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A short class with Sarah and her students. The other ways are under More.
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Today, we'll learn about how double acting steam hammers operate. Can someone tell me what we mean by 'double acting'?
I think it means it works in two directions, up and down?
Exactly right! In these hammers, air is alternately supplied to two cylinders. Let's break this down. What happens during the upward stroke?
Air goes into the lower cylinder, which pushes the hammer up into the upper cylinder.
Great! And what happens to the air already in the upper cylinder?
It gets expelled through the exhaust.
Correct! This mechanism allows for efficient operation. Remember, the acronym AEA for Air Expulsion Afterward helps us remember this process. Can anyone explain the downward stroke?
In the downward stroke, air is supplied to the upper cylinder, pushing the hammer down into the lower cylinder!
Excellent! You've all grasped the concept well.
Now that we understand how the hammer operates, let's discuss its applications. What kind of piles do you think are suitable for double acting steam hammers?
Maybe light to medium weight piles?
Right! These hammers are designed for lighter conditions. They shouldn't be used for very hard soils or concrete piles. Why do you think that is?
Because they could damage the concrete with their high blow rate!
Precisely! The hammer can produce 95 to 300 blows per minute, which is too much for concrete. Let's remember the phrase: 'light but efficient'. Can you think of types of soil where they would perform best?
Normal soil with regular friction would work well.
Absolutely! You've got the hang of it!
Let’s wrap up our discussion on design considerations. Can anyone tell me how the reliance on steam energy affects the hammer's design?
It allows for the use of lighter hammers, right?
Exactly! Since most energy comes from steam, less mass is needed in terms of the hammer’s weight. But what are the conditions where these hammers aren’t suitable?
They shouldn't be used for tough soils, especially high friction clays.
Correct! They must also avoid concrete piles due to the potential for damage. So remember: lightweight, high blow rate, limited applications.
An operation that uses air supply to create both upward and downward movements of the hammer.
Most energy for the hammer's function is derived from steam energy, allowing for lighter designs.
Best suited for light to medium piles in normal soil conditions; unsuitable for concrete piles and hard soils.
The efficiency and effectiveness of the hammer are linked to its maximum blow rates.
For hammers that act both ways, use lighter ones to save the days.
Imagine a team using a double acting steam hammer on a sunny construction site, watching the hammer rise and fall like a dance, efficiently striking the ground for their essential work.
Remember the 'HAIR' – Hammer Action In Rhythm for how the double acting hammer works with air and steam.
DASH – Double Acting Steam Hammer for easy recall of its full name.
Term
Double Acting Steam Hammer
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Term
Blow Rate
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Refers to a mechanism that operates in both upward and downward motions through the supply of air.
The rate at which a hammer strikes, typically measured in blows per minute.
The resistance encountered by the pile as it penetrates the soil, affecting ease of driving.
The release of air from the cylinder after the hammer has been raised.
The operating mechanism of double acting steam hammers is defined, detailing the roles of air supply in alternating strokes and their specific applications in various soil conditions.
This section elaborates on the operating principles of double acting steam hammers, explaining how air is supplied alternately to the upper and lower cylinders to create upward and downward strokes, respectively. It highlights the hammer's suitability for light to medium piles and emphasizes its limitations regarding use with heavyweight piles and concrete.
The double acting steam hammer operates through alternating air supply to its two cylinders, enabling it to drive piles efficiently. In the upward stroke, air is supplied to the lower cylinder, propelling the hammer upward into the upper cylinder and expelling air through exhaust. Conversely, during the downward stroke, air enters the upper cylinder, pushing the hammer down into the lower cylinder while expelling air. This dual operation allows powerful blows, primarily powered by steam energy, facilitating the use of lighter hammers and shorter strokes compared to single acting hammers.
These hammers are specifically designed for lighter applications, being effective for driving light to medium weight piles into soil with normal frictional resistance. However, they are unsuitable for very hard soils with high resistance, particularly not recommended for driving concrete piles due to their high blow rates (95-300 blows per minute), which could cause damage. Overall, the mechanism allows for an efficient, compact design due to the reliance on steam energy rather than heavy weights.