Although the thing parked in the Tiangong Ministry is not the most beautiful one among the trains Zhang Nan has ever seen, and even the antique trains Zhang Nan has seen in the book are much better than the one among the Tiangong Ministry, Zhang Nan could still tell at a glance that the black guy is a train.

Zhang Nan quickly walked to the steam train and looked carefully. Although due to the limitations of craftsmanship and no tools such as lathes, the craftsmen of the Tiangong Department still made a train that was so simple that it could not be as simple as possible.

"Bang, bang." Zhang Nan tapped the big guy with his hand, making a dull sound, and Zhang Nan also got a hand of oil stains.

It can be seen that in order to prevent this guy made of iron from rusting, the craftsmen of the Tiangong Department also took some effort to apply oil to the entire exposed car body, but Zhang Nan didn't know what oil it was.

"Qingquan, why do you have time to come to Tiangong Ministry?"

Zhang Nan turned his head and found that Mo Zu had just walked in from the gate of the Tiangong Department, and he saw that he had just returned from going out.

"Ah, aren't you here to find Mo Zu, who are asking for some people who are accomplished in building houses? Recently, I want to open a supermarket and need to build a house. I originally wanted to find someone from the Ministry of Works, but after thinking about it, it was still too troublesome, so I came to the Ministry of Works." Zhang Nan said with a smile.

"Then you are looking for the right person. Do you still remember the ones built by our Momen in the mountains? They were all built by our Momen. What is the supermarket you are talking about? Do you need Qimen Dunjia or something? If you want to hide this supermarket, I can guarantee that few people can find it." Mo Zu said proudly.

Zhang Nan looked at Mo Zu's mysterious pride and didn't know what to say.

"By the way, Mo Zu, how long have you made this thing?" Zhang Nan said, then pointed to the steam train beside him.

"Ah, you said this, it's been half a month, but it's still being improved. This thing is not a finished product. We still can't think of a good way to solve some things." Mo Zu scratched his head and said. It seems that this train has caused some trouble to Mo Zu, who has been working in a clever life.

"For example, what? Let's see if I can help solve it." Zhang Nan said. After all, although Zhang Nan is not clear about the structure of the train, the one Mo Zu brought out is still somewhat different from the train. Zhang Nan felt that he could still make some constructive suggestions.

"For example? This wheel alone has troubled us for a long time. Old man, I have been thinking for a long time, but wooden wheels cannot bear the weight of large amounts at all. For bronze wheels or iron wheels, it is almost impossible to carry goods on the ground. Every time you go out, there are deep traces on the ground. Moreover, the iron wheels are very easy to deform. After loading the goods you have looked at, they will not be able to use them again in a short time. They can only be rebuilt."

Mo Zu kicked the train wheel in front of him with his feet. It seems that Mo Zu has been worried about this problem for a long time.

Zhang Nan bent down and saw that the iron wheels installed on the train were indeed somewhat deformed and were seriously worn.

"Since that's the case, why not use steel?" Zhang Nan thought for a while and said.

After hearing Zhang Nan's words, Mo Zu smiled bitterly, and then said, "Qingquan, you can easily say it. You can't get this steel just by saying it. You have to know that the smelting of this steel is more than ten times more difficult than this iron. If you don't pay attention, it's easy to scrap a pot of materials. The Ministry of Tiangong does not have so much money to let us use steel to make this thing."

Zhang Nan nodded without comment. After all, the Tang Dynasty is not the current one. Steel is not a metal that can be consumed for the Tang Dynasty. Although he has mastered the technology of steelmaking, if he looks at the steelmaking, the Tang Dynasty cannot do this now.

Zhang Nan looked at the worn iron wheel and thoughtfully, but he couldn't catch the most important point in his mind.

Suddenly, Zhang Nan thought of what was missing from this simple train.

"Mo Zu, have you ever thought about laying the tracks on the wheels of this thing?" Zhang Nan asked.

"Trail? What is that?" Mo Zu said.

"Simply put, it is to let this thing drive on a specific trajectory. With that thing, the train should be able to drive stably."

"This seems to be a method. This iron wheel is very difficult to control, and as the body lengthens, the direction is more difficult to rotate. If it can be driven on a specific route, it would be better." Mo Zu thought about it and it seemed that it was much better than running around on the ground.

"Qingquan, do you call this train?" Mo Zu asked.

"Yes, after all, it is powered by fuel." Zhang Nan nodded and said.

"Well, we were arguing about not having a good name at the beginning. The name of a train is good, so this thing is called a train." Mo Zu said as if he had solved a problem.

"But even if the track you mentioned is laid, the weight of the car remains unchanged. If the land should sink, will it fall? Isn't the effect of force mutual?"

Mo Zu suddenly came out of his mouth with force, which shocked Zhang Nan. However, Zhang Nan quickly realized that this sentence must have been Mo Zu's view from the junior high school physics textbook, and he immediately felt relieved.

"That's not. The wheels are iron, and this track is also made of iron. The wheels on both sides correspond to two rails. The railway's subgrade section is trapezoidal, because the trapezoidal shape can disperse the force well. The top is the rail, and then the sleeper is the gravel under the sleeper, which also disperses the force. Below the gravel is our dirt road." Zhang Nan said.

"Can this work?" Mo Zu said with a look of suspicion. It seemed that Mo Zu still didn't believe it. He could solve this problem by adding two extra rails and laying a few more wood.

"Is it OK? You have to try it before you know it. But if Mo Zu, you use my method, the iron wheel will definitely not press down the ground anymore." Zhang Nan said with a smile.

"Well, that old man, I'll try it according to the method you said. If it succeeds, this train can pull very heavy goods, which is a powerful weapon for the country." Mo Zu said excitedly.

"Mo Zu, don't be excited. You can find out the person I want first. I know very well what kind of changes this train can make to the Tang Dynasty." Zhang Nan also said with a smile.
Chapter completed!