A reverse drive engaging mechanism (12) for a feeder (16) of an agricultural combine (10), including a power unit (56) having an output gear (60) drivingly rotatable by the power unit (56) about an output axis (62), and support structure (72) supporting the power unit (56) and configured to be fixedly mounted proximate to a drive gear (54) of a mechanism to be reversed (14). The support structure (72) supports the power unit (56) such that when the support structure (72) is mounted the output axis (62) will be substantially parallel to a drive axis (64) about which the drive gear (54) is rotatable, and the support structure (72) allows the power unit (56) to be moved substantially linearly in a transverse direction relative to the axes (62, 64) between a disengaged position wherein the output gear (60) is disengaged from the drive gear (54), and an engaged position wherein the output gear (60) is engaged with the drive gear (54). The mechanism (12) includes an actuator (100) controllably operable for linearly moving the power unit (56) at least from the disengaged position to the engaged position, the actuator (100) being operable for initially causing initial rotation of the output gear (60) during the engagement with the drive gear (54), and a mechanism (130) for withdrawing or disengaging the output gear (60) from the drive gear (54) after use.
