You are a complete beginner. Seeing that the reward points are quite a lot, I will reply to you.
1. How to describe the rotation of (1) that passes through (2) and (3) and finally leads to the rotation of (4)? How to write the direction of rotation?
1 is provided with a first rotation axis, and 4 is provided with a second rotation axis. When working, 1 rotates along the first rotation axis, driving 2 to rotate. Driven by 2, 3 rotates at an angle relative to 2, and finally 3 drives 4 to rotate along the second rotation axis. In this embodiment, the first rotation axis is perpendicular to the second rotation axis
2. Can the icon (2) be used to represent the bevel gear in the drawings of the description?
Yes
3. Do you need to explain specifically what (1), (2), and (3) represent? Should it be written in the manual or in the pictures attached to the manual?
The instructions can be defined as follows: an XX device, which includes 1, 2 that is rotatably connected to 1, 3 that is rotatably connected to 2, and 4 that is rotatably connected to 3. If it is defined in the description, there may be no accompanying drawing description.