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5.2. Utilizing Production Curves for Estimation
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Today we're going to discuss the concept of cycle time in bulldozer operations. Cycle time consists of fixed and variable time components. Can anyone tell me what 'cycle time' means?
Isn't it the total time for a bulldozer to finish one complete operation?
Exactly! Now, cycle time is made up of fixed time, which includes the maneuvering time, and variable time, which includes push and backtrack times. Does anyone understand why we categorize them this way?
The fixed time stays constant, but the variable time changes depending on conditions like haul distance?
Correct! The push and backtrack times can change based on how far the material needs to be moved. Let’s remember this with the acronym PBC: Push, Backtrack, and Constant - indicating which times change and which does not during operations.
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Now let’s look at how we calculate productivity. It’s expressed in loose cubic meters per hour. Who can explain the formula we use for this?
Is it the blade load divided by the cycle time?
Yes, great! Blade load can be found through specifications or measurements. Why do you think it's important to clearly define whether we're discussing loose or compacted states?
Because it affects the volume we’re actually able to move?
Exactly! It’s critical for accuracy. Just remember the phrase: 'Loose is Boost.' The looser the material, the easier it is to handle, hence higher productivity.
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Let’s talk about job efficiency next. Why do you think we can't expect a bulldozer to work for a full hour?
It might face delays or breakdowns?
Or the terrain might not allow for full use of the machine?
Exactly! We have to adjust our productivity estimates based on estimated working time. For instance, if our machine operates for 50 minutes out of an hour, how do we calculate efficiency?
We’d divide the working time by 60, right?
Right again! So let's say a bulldozer operates for 50 minutes; its efficiency would be 50/60. This final productivity then guides our project bids.
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Now we’re moving onto production curves, a valuable resource from equipment manufacturers. What do you think we can find in these curves?
They show the productivity based on dozing distances, right?
Exactly! However, these curves represent ideal conditions. What should we do if our site conditions differ?
We need to apply correction factors based on our actual conditions, like terrain or material type?
Spot on! To remember this process, think 'Ideal to Real.' We assess ideal figures from the curve and adjust them to fit our project’s reality.
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Let’s wrap it up with cost estimation for bidding. Why is understanding unit cost essential?
The unit cost affects how much to charge for the project, right?
Correct! The unit cost reflects all operating expenses and productivity estimates. Can you connect this back to what we discussed about job efficiency earlier?
If we don’t estimate job efficiency properly, we might charge too little or too much for our work!
Exactly! Always remember: 'Effort Equals Earnings.' Adjust your estimates carefully to ensure profitability.
Overview
Short Summary
This section outlines the procedures and considerations necessary for estimating bulldozer productivity using production curves, incorporating factors like cycle time, haul distance, and job efficiency.
Medium Summary
In this section, various factors affecting bulldozer productivity are explored, including cycle time (divided into fixed and variable components) and the importance of haul distance. The section emphasizes using production curves provided by manufacturers to determine productivity under various project conditions and highlights the need for correction factors based on real site conditions.
Detailed Summary
Detailed Summary
In this section, we delve into the critical aspects of estimating the productivity of bulldozers using production curves. The key points discussed are:
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Cycle Time: The total time required for a bulldozer to complete a full operation cycle is composed of push time, backtrack time, and maneuver time. These are crucial for determining efficiency.
- Fixed Time: This is constant and includes maneuver time, which varies based on transmission type (manual vs. automatic).
- Variable Time: This consists of push and backtrack time, which depend on haul distance and travel speed.
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Productivity Calculation: Productivity is expressed in loose cubic meters per hour. It's calculated using the formula:
- Productivity = Blade Load / Cycle Time, where Blade Load can be determined through manufacturer specifications or field measurements.
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Job Efficiency: Recognizing that the bulldozer is not operational for the entire hour (due to various factors such as terrain conditions) is vital. The section outlines how to adjust expected productivity by calculating job efficiency.
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Cost Estimation: The unit cost of production is crucial for bidding, calculated as the hourly cost of machine operation divided by productivity, providing essential data for project management.
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Use of Production Curves: The section introduces production curves as a reliable tool from manufacturers to estimate productivity based on dozing distance and conditions of the project site. It highlights that these curves assume ideal conditions, and corrective factors must be applied to cater for actual project site conditions affecting productivity.
Understanding these components of bulldozer productivity is essential for efficient project planning and accurate bidding in construction and earthmoving operations.
Audio Book
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Create a free accountSo, 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 it takes for a bulldozer to complete one full operation cycle. This includes the time it spends cutting into the earth, pushing the material, dumping it, and then backtracking to its original position to start the operation again. Understanding cycle time is crucial because it helps in estimating how quickly and efficiently a job can be done.
Examples & Analogies
Imagine a chef preparing a dish. The cycle time for the chef would include gathering ingredients, cooking, plating, and cleaning up before starting the next dish. Similarly, the bulldozer's cycle time includes all its operational steps.
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Create a free accountSo, we call this as fixed time, this is fixed time and this one is variable time, your push and backtrack time it is called this variable time...
Detailed Explanation
In estimating cycle time, we can categorize the time required into fixed time and variable time. Fixed time is the time that stays constant, regardless of the operation, such as the time taken for maneuvering the gears. Variable time, on the other hand, changes based on conditions such as haul distance. For instance, if the distance to push materials is longer, it takes more time, thus increasing the cycle time.
Examples & Analogies
Think of driving a car. The time spent in traffic lights or stop signs is fixed (as they happen in every trip), whereas the time spent on the highway can vary depending on traffic or road conditions, similar to the variable time in bulldozer operations.
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Create a free accountTo 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 and backtrack times accurately, one must understand the travel distance, which is the distance materials need to be moved. Additionally, understanding the speed of the bulldozer during this operation is paramount as these two factors directly influence the total time taken for each cycle. Hence, accurate estimates of push and backtrack time can be achieved by measuring these distances and the bulldozer's speed.
Examples & Analogies
If you think about running a race, knowing how far you need to run (distance) and the speed you can maintain helps you estimate how long it will take to finish. Just like in bulldozing, the time it takes is determined by how far you’re going and how fast you can get there.
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Create a free accountSo, 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...
Detailed Explanation
Maneuver time is the time required for operational adjustments, like changing gears or altering speed. This time can vary based on the type of transmission system—whether it’s manual or automatic. For instance, a bulldozer with a power shift system can change gears more quickly than one with a manual transmission, significantly influencing the overall cycle time.
Examples & Analogies
Consider riding a bicycle with gears. Shifting gears can make pedaling easier or harder depending on the terrain. If the bike has automatic gears, it shifts for you, making it quicker. In regular bicycles, you manually shift, which might take longer during a challenging ride, just like manual vs. automatic operations in bulldozers.
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Create a free accountNow let us see how to estimate the productivity of the bulldozer.... So, the production here is expressed in loose meter cube per hour...
Detailed Explanation
Estimating the productivity of a bulldozer involves calculating how much material (in loose cubic meters) it can move in one hour. This is done by understanding the blade load capacity and the cycle time for operations. The formula involves dividing blade load by cycle time to achieve productivity metrics. Accurate productivity estimates help in the planning of earthmoving projects.
Examples & Analogies
Think of a water jug and how much water it can pour. If you know how quickly you can pour it (cycle time) and how much it holds (blade load), you can quickly determine how much water you can serve in an hour.
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Create a free accountAfter 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...
Detailed Explanation
Job efficiency accounts for the actual operational time of the bulldozer compared to total available time. A bulldozer might not work continuously for an hour due to breaks, maintenance, or slowdowns in operation. Therefore, understanding the efficiency factor, which is the ratio of actual working time to available time, is vital in making accurate productivity estimates.
Examples & Analogies
Imagine studying for an exam. If you only study for 30 minutes effectively out of an hour due to distractions or breaks, your study efficiency is only 50%. Likewise, the bulldozer’s operation efficiency impacts its productivity.
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Key concepts
Core takeaways and short definitions to help you quickly recall the key ideas from this section.
- Cycle Time:
Total time for operation, comprising fixed and variable times.
- Blade Load:
The amount of material a bulldozer can move per cycle.
- Job Efficiency:
Actual work operational time versus total time.
- Production Curves:
Charts that help to estimate productivity based on specific conditions.
- Correction Factors:
Adjustments to ideal productivity based on real-world conditions.
Examples
Step-by-step examples to apply the section's ideas and test your understanding.
If a bulldozer has a blade capacity of 1.5 cubic meters and a cycle time of 6 minutes, then its productivity can be estimated as 15 cubic meters per hour, assuming it operates efficiently.
Using a production curve from the manufacturer, we can find that for a dozing distance of 60 meters, the estimated production might be 10 loose cubic meters per hour. If job efficiency is 50 minutes per hour, this would adjust the actual productivity figure.
Memory aids
To calculate how much we can load, / Use the time and distance road; / Remember Curve and Factor too, / For estimates that are true!
Once there was a bulldozer named Benny who loved to work on the hill. However, Benny knew that every time he pushed dirt, he had to check his cycle time and blade load to make sure he was efficient and could finish the job under budget!
Remember the acronym 'PBC' for Push, Backtrack, and Constant when discussing cycle times for bulldozers.
Flash Cards
Glossary
Cycle Time
The total time required for a bulldozer to complete one complete operation.
Fixed Time
The constant part of cycle time, including maneuver time.
Variable Time
The part of cycle time that varies based on factors such as haul distance.
Job Efficiency
The ratio of actual operational time to the total available time for work.
Production Curves
Graphs that display the expected productivity of equipment based on variables like distance.
Correction Factors
Adjustments made to ideal productivity estimates to account for actual project conditions.