Mu Niu Liu Ma

Mu Niu Liu Ma (木牛流馬) are cart like tools that invented by Zhuge Liang (諸葛亮), Pu Yuan (蒲元) and others in China at AD231-234. In English, Mu Niu (木牛) is Wooden Ox, Liu Ma (流馬) is Flowing Horse. They both used for military food delivery.

Since not much literature records left about these tools, many people guess Mu Niu Liu Ma should be a single-wheeled cart. Single-wheeled cart is matched the meaning of Flowing Horse, but Wooden Ox should be another tool. Many people tried to reproduce the Wooden Ox before, so you can find various prototype on the web. Some look good, some just install wheel in four legs and some actually are strandbeest, all of them cannot meet my imagination.

This instructables try a different way to reproduce the Wooden Ox based on the limited literature records and my interpretation.

Ref.:

https://zh.wikipedia.org/wiki/木牛流马

Distinguish various sizes of screw is very time consuming, so every project I only select one screw type. This project I selected flat head 8 mm M3 screws, it only requires 10-14 pieces but more spares are always welcomes.

Since the contents of various literature records have contradictions, so I only picked some points that can meet my imagination.

Quote from "Annotated Records of the Three Kingdoms":

木牛者，方腹曲頭，一腳四足，頭入領中，舌著於腹。載多而行少，宜可大用，不可小使；特行者數十里，群行者二十里也。曲者為牛頭，雙者為牛腳，橫者為牛領，轉者為牛足，覆者為牛背，方者為牛腹，垂者為牛舌，曲者為牛肋，刻者為牛齒，立者為牛角，細者為牛鞅，攝者為牛鞦軸。牛仰雙轅，人行六尺，牛行四步。載一歲糧，日行二十里，而人不大勞。

Points picked:

1. It has a square body and four legs
2. It can carry a lot but travel a short distance
3. It could carry heavy load without much strain on the people

Quote from "Romance of the Three Kingdoms/Chapter 102":

眾將看了一遍，皆拜伏曰：「丞相真神人也！」過了數日，木牛流馬皆造完備，宛然如活者一般﹔上山下嶺，皆盡其便。眾軍見之，無不欣喜。孔明令右將軍高翔，引一千兵駕著木牛流馬，自劍閣直抵祁山大寨，往來搬運糧草，供給蜀兵之用。

Points picked:

1. All the generals bowed to him, thinking that Zhuge Liang (諸葛亮) was a god for inventing it.
2. It look like a living beings.
3. It is used to transport food on rugged mountain roads.

Quote from WiKipedia:

流馬是一個向上開口的，左右側壁近上緣的垂直中心線上各有一個孔的木箱。木牛的那根三尺長的軸就穿過流馬的這兩個孔，流馬可以在該軸上前後幌動。為了不使箱中粟、米之類的載荷左右移動，有一塊縱向隔板把箱一隔為二，而且糧食是先裝入布袋再裝入箱中的。

Points picked:

1. Wooden box opens upward.
2. A longitudinal partition is used to divide the box to prevent the load moving left and right.

Quote from "SOHU":

据当地(陕西省汉中市勉县黄沙镇)的老人描绘，传说中的“木牛流马”是用木头做的马头，并由其他零星的小块组成马身子，再装上马腿，在肚子中间安上了齿轮，木马后边有一个扳手，操作比较方便，一压便可走一步，再一压又走一步。

Points picked:

1. It have gears inside the body.
2. A wrench at behind and easy to operate.
3. One press will make it move one step, press again move another step.

Ref.:

https://zh.wikipedia.org/wiki/木牛流马

https://zh.wikisource.org/zh-hant/三國演義/第102回

https://www.sohu.com/a/226529951_215157

During "Three Kingdoms" period, Zhuge Liang (諸葛亮) do many things that make people think he have magical power. He can predict when the weather will turn windy and foggy; His tactical formation (八陣圖) can winning with less; His Zhuge Crossbow can fire 10 rounds in a row.

Wooden Ox also a symbol shows his magical power. At that war period, there are lack of ox or horse to delivery food to the battlefront. The Wooden Ox does not need to eat or drink, but it can deliver food like a real ox. It is a magical tool, so walking like a living being is essential to this symbol.

According to the literature Records points picked, my interpretation is:

1. Carry heavy load but walk slow.
2. Have 4 legs, walk like living beings.
3. Legs connected to gears.
4. Man working with wrench from behind.

Most previous versions found on the web were made with two front legs moving first and then the hind legs, but this not look like ox walking. Ox first steps with its two legs on one side, and then two legs on the other side. So I connected 2 legs on one side with gears, then the man behind can operate walking with the tail (the wrench).

Before 3D Modeling my imagination, let's create a LEGO PoC first.

I use the LEGO battery as a heavy load. Base on this body, attached 4 legs. 2 legs on left attached together, same on the right. So 2 legs on the same side move on the same way. When shift the body weight to the left, the right legs move forward; then shift the body weight to the right, the left legs move forward, and so on. Keep shifting the body weight, the Wooden Ox will move forward and look like walking.

I am using Autodesk Fusion for this project 3D Model design, below few steps show how I design the components with Autodesk Fusion.

AA battery should be a worldwide easy accessible heavy load, so I design the body can store 8 AA batteries. And it opens upward, a longitudinal partition is used to divide the box to prevent the load moving left and right.

The body design should keep the center of gravity as low as possible, so the leg and gear joints, i.e. the screw holes, set near the top of the body.

The leg moving range is arbitrary, so I create a box between front and hind legs on each side to limit the moving range. And the range is adjustable by screws while testing.

Then adjust the body edge details to make it look better.

Create gear 3D model in Fusion is very easy, simple run the UTILITIES -> ADD-INS -> Scripts and Add-ins (or hotkey Shift-S), then run SpurGear. To reserve a little bit for 3D print size error, the Pitch Diameter should be a little bit smaller than the distance of 2 screw holes. The distance between 2 screw holes are 23.9mm, so I adjust the Module to 0.98 to make Pitch Diameter as 23.52mm.

For simplicity, 4 legs are the same. I use a big sphere intercept with the leg to make the foot bottom become round shape. This makes the wooden ox can move forward and swing left and right easily.

The ox head simply combine few shape to make it look like an ox, no mechanical function.

The tail is actually the wrench to operate the Wooden Ox. The real ox tail should point to the ground, but the wrench cannot set too low in order to use it shift the balance of Wooden Ox.

The 3D Modeling stay tuning.

If your are using Fusion, you can get the latest online project for your reference: https://a360.co/3YG1oMt

Please download and 3D print the model at Thingiverse: https://www.thingiverse.com/thing:7039372

Please follow the video for the assembly.

Put 8 AA batteries, or other load you have in hand, in the body as a load. Then operate by pushing the tail like the video do.

Wooden Ox is used to transport food on rugged mountain roads, so it should able to stand still while climbing up slope. In contrast, wheel cart will slide down the slope if not pay attention on it.

If only going down the slope, wheel cart will be much faster. In this case, Flowing Horse can do the job.

This test temporary installed a crank with some load on it. It shows that the Wooden Ox can walk by shifting its balance.

No one knows the real Wooden Ox look like, this project is just the beginning. Many improvement can be made:

1. The wrench connected to the leg gear to operate.
2. The gear connected between left and right legs for interaction.
3. Imporve the body and leg joints make shifting balance smoother.
4. Top cover to make it more look like an ox.

Some literature records mention people can ride on the Wooden Ox. If the top cover made like a saddle, rider can shift the balance while riding. It should be look more like a living beings!