fixed time relates to operations like gear changing, while variable time depends on haul distance and machine speed. The relationship between these variables signifies that push and backtrack times fluctuate with haul distance, emphasizing the need for accurate distance and speed measurements, which can be derived from performance charts.
Moreover, the section elaborates on how to estimate bulldozer productivity, stressing the importance of distinguishing between loosened and compacted material states. The approaches covered include calculating productivity through blade load divided by cycle time, making use of performance charts, and leveraging manufacturer-supplied thumb rules. Additionally, correcting for operational inefficiencies such as job efficiency or adverse terrain conditions is discussed in depth.
The narrative culminates in the acknowledgment that accurate productivity estimation is essential for cost analysis in bidding contexts, ensuring realistic profit projections.
Audio Book
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Cycle Time of the Bulldozer
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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. So, you are going to cut the earth, push the earth, dump it at the required place, then backtrack, backtrack in the sense you are going to return, return back to the original position where you want to do the dosing operation again.
Detailed Explanation
The cycle time for a bulldozer is the total time it takes to perform a full operation which includes cutting, pushing, dumping, and returning. Cycle time is essential to understand bulldozer efficiency, as it outlines how long the machine spends on various tasks. The process is sequential: first, the bulldozer cuts the earth, then pushes it to the desired location, dumps it, and finally backtracks to prepare for another cycle. Hence, each of these steps contributes to the overall cycle time.
Examples & Analogies
Think of a bulldozer like a delivery truck making a round trip. It has to stop at a warehouse to load, drive to the delivery location, drop off the items, and then return to the warehouse. Just as you would measure how long the truck takes for the entire round trip, measuring the bulldozer's time to complete its tasks helps assess its overall effectiveness.
Fixed vs. Variable Time
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So, other things are maneuvering, maneuvering in the sense whatever adjustments you do, like for increasing the speed, accelerating or decreasing the speed, changing the gear, so the time needed for changing the gear, all those things comes under the maneuvering. 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? Because it is variable depending upon your haul distance.
Detailed Explanation
In bulldozer operations, 'maneuvering' refers to the adjustments made by the operator, such as changing gears or speeds, which takes a relatively consistent and predictable amount of time, termed as fixed time. On the other hand, 'push time' and 'backtrack time' are classified as variable time because they can change based on the haul distance—the further the distance, the more time it will take to push and return.
Examples & Analogies
Imagine a runner participating in a race. The time they take to start running (fixed time) is relatively short and consistent. However, the time it takes to complete the race (variable time) will differ based on the distance of the race. Longer races take more time, similar to how bulldozer push time and backtrack time increase with greater haul distances.
Determining Speed and Travel Distance
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So, to know the push time and the backtrack time, I need to know the travel distance or the dozing distance or the haul distance. I need to know the travel distance and I also need to know the speed. 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
To accurately measure push and backtrack times, it’s crucial to know both the distance traveled (haul distance) and the speed of the bulldozer. Speed can be derived from a performance chart that outlines how different conditions affect the bulldozer’s performance. Understanding these factors helps in calculating the time taken for each part of the bulldozer's cycle.
Examples & Analogies
Think of it like planning a road trip. Before setting out, you would first determine the distance to your destination and how fast you plan to drive. This knowledge allows you to estimate how long the journey will take, just as understanding distance and speed helps the operator estimate the bulldozer's operational time.
Maneuver Time and Transmission Types
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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, so that is what is called as a maneuver time. So, this maneuver time will depend upon the type of transmission. So, in all the machines, there are 2 types of transmission possible.
Detailed Explanation
Maneuver time refers to the amount of time taken to make adjustments such as changing gears, accelerating, or decelerating. This time can vary significantly depending on the type of transmission in the bulldozer. The two common types are direct transmission, where the operator manually changes the gears, and automatic systems, which adjust these settings without manual input.
Examples & Analogies
Consider driving a car: if you have a manual transmission, you have to shift gears yourself, which can take extra time and practice. In contrast, with an automatic transmission, the car shifts gears on its own, making driving smoother and quicker in some situations. Similarly, the transmission type in bulldozers influences how quickly it can respond to the operator’s commands.
Estimating Productivity
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So, let us see how to estimate the productivity of the bulldozer. So, we are going to estimate the productivity in loose meter cube per hour. As I told you whenever you express the volume, you should be very specific that whether you are expressing the volume in the loosen state or bank state, that is natural state or in the compacted state.
Detailed Explanation
To estimate productivity, which is measured in loose cubic meters per hour, it’s important to specify the condition of the material. Loose state means that the material has been excavated and is much easier to handle than when it is in its natural packed form, known as bank state. This distinction is essential to provide accurate estimates of the bulldozer's output.
Examples & Analogies
Imagine filling a bag with sand. If you pack the sand tightly into the bag (bank state), it will look different and weigh more than when you simply scoop loose sand into the bag (loose state). Just like estimating how much sand you can carry, estimating productivity requires knowing the state of the material being moved.
Calculating Unit Cost of Production
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So, for that you need to know unit cost is nothing but cost per loose meter cube. Say I am going to find it in the loosen state cost per meter cube of earth moved, I need to calculate. It is nothing but your hourly cost associated with the machine divided by the hourly productivity.
Detailed Explanation
To find the unit cost of production for earthmoving, you calculate the cost associated with the bulldozer’s operation over an hour and then divide that by the calculated productivity. This gives you the cost per loose cubic meter moved, which is critical for budgeting and bidding in construction projects.
Examples & Analogies
Think of a lemonade stand. If you spend $5 on ingredients and can make 10 glasses of lemonade in an hour, the unit cost per glass would be $5/10 = $0.50. Similarly, knowing how much it costs to operate the bulldozer helps in setting the right prices for the services it provides.
Job Efficiency and Working Time
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So, after estimating this, you have to take into account the job efficiency. So, one thing you should know that your machine is not going to be operated for the entire 60 minutes in an hour. So, depending upon your project condition, it may operate for 45 minutes or 50 minutes. So, it may even operate only for 30 minutes, it depends upon your project condition.
Detailed Explanation
Job efficiency is the proportion of time the machine is actually working compared to the total available time in an hour. This efficiency can be influenced by factors such as the project's specific conditions and operational delays. For accurate productivity estimates, it's crucial to take this efficiency into account.
Examples & Analogies
Imagine you have a one-hour study session. If you only focus and work effectively for 30 minutes, your study efficiency is 50%. Recognizing how much time is effectively spent on tasks, much like in our bulldozer example, helps in realistic planning and goal setting.
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 operational time, including cutting, pushing, and maneuvering activities.
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Fixed Time: Time related to actions that don't vary with haul distance.
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Variable Time: Time that changes according to the distance and speed of operations.
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Blade Load: The weight of the material lifted by the bulldozer.
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Job Efficiency: The effective time spent on work compared to possible operational time.
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Correction Factors: Adjustments made to productivity estimates based on variable conditions.
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 cycle time of 8 minutes and a blade load of 70 cubic meters, the productivity in loose cubic meters per hour can be calculated as (70 / 8) * 60 = 525 cubic meters per hour.
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In cases of adverse conditions like poor visibility, a correction factor of 0.9 may be applied to adjust productivity estimates.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
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In cycle time, all parts unite, cutting, pushing, states in sight.
📖 Fascinating Stories
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Imagine a bulldozer named Turbo. Each day, Turbo would measure how far he pushed after cutting the ground and then return. Turbo learned that his time spent switching gears was always the same, but the time he took depended on the haul distance.
🧠 Other Memory Gems
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Cyclic Push Maneuver (CPU) - Remember the key activities in cycle time.
🎯 Super Acronyms
FAST
- Fixed
- Average hauled distance
- Speed
- Time. A way to remember factors affecting productivity.
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 required to complete a full operation consisting of cutting, pushing, and maneuvering.
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Term: Fixed Time
Definition:
The time component that remains constant regardless of the haul distance, typically includes gear changes.
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Term: Variable Time
Definition:
The time component that fluctuates with factors such as haul distance and speed of the bulldozer.
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Term: Blade Load
Definition:
The amount of material that a bulldozer can carry in one load.
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Term: Job Efficiency
Definition:
The effective operating time of the bulldozer relative to its potential maximum operating time within an hour.
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Term: Correction Factor
Definition:
A multiplier used to adjust productivity estimates based on various operational conditions.