In the Daming Arsenal in the outer city, in the open space in front of the warehouse, a carriage was suspended. Underneath the carriages, dozens of craftsmen are busy changing wheels.

Near this group of busy craftsmen, there is also a group of officials from the Ministry of Industry who are nervously recording something, and Yao Jing, the director of the Department of Cleaning and Cleaning of the Ministry of Industry, is looking at the suspended carriage with a worried face.

"Will this rope break? Just a few people pulling the rope, do they insist on staying..."Yao Jing couldn't help but worry, and asked the steward who accompanied her.

The steward accompanying the arsenal explained with a smile on his face: "These suspended ropes are not ordinary hemp ropes, but newly developed ropes mixed with iron strands, which are several times stronger than ordinary hemp ropes.

It is similar to the manufacturing method of the big pendulum rope in the drum tower, and the big pendulum has been hanging for several months without problems, which shows how reliable this rope is.

As for the craftsmen, they are not pulling the ropes, but looking after the traction of the suspended carriages. This way of using the pulley group to suspend heavy objects, which can save two-thirds of the force, was designed by Sun Daren and several academicians of the Academy of Sciences.

However, Sun Daren thinks that although this rope is strong, it has too much friction, and is ready to replace it with a smooth wrought iron chain, but the wrought iron chain that is available now has not yet been made..."

When the two were watching the craftsmen and talking, Sun Yuanhua was walking towards here with the emperor.

“… After trying out the horse-drawn railway transportation method for half a month, the ministers and others found that although this road transportation mode is far less labor-saving than the horse-drawn carriage, the wear and tear of the axle is very large.

Chen had seen the Jianyi made by Guo Shoujing in the former Yuan before, and four small cylinders were installed between the Baike ring and the equatorial ring to reduce friction, and the minister thought if he could apply this method to the axle to reduce the wear and tear of the axle..."

On the way to walk, Sun Yuanhua explained to Chongzhen the reason for changing the wheels today. Zhu Youzhen was still thinking about what the relationship between this cylinder and the axle was, but when he walked to the scene and saw the real thing, he finally understood.

The carriages running on the horse-drawn railroad were changed according to ordinary horse-drawn carriages, and although the shape of the appearance and the number of wheels changed, the principle of operation did not make a fundamental change.

The connection between the axle of the carriage and the wheel is also in direct contact between the bearing and the tile cover.

Compared with modern bearings, this primitive bearing is obviously not suitable for the fast running speed on the rails, and it is easy to quickly increase the temperature due to the high-speed friction of the axle, thus burning the end of the axle.

Sun Yuanhua imitated Jianyi by adding 12 small cylinders between the bearing and the tile cover, thus forming a primitive roller bearing. Although these wheels have not yet been installed, and the axles have not been tested, Zhu Youjian can already confirm that today's test will be successful.

Zhu Youzhen stroked a large bearing placed on the ground, then stood up and said to Sun Yuanhua: "If you want to make such a bearing, these small cylinders must be processed very finely, can the arsenal do it?" ”

Sun Yuanhua was no longer surprised by Chongzhen's expert, and he said without any surprise: "Now the degree and measurement standards in the weights and measures standards of the Academy of Sciences have been fully implemented. The arsenal can already process parts according to uniform specifications and dimensions, and only need to calculate tolerances.

Although the processing requirements of the small cylinder are fine, its processing method is not complicated, but the craftsmanship of the craftsman is high. The only problem was the material used for such a small cylinder, which was both wear-resistant and hard.

The ministers had experimented with several materials before, but none of them could withstand the weight of the carriages used on the horse-drawn railway.

In the end, two possible materials were selected for the bearings of the two carriages, one was bronze. The other is the crucible steel newly developed by the arsenal. ”

Zhu Youzhen subconsciously interrupted Sun Yuanhua and asked, "Crucible steel?" ”

"According to His Majesty's guess, the internal structure of the iron sheet was observed with a microscope at the same time. According to the minister, assuming that steel and iron are the same substance, but the performance difference is caused by the difference in carbon content, then if you want to improve the iron quality, you only need to eliminate impurities and adjust the carbon content.

Therefore, the ministers referred to the ancient method of filling steel, made crucibles with graphite clay, and then cut the carburized iron into small pieces and placed them in it, and then isolated it from the air to prevent the incursion of impurities. It was then heated in a glazed kiln, and finally a kind of steel was obtained.

This kind of steel should belong to the high-carbon steel mentioned by His Majesty, with uniform and hard texture, and better performance than Suzhou steel. That is, the production quantity is not large, and the cost is relatively high.

Originally, they planned to use this steel as a processing tool, but now they are using it to make bearings. Sun Yuanhua simply explained to Chongzhen.

Looking at the irrepressible excitement between Sun Yuanhua's eyebrows, Zhu Youzhen couldn't help but praise a few words. Being able to make crucible steel is obviously a great step forward for Daming's steel production technology.

However, it was not enough for Daming to enter the age of steel, Zhu Youzhen said to himself silently in his heart.

When Chongzhen and his party arrived, the wheels on the frames of the two carriages were almost placed. The suspended carriage was then placed back on a frame parked on the rails and loaded with goods.

The open-top wagons were originally designed to carry 8 tonnes of cargo per carriage, but in practice, they could only carry about 4 tonnes.

Now, after the new bearing, the test will be carried out according to the load of 4 tons. Thanks to the new type of pulley, the same as the iron-wood portal load-bearing frame, the iron blocks used for the test were quickly loaded into the carriage.

The railroad tracks in the arsenal are about 1 kilometer long, and it takes less than 20 minutes to make a round trip between the two carriages. As soon as the truck stopped, a group of craftsmen stepped forward to check the wear and tear of the new bearings.

Sun Yuanhua seemed to have forgotten the existence of the emperor beside him, and hurriedly walked to the wagon on the railroad tracks, and checked the axle with the craftsmen.

This act of throwing the emperor aside made Wang Chengen, who was standing behind Chongzhen, very dissatisfied, and he took a few steps forward, wanting to call Sun Yuanhua back.

However, Chongzhen stopped Wang Chengen and said: "That's it, let Sun Langzhong take a look, the first task of the arsenal today is to test the new bearings, let's not interfere with them, and wait here to hear the results." ”

With the emperor's words, the group immediately stood on the side and waited quietly. The craftsmen of the arsenal were quite meticulous in inspecting the bearings, and it took more than half an hour for Sun Yuanhua to turn back.

Before he could get in front of the emperor, he couldn't help but say with joy on his face: "Your Majesty, there is no sign of damage to the bearings of both materials, and the speed of the wagon has doubled, and the horses it pulls look much easier. The next step is to increase the weight of the cargo and see if it can be improved..."

Zhu Youzhen listened carefully to Sun Yuanhua's explanation, and he was also very happy, which meant that the plan to build a railway that could operate had finally solved the technical problems.

But then he looked at the rails of different lengths on the railway, and asked with some concern: "How many meters can the length of the rails that can be mass-produced now?" ”

Sun Yuanhua replied without thinking: "No more than 35 meters." If it is longer, it will not be able to be processed. ”

Zhu Youzhen calculated in his heart, then frowned and said: "A rail is only about 70 catties, and one person can easily carry it." If I want to build such a railway in the wilderness, how can I ensure that these tracks are not stolen? ”

Sun Yuanhua suddenly opened his mouth a little, he can come up with all kinds of wonderful ways to solve technical problems, but for this kind of social problems, he is a little skilled.

In desperation, he subconsciously said: "Otherwise, we can increase the specifications of the same length of rail, make it stronger and heavier, so that the rail is more durable." ”

Yao Jing, the director of the Ministry of Works, who was standing on the side, suddenly objected: "If this is the case, wouldn't the cost increase a lot, and the iron material that could have built two railways can only be built now."

In Yichen's opinion, we should still put more effort into protection, such as setting up a few more rest stations and increasing the number of people patrolling and guarding the railway..."

Zhu Youzhen thought for a while, and then said: "It is true that measures to protect the railway should be strengthened, but making longer rails makes it difficult for people to steal is also a way. Sun Langzhong, if you want to more than double the length of the railroad rails, how can you do it? ”

Sun Yuanhua thought for a long time, and then said uncertainly: "If you want to increase the pouring length of the rails, I think that I need to start from the ironmaking plant to improve the quality of the molten iron, and strive for the molten iron to meet the requirements of making rails when the molten iron is baked, and then immediately cast the rails."

This will not only lengthen the length of the rails, but also improve the quality of the rails, and at the same time reduce the cost of making rails. ”

Zhu Youzhen thought for a while, and then said to Sun Yuanhua and Yao Jing: "Sun Langzhong will go to Mentougou in a few days to investigate and see where is suitable for building an ironworks and railroad yard near Mentougou.

There are coal, iron, and limestone in Mentougou, and the raw materials for ironmaking should be available. The construction of the railway from Mentougou to the capital can reduce a lot of freight costs, and at the same time, it can also accumulate engineering construction experience for the construction of the new iron plant in Tangshan.

As for Director Yao, wait for today's bearing test to be successful. In three days' time, I will invite some merchants and gentry to visit, and I hope you will be able to prepare a little more for the convenience of transporting goods by rail..."

When Sun Yuanhua sent the emperor away, he couldn't help but ask with some doubts: "Your Majesty, do you really want to hand over the railway to those merchants and gentry to invest in construction?"

The minister thought that although the railway was not as good as the canal water transport, it was much easier to build a railway than to dig a canal.

With the capacity of the railway, it will definitely become the only way to transport goods through the canal in the future. If the Grand Canal is the lifeblood of the Ming Dynasty to communicate the north and the south, the railway may be the lifeline of the plain without canals.

How could such an important mode of transportation be entrusted to the merchants and gentry to build and manage? I'm afraid this may not be beneficial to the Ming Dynasty. ”