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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 explore double acting steam hammers. Can anyone explain how they operate?
They use air to move the hammer up and down?
Exactly! When air is supplied to the lower cylinder, it pushes the hammer upward, and the air in the upper cylinder is expelled. Can someone tell me what happens next?
Then, air is supplied to the upper cylinder, and the hammer goes back down?
Right! This alternating process allows the hammer to perform many strikes. Remember the acronym 'UP-EX' for Upward pressure and Exhaust in the upper cylinder, and 'DOWN-EX' for Downward pressure and Exhaust in the lower cylinder.
How much energy does the double acting hammer derive from steam?
90% of the energy?
Precisely! This high energy efficiency allows us to use lighter hammers. Can someone explain why lighter hammers are effective?
Because we don't need the weight for momentum if steam provides most of the energy?
Exactly! This makes them compact and ideal for light to medium weight piles. You can think of it as 'STEAM for Strength'.
Why do you think double acting hammers are not recommended for concrete piles?
Because their blow rate is too high?
They work well only in normal soil conditions, not in tough soil like hard clay?
Exactly! Thus, it’s crucial to choose the right hammer for the right type of pile.
In a construction site using double acting steam hammers, they are primarily employed to drive steel piles into softer soils, effectively utilizing the compressed air system.
A project attempting to use a double acting hammer for concrete piles faced cracking due to the hammer's high rate of blows.
Double act with steam and air, lighter hammers without a care.
Imagine a construction site where workers cheer as the steam hammer springs into action, lifting and falling like a dancer, but careful not to step on the toes of concrete!
Remember 'SLEEK' for factors of double acting hammers: Steam source, Lighter construction, Efficiency, Energy boost, Knock number of blows.
USE for understanding double acting hammers: Upward and downward strokes, Steam energy source, Efficiency over weight.
Term
What is the blow rate range of double acting steam hammers?
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Term
Explain the significance of steam energy in double acting hammers.
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This section discusses the functioning of double acting steam hammers, the application context for pile driving, and the limitations regarding concrete piles.
The section explains how double acting steam hammers operate, detailing the airflow mechanics that drive the hammer upward and downward. It emphasizes the lighter design of the hammer, its suitability for light to medium weight piles, and its limitations when applied to concrete piles due to the risk of damage from high blow rates.
This section elaborates on the operation principles of double acting steam hammers, which utilize compressed air or steam to drive a hammer that alternates between upward and downward strokes. When air is introduced into the lower cylinder, it raises the hammer into the upper cylinder, displacing air to the exhaust. Conversely, supplying air to the upper cylinder pushes the hammer back down, leading to a continuous cycle that allows the hammer to strike with high energy. Notably, approximately 90% of the hammer's energy comes from steam, permitting the use of lighter, compact hammer designs suitable for light to medium weight piles in soil with normal friction resistance.
However, this type of hammer is not recommended for driving concrete piles due to their significant blow rates (95 to 300 blows per minute), which can cause damage to the concrete. The section also underscores that these hammers are effective in soil conditions with typical friction, making them more appropriate for non-concrete applications.