Explanation: Yu key to control things small and very important. Jurisdiction, the fixed position wheel and axle, the pin hole into the shaft. Source: Southern Liang Liu Xie, "Wen Xin Diao class thing," lent to the story, though small achievements, Pi-inch rule over the wheel, foot transportation hub off also. "
No. 2
Yu controlled the key things is small but very important. Jurisdiction, the fixed position wheel and axle, insert the shaft hole of the pin. Southern Liang Xie, "Wen Xin Diao thing type": "lent to the story, though small achievements, analogy-inch rule over the wheel, foot transportation hub off too."