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A short class with Sarah and her students. The other ways are under More.
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Today, let’s explore the world of scrapers and pushers. Can someone tell me, what do you think is the function of a scraper in a construction project?
Isn't it used to move soil and materials around?
Exactly! Scrapers are critical in efficiently moving bulk earth materials. They can load, haul, and dump material. Now, how about pushers? What’s their role?
They help the scraper load more material, right?
Yes! Pushers assist scrapers, especially in loading phases to maximize capacity. Remember the acronym SPAT – Scraper Pushes And Transports!
That's a great way to remember it!
Now, let’s move on and discuss how we estimate the productivity of scrapers.
Cycle time estimation is crucial for calculating productivity. Can anyone explain what factors might affect the cycle time of a scraper?
Things like loading time, dumping time, and travel distance?
Exactly! Each phase, from loading to hauling and back, takes time. For instance, if the loading time is too long, what might happen?
It would lower the overall productivity!
Correct! We can remember this with the phrase 'Time is Money' – demonstrating how time efficiency impacts costs. Let’s calculate some examples next.
The swell factor is an essential concept we have to understand. Who can tell me what the swell factor represents?
It’s the ratio of loose to bank dry unit weight?
Correct! And in our case, the swell factor even increases due to additional pressure from the pusher. Why do we need to consider this?
Because it affects the actual load we can carry, right?
Exactly! Always consider the swell factor when calculating effective volumes. Remember – SWELL stands for Scraper Weight and Efficiency Loads Lifted.
Working in unison is essential. How can we determine how many scrapers one pusher can efficiently serve?
By comparing their cycle times?
Exactly! The ratio of scraper cycle time to pusher cycle time gives us an idea of balance. This is critical to reducing wait times.
So, if the scraper takes longer, we’d need more pushers!
Yes! A good memory aid is BUNCH – Balancing Using Not just Cycles but Harmony in production.
Equipment for moving earth and materials.
Assist scrapers in loading to improve efficiency.
The basis for measuring productivity and operational efficiency.
Important for calculating effective volumetric carries.
Influences the performance of vehicles on different surfaces.
Digging with a scraper's might, hauling dirt both day and night.
Picture a busy construction site where a pusher helps a large scraper load soil faster, making every operation efficient.
SPAT – Scraper Pushes And Transports material efficiently.
BUNCH – Balancing Using Not just Cycles but Harmony in production.
Term
What is a scrape?
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Term
Define cycle time.
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Term
What is a pusher used for?
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A type of earth-moving equipment that loads, hauls, and dumps materials.
A machine that assists scrapers in loading materials more efficiently.
The ratio that indicates the increase in volume of material when transitioning from a bank state to a loose state.
The total time taken for one complete cycle of a machine's operation.
The resistance encountered by a vehicle when moving over a surface.
This section introduces and explores the fundamental concepts and operations involved in earth-moving equipment, specifically scrapers and pushers.
The section provides an overview of scrapers used in earth-moving operations, detailing their productivity estimation, operational components, and management of the equipment during various phases of construction. A strong emphasis is placed on understanding the relationship between scrapers and pushers, the estimation of productivity, and the cycle time assessment.
In this section, we delve into the intricacies of Earth Moving Equipment, focusing particularly on scrapers and their interdependent relationship with pushers. The lecture begins by recapping the components of the scraper's production cycle and introduces the challenges associated with estimating the productivity of these machines. Key terms, such as swell factor and rolling resistance, are discussed in relation to the specifics of operating a scraper loaded with material, namely dry earth soil. We learn how to use the swelling factor to convert load volumes and how an understanding of the scraper's operational efficiencies can improve performance.
Key points include: