An assembly for vibrating a compacting drum of a compacting machine includes a shaft rotatably mountable to a compacting drum of the compacting machine. The center of mass of the shaft is offset from the geometrical rotation axis of the shaft. An outer eccentric member is arranged outside of the shaft, wherein the center of mass of the outer eccentric member is offset from the geometrical rotation axis of the shaft. The outer eccentric member is displaceably mounted relative to the shaft for adjustment of the eccentricity of the assembly. An extension of the outer eccentric member in a direction parallel with the geometrical rotation axis of the shaft is at least two times an average extension of the outer eccentric member in a radial direction perpendicular to the geometrical rotation axis of shaft such that a mass of the outer eccentric member forms a distributed load along the geometrical rotation axis of the shaft.