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Interactive Audio Lesson
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Understanding Cycle Time
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Today, we'll start discussing what cycle time means in bulldozer operations. Who can tell me what cycle time includes?
Is it the total time it takes for a bulldozer to complete a full operation?
Exactly! It involves pushing, backtracking, and maneuvering. Cycle time can be broken down into fixed and variable components. Can anyone name a fixed part of the cycle time?
The maneuver time?
Correct! The maneuver time depends on the type of transmission. If you're using manual transmission, it will take longer than automatic. A helpful tip to remember this is the acronym 'MT' for Maneuver Time!
And what about variable time? What does that depend on?
Variable time varies with haul distance and speed, right! Understanding these components will help us estimate bulldozer productivity more effectively. Remember, push time and backtrack time are key in this regard.
So, to make accurate calculations, we need to know both the distance and the speed of the machine!
Absolutely! Good observations everyone. Let's move on to how we can determine these speeds accurately.
Determining Speed for Productivity
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Now that we understand cycle time, let’s talk about how to calculate speed. Who remembers where we can find the speed in context to bulldozers?
From the performance chart!
Exactly! The performance chart provides data on speed considering various project conditions. Can someone explain what those conditions might be?
It could be the total rolling resistance and the grade resistance based on terrain conditions.
Right again! When we input these values into the performance chart, we can find the speed based on total resistance. This ultimately helps us calculate the variable times for the cycle!
So every small detail, like the type of terrain, really matters in determining speed!
Absolutely! With this knowledge, let’s consider the influence of soil density on our productivity calculations.
Correction Factors in Productivity
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Let’s shift to correction factors that adjust our productivity estimates. Who can explain why it's essential to apply these factors?
Because the ideal production values don’t always reflect actual operating conditions!
Exactly! The curves are based on ideal conditions, such as 100% job efficiency. However, real-world scenarios can greatly differ. What are some examples of these correction factors?
Operator skill level and type of material being moved!
Also, the visibility conditions, like if it's really foggy or dusty!
Perfect examples! Each of these factors impacts overall productivity, requiring adjustments based on project performance. Can anyone summarize why we need to be cautious when using manufacturer data?
Because the ideal conditions may not represent our actual job site!
Exactly! It's vital to ensure our estimates reflect the challenges of real conditions!
Introduction & Overview
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Quick Overview
Standard
The section explains how productivity estimates for bulldozers depend on various correction factors, including haul distance, soil conditions, operator skill, equipment type, and job efficiency. It methodically breaks down the cycle time components, including push time, backtrack time, maneuver time, and job efficiency, stressing the significance of these factors in accurate productivity calculation.
Detailed
In this section, we delve into the role of correction factors in estimating the productivity of bulldozers during earthmoving operations. The productivity of a bulldozer, measured in cubic meters per hour, is affected by several elements such as cycle time, which itself comprises fixed and variable time factors. The fixed maneuver time varies based on the type of transmission used (manual vs. automatic), whereas the variable times – push time and backtrack time – hinge on haul distance and operating speed. These factors are critical in determining accuracy in productivity estimates as they are heavily influenced by project conditions including soil density, visibility, operator skill and type of material being moved. The section emphasizes calculating productivity using performance curves provided by manufacturers, correcting ideal values with correction factors applicable to the specific project conditions, thereby offering a comprehensive understanding necessary for effective planning and bidding processes.
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.
Detailed Explanation
The cycle time of a bulldozer includes the entire operational sequence from cutting to pushing, dumping, and returning to the start position. Understanding this cycle helps in estimating how long each task takes, which is crucial for productivity calculations.
Examples & Analogies
Think of a bulldozer as a chef preparing a meal. Just like the chef has to cut the vegetables, cook them, serve them, and then clean the kitchen before starting another meal, the bulldozer goes through a similar process of cutting, pushing, and resetting.
Fixed Time vs. Variable Time
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We call this fixed time and this one is variable time. Your push and backtrack time is variable depending upon your haul distance. So, greater your haul distance, greater will be a push time and return time or backtrack time.
Detailed Explanation
Cycle time can be divided into fixed time and variable time. Fixed time refers to consistent tasks such as maneuvering, while variable time depends on factors like haul distance. Longer haul distances require more time, thus affecting the overall productivity estimation based on distance traveled.
Examples & Analogies
Consider a courier delivering packages. The base time for preparing and loading is fixed, but the delivery time increases significantly with longer distances. Similarly, in bulldozer operations, the push and return times vary with distance just like the delivery time.
Determining Speed and Haul Distance
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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. I can determine the speed from the performance chart.
Detailed Explanation
To estimate how quickly a bulldozer can work, you need to know the speed, which is determined using a performance chart, and the distance it has to cover. These elements together help calculate time required for pushing and backtracking, influencing productivity.
Examples & Analogies
Imagine a delivery route mapped out on a GPS. The speed limit (performance chart) and distance (haul distance) determine how long it will take to reach a destination. Similarly, for a bulldozer, speed and distance dictate operational timings.
Maneuver Time
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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.
Detailed Explanation
Maneuver time refers to the time taken for adjustments like speed changes and gear shifts. This element is critical as it varies based on the transmission type (manual vs. automatic), thereby impacting overall cycle time and productivity.
Examples & Analogies
Think of a driver in a car. When switching from driving slowly in traffic to speeding on a highway, the time it takes to adjust the speed (maneuvering) is essential. In bulldozer operations, similar adjustments can either slow down or speed up productivity.
Blade Capacity and Cycle Time
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The production here is expressed in loose meter cube per hour, that means you have cut the earth and loosen the material after loosening in it, what is the productivity.
Detailed Explanation
Productivity is measured in loose cubic meters per hour and involves calculating the blade capacity, which is the amount of earth moved in one cycle. This also ties in with cycle time, where the total time taken in cutting, pushing, and maneuvering influences the output.
Examples & Analogies
Consider a construction worker filling buckets of sand. If each bucket represents blade capacity, and it takes time to fill, carry, and return, the total number of buckets filled per hour reflects productivity. For bulldozers, the same principle applies but on a larger scale.
Job Efficiency and Working Time
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One thing you should know that your machine is not going to be operated for the entire 60 minutes in an hour. Depending upon your project condition, it may operate for 45 minutes or 50 minutes.
Detailed Explanation
Job efficiency must be factored in, as bulldozer operations don't run continuously for an hour due to breaks and delays. This efficiency percentage, when applied to calculated productivity, gives a more accurate estimate of output.
Examples & Analogies
Imagine a student studying for only 50 minutes of every hour due to distractions, resulting in less knowledge gained than if they studied continuously. Similarly, bulldozers work only part of the hour, thus requiring adjustments in productivity calculations.
Correction Factors
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As I told you, these production curves are drawn based upon ideal conditions. What are all ideal conditions? It is drawn assuming 100% job efficiency...
Detailed Explanation
Correction factors are applied to adjust for discrepancies between ideal and real work conditions, such as soil density, operator skill, and machine type. These adjustments refine productivity estimates by incorporating real-world variations.
Examples & Analogies
Think of trying to bake a cake using a recipe that assumes perfect kitchen conditions. Factors like oven temperature variations or ingredient quality can change the outcome. For bulldozer operations, similar real-world conditions require adjustments to productivity estimates.
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 duration to complete all bulldozer operations, segmented into fixed (maneuver) and variable (push and backtrack) components.
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Push Time: Duration to push material is dependent on haul distance and operational speed.
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Maneuver Time: The time related to changing speeds or gears, which can differ based on the transmission type used.
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Correction Factors: Adjustments incorporated to account for real-world variances from ideal conditions.
Examples & Real-Life Applications
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Examples
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If a bulldozer's push time is calculated to be 5 minutes for a 100-meter haul, and backtrack time is 3 minutes, then the total variable cycle time is 8 minutes.
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Assuming an operator has average skills, correction factors must be considered to modify the ideal productivity estimates pulled from manufacturer performance curves.
Memory Aids
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🎵 Rhymes Time
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Cycle time’s what we need to know, / Push and backtrack, let it flow, / Maneuver time is in the game, / Productivity’s the end goal, that’s our aim!
📖 Fascinating Stories
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Imagine a bulldozer named 'Buddy' who loves to move earth. Every time he pushes, he takes a long trip to a distant pile. But sometimes, Buddy has to backtrack quickly to get more earth. If Buddy is fast, he finishes his job quicker. However, if the visibility is poor or the haul distance is long, Buddy takes longer. Correction factors help Buddy plan better for his tasks!
🧠 Other Memory Gems
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RAP – Remember (R) the Adjustment (A) for Productivity (P) to account for various conditions affecting the bulldozer’s performance.
🎯 Super Acronyms
MVP – Maneuver (M), Variable push (V), and correction Factors (P) highlight the key components for estimating 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 taken for a bulldozer to complete its operation, including push time, backtrack time, and maneuver time.
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Term: Maneuver Time
Definition:
The fixed time required for changing speed, gear adjustments, and other operational maneuvers.
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Term: Push Time
Definition:
The variable time taken to push material based on the haul distance and speed.
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Term: Backtrack Time
Definition:
The variable time taken to return to the original position with an empty blade.
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Term: Correction Factors
Definition:
Adjustments applied to ideal productivity values to account for real-world conditions affecting operation.