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Today we're going to understand the cycle time of a bulldozer. Cycle time comprises push time, backtrack time, and maneuver time. Can anyone tell me what push time means?
Is it the time taken to push the material forward?
Exactly! Push time varies based on haul distance and the speed of the machine. Now, what about backtrack time?
Is that when the bulldozer returns to its starting point?
Correct! It’s typically less than push time since the bulldozer travels empty. Good job! Let's remember: 'P for Push and B for Backtrack.' It helps to recall their sequence.
Next, let’s consider maneuver time. This time is affected by how the bulldozer changes gears. What two types of transmission are there?
There’s manual gear change and automatic gear change?
Right! The choice affects maneuver time: 0.05 minutes for automatic and 0.1 minutes for manual. Can anyone remember the mnemonic for this?
I think it’s ‘Auto = Fast, Manual = Slow’ to help remember the differences!
Great memory! Remembering these nuances is key to understanding bulldozer productivity.
Now, let’s calculate productivity. It’s defined as blade load divided by total cycle time. What factors influence this calculation?
I think the haul distance and speed of the machine are important?
And the job efficiency factor too, right? The machine won’t be working the entire hour.
Exactly! Adjusting for work efficiency is crucial for accurate estimates. Can someone give an example?
If a bulldozer works for 45 minutes, it means the efficiency is 45/60 or 0.75!
Well done! So, productivity estimation is critical for efficient project management.
Finally, let’s discuss cost estimation. Why do you think it's important in bidding?
So we can quote a fair price and not lose money during the project?
Exactly! Knowing unit costs helps plan effectively. What’s the formula to find the unit cost of production?
It's the hourly cost divided by hourly productivity!
Perfect! Always remember to evaluate costs thoroughly to avoid unfortunate miscalculations.
If a bulldozer has a push time of 5 minutes, backtrack time of 3 minutes, and maneuver time of 1 minute, its cycle time is 9 minutes.
Using an average efficiency of 0.8, if the productivity is calculated at 30 loose cubic meters per hour, the effective output would be 30 * 0.8 = 24 loose cubic meters per hour.
Push and backtrack, then maneuver right, cycle time together, keeps productivity in sight.
Imagine a bulldozer racing against time. It pushes heavy dirt, takes a swift backtrack, and adjusts gears to keep going.
PBM - Push, Backtrack, Maneuver; remember the order for cycle time.
C for Cycle, P for Push, B for Backtrack, M for Maneuver - all parts of time!
Term
Cycle Time
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Term
Push Time
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The total time taken for a bulldozer to complete its work cycle, including push time, backtrack time, and maneuver time.
The time spent pushing material forward by the bulldozer, influenced by haul distance and speed.
The return journey of the bulldozer after pushing material, generally shorter than push time.
Time required for the bulldozer to change gears and adjust speed, affected by transmission type.
The actual time the bulldozer operates effectively within an hour, typically less than 60 minutes.
The amount of material the bulldozer blade can carry at one time.
The cost associated with moving a unit volume of material, calculated as hourly cost divided by hourly productivity.
This section explains how to estimate the productivity of bulldozers, focusing on cycle times and factors affecting performance.
In this section, we delve into the components of bulldozer productivity, including cycle time, push and backtrack times, maneuvering, and how to calculate these based on operational conditions and efficiency factors. It highlights the importance of accurate estimations for effective project management.
In this section, we detail the critical elements involved in estimating bulldozer productivity, defined primarily in terms of loose cubic meters per hour. The bulldozer’s cycle time encapsulates various components such as push time, backtrack time, and maneuver time, each significantly influenced by the haul distance and machine speed.
Key concepts include: