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Interactive Audio Lesson
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Understanding Cycle Time
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Today, we are going to discuss cycle time, which is crucial for estimating bulldozer productivity. Can anyone tell me what cycle time comprises?
Isn't it the total time taken to complete one full operation?
That's correct! Cycle time includes the push time, backtrack time, and maneuvering time. Remember the acronym 'PBM' — Push, Backtrack, Maneuver.
What factors influence the push and backtrack times?
Great question! The push and backtrack times vary based on haul distance and the machine's speed. Larger haul distances lead to longer push and backtrack times.
How do we determine the speed?
Speed can be determined using performance charts. We will discuss those next!
To summarize, cycle time is made up of push time, backtrack time, and maneuver time, abbreviated as PBM.
Estimating Productivity
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Let's now discuss productivity estimation. How do we calculate it?
Isn't it the blade load divided by cycle time?
Exactly! Productivity is measured in loose cubic meters per hour. Remember, it's vital to specify whether we're referring to the loose state or bank state.
What about job efficiency? How does that affect productivity?
Job efficiency reflects the actual working time of the machine. If a bulldozer operates for 50 minutes in an hour, we adjust productivity using a factor of 50/60.
So, we need to multiply the initial productivity by that efficiency factor?
Correct! Keep in mind that accurate estimations ensure proper project bidding.
In summary, productivity is calculated by blade load divided by cycle time, adjusted for job efficiency.
Cost Estimation
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Now, let's talk about the cost estimation of the earthmoving operation. Who can explain what we need to calculate the cost?
We need to find the hourly cost of the machine and divide it by productivity, right?
Exactly! We must sum up all costs related to ownership and operation to find the hourly cost.
What if we underestimate these costs?
Underestimating costs can lead to inaccurate bidding and potential financial issues further down the project. That's why thorough knowledge of estimation is essential.
To sum up, to find the cost per loose cubic meter, divide hourly machine cost by productivity.
Correction Factors
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Finally, let's discuss correction factors which help adjust the productivity based on real-world conditions. Why do we need these factors?
Because the ideal conditions can differ from actual job site conditions!
Exactly! Factors include soil density, operator skill, and grading conditions. Such variations can severely impact productivity.
How do we apply those correction factors practically?
You find the ideal production from curves and apply the correction factors based on project conditions. This gives you the actual value!
In summary, correction factors adjust productivity estimates to account for real-world variations, ensuring more accurate calculations.
Introduction & Overview
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Quick Overview
Standard
The section delves into different approaches for estimating bulldozer productivity, including the calculation of cycle time based on hauling distance, the use of performance charts, and correction factors for real-world job conditions. It emphasizes the importance of accurate estimation for cost management in earthmoving projects.
Detailed
Detailed Summary
In this section, the estimation of bulldozer productivity is comprehensively discussed. A bulldozer's cycle time is vital for understanding productivity, which consists of several components:
- Cycle Time Components: Cycle time includes fixed times (like maneuvering time) and variable times (like push and backtrack time). Variable times are influenced by haul distance and machine speed, while maneuver time varies based on whether the bulldozer uses manual or automatic gear changes.
- Estimating Cycle Time: To calculate cycle time, one needs to know the hauling distance, machine speed (determined from performance charts), and gear-changing effects.
- Productivity Calculation: Productivity is expressed in loose cubic meters per hour, calculated by dividing the blade load by the total cycle time. The section details the significance of job efficiency in the calculation, which affects the effective working time of the bulldozer.
- Cost Estimation: It is crucial to estimate the unit cost associated with earthmoving operations accurately, which factors into bidding for contracts. Understanding ownership and operating costs also plays a role in determining hourly costs and pricing strategies.
- Correction Factors: The section explains that standard production curves from manufacturers must be adjusted with correction factors to accommodate actual project conditions, such as terrain, material type, and operator efficiency. Various factors, like soil density and traction coefficients, are discussed in relation to their impact on productivity.
Through these components, the section aims to equip the reader with the necessary tools to make accurate estimations of bulldozer productivity, thereby optimizing project planning and cost management.
Audio Book
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Cycle Time and Maneuvering
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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.
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.
Detailed Explanation
Cycle time for bulldozers includes different components, primarily the time taken to push, backtrack, and maneuver into position. The cycle time is composed of fixed time and variable time. Fixed time refers to the adjustments needed to operate the bulldozer, like changing gears or accelerating, while variable time depends on how far the bulldozer needs to push and the backtrack distance, which alters with the haul distance. Essentially, push and backtrack times vary based on how far you need to move. If you have to move farther, your times will increase, which is why they are considered variable.
Examples & Analogies
Think of the bulldozer as a runner in a race. When the runner has to navigate obstacles (like changing gears or accelerating), that time is fixed irrespective of the distance to the finish line (maneuvering time). However, running between two points (pushing and backtracking) can take longer if the distance increases, just like the bulldozer takes longer to push earth if the haul distance is longer.
Calculating Push Time and Speed
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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. So, with the help of the performance chart, you can determine the speed.
Detailed Explanation
To estimate the push time and backtrack time for the bulldozer, one must determine two key variables: the travel distance (also known as the haul distance) and the speed of the bulldozer. The speed can be derived from a performance chart, which represents the speed against total resistance. Knowing both the distance and speed allows us to calculate the time required for these operations.
Examples & Analogies
Imagine planning a road trip where you need to know how long it will take to reach your destination. You need to know the distance to drive and your average speed. Similar to using a performance chart, you could look up the average speed based on your vehicle's condition (like how the bulldozer determines its speed based on resistance).
Maneuver Time and Transmission Type
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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.
Detailed Explanation
Maneuver time refers specifically to the time taken for adjustments such as changing gears or modifying the speed settings of the bulldozer. This time can vary significantly based on the type of transmission used by the machines. There are typically two types of transmission systems: direct transmission, where the operator manually shifts gears, and automatic transmission, which can adjust gear shifts without manual input.
Examples & Analogies
Consider driving a car with a manual transmission compared to an automatic one. When using a manual car, you have to manually change gears, which can take time and requires attention. In contrast, an automatic car takes care of gear changes for you, allowing for a smoother and faster driving experience. This difference in changing gears affects how quickly the vehicle (or bulldozer) can react to changes in conditions.
Estimating Productivity
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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. 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 the productivity of a bulldozer, we need to express it in terms of volume moved, typically in loose cubic meters per hour. It is crucial to specify whether we're discussing the volume in its loosened state (after excavation) versus its natural state (before excavation) because this significantly influences calculations. The basic formula for calculating productivity is the blade load divided by cycle time.
Examples & Analogies
Think of estimating how much popcorn a popcorn machine can pop in an hour. If you describe it in terms of popped popcorn versus unpopped kernels, it gives a different picture. When measuring bulldozer productivity, specifying whether the material is loose or compacted is similarly important.
Factors Affecting Unit Cost of Production
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Now, 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 must be factored into the overall productivity calculation. A bulldozer won't operate continuously for the full hour due to various factors like project conditions and operational inefficiencies. For example, if a bulldozer operates for only 50 minutes out of an hour, the overall productivity must be adjusted to reflect that reduced operating time. This adjustment allows for a more accurate representation of real-world effectiveness.
Examples & Analogies
Think about studying for a school exam. Even though you plan to study for an hour, distractions like phone notifications, snack breaks, or just losing focus can reduce your effective study time to only 45 minutes. You have to adjust your study plan accordingly. Similarly, bulldozer operation needs to account for non-productive time.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
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Cycle Time: The total time for a bulldozer’s operational cycle, comprising push, backtrack, and maneuvering times.
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Blade Load: The volume of material moved in a single cycle, critical for calculating productivity.
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Job Efficiency: The effective working time of a bulldozer compared to its available time.
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Production Curves: Graphical representation of expected productivity based on ideal conditions.
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Correction Factors: Adjustments made to productivity estimates to reflect real-world operating 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 blade load of 2 cubic meters and a cycle time of 10 minutes, its productivity would be 12 cubic meters per hour.
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To apply correction factors, if the ideal productivity from the curves is 100 cubic meters but poor visibility reduces expected productivity by 20%, actual productivity would be 80 cubic meters.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
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In every push and backtrack, remember the time; with PBM in mind, productivity will shine!
📖 Fascinating Stories
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Imagine a hardworking bulldozer named Benny. Benny always checks his cycle time, ensures his blade load is full, and never forgets to adjust for conditions — Benny's operational success teaches everyone about productivity!
🧠 Other Memory Gems
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PBM for Cycle Time: Push, Backtrack, Maneuver. Each aspect is key for measurement!
🎯 Super Acronyms
PBL for Productivity
- P: = Push load
- B: = Backtrack load
- L: = Load volume.
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 taken to complete a full operational cycle of a bulldozer, comprising push time, backtrack time, and maneuvering time.
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Term: Blade Load
Definition:
The volume of material that the bulldozer’s blade can carry, critical for calculating productivity.
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Term: Job Efficiency
Definition:
The proportion of time the bulldozer operates effectively compared to the total time available, typically expressed as a percentage.
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Term: Production Curves
Definition:
Graphs that represent the expected productivity of equipment under ideal conditions based on various factors.
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Term: Correction Factors
Definition:
Adjustments made to ideal productivity estimates to account for real-world operating conditions, such as soil density and operator skill.