Patent ID: 7204455

Claim:
Drive assembly comprising an articulated member having first and second portions arranged such that the portions move relative to each other, and a drive mechanism for imparting motion to the articulated member, the drive mechanism comprising: a drive member for imparting a cyclic motion on the articulated member; and a control member for controlling, in a predetermined manner, the relative position of the first and second portions during each cycle of the cyclic motion of the articulated member, wherein the drive mechanism is arranged such that, during each cycle of the articulated member, the control member operates on the articulated member in two phases, the control member moving in a first direction during the first phase, and in a second, generally opposite direction, during the second phase, wherein the drive mechanism is arranged such that, during the first phase of operation of the control member, the drive member is engaged with the control member such that the drive member moves in generally the same direction as the control member, wherein the drive mechanism is arranged such that, at the beginning of the second phase of operation of the control member, the control member becomes disengaged from the drive member and thereby returns in the second, generally opposite, direction.