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Today, we will discuss the cycle time of a bulldozer. Cycle time includes push time, backtrack time, and maneuver time. Can anyone tell me what push time is?
Isn't that the time it takes to move the earth forward?
Exactly! Push time is influenced by the haul distance. What about backtrack time?
That's when the bulldozer returns to the original position, right?
Correct! Backtrack time is generally shorter than push time because the blade is empty. Now, let's discuss maneuver time.
Is that the time it takes to change gears or adjust speed?
Great! It varies depending on whether the bulldozer has automatic or manual gear changes. Remember, we categorize push and backtrack time as variable time and maneuver time as fixed time.
To summarize, cycle time is made up of three components: push time, backtrack time, and maneuver time, with varying influences depending on distance and machine type.
Now let's discuss how we estimate bulldozer productivity. What do we need to start with?
We need to know the blade load and cycle time!
Correct! Blade load can come from the manufacturer or field measurements. Cycle time includes both push and backtrack time, which depends on haul distance. Can anyone recall how we calculate push time?
It's based on the haul distance and speed, which we can find using the performance chart!
Exactly! Once we have that, we can calculate productivity in loose meter cubes per hour. Don't forget to factor in job efficiency; machines rarely work for a full hour. What does a typical job efficiency look like?
It can be anywhere from 30 to 50 minutes per hour depending on project conditions!
Well done! So, we must multiply the estimated productivity by this job efficiency to get a realistic figure.
Now, let’s explore how to calculate the unit cost of production. What does this refer to?
It’s the cost per loose meter cube of earth moved!
Exactly right! To calculate unit cost, we need the hourly cost of the machine and its productivity. What are some components that contribute to the hourly cost?
Ownership costs, operating costs, and operator wages!
Perfect! Once we gather all those components and have our productivity figure, we can divide the hourly cost by productivity to find the unit cost of production.
And this is critical for project bidding, right?
Absolutely! Accurately estimating these costs is vital for your bidding strategy. Remember, underestimating costs can lead to serious financial issues down the line.
The complete time needed for a bulldozer to finish a dozing operation.
Fixed time taken for gear changes or speed adjustments that varies with transmission type.
Variable times dependent on haul distance and project conditions.
The actual productive time of the bulldozer during an hour.
The cost per loose meter cube, critical for project bidding.
If a bulldozer operates for 40 minutes in an hour and has a productivity of 100 loose meters cubed per hour, then the effective output is 66.67 loose cubic meters.
For a bulldozer with a 1.5-meter blade load and a cycle time of 2 minutes, the productivity would be calculated as 90 loose cubic meters per hour (blade load divided by cycle time).
Cycle time's the game I play, Push and backtrack every day!
Once upon a time, there was a bulldozer named Bulldo who had to push earth and then return back to his point. He learned that timing was everything — cutting, pushing, and maneuvering made him the fastest on the job site!
Remember the acronym 'P.B.M.' for 'Push, Backtrack, Maneuver' to recall the key components of cycle time.
C.P.B. for Cycle, Push, Backtrack — the essential elements of bulldozer operations.
Term
Push Time
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Term
Backtrack Time
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Term
Maneuver Time
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Term
Productivity
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The total time taken by a bulldozer to complete a full sequence of operations, including push, backtrack, and maneuvering.
The time required for the bulldozer to push earth during its operation.
The time needed for the bulldozer to return to its original position after dumping the earth.
The time taken for operational adjustments such as changing gears or altering speed.
The volume of earth that the bulldozer's blade can carry during operation.
The actual working time of the bulldozer in a given hour, expressed as a fraction of 60 minutes.
The cost incurred for moving one loose meter cube of earth, calculated as hourly cost divided by productivity.
This section explores the cycle time, productivity estimation, and cost analysis involved in earthmoving operations, particularly focusing on bulldozer efficiency.
The section discusses key elements of earthmoving operations, including cycle time components such as push time, backtrack time, and maneuver time. It elaborates on how to estimate productivity, considering factors like haul distance, material type, and operator efficiency. It emphasizes the importance of calculating unit cost of production for effective bidding.
In this section, we analyze the unit cost of production in earthmoving operations, particularly for bulldozers. Key components of cycle time are introduced, including push time, backtrack time, and maneuver time. Push time and backtrack time are categorized as variable times influenced by haul distance and operating speed, while maneuver time depends on the type of transmission. The section delves into how to estimate the bulldozer's productivity—expressed in loose meter cubes per hour—by assessing blade load and cycle time. Correction factors related to project conditions, operator skill, and material type are discussed in relation to production curves. The unit cost of production, defined as the cost per loose meter cube of moved earth, is calculated by dividing the hourly machine cost by productivity. This information is crucial for effective cost estimation and bidding strategy in construction projects.