A drive coupler (102, 104) for coupling a reciprocating knife (106) to a drive member (112, 114) is provided, wherein the reciprocating knife (106) includes at least one elongate bar (120, 122, 180, 182) having a longitudinal extent and fixed to a plurality of blades (138), wherein the at least one elongate bar (120, 122, 180, 182) is supported on support members (140) that constrain the at least one elongate bar (120, 122, 180, 182) to reciprocate in a direction generally parallel to the longitudinal extent of the at least one elongate bar (120, 122, 180, 182), the drive coupler (102, 104) comprising: a first elongate strap (146, 162) configured to be attached to the at least one elongate bar (120, 122, 180, 182)； a second elongate strap (146, 162) configured to be attached to the at least one elongate bar (120, 122, 180, 182)； and a means (152, 164, 187, 189, 193, 200) for (i) flexing the first elongate strap (146, 162) with respect to the second elongate strap (146, 162), (ii) for flexing the first elongate strap (146, 162) with respect to the drive member (112, 114), and (iii) for flexing the second elongate strap (146, 162) with respect to the drive member (112, 114).
