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Assembly of clearance-fitted parts 1. When assembling clearance-fitted parts, it is necessary to measure the diameters at both ends and in the middle of the hole-and-shaft fitting area; measurements should be taken at positions 90° apart in the radial direction at each location. Based on the average measured interference value, the appropriate assembly method should be selected. 2. When assembling tight-fitting parts at room temperature, the mating surfaces should be cleaned thoroughly and coated with a lubricant free of molybdenum disulfide additives. Even force should be applied during assembly, and the parts should not be struck directly. 3. For the assembly of longitudinal interference fits, pressing is generally used as the installation method; the pressing equipment must have sufficient pressure, and the fitting shall not be subjected to any loads within 24 hours after pressing. The assembly of transverse interference fits generally employs the temperature difference method. When using this method, it is necessary to check the relative positions and dimensions of the assembled parts in accordance with the technical documents; heating or cooling should not cause rapid changes in temperature. 4. When assembling using the hydraulic oil filling method, the roughness of the mating surfaces should first be checked in accordance with technical requirements; if no specific specifications are given, the Ra value for roughness should be between 1.6 and 0.80. Oil grooves and edges need to be smoothed and rounded off. 5. When the static fit components use a double-key fit, it is necessary to check separately whether the dimensions of the keyways in the shaft and hole, as well as their centerlines, meet the technical requirements. If the deviations are too large, it is necessary to discuss possible solutions with the technical department. 6. The heating temperature for the assembly of interference-fit components should be calculated using formula (20): t = (σmax + σ0) / αd + tH---------------------------------------------------(20) σmax – the maximum interference value as actually measured, in mm; t – the heating temperature, in °C; α – the linear expansion coefficient of the component being heated ； σ0 – the minimum clearance required for assembly, in mm; d – the fitting diameter of the part to be heated, in mm; tH – room temperature, in °C. 7. When heating parts that fit together tightly, the temperature should be uniform to prevent localized overheating. The expanded size due to heating can be measured using a caliper; the setting for the caliper is the sum of the maximum diameter of the shaft and the minimum assembly clearance. The caliper can be quickly fitted in once it can be inserted loosely into the hole of the heated part. The front axle of the assembly should be coated with a layer of lubricant, and the assembly tools must be ready; it must be assembled in one go. 8. The relative positions after assembly shall comply with the provisions in the equipment’s technical documents and drawings, and uniform cooling shall be ensured to prevent rapid cooling in certain areas.