There is no doubt that the only materials that Shen Nong can use to make pulley sets are wood, bone and stone.

The quality of the bones is not hard enough, and it is easy to be dragged out of cracks by heavy objects, which is a great safety hazard.

The stone is too heavy and inconvenient to carve, so Shen Nong finally set his sights on wood, the quality of wood is between bone and stone, and the weight is lighter than stone and slightly heavier than bone, so it is the best choice for Shen Nong to use as a material for pulley.

In fact, it is very easy to make a pulley, the only difficulty is whether the pulley can rotate smoothly during the movement, so that the user can only spend 10% of the strength to pull 50% of the heavy objects that can be pulled.

Borrowing the tools he usually used to make woodware from Uncle Peibang, Shen Nong returned to the small cave where he lived and began to study it.

The first step is to sharpen a piece of wood into a circle, and then cut a smooth round hole in the center of the round wooden wheel, so that when the time comes, you only need to insert a wooden stick into the round hole as a 'shaft', and the round wooden wheel can be rolled.

If you want to make the wood into a circle, this is not difficult for Shen Nong, he used two branches last time to teach Cang and others how to draw a circle correctly through the 'compass principle', so Shen Nong only needs to repeat the old trick this time, and when the wooden wheel is done, Shen Nong also carefully carved a whole circle of dents on the surface of the wooden wheel, so that the rope can be fixed in it and dragged at that time.

However, this step is only the basics, and in order to become a qualified pulley, the round wooden wheel still needs to be improved.

I saw Shen holding a bone knife that had been sharpened to a sharp point and kept digging and chiseling a piece of wood, although he was not a professional carpenter, but he could still chisel out the general shape he wanted in his mind with the brute force of a quasi-warrior.

Not long after, a square wooden box larger than the round wooden wheel appeared in Shen Nong's hand.

The upper and lower parallel surfaces of this wooden box are empty, which is equivalent to having no bottom and no cover.

Shen Nong nodded with satisfaction to the wooden box in his hand, and then used a bone knife to dig two round holes with a diameter of three fingers in the center of the left and right sides of the wooden box.

"Whew!" Blowing all the sawdust in the wooden box that was cut out by himself, Shen Nong took the previous wooden wheel and inserted it into the wooden box in an upright position, only to see that Shen Nong deliberately put the round hole in the center of the wooden wheel and the round hole on the left and right sides of the wooden box into a parallel line, and then took out a slightly straight branch and inserted it into the round hole on the left side of the wooden box, and the wooden stick drilled three holes in a row, and it was very smooth to penetrate the right side of the wooden box.

The height of the inside of the wooden box is longer than that of the wooden wheel, so the wooden wheel is supported by the branches and suspended in the wooden box.

"It's finally done. Shen Nong rubbed his somewhat sore arm, stretched out his hand and pressed it on the wooden wheel, only to see that the wooden wheel was instantly rotating rapidly in the wooden box, and it seemed that the smoothness of rotation was still very high.

"Let's test it first, if the weight of this pulley is high enough, I will give the production method to a few people in the warehouse, and let them make a large number of pulleys to form a pulley set for efficient soil discharge. Shen Nong thought to himself, so he got up and walked out of the small cave with the wooden box.

The difference between the fixed pulley and the movable pulley is that the former is fixed on a plane and cannot move in position, while the movable pulley can move together with the movement of the pulled object.

After walking out of the small cave, the first thing Shen Nong did was to find a thick wooden stick first, and replace the branches of the wooden box, since it is necessary to test how many things the pulley can pull, the quality of the shaft is naturally very important, otherwise the pulley will carry heavy objects, once the shaft can not bear the weight and break, then the entire pulley will be destroyed.

In the pulley block, the rope that pulls the heavy object is also a very critical component, if there is no rope with strong enough quality, then I am afraid that the rope will break at any time in the process of pulling the heavy object halfway.

In this case, the kind of black vine that grows in the forests near the Huangqiu tribe comes in handy.

Black vine is a plant, Shen Nong knew how tough this vine was when he made a flat shoulder for the flying shell before, a black vine is enough to suspend the whole body weight of an adult clansman, and it will not break, and more importantly, the black vine is very thin, Shen Nong can bundle more than a dozen black vines together, and then twist them to form a rattan rope, so as to increase the weight of the bearables. Assuming that a black rattan can lift the weight of a person's back, the rattan rope twisted by a dozen black rattans can at least increase this weight several times.

Calling the peck of the woman who went out this time but didn't bring back it, Shen Nong asked him to help him start testing the weight of the pulley.

"Wu, what is this?" asked Bone curiously.

"Good stuff. "Regarding the tool of the pulley, Shen Nong really doesn't know how to explain it to others, think about it or not explain it, anyway, just use it like this, know what the principle is for, and don't need to take the exam.

Shen Nong used a twisted black rattan rope to pass through the wooden box, and then climbed to the tree and tied the black rattan rope to a thick treetop, and then he reached out to catch the second black rattan rope thrown up from below by the peck, and fixed it on the wooden wheel in the wooden box.

After doing all this, Shen Nong flew down the tree, and at the same time held one end of the black rattan rope in his hand, and handed the other end to the pecking bone and said: "You grab this, I will pull you up later, you remember to hold on to this rope firmly, don't let go." ”

"Oh. Bone nodded, indicating understanding.

Shen Nong didn't talk much nonsense, he directly grabbed the black rattan rope with both hands and pulled it down hard.

Shout!

I saw that the whole person flew up in an instant, and his body swayed high in the air, looking very light.

"How do you feel?" Shen Nong asked, holding the black rattan rope in both hands, looking up at the peck.

"Pretty good, pretty good. ”

"Okay, then you can come down. Shen Nong let go slightly, and then the bone-pecking body fell back to the ground from mid-air.

"It seems that a pulley and black rattan rope are enough to bear the weight of an adult, if it is equipped with a movable pulley to form a pulley group, and a few more groups are made in terms of quantity, it should not be a problem to improve the drainage efficiency of the soil at the bottom of the gully. Shen Nong said confidently.