"Dear officials, the young ones are polite, and the young ones are polite!"

Chen Qiankun bowed all the way, smiling all the way, and greeted Xu Ping under the shade of the tree, "I have seen the deputy envoy."

Xu Ping said: "This carriage was made by your supervisor. Let me tell you why using two wheels in this way can bring more goods than four wheels, and it is easier to get horses?"

Chen Qiankun was stunned and bowed down again: "What kind of person is the young man? How dare you speak in front of all the officials!"

"You are a very excellent craftsman. The carriage you make is durable, flexible and lightweight. If you sell well, no one of the officials here can earn more money than you can give the court. Why should you look down on yourself?"

Seeing that Chen Qiankun was still frightened, Xu Ping said again: "I'm going to hide it from you. Your monthly salary is more than half of the officials here. If you work more, the court will not treat you badly. Of course, everyone has their own ministry. If you can't do what officials do, you can't do what officials do. People have different status, but you also rely on your own skills to make a living. You don't owe anyone, and you don't need to be careful at all times."

After hearing this, Chen Qiankun saluted repeatedly: "The deputy envoy is too kind, how can the young ones afford it? He will kill the young ones!"

"Okay, don't say these false words, just come to the table and say it!"

Chen Qiankun bowed repeatedly, arrived at the table, and bowed to everyone: "You are so ugly, don't blame me, all the officials."

After saying that, he put the bag in his hand on the table, opened it, and said, "These things were made by Deputy Envoy Xu when he was about to make a carriage. When he was about to make a carriage, he discussed the shapes with several of us craftsmen and waited there. It looked concise and clear. All the officials were used to reading the books of sages and had a smart mind. They were not like us rough people. You can understand it at a glance."

As he spoke, Chen Qiankun placed a small two-wheeler and a small four-wheeler in the bag on the table.

Pressing the two-wheeled car with his hand, Chen Qiankun said, "Please look, when these two-wheeled car are made, what is necessary is to sink in the front, that is, when the empty car is placed on the ground, the shaft in the front will fall to the ground. Of course, we really made the car, and there is a rack in front. After the horse is removed, the rack supports the car."

Speaking of this, Chen Qiankun cleared his throat and said, "Officials all know that both horses and mules are used to carrying weights. If they use them to pull the plow and plow the fields, they will be tired very quickly, which is not possible. The same is true for horse carriages. If they just rely on horsepower to pull forward, like a four-wheeler, then they will not be able to support them and overdraw their horsepower. The two-wheeler carriage will divide part of the weight of the carriage to the horse, which is equivalent to letting the horse carry and pulling it, and it is not easy to get tired."

After saying that, Chen Qiankun looked back at Xu Ping who was standing not far away. Seeing Xu Ping nodding to him with a smile, he became confident without realizing it. He pointed to the model on the table again to explain.

He gently supported the two-wheeled carriage with his hands, Chen Qiankun said, "Please look, as long as you hold the car up, you don't need to use force, the car can walk forward by itself. What is this? At that time, several of us craftsmen gathered together, and they were puzzled. Later, Deputy Envoy Xu explained to us that the weight of the car was in front, and this weight could be considered as gathering at a point, and then, it was equivalent to having such a force pulling the wheel forward."

Xu Ping thought to himself that the center of gravity was called the center of gravity. He talked about this concept at that time, but unfortunately the craftsman still couldn't understand it and could not remember it. The center of gravity is equivalent to the gravity of the car that is gathered at this point, vertically downward, and acting on the wheel, and a gravity torque opposite to the friction torque is generated. At this time, gravity becomes the driving force for the car to move forward.

The center of gravity of the four-wheeled carriage is between the front and rear axles. Gravity is equivalent to the power of the car moving forward to the rear wheel, while the front wheel increases the resistance of the car moving forward. If the two cancel each other, the effect of the two-wheeled carriage will not be as good as the two-wheeled carriage.

In fact, how many wheels are just appearances. The real key is to make the center of gravity located in front of all driven wheel axles, so that the torque of gravity to the driven wheel is opposite to the frictional torque, and becomes the driving force for the car to move forward, which is equivalent to reducing the load of the car.

The key to using a two-wheeled carriage is two points. The horse can carry weights. Under this premise, it is reasonable to use gravity and divide the load in the car bucket into two parts, allowing the horse to carry and pull, so as to make full use of the horse's power.

This is designed based on the characteristics of the use of the livestock. For example, cattle cannot carry weights, and the traction force is much greater than that of a horse. It is actually used to transport goods and is suitable for the shape of a four-wheeled carriage. The same is true if you use a horse pull.

This is best reflected in Xu Ping's freight truck in his previous life. From the very beginning, the full-trailer was equivalent to a four-wheeled carriage. Later, it became increasingly popular for heavy loads, and the mainstream became a semi-trailer. The biggest feature of the semi-trailer is that the center of gravity is located in front of all the driven wheel axles. One is to increase the adhesion of the driving wheel, and the other is to use gravity torque to reduce the traction load of the car, which is basically the same as the two-wheeled carriage. However, those vehicles with very small friction torque do not have this requirement. For example, trains have always used pure traction.

Although these mechanics knowledge are not complicated, it is still difficult for people of this era to explain it clearly and let them understand it. Xu Ping could only use the model, add his own explanation, and the wisdom of these craftsmen to let them understand and accept this truth.

Although Chen Qiankun is timid and has good eloquence, he speaks clearly and smoothly all the way.

After saying that, Chen Qiankun bowed to everyone: "I am ugly, I wonder if the officials have anything to ask?"

Hu Su in the crowd said, "This Attendant, you just said that you should lift the two-wheeled car with your hands. If you put it flat, you will walk forward by yourself. But if we lift the car with your hands, our arms are different. Instead, it will be easier to use a cart or pull the cart to make it move forward. Is this the reason?"

Chen Qiankun smiled and nodded: "The official is right, and the car will be sore after lifting it for a while."

Wang Zhu and Hu Su looked at each other and asked with a smile: "Isn't that still a four-wheeled carriage light?"

Chen Qiankun bowed: "At that time, some of us craftsmen also asked Deputy Envoy Xu, and I told several officials what the Deputy Envoy said at that time. I felt tired when carrying the car with my hands because we cannot carry too heavy things with our hands, but we can move heavier things by pulling or pushing. Horses are different from us, and carrying a strong man can still walk as fast as flying. It is no problem to walk dozens of miles a day. Besides, it is not as heavy as the things we pull on our shoulders, but we feel tired after pulling heavy objects for a while, but carrying a load can travel far. The same is true for horses. Speaking of the carriage, if we do not carry the carriage with our hands, but hang it on our shoulders with a strap, will the officials feel that the two-wheeled carriage is more tiring than the four-wheeled carriage?"

...
Chapter completed!