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Causes of shaft sleeve seizure in screw pumps and solutions. A screw pump is a type of positive-displacement pump with a specific design; it consists mainly of a drive motor and reducer, a coupling and connecting rod box, as well as a stator and rotor. By analyzing the effects of the medium and rotational speed on the clearance of the screw pump shaft sleeve in cases of seizure, a remedial plan was proposed to address such seizures. I. Analysis of the reasons for the seizure of the screw pump shaft sleeve: Based on the operating conditions of sliding bearings, the fit between the sleeve hole and the shaft is generally a clearance fit. The dimensional tolerances for the shaft diameter and the sleeve hole diameter specified in the part drawings are determined such that a reasonable clearance exists between the shaft and the sleeve hole at an average operating temperature of 20°C. There are many factors that can cause overheating in sliding bearings. When the bearing structure is properly designed and the right materials are used, overheating in sliding bearings is mainly caused by an improper size of the radial clearance, as well as improper installation and use. The influence of the radial clearance of sliding bearings on bearing overheating failures: The radial clearance Δ of a sliding bearing is the difference between the diameter of the bearing hole and the diameter of the shaft journal. A certain radial clearance must be maintained in sliding bearings, and its functions are as follows: it is a basic requirement for enabling a movable connection between the shaft and the bearing ； It ensures the operational precision of the control axis ； It is an important condition for the formation of liquid lubrication. Therefore, the radial clearance of a sliding bearing is very important; either too large or too small is harmful. If the gap is too small, it is difficult to form a lubricating film; as a result, frictional heat cannot be dissipated, causing the bearing to overheat. In severe cases, this can lead to the bearing seizing” ； If the gap is too large, it is difficult to form an oil film, which reduces the precision of the machine’s operation, causes severe vibrations and noise, and may even lead to bearing burnout. During the actual use of bearings, if the clearance is too small, frictional heat cannot be dissipated easily. Moreover, since the lubricating oil used is residue oil containing many impurities, these impurities can easily enter the clearance, causing the bearings to overheat. In severe cases, this can lead to the bearings sticking together, resulting in bearing wear. II. Prevention and improvement measures against bearing sleeve seizure: To prevent overheating problems in the bearings, the radial clearance can be increased to Δ=0.03 mm. At this point, although the bearing’s mating pairs can still function properly, its service life is significantly reduced. Therefore, when determining the radial clearance of the bearing, it should be kept as small as possible while ensuring normal operation of the bearing. After the bearings are assembled, they should first undergo proper running-in and trial operation in accordance with the relevant specifications, after which the load should be increased gradually to smooth out any protrusions on the mating surfaces of the shaft and bearings, before the system can be put into normal operation. Otherwise, even if the clearance is not set to a small value, failure to conduct a running-in test after assembly and putting the unit into normal operation can lead to bearing overheating or even bearing burnout. To this end, the radial clearance of the sliding bearing should be controlled between 0.10 mm and 0.15 mm. The radial clearance of sliding bearings has a significant impact on bearing overheating and lifespan; therefore, it is essential to keep the radial clearance within a reasonable range. When determining the radial clearance of bearings, it is necessary to take into account all factors that affect this clearance. In addition to the diameter of the shaft, rotational speed, load, and the precision of the machine, the following points should also be considered: a> and the bearing material. Different bearing materials have different expansion coefficients, and thus different clearances. b>、roughness of the shaft and bearing surfaces. c>、geometric shapes of the journal and bearings as well as errors in their relative positioning (i.e., roundness, cylindricity, coaxiality, etc.). d>: The operating temperature of the bearing. f>, sudden changes in operating conditions during startup.