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Today we're discussing cycle time for bulldozers. Can anyone tell me what cycle time refers to?
It's the total time to complete a task, right?
Exactly! Cycle time includes both fixed time and variable time components. The fixed time doesn't change, while variable time does depend on factors like haul distance. Can someone explain how these times affect productivity?
The shorter the cycle time, the more productive the bulldozer can be, right?
Right! Remember, we have fixed times like maneuvering gear changes. A good memory aid is the acronym 'FAV'—Fixed-time Adjustments and Variable-time performance. Always keep that in mind!
How does the type of transmission affect fixed time?
Great question! Direct transmission takes longer than power shift mode due to manual gear changes versus automatic ones. These differences impact overall efficiency and should be considered in estimations.
Is there a specific formula to calculate these times?
Yes! If you know the haul distance and speed, you can calculate push time. It's all interconnected! Remember, good estimates lead to better planning for productivity.
In summary, understanding cycle time helps improve productivity. Remember the terms fixed time and variable time carefully!
Now, let's discuss performance charts. They help us know the speed of our bulldozer, which is vital for calculating cycle time.
How do we read those charts?
The speed is on one axis, and the total resistance on the other. Can anyone guess what factors we consider for total resistance?
Rolling resistance and grade resistance?
Exactly! Remember 'RG'—Rolling and Grade resistance. By knowing these, we can accurately determine how fast our bulldozer can operate.
What happens if we underestimate these factors?
We might overestimate productivity, ultimately affecting our project planning and costs. This is why understanding these charts is crucial.
Can you show us an example?
Sure! Let's say the performance chart indicates a speed of 5 meters per second based on our project’s rolling resistance. We can now calculate push time accurately.
In summary, understanding performance charts enhances our ability to estimate bulldozer productivity accurately.
Now we’ll estimate productivity! Can anyone remind us how we calculate productivity in earthmoving using bulldozers?
Is it the blade load divided by cycle time?
Exactly! What do we need to know for blade load?
The type of blade and its capacity?
Absolutely! Additionally, knowing the haul distance and speed is crucial as they influence cycle times. Don't forget the acronym 'BLHS'—Blade Load, Haul, Speed.
What about job efficiency?
Good point! Always factor in job efficiency; machines usually work less than 60 minutes an hour. What could be a typical efficiency?
It could be around 45 minutes or so, right?
Exactly! That brings us to adjusting our productivity calculations based on efficiency. In summary, for each machine operation, consider load, cycle time, efficiency, and project conditions.
A duration encompassing all operations on a bulldozer.
Time required for actions that remain constant regardless of distance.
Time that changes depending on project-specific factors.
Adjustments made by the operator affecting efficiency.
Tool for understanding bulldozer speed and resistance.
Cycle time takes a while to measure, fixed time's a treasure, variable's the pleasure.
Imagine a bulldozer at a construction site, always adjusting its gears. It takes consistent time to shift gears (fixed) and different times to push soil depending on the distance (variable), making it a smart worker in the field.
Use 'CVFM' to remember: C for Cycle time, V for Variable time, F for Fixed time, and M for Maneuvering time.
Remember 'R-G' for Rolling and Grade resistance, critical in using performance charts.
Term
What is cycle time?
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Term
What influences variable time?
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Term
What is fixed time?
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The total time taken to complete all operations involving a bulldozer, consisting of fixed and variable time.
The portion of cycle time that remains constant regardless of operational conditions.
The portion of cycle time that varies depending on external factors such as haul distance and speed.
The time taken to adjust the bulldozer's operation, including gear changes and acceleration, affecting overall efficiency.
Graphical representation of a bulldozer's speed versus its resistance, aiding in operational assessments.
This section discusses the concepts of cycle time in bulldozer operations, distinguishing between fixed and variable time components and their implications on productivity.
The section elaborates on cycle time for bulldozer operations, identifying the fixed time (related to gear changes and maneuvering adjustments) and variable time (dependent on haul distance and speed). Understanding these concepts is crucial for accurate productivity estimations in earthmoving operations.
In bulldozer operations, the total cycle time necessary for tasks, such as cutting and pushing earth, comprises both fixed and variable components.
Fixed Time: Refers to the constant time required for actions that do not vary with the task's distance or conditions. This includes:
Variable Time: This part of the cycle time changes based on project conditions and includes:
For effective productivity estimation, knowing these times allows operators to calculate the bulldozer's output in loose meter cubes per hour, factoring in machine efficiencies and operational characteristics. Efficiencies impact the total operational time, typically working less than 60 minutes per hour in real project conditions.
Additionally, different methodologies exist for estimating productivity. These include: