6.2.1. Rotating Eccentric Weights

So, basically what to do here is, so this is a setup of the double acting steam hammer, you can see two cylinders one is the upper cylinder, other one is a lowest cylinder. Now in the upward stroke what you do is, you supply air into the lower cylinder. So, when you supply into this, this is the lowest cylinder, when you supply air into the lower cylinder, the hammer which was earlier in the lower cylinder will be pushed up into the upper cylinder.

The section begins with an overview of a double acting steam hammer, which consists of two cylinders: an upper and a lower one. During the upward stroke, air is supplied to the lower cylinder, which causes the hammer to rise into the upper cylinder. This upward movement is essential for the hammer's operation as it prepares for the downward stroke.

Imagine a pair of connected pistons in a bicycle pump. When you push down on the pump (like supplying air to the lower cylinder), it forces the air up into the top part of the pump (the upper cylinder) where it builds pressure.

So, the hammer is pushed up into the upper cylinder, the air which was already there in the upper cylinder will expel out to the exhaust. So, basically what you are doing here is you supply air into the lower cylinder. So, that will push your hammer upward into the upper cylinder and the air which was already in the upper cylinder will be released through the exhaust, now your upward stroke is complete.

As the hammer moves into the upper cylinder, the air that was once in that cylinder is expelled through the exhaust, completing the upward stroke. This action is crucial because it clears the upper cylinder for the next cycle, ensuring there’s space for effective function.

Think of a balloon: when you squeeze it in one place (like supplying air in the lower cylinder), the air rushes to another spot and if you squeeze it tightly, the air escapes out the other end. This is similar to how the air in the upper cylinder gets pushed out.

So, what are you doing the downward cylinder? You supply air through the inlet into the upper cylinder. So, when you are supply air into the upper cylinder, the hammer which was already there will be pushed into the lower cylinder. And air which was already in the lower cylinder will be expelled out through the exhaust.

In the downward stroke, air is supplied to the upper cylinder, which in turn pushes the hammer down into the lower cylinder. This movement expels the air that was previously in the lower cylinder, allowing the cycle to repeat. This back-and-forth movement is what gives the double acting hammer its efficiency and effectiveness.

Picture a seesaw: as one side goes up (supply air to upper cylinder), the other side goes down (hammer pushed into lower cylinder). When one side rises, the other side drops down, creating a continuous motion.

So, another important thing we need to know with respect to double acting hammer is in this most of the blow energy is the derived from the steam energy. Both for the upward stroke as well as for the downward stroke, the blow energy is derived mainly from the steam energy.

The blow energy, which is the force exerted by the hammer on the material, primarily comes from steam energy. This energy drives both the upward and downward strokes, allowing the hammer to perform its function efficiently without needing a heavy hammer.

Think of a kettle: when steam builds up inside, it pushes against the lid. Similarly, in the hammer, steam energy builds up and provides the necessary force to drive the hammer up and down.

So, that is why, for the double acting hammer we need not for a heavier hammer. We can go for lighter hammers, smaller in size and you can go for the shorter stroke or shorter height of fall.

Since the energy required to operate the hammer is derived mostly from steam, the design of the double acting hammer allows for lighter weights and shorter strokes. This contributes to ease of use and maneuverability, making these hammers advantageous for certain types of work.

Consider a toy car powered by a rubber band. The rubber band doesn’t need the car to be heavy; instead, it just needs enough tension to propel it forward. Similarly, the steam energy drives the lighter hammer effectively.

So, it is basically designed for this kind of conditions only, and you should never use this double acting hammer for concrete pile. Because these double acting hammers, they basically have a very high blow rate, if you look into the blow rate, you can see that the blow rate will be 95 to 300 blows per minute.

Double acting hammers are specifically designed for light to medium weight piles and normal soil conditions. They work well within a specific blow rate, but their high frequency is not suitable for driving concrete piles, as it can cause damage.

Imagine using a soft rubber hammer to tap a nail into the wall; the hammer is light and effective for that job. Now think about using the same light hammer to smash concrete—it's not effective and might cause damage!

So, let me summarize what we discussed, so your use of steam energy in driving the ram allows use of shorter stroke and compact hammer than single acting hammer.

In conclusion, the use of steam energy in the double acting hammer allows it to be more compact and efficient than single acting hammers, making it suitable for certain conditions and tasks.

Think of a compact toolbox that has all the essential tools neatly arranged, versus a larger toolbox that is cumbersome to carry. The compact toolbox (double acting hammer) is more efficient for quick jobs.

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