Patent ID: 8206061

Claim:
An eccentric vibratory shaft comprising: a first rotor shaft coaxially spaced apart from a second rotor shaft, the first and second rotor shafts being coupled together by an offset shaft; the offset shaft including a first angled portion, a second angled portion and a center portion disposed between and coupling the first and second angled portions, the first angled portion being coupled to the first rotor shaft, the second angled portion being coupled to the second rotor shaft; the first and second angled portions being angled with respect to a first axis passing through the first and second rotor shafts such that the center portion is offset from and at least substantially parallel to the first axis, wherein the offset shaft has an I-beam cross section, and wherein a ratio of a first moment of inertia to a second moment of inertia ranges from about 10 to about 16 m −1 .