Abstract: The invention provides a vibrator for shaking materials, comprising a drive, a shaft which can be connected to the drive and which is supported on the casing, at least by a bearing, and further comprising an imbalance member supported by the shaft, in the form of an inert mass arranged eccentrically of the shaft.As a means of improving a vibrator of this type to make it easier to mount, the invention provides that the imbalance member (10) should be arranged loose on the shaft (5). It is desirable for the imbalance member (10) to be provided in contact with the shaft (5) and at least partly enclosing it. If the imbalance member (10) is semi-cylindrical and has bearing boxes (12) at both ends, in accordance with a further embodiment of the invention, the bearing boxes will be light compared to the inert mass of the imbalance member, and their only function will be to surround the shaft and provide a contact surface or contact line.