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Today, we will learn about cycle time in bulldozer operations. Cycle time consists of push time, backtrack time, and maneuver time. Who can tell me what push time is?
Push time is how long it takes for the bulldozer to push the earth.
Exactly! Now, what about backtrack time?
That's the time taken for the bulldozer to return to its starting position.
Right! So, these two are classified as variable times. Can anyone tell me what maneuver time is?
Maneuver time is the fixed time needed to change gears or speed.
Great! So to summarize, push and backtrack times depend on distance and speed, while maneuver time is fixed. Understanding these components is crucial for accurate productivity estimates.
Now, let’s talk about estimating productivity. Who can explain what we need to calculate productivity per hour?
We need the blade load and the cycle time.
Correct! And remember, we also have to apply job efficiency. What factors might affect how long the machine can actually operate in an hour?
Site conditions and operational efficiency.
Exactly! If the machine operates for only 30 minutes in an hour, we must calculate that into our estimates. Let's try a quick example: If a bulldozer has a cycle time of 10 minutes and operates at 0.5 meters per second, how much can it move in one hour?
In an hour, there are 60 minutes, so it could complete 6 cycles.
Right! And if each cycle moves 3 cubic meters of earth, what is the total productivity?
18 cubic meters per hour!
Great work! Always remember to multiply by job efficiency for practical applications.
Let’s now discuss thumb rules for estimating bulldozer productivity. What do you recall about thumb rules?
They provide quick estimates based on horsepower and dozing distance.
Exactly! For instance, how do we calculate productivity using the thumb rule?
We multiply net horsepower by a constant according to the dozing distance.
Correct! And it’s important to adjust these estimates based on job conditions, such as machine operation time. What should we consider when applying these estimates in the field?
We need to account for job efficiency and environmental factors!
Perfect! Remember, estimates help us plan projects efficiently, making them essential in construction.
The total time needed for a bulldozer to complete its work cycle.
Amount of time spent pushing material to a target.
The return time after pushing the material.
Fixed time for adjustments during operation.
Actual working time of the bulldozer within an hour.
Quick estimation techniques for productivity.
Cycle time is key, push, backtrack, and gears you'll see!
Imagine a bulldozer on a hill. It pushes earth with skill, then backtracks, the operator thrills, ensuring productivity fulfills.
To remember cycle time: P, B, M! (Push, Backtrack, Maneuver).
J.E. for Job Efficiency – Just Exploit every minute effectively.
Term
What are the components of cycle time?
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Term
What is job efficiency?
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The total time required for a bulldozer to complete one cycle of operation, including push, backtrack, and maneuver times.
The time taken for the bulldozer to push material to a designated area.
The time taken for the bulldozer to return to its original position after dumping material.
The time needed for adjusting the speed or changing gears during bulldozer operation.
The actual operational time of the bulldozer within an hour, typically less than 60 minutes.
Simple guidelines for estimating bulldozer productivity based on horsepower and dozing distance.
In this section, we learn about estimating bulldozer productivity using cycle times, maneuver times, and thumb rules.
This section focuses on the essential components determining bulldozer operation efficiency, including cycle time calculation, the importance of push and backtrack times, and using thumb rules for productivity estimation based on horsepower and dozing distance. Various factors affecting productivity, like machine transmission type and terrain conditions, are highlighted.
In this section, we explore the critical concepts for estimating bulldozer productivity through cycle times and thumb rules. The process begins with understanding the cycle time, which consists of push time (the time it takes to push the earth), backtrack time (the time needed to return to the original position), and maneuver time (the adjustments made during operation). Push and backtrack times are categorized under variable time, with their values depending on haul distance and speed, determined from performance charts. Conversely, maneuver time is fixed, with its duration influenced by the machine's mode of transmission—either direct manual shifting or automatic gear changes.
The discussion transitions into productivity estimation approaches, emphasizing that estimating productivity in terms of loose cubic meters per hour necessitates knowledge of blade load and cycle time. The text elucidates that job efficiency should also be factored into productivity estimates, which can vary based on operational time within one hour.
Moreover, thumb rules are introduced as methods to estimate productivity based directly on the machine's horsepower and dozing distance—offering a quick approximation. Finally, the productivity curves based on ideal conditions are discussed, underlining that these curves often require correction factors for practical, on-site applications.