1. First determine the bolt specifications (diameter, strength grade)→ Check the torque standard for bolt tightening (such as high-strength bolt grade 10.9 M42 torque of approximately 2800N · m);
2. Select the rated torque of the wrench based on the torque value (1.1 times the bolt torque is required);
3. Select type based on homework space: select empty type for narrow space, and drive type for general working conditions;
4. Select power source according to environment: choose pneumatic pump station for explosion-proof occasions, and electric pump station for conventional workshops.