“Tr44×8 - 8c”是一种梯形螺纹的标注，含义如下：
• Tr：表示梯形螺纹的特征代号。
• 44：是螺纹的公称直径，即螺纹大径为44mm。
• 8：指的是螺距，即相邻两牙在中径线上对应两点间的轴向距离为8mm。
• 8c：代表螺纹的公差带代号，其中“8”是公差等级，“c”是基本偏差代号。
“Tr44×8 - 8c” is a kind of trapezoidal thread labeling, the meaning is as follows:
- Tr: It indicates the characteristic code of trapezoidal thread.
- 44: is the nominal diameter of the thread, that is, the thread diameter is 44mm.
- 8: means the pitch, i.e. the axial distance between two adjacent teeth at two corresponding points on the center diameter line is 8mm.
- 8c: represents the tolerance zone code of the thread, where “8” is the tolerance grade and “c” is the basic deviation code.