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A short class with Sarah and her students. The other ways are under More.
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Today, we will discuss the concept of cycle time in bulldozer operations. Can anyone tell me what cycle time includes?
Does it include the time taken for the bulldozer to cut and push the earth?
Exactly, it encompasses cutting, pushing, and maneuvering times. We refer to these as fixed time and variable time. Can anyone explain the difference?
Fixed time is when the bulldozer maneuvers, while variable time changes with haul distance?
Correct! The variable time increases with haul distance and is influenced by the speed of the machine. Remember: 'H' for Haul distance leads to 'V' for Variable time!
Now let's dive into how different terrains can impact bulldozer productivity. Who can share how slope affects cycle time?
Working uphill adds resistance and slows down the bulldozer, right?
Correct! And what about moving downhill?
Going downhill increases speed, helping productivity!
Exactly! This means we need to factor in the terrain slope when calculating productivity.
Let's talk about job efficiency. Why do you think it’s important to consider how often the bulldozer runs during the hour?
Because we can't assume it works all the time; we have to consider downtime.
Exactly! If a bulldozer operates for only 30 minutes in an hour, how would we calculate effective productivity?
We would multiply the theoretical productivity by that efficiency factor.
Right! Remember: Efficiency decreases operational time, so always account for it!
Understanding performance charts is crucial. Who can describe how we might use these charts?
They help us find the speed based on rolling and grade resistance.
Great! Approximate haul distance and conditions, and you can evaluate what performance to expect.
So, we can use that to adjust our productivity calculations?
Precisely! Always refer to these valuable resources to ensure accurate predictions.
The distance material must be moved, impacting push times.
Comprises fixed (maneuvering) and variable times (push and backtrack).
Actual working time percentage affecting overall productivity.
The influence of factors like slope and soil type on bulldozer operations.
Push and pull through mud and clay, the cycle time guides our way!
Imagine a bulldozer navigating a steep hill, struggling to push heavy earth but swiftly gliding down, reminding us how terrain truly influences its journey.
C.H.A.R.T - Cycle time, Haul distance, Adjust for terrain, Remember job efficiency, Track speed.
P.H.A.S.E - Push, Haul, Adjust speed, Slope effect.
Term
What is cycle time?
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Term
What is job efficiency?
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The total time taken for a bulldozer to complete a cycle of cutting, pushing, and returning.
The time that changes based on factors like haul distance and machine speed.
The consistent time taken for maneuvers like gear changes which does not vary.
The actual working time of the bulldozer during an hour, considering factors such as downtime.
Graphs that depict the relationship between machine resistance and achievable speed.
The distance the bulldozer must move material from the cutting site to the dumping site.
This section explores the impact of terrain on bulldozer productivity, detailing how factors such as cycle time, haul distance, and soil resistance affect overall performance.
In this section, we investigate the various factors influencing bulldozer productivity, including cycle time related to cutting, pushing, and maneuvering. We examine how haul distance and terrain characteristics such as slope and soil type can alter push and backtrack times, ultimately affecting the efficiency and cost of earthmoving operations.
In this section, we delve into the critical factors that impact bulldozer productivity, particularly focusing on cycle time, which includes cutting, pushing, and maneuvering operations. The cycle time comprises fixed and variable components:
The importance of knowing the haul distance and equipment speed, which can be determined using performance charts, is emphasized. The section also highlights how productivity calculations must consider job efficiency, which varies depending on project conditions (e.g., machine-operating time).
Additionally, the variation in terrain affects the rolling resistance and grade resistance of a bulldozer, influencing optimal speed and thus productivity. For example, working uphill increases resistance and decreases speed, while downhill operation enhances speed and, therefore, productivity.
Finally, we touch upon correction factors necessary for adjusting productivity estimates based on real project conditions versus the ideal scenarios reflected in production curves.