It is said to be the hand of Zhan Tianyou, but it is actually a metaphor from Brother Shun.
In fact, it is called a coupler. There are many forms, and the forms cannot be connected to each other. The most commonly used coupler in China is the automatic coupler, also called "Zhan's coupler". There is a misinformation that Zhan Tianyou invented it, but this is not true:
The automatic train hook was invented by American Elie Hamilton Jenne. Jennet patented the invention on April 21, 1868. Later, Jenneh continued to improve and obtained a second patent on April 29, 1873.
The automatic train hook invented by Jennet is basically the same as the automatic hook used in today's trains. The train hook invented by Janney is written in English as "Janney
CoupIer". The catalog of early railway materials in my country briefly translated it as "Zhan's coupler". Since Zhan Tianyou was the most famous railway engineer in early my country, some people mistakenly believe that Zhan Tianyou invented the automatic train hook.