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A short class with Sarah and her students. The other ways are under More.
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Let's start with the basic components of cycle time for scrapers and pushers. Can anyone tell me what factors influence these times?
Is it mainly loading and dumping times?
Exactly! Loading, dumping, and traveling times all contribute to the cycle time. Additionally, the swell factor plays a significant role when calculating weights. What do we remember about the swell factor?
It’s the ratio of loose volume to bank volume! But it increases by 10% when using a pusher, right?
Correct! This increase is due to the additional compaction from the pusher. Remember, it’s essential to account for density changes in material as well.
How do we handle the different loading times?
Great question! We use average times provided by manufacturers, which are crucial for accurate cycle time calculations.
So, knowing these components helps us estimate total cycle time effectively?
Exactly! Let’s summarize: cycle time is affected by loading and dumping times, swell factor, and operational efficiency of the machines. Keep these in mind!
Now that we understand the factors, let's calculate the productivity of a scraper. If the heaped capacity is 23.70 m³ and we load 95% of that, how much are we loading?
That would be 22.52 m³!
Exactly! Now, when converting to bank volume using the swell factor of 0.80, what’s the volume?
We have to multiply 22.52 by 0.80, which gives us 18.016 m³.
Close! But first, we need to account for the 10% increase in the swell factor due to compaction with the pusher. Can someone calculate that for me?
So we calculate 22.52 * 0.8 * 1.1 = 19.82 m³.
Great job! Knowing how to process these calculations is vital for estimating cycle time realistically.
We've talked about productivity, now let’s discuss balancing machines. Why do you think it's vital to balance the number of scrapers with the pushers?
To minimize wait time for the machines and maximize productivity! Right?
Exactly! One pusher can assist several scrapers, typically 4 to 5. How can we determine the right number for efficiency?
By comparing their cycle times?
Absolutely! To find the balanced number of scrapers per pusher, we divide the scraper cycle time by the pusher cycle time. Who can recall what those times are?
The scraper cycle time is 7.78 minutes, and the pusher cycle time is 1.37 minutes!
Perfect! Now, can anyone calculate the number of scrapers that can be optimally served by one pusher?
It would be 5.68 scrapers, but we’d round that down, right?
Correct! Thus, we consider the economics for either 5 or 6 scrapers to finalize our decision.
If a scraper has a heaped capacity of 23.7 m³ and is loaded to 95%, the effective load volume becomes 22.52 m³. Then considering the swell factor, the bank volume to manage is calculated using the increased swell factor due to compaction by pushers.
The operational efficiency was benchmarked by estimating that one pusher can operate concurrently with approximately 5 to 6 scrapers, based on their cycle times.
Swell’s that change from loose to tight, ten percent on pushers makes it right!
Imagine a construction site where pushers are hard at work. As each scraper fills up, the swell factor quietly rises, hiding within the machine's efficiency, revealing the secrets of earth moving.
L-D-T – Loading, Dumping, Traveling – the three core components of cycle time!
CYCLE - Comprehensive Yield through Calculated Loading and Efficiency.
Term
What is the cycle time?
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Term
What role does the swell factor play?
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A ratio that describes the increase in volume of soil when it is excavated and moved, representing the relationship between loose and bank volumes.
The total time taken to complete a full operating cycle by a scraper or pusher, including loading, hauling, and dumping.
The force that resists the motion of a vehicle on a surface, typically measured in kg per ton.
This section outlines the cycle time for scrapers and pushers, focusing on productivity estimation and the balance of interdependent machines.
In this section, we delve into the cycle times associated with scrapers and pushers, exploring the influential factors such as swell factor, loading times, and haul distances. We also highlight the importance of balancing the number of scrapers and pushers to optimize productivity within the construction process.
In this section, we explore the cycle time for scrapers and pushers, key pieces of earth-moving equipment. We begin by discussing the various parameters that affect cycle time, including the swell factor, rolling resistance, and the weight of the material being transported. The swell factor is critical in determining the conversion between loose volume and bank volume of materials, which is essential for accurate weight estimation. Notably, the swell factor increases by 10% when pushers are used, due to additional compaction pressures.
We also detail the operational side, such as the estimated average loading, dumping, and turning times which contribute significantly to the overall cycle time. With the introduction of practical examples, we see how to calculate the production rates and the costs associated with moving earth materials. Another crucial aspect is the coordination of scrapers and pushers; the section illustrates how to balance their use to maximize operational efficiency. Ultimately, understanding cycle time is vital for project planning and execution, ensuring machines operate at optimal capacity and reducing costs.