Eccentric shaft assembly having fixed and movable eccentric masses

A drum assembly for a compacting machine, the drum assembly comprising:

• an eccentric shaft rotatable about a rotational axis in first and second rotational directions;
• said eccentric shaft including a fixed eccentric mass and a movable eccentric mass;
• said movable eccentric mass coacting with said fixed eccentric mass in said first rotational direction and partly balancing said fixed eccentric mass in said second rotational direction;
• said fixed eccentric mass having a section defining a maximal radial extension (UB) with respect to said rotational axis;
• said maximal radial extension (UB) being delimited by an imaginary arc-shaped curve having a diameter (D) and being defined by points and/or segments of the outer periphery of said fixed eccentric mass;
• said fixed eccentric mass defining a section plane perpendicular to said rotational axis and said section plane and said rotational axis conjointly defining an intersection point;
• said imaginary arc-shaped curve having a point (P) thereon coinciding with said intersection point or said point (P) being on said imaginary arc-shaped curve at a location closest to said intersection point at a distance A≦0.1(D) therefrom;
• a drum for imparting vibration to a surface;
• said drum having a gable end and a cassette mounted in said gable end;
• said eccentric shaft having respective ends and being mounted in said cassette;
• and,
• said cassette having a set of bearings for rotatably mounting corresponding ones of said ends therein.