Tian Min was also in front of the crowd of onlookers, and when he saw Li You, he greeted him and accompanied him to watch the two carriages together.

The difference between these two carriages and the previous carriages of the Tang Dynasty is that it is four-wheeled, whereas before the Tang Dynasty carriages were two-wheeled.

When many people watch domestic costume dramas or some old photos, they will find that China has always been a two-wheeled carriage, and there has never been a four-wheeled carriage like in the Sherlock Holmes case, shuttling through the streets and alleys, but in fact, the four-wheeled carriage is completely explosive in terms of load and comfort, and the Queen of England also sits in a four-wheeled royal carriage when she goes out. So what is the reason why China has always been a two-wheeled carriage and not a four-wheeled carriage?

There is only one fundamental reason why there is no four-wheeled carriage in ancient China, that is, the Chinese have not solved the steering problem of the four-wheeled vehicle, the Chinese's four-wheeled vehicle is simply installed on a fixed frame, so it cannot be steered, although such a four-wheeled carriage looks like it has four wheels, but it has no practical value, even if there are forty wheels, it is useless.

Although the four-wheeled vehicle that appears in the Qingming Shanghe diagram has four wheels, it is a typical four-wheeled vehicle that cannot be steered, and this kind of vehicle was used until the early fifties after the founding of the People's Republic of China. Four narrow wooden wheels with iron hoops are mounted on the frame and pulled by three or four oxen, and the steering problem is solved by the four oxen pulling hard and hard. (To be exact, it is to solve the steering problem by rutting, the wheels press the road surface deep into two ditches, and the wheels roll in the ditch, and the purpose of Qin Shi Huang to engage in car with the track is for this convenience.) People born in the 40s have seen it in the countryside of the north.

If you want to make a four-wheeled carriage, you must first make a steering differential to solve the problem of four-wheel steering, and the West invented the bogie, and the four-wheeled car can turn freely. Western quad bikes have the first two wheels mounted on one frame, the rear two wheels mounted on the other, and the rear frame framed on the front frame connected by a vertical axle. It's actually a combination of two two-wheelers. This is the famous four-wheeled steering problem, which is a timeless problem, but unfortunately the Chinese have not solved it for thousands of years. Until the arrival of Westerners, the Chinese used two-wheeled vehicles.

The four-wheeled carriage appeared in Europe in ancient Rome, but it was not widespread until the Celts in the 15th century, and the four-wheeled carriage played an important role in the Hussite wars. The Napoleonic era was the pinnacle of four-wheeled carriages, with a carrying capacity of 1.5 tons, which were used to tow heavy artillery and transport the logistics of the army.

The four-wheeled carriage Li You has long wanted to do it, but this matter is simple to say, but it is a very complicated matter, because to build a four-wheeled carriage, it is not just as simple as building two two-wheeled carriages connected together as mentioned above, but to build the relevant industrial chain.

For example, screws, bolts, nuts, gears, racks, springs, bearings, shock absorbers, etc., which can be divided into very fine, such as bearings, to have high strength steel, to be able to manufacture and process steel rings of different sizes, which requires precision cutting means, which also requires high-strength cutting tools, to have a high finish, to have the corresponding polishing machinery. To make steel balls, there must be corresponding molds, and in order to prevent the wear of bearings, there must be corresponding lubricating oil.

These seemingly insignificant things play an important role in the entire industrial manufacturing field. In general, ancient Chinese technology has been backward for a long time, so it is impossible to produce four-wheeled carriages with four-wheel steering capabilities.

Soon after Li You came to the imperial court, he set up a research institute in the research institute to study the manufacture of four-wheeled carriages, which is a shortcut to improve the entire technological level of Datang. With such an industrial processing foundation, and then to develop other industrial manufacturing in Datang, the speed of progress will be accelerated.

Under the guidance of Li You, it took three years for the institute to finally complete the manufacture of the four-wheeled carriage.

Bai Hu drove the carriage, and Li You, Yu Chi Baoqi, Tian Min and Zhao Fu experienced the four-wheeled carriage together.

When the carriage was speeding away, Tian Min was very curious and asked, "Your Highness, why didn't the carriage feel a big bump when it ran so fast?" ”

Li You asked the white tiger to stop, led everyone out of the carriage, came to the side of the wheel, he pointed to the part that connected the car and said: "See those two steel plates, they can vibrate up and down with the movement of the vehicle, which weakens the vibration felt on the carriage." This one is called a leaf spring shock absorber. ”

The next morning, the two carriages appeared in the square in front of the Suzaku Gate.

Li Shimin took the civil and military officials to visit the two carriages and personally experienced them.

After Zhao Fu finished introducing the passenger carriage, he pointed to the freight carriage and introduced: "Your Majesty, this freight carriage can carry 2,000 catties, and it can travel more than 35 miles per hour on the cement road, and no less than 20 miles per hour on ordinary roads." ”

Li Jing was very happy, and he said: "Your Majesty, the freight carriage of our Datang in the past can carry up to 500 catties, and the travel speed is no more than 10 miles. With such a transportation capacity, it is greatly convenient for the movement of troops. "In ancient times, the weight of a carriage could reach 800 catties, but it could only travel slowly, and it was impossible to run quickly.

Li Shimin likes to be tall, he asked: "If it is six wheels, eight wheels, or even ten wheels, can it transport more goods?" ”

Li You said: "What my father said is that under the condition of good road conditions, it is feasible to increase the number of horses to be towed, and it can be called a load-carrying freight carriage. ”

Li Shimin was very happy and grinned.

Li You said: "Father, the manufacture of four-wheeled carriages is not only the invention of a new means of transportation, but also marks a new level of industrial manufacturing in Datang.

Let's put it this way, let's take the manufacture of bows and crossbows as an example, the same number of craftsmen, for example, is 500 people, in the same time, if the Goguryeo people can make 1,000, the current level of craftsmanship in the Tang Dynasty can make 10,000, the efficiency is ten times that of them, and the quality will be much higher than their production level.

It can be said that Datang now has a strong foundation for weapon production, and it also has greater war potential. Of course, when used in civil use, Datang's industrial manufacturing development has also reached a new level. ”

With the help of Li You, Datang's industry, agriculture, science, education, and health are speeding up its development, and Datang, which was originally higher in overall strength than neighboring countries, has increasingly widened the gap with contemporaries.

Li Shimin was very happy and said, "Well done, I want to reward you greatly." ”

Li You suddenly burned a little, and when he said something, he was directly questioned by everyone.