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A short class with Sarah and her students. The other ways are under More.
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Today, we're going to discuss cycle time and its components. Can anyone explain what we mean by cycle time?
Is it the total time taken for one complete operation of the bulldozer?
Exactly! Cycle time includes push time, backtrack time, and maneuvering time. Push time varies depending on haul distance, while backtrack time is generally less because the bulldozer returns with an empty blade.
What’s maneuvering time?
Maneuvering time is the time required for adjusting speeds or shifting gears, which can differ based on whether the machine has manual or automatic transmission. Remember, more time can lead to increased cycle time!
So, as the haul distance increases, the push time increases too?
Correct! That’s why knowing your project's haul distance is crucial when calculating productivity.
Remember: CYCLE = Cut + Maneuver + Backtrack. Let’s move to the next topic.
Now, let's analyze how manipulation time varies with transmission type. Can anyone share what we might expect?
I think automatic gear shifts might be faster.
Absolutely! Automatic systems typically reduce maneuver time, which is around 0.05 minutes compared to 0.1 minutes for manual shifting. This distinction can really affect our cycle time.
Why does that matter for productivity?
Good question! If we reduce tricky maneuvering times with automatic gear shifts, we enhance productivity on the job site!
So, for better productivity, should we prefer automatic transmissions?
If improved cycle times are your goal, yes! But remember to balance that with machine costs and suitability for the job.
To summarize this session: the type of transmission can significantly influence maneuver times, aiding productivity enhancements.
Next, let's talk about estimating productivity. Does anyone recall how to express it?
Is it the blade load divided by cycle time?
Yes! We express productivity in loose cubic meters per hour. But don't forget to define whether the volume is in the loose or bank state.
And we need to account for efficiency, right?
Exactly! Job efficiency reflects the actual operational time. If a bulldozer operates for only 50 minutes in an hour, that’s a factor to multiply with your productivity.
Can you clarify how we find the cycle time again?
Definitely! We sum push time, backtrack time, and maneuvering time. This whole calculation helps us understand the operational costs for bidding!
Let’s wrap this up: Productivity estimation involves blade load, cycle time, and job efficiency.
Finally, let's discuss correction factors. Can anyone tell me why we need them?
To adjust our estimates based on the actual work conditions?
Exactly! Standard curves assume ideal conditions, and we must adjust for real site conditions with factors like operator skill and material type.
So, if the operator is less skilled, the productivity will drop?
That's right! Likewise, tough materials can reduce productivity. Always analyze your specific conditions to apply the correct factors.
What about site visibility? Does that affect productivity?
Yes! Poor visibility reduces productivity. When making your estimates, always apply the relevant correction factors carefully.
So the take-home message is: Correctly applying factors gives a more realistic picture of productivity.
The total time required for completing one operational round with a bulldozer, including its various components.
The time it takes for the bulldozer to move earth.
The time required for shifting gears and adjusting speeds.
How much the bulldozer is actually working versus total available time.
Adjustments made to productivity estimates based on real-world conditions.
If a bulldozer's push time is 10 minutes for 100 meters and its backtrack time is 5 minutes, the cycle time for this operation, excluding maneuvering wood be 15 minutes. If maneuvering takes an additional 2 minutes, the total cycle time becomes 17 minutes.
A bulldozer operating under ideal conditions might produce 100 loose cubic meters of earth per hour. However, if the operator's skill is average, and visibility is poor, the productivity may drop to around 80 loose cubic meters.
For bulldozer speeds, don’t you see, Maneuver fast and push with glee, Cycle time we must check, To keep our work in perfect spec!
Imagine a bulldozer preparing for a race. It takes time to push, to come back, and to shift gears. The faster it manages to shift gears, the faster it finishes tasks, but if it stops to think about adjustments too much, it slows down!
Remember P(BM)C: Push - Backtrack - Maneuver - Cycle; each letter stands for a component of cycle time.
CAM = Cycle, Adjust, Measure; framework for keeping productivity on track: measure what matters.
Term
Cycle Time
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Term
Maneuvering Time
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Term
Job Efficiency
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The total time taken for completing one full operational cycle of the bulldozer, including cutting, pushing, dumping, and returning.
The time required for the bulldozer to push material from a cut to the dumping location.
The time taken for the bulldozer to return to its original position after dumping the material.
Time needed for shifting gears, changing speed, and other adjustments that affect the bulldozer's operation.
A measure of how effectively the bulldozer is operated within a given period, usually reflected as a percentage.
The section explores various factors that influence the productivity of bulldozers, including cycle time, maneuvering time, and job efficiency.
This section delves into the factors affecting bulldozer productivity, focusing on cycle and maneuvering times as influenced by haul distance and gear type. It emphasizes the need to consider job efficiency, operational conditions, and correction factors based on specific site characteristics when estimating productivity.
The section covers key factors influencing the productivity of bulldozers, first explaining the importance of cycle time, which includes push time, backtrack time, and maneuvering time. Cycle time can be affected by haul distance, as longer distances generally increase both push and backtrack times.
Maneuvering time, which is necessary for adjustments like changing speed or gears, varies between manual and automatic gear systems and can significantly impact the overall cycle time. The section stresses the calculation of speed from a performance chart, emphasizing the role of terrain conditions in determining resistance and speed.
Additionally, the section outlines how to estimate productivity in loose cubic meters per hour, relating it to the blade load divided by cycle time, while accounting for job efficiency, which describes the actual operational time of the machine relative to one hour. Lastly, it emphasizes the importance of accurate estimation of unit costs, as these calculations directly affect bidding and operational planning.