The Roots blower has high vibration

Thread Content

An 18kw Roots blower (powered by an 18kw motor) originally had a loose and shifting belt on the motor (the belt was aged and cracked); the vibration was not severe. After installing a new belt and tightening it, the vibration from the motor became extremely high. When the belt was loosened again, the vibration decreased slightly, but it could not return to its original level. The radial vibration (in the up-and-down direction) on the motor side was measured at 4–5 mm/s, while the radial vibration in the horizontal left-right direction was as high as 8–9 mm/s ； The vibration at various points on the fan side is slightly lower than that at the motor ； There is an elastic pad between the base frame and the ground, and the base still vibrates; the magnitude of these vibrations is similar to that of the motor’s vibrations. Axial vibrations are relatively small. After replacing the motor bearings, the radial vibrations (in the up-and-down direction) on the motor side were 2–3 mm/s, while the radial vibrations in the horizontal left-right direction were as high as 4–5 mm/s, which is still considered quite high ； The vibration of both the fan and the foundation has decreased by the same amount. Now the question is whether this is caused by a problem with the motor, the foundation framework, or the fan itself Since the vibration throughout the fan is less than that of the motor, it seems unlikely that the issue lies on the fan side ； The foundation is not significantly loose (but the fastening screws at the bottom have become damp and rotten) ； The motor has new bearings installed, but the vibration remains high. No obvious outward movement of the bearing rings can be detected in the outer cover. After the motor started experiencing severe vibration levels (8–9 mm/s), it has been operating with these high vibration levels for almost a month since the bearings were replaced. In reality, the vibration is more noticeable in the horizontal direction, caused by the tension of the belt, while the vibration in the vertical direction is less severe. I earnestly ask for some expert advice!