Abstract: An automatically engageable and disengageable drive coupler mechanism is provided in which separate drive and driven couplers are automatically coupled to and uncoupled from each other simply by moving the couplers into and out of contact with each other in a radial direction or an axial direction or a combination thereof. The driven coupler includes a lug arrangement rotatably mounted on a mounting member at the end of a driven shaft and having a pair of driven lugs on opposite sides of the driven shaft which are rotatable about an axis intersecting and normal to the axis of elongation of the driven shaft. A leaf spring coupled to the mounting member resiliently biases the lug arrangement into a neutral position in which the lugs extend outwardly in the direction of the axis of elongation of the driven shaft while at the same time permitting rotation of the driven lugs out of the neutral position in either of opposite directions against the resistance of the spring.