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Interactive Audio Lesson
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Cycle Time Overview
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Today, we will discuss the concept of cycle time in bulldozer operations. Can anyone tell me what cycle time includes?
Does it include the time taken for the bulldozer to cut and push the earth?
Exactly, it encompasses cutting, pushing, and maneuvering times. We refer to these as fixed time and variable time. Can anyone explain the difference?
Fixed time is when the bulldozer maneuvers, while variable time changes with haul distance?
Correct! The variable time increases with haul distance and is influenced by the speed of the machine. Remember: 'H' for Haul distance leads to 'V' for Variable time!
Impact of Terrain on Productivity
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Now let's dive into how different terrains can impact bulldozer productivity. Who can share how slope affects cycle time?
Working uphill adds resistance and slows down the bulldozer, right?
Correct! And what about moving downhill?
Going downhill increases speed, helping productivity!
Exactly! This means we need to factor in the terrain slope when calculating productivity.
Job Efficiency Considerations
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Let's talk about job efficiency. Why do you think it’s important to consider how often the bulldozer runs during the hour?
Because we can't assume it works all the time; we have to consider downtime.
Exactly! If a bulldozer operates for only 30 minutes in an hour, how would we calculate effective productivity?
We would multiply the theoretical productivity by that efficiency factor.
Right! Remember: Efficiency decreases operational time, so always account for it!
Using Performance Charts
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Understanding performance charts is crucial. Who can describe how we might use these charts?
They help us find the speed based on rolling and grade resistance.
Great! Approximate haul distance and conditions, and you can evaluate what performance to expect.
So, we can use that to adjust our productivity calculations?
Precisely! Always refer to these valuable resources to ensure accurate predictions.
Introduction & Overview
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Quick Overview
Standard
In this section, we investigate the various factors influencing bulldozer productivity, including cycle time related to cutting, pushing, and maneuvering. We examine how haul distance and terrain characteristics such as slope and soil type can alter push and backtrack times, ultimately affecting the efficiency and cost of earthmoving operations.
Detailed
Detailed Summary
In this section, we delve into the critical factors that impact bulldozer productivity, particularly focusing on cycle time, which includes cutting, pushing, and maneuvering operations. The cycle time comprises fixed and variable components:
- Fixed Time: Refers to the maneuvering time required for adjustments, such as changing gears or altering speed. This varies based on the type of transmission used, whether it is manual (requiring more time) or automatic (which reduces the maneuver time).
- Variable Time: Relates to the push and backtrack times, which depend on the haul distance. As the haul distance increases, both push and return times will also increase, directly impacting productivity.
The importance of knowing the haul distance and equipment speed, which can be determined using performance charts, is emphasized. The section also highlights how productivity calculations must consider job efficiency, which varies depending on project conditions (e.g., machine-operating time).
Additionally, the variation in terrain affects the rolling resistance and grade resistance of a bulldozer, influencing optimal speed and thus productivity. For example, working uphill increases resistance and decreases speed, while downhill operation enhances speed and, therefore, productivity.
Finally, we touch upon correction factors necessary for adjusting productivity estimates based on real project conditions versus the ideal scenarios reflected in production curves.
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 of a bulldozer includes several activities: cutting, pushing, dumping, and backtracking. When operating a bulldozer, it is not just about pushing material; it also involves maneuvering to ensure the bulldozer can efficiently return to its starting point after dumping the material. Each of these actions requires time, and when added together, they form the complete cycle time of the machine.
Examples & Analogies
Think of the cycle time as making a sandwich. First, you gather your ingredients (cutting), then you assemble the sandwich (pushing), you put it on a plate (dumping), and finally, you return to the counter for more ingredients (backtracking). Each step takes time, just like the bulldozer's actions.
Understanding Maneuvering 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 is called this variable time.
Detailed Explanation
Maneuvering time refers to the adjustments made during the operation of the bulldozer, such as changing speed or shifting gears. This time can be classified into fixed and variable. Fixed time pertains to the routine controls needed irrespective of external conditions, while variable time depends on the specific conditions like the haul distance, which affects how long it takes to push or backtrack.
Examples & Analogies
Consider driving a car. When you need to change lanes, you might take a moment to signal and check your mirrors (maneuvering time). Regardless of traffic conditions, these actions are part of your driving routine (fixed time), but how long you can accelerate to change lanes could vary based on traffic (variable time).
Determining Push and Backtrack Time
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Because it is variable depending upon your haul distance. So, greater your haul distance greater will be a push time and return time or backtrack time. So, this is solely dependent upon your haul distance, so that is why we call it as variable obviously it depends upon the speed also.
Detailed Explanation
The push and backtrack times are variable and depend primarily on the haul distance. The farther you need to push material, the longer it will take. Additionally, the speed of the bulldozer also plays a critical role; the greater the speed, the less time it takes to push or return. This relationship illustrates why understanding both the distance and speed is crucial for estimating operational efficiency.
Examples & Analogies
Imagine you have a cart filled with groceries. If you're at the end of a long driveway and must push the cart to your house, it will take more time than if you were close by. If you could run faster (like increasing speed), you would cut down the time it takes to reach your house, just as a faster bulldozer reduces push and backtrack time.
The Role of Terrain and Conditions
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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.
Detailed Explanation
To accurately determine the push and backtrack times, it's essential to have specific measurements: the distance the bulldozer must travel (dozing distance) and the speed at which it can move. These factors are crucial for understanding how terrain impacts overall productivity, particularly how the bulldozer performs in different conditions.
Examples & Analogies
If you're going for a run, knowing the distance of your route is vital. If it's a flat pathway, you might run faster than if it's uphill (difficult terrain), so just as with the bulldozer, knowing both the distance and your pace helps you estimate how long you'll be out.
Calculating Productivity
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So, now let us see how to estimate the productivity of the bulldozer. So, we are going to estimate the productivity a 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
Estimating bulldozer productivity requires understanding the unit of measure you're using. Productivity is typically expressed in loose cubic meters per hour, which means you're accounting for the volume of material once it's been disturbed and loosened, not in its original compacted form. This distinction is essential for accurate reporting and planning.
Examples & Analogies
Think about baking cookies. If a recipe calls for flour in its compressed state, but you need to know how much flour you have once you fluff it up, it changes the measurement. Just like flour expands when it's loosened, earth expands when it's excavated, making understanding these states essential for getting accurate amounts.
Definitions & Key Concepts
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Key Concepts
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Haul Distance: The distance material must be moved, impacting push times.
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Cycle Time: Comprises fixed (maneuvering) and variable times (push and backtrack).
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Job Efficiency: Actual working time percentage affecting overall productivity.
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Terrain Effect: The influence of factors like slope and soil type on bulldozer operations.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
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Example 1: The bulldozer's push time increases on a steeper slope, resulting in longer cycle times.
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Example 2: A bulldozer working on soft, non-cohesive sand experiences decreased productivity due to poor blade interaction.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
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Push and pull through mud and clay, the cycle time guides our way!
📖 Fascinating Stories
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Imagine a bulldozer navigating a steep hill, struggling to push heavy earth but swiftly gliding down, reminding us how terrain truly influences its journey.
🧠 Other Memory Gems
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C.H.A.R.T - Cycle time, Haul distance, Adjust for terrain, Remember job efficiency, Track speed.
🎯 Super Acronyms
P.H.A.S.E - Push, Haul, Adjust speed, Slope effect.
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 for a bulldozer to complete a cycle of cutting, pushing, and returning.
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Term: Variable Time
Definition:
The time that changes based on factors like haul distance and machine speed.
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Term: Fixed Time
Definition:
The consistent time taken for maneuvers like gear changes which does not vary.
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Term: Job Efficiency
Definition:
The actual working time of the bulldozer during an hour, considering factors such as downtime.
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Term: Performance Charts
Definition:
Graphs that depict the relationship between machine resistance and achievable speed.
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Term: Haul Distance
Definition:
The distance the bulldozer must move material from the cutting site to the dumping site.