At this point, Li Mengxi understood why the craftsmen said that the pulley was not easy to use in the first place. It was because it was really not easy to use and there was really no manpower to use it.

Li Mengxi realized that later generations of telescopic cranes could not be made in the late Han Dynasty, and even if they were made, the cost-effectiveness would be very low.

When building a city, booms are useful, but not when ramming walls. Because when building a city, the walls are so high and there is so much earthwork. If you hit one point with a boom, you have to keep hitting that one for two months.

point.

When it comes to building a house, after a while, you have to move it and smash the next point.

The amount of work involved in building a city and building a house determines that the cost-effectiveness of a simple tool like a boom is completely different for different projects.

Li Mengxi scratched his head, frowning and wondering, should he really give up the pulley block?

Li Mengxi was not willing to give up.

——

Li Mengxi failed to come up with a solution, so the blacksmiths brought the iron bars that Li Mengxi wanted on carts.

The blacksmiths said that in order to cast this iron bar, several anvils were melted.

Li Mengxi glanced at the huge piece of iron in Heibuliqiu's box. He thought, such a big piece of iron weighed several hundred kilograms.

With the iron block in hand, the craftsmen worked together to hang the square iron block on the boom, and then began to verify the effect of use.

The mold was rearranged and filled with soil. Then, a craftsman pulled the rope hard and lifted the iron block high.

Letting go, the iron block fell straight down with a loud sound.

Li Mengxi went over to check, and he saw that because the mold was placed against the iron block, the bottom of the iron block was square and square, and the mold was also generally wide. Therefore, when the iron block was smashed down, it was smashed inside, outside, left, and right.

, no dead ends.

The test was successful, and standardized operations are useful. When I used stones to hit them, because the stones were smaller than the mold, the edges could not be hit, so I had to rely on people to constantly fine-tune them left and right. Now I have a regular-shaped iron block.

It perfectly fits the mold, so no manual fine-tuning is required.

Technology is complicated and subtle. Whenever Li Mengxi thinks there are no shortcomings, problems will always appear inadvertently.

Iron blocks weighing several hundred kilograms were constantly being lifted and dropped, and they were constantly being pounded.

Suddenly, a board fell down.

At first, both Li Mengxi and the craftsmen thought it was because the mold was not stable. The craftsmen fixed the mold and stopped paying attention.

But then, after some time, another board fell.

The craftsman went over again to lift the plank and strengthen it again.

I thought everything was fine, but not long after, there was a sound of winter, the iron lump fell again, and the board fell again.

After this one after another, Li Mengxi finally realized that something was wrong.

He walked over and took a closer look, but he didn't understand.

I turned around and asked the city builder. The city builder was also confused and didn't know what was wrong.

Since he couldn't understand, after several attempts, Li Mengxi took half a step back and asked people to continue to pull up the iron lump and smash it down.

Li Mengxi was under the iron lump, just one step away from where the iron lump fell. The craftsmen did not dare to move rashly for fear of hitting Li Mengxi.

Everyone advised Li Mengxi to stay away.

Li Mengxi refused to leave. He raised his head and glanced. To be honest, he was a little scared that the boss was hanging on top like an iron lump. However, he couldn't bear to look at it and couldn't see clearly.

He asked the city-builders behind him to pay attention. Once they see the rope is broken, they should quickly pull your military advisor back.

The city builder didn't dare to relax. He grabbed Li Mengxi's shoulders tightly and stared up with wide eyes, not even daring to close his eyes.

"Smash!" Li Mengxi ordered.

The person pulling the rope heard the order and put down the rope, and the big iron lump fell down with a loud sound. Li Mengxi's eyes followed the falling trajectory of the iron lump at high speed. When the iron lump hit the bottom, Li Mengxi saw that after the iron lump hit the ground, left and right

It swayed a lot.

Just these few swings, it kept bumping against the wooden boards on the left and right sides, causing the wooden boards to creak.

Seeing this, Li Mengxi understood that the mold had been knocked over by an iron lump.

But, why.

Not knowing why, Li Mengxi had someone lift the iron lump out and throw it to the ground.

Li Mengxi squatted aside, leaning on his chin and frowning as he observed this ordinary, square-shaped iron lump. He frowned and thought for a long time, and then Li Mengxi understood.

The blacksmiths cast the iron lump into a thin and long shape, similar to the shape of a wine box. Because it is too long, it will definitely sway sideways when it falls from a high place.

And if it is shaped like a scale with a big top and a small bottom, then when it falls, it will not sway and will fall very steadily.

"...the center of gravity." Li Mengxi said, it was because of the center of gravity. He clapped his hands and stood up.

It is best to make the iron lump of rammed earth into the shape of a weighing weight. This shape will be stable when smashed and will not sway, so it will not knock over the mold.

Calling the messenger again, Li Mengxi asked the messenger to go to the blacksmith camp and ask the blacksmith camp to cast another iron lump. The iron lump made this time should be in the shape of a weighing weight with a small top and a big bottom.

The messenger took the order and left.

The heavy object used to ram the earth should be called a [heavy hammer].

I didn't expect that the center of gravity of the weight would affect the use effect.

Li Mengxi looked at the square rectangular iron block. He touched his chin and pondered. Apart from the center of gravity, does the shape have any influence?

For example, which one is better, a spherical iron ball or a flat iron lump?

After thinking for a moment, Li Mengxi recalled a knowledge point, which was related knowledge such as pressure, pressure, and stress area.

For iron balls and iron blocks of the same weight, when the iron ball is dropped, the contact area with the soil is a small point, while when the iron block is dropped, the contact area with the soil is a large area.

In other words, the iron ball exerts stronger pressure on the soil and can smash the soil more solidly.

When Li Mengxi raised his head and looked far away, he saw at a glance that on the wall half a man high not far away, the people there did not use stones to ram the earth, but used another method. The people held a wooden stick.

There was a small millstone on one end of the wooden stake, with the millstone on top and the wooden stake on the bottom. The peasants held the stake, which was heavy on the top and light on the bottom, and pounded it into the soil.

Seeing this scene, Li Mengxi felt that his guess had been confirmed.

Calling the messenger again, Li Mengxi asked the messenger to go to the blacksmith camp again. This time, he asked the blacksmith camp to make two iron blocks of average weight, one in the shape of a weight and the other in the shape of a sphere.

——

About an hour later, the blacksmiths sent over two iron lumps of medium and small sizes. According to the requirements, one was like a weight, big up and down, with a flat bottom, while the other was an iron ball.

At the beginning of the test, he randomly found a flat open space and felt that the soil quality nearby was about the same. Li Mengxi asked people to move the boom over and bury it. Then, he first lifted it with an iron lump and smashed it on the ground three hundred times.

This chapter is not over yet, please click on the next page to continue reading the exciting content! Then, change to the other side, the same height, the same soil quality, and hit it with the iron ball three hundred times.

After three hundred hits each, Li Mengxi took a closer look and saw a clear comparison.

Where the iron ball fell, a thin fold of soil was collected, and where the iron ball fell, a deep pit was created.

At the end of the test, I guessed it correctly. Sure enough, pressure has a great influence on the effect of rammed earth.

Li Mengxi thought, how about making an iron drill that looks like a giant thumbtack? The iron drill has a greater pressure than the iron ball.

But considering that the pressure of the iron drill is strong, but it is too strong, the iron drill will fall down and get stuck directly in the soil, making it impossible to pull it out.

Furthermore, a thumbtack-like structure that is heavy at the top and light at the bottom will inevitably roll and sway.

Based on these two considerations, the center of gravity is as low as possible and the contact area is as small as possible. The iron ball is the optimal shape for the rammed earth tool.

After acquiring important engineering knowledge, Li Mengxi immediately took out the paper from his waist, took out the pen from the bamboo tube, and scribbled down the acquired knowledge.

After writing, fold the paper and put it in your pocket.

The last and most critical question remains. The weight is easy to use and the pulley is easy to use, but the pulley boom cannot move or expand or contract. What should I do?

Li Mengxi frowned and thought, simulating the working process of the boom in his mind. If the boom is to be practical enough, then it must be able to rotate left and right. At this time, a problem lies in the rotation of the boom left and right.

Easy, but the length of the horizontal bar is fixed, and the fixed-length horizontal bar is difficult to match the constantly changing construction distance.

Li Mengxi thought about how to make the iron ball fall steadily into the mold without changing the horizontal bar.

Thoughts were swirling, and a strange picture gradually appeared in Li Mengxi's mind. He thought of when he was a child, he tied a toad with a rope and put it in a bottle, then walked away, slowly pulled the rope, and slowly pulled the toad without knocking the bottle over.

Get the toad out.

"...Yes!" Li Mengxi's eyes lit up, and he had a solution.

Li Mengxi decided to make a long tube. The long tube stood on the mold, and the weight and rope hung in the tube. Then, he fixed the position of the weight by moving the long tube. Wherever it was in the long tube, the weight would inevitably fall.

Where to hit.

With the solution in hand, Li Mengxi immediately went to the carpenter's camp. He asked the carpenters to make a one-foot-long tube as fast as possible that was as thick as a bucket.

——

Towards evening, the carpenters hurriedly made the long tube Li Mengxi needed.

In an open space in the city, Li Mengxi led the craftsmen to start experiments.

Place the long wooden tube flat on the ground, hang the weight into it, and let people pull the rope, and the pulley will rotate. After the weight is lifted high, the person pulling the rope lets go, and with a sound of winter, the weight falls.

Then, the boom does not move, and there is no need to move the horizontal bar, so that the wooden tube can be moved further.
To be continued...