US Patent 8393825 Vibratory compactor

A vibratory compactor machine includes a machine frame and a roller drum rotatably coupled to the frame and rotatable about a drum axis oriented generally traverse to the direction of travel of the machine. A vibration assembly is disposed inside the roller drum. The vibration assembly includes a first eccentric member and a second eccentric member rotatably disposed in the roller drum and rotatable about a respective first and second eccentric axes orientated perpendicularly to the drum axis. The roller drum rotates about the drum axis independently of the vibration assembly and the first and second eccentric members.