A head for an agricultural machine , the head comprising: a frame including a center segment defining a first longitudinal axis and a wing defining a second longitudinal axis ; and a motion control assembly connecting the center segment and the wing such that the wing is movable relative to the center segment between a deployed position and a non-deployed position by means of an actuator , wherein the motion control assembly includes the actuator , a first link and a second link , each link having a first end pivotally coupled to the center segment and a second end pivotally coupled to the wing such that the center segment , the wing , and the first and second links define a four-bar linkage; with the actuator pivotally coupled to the center segment and to a control tab on the first link at a position offset from a longitudinal axis of the first link ; wherein the motion control assembly is configured to maintain the second longitudinal axis in a parallel relationship with the first longitudinal axis as the wing moves between the deployed position and the non-deployed position, wherein the motion control assembly is configured such the wing is movable from the deployed position to the non-deployed position along a continuous arc, wherein the center segment includes a first end surface , wherein the wing includes a second end surface , and wherein the first end surface is adjacent the second end surface in the deployed position of the wing and the first end surface is remote from the second end surface in the non-deployed position of the wing , characterized in that the first end surface and the first longitudinal axis define a first oblique included angle , and wherein the second end surface and the second longitudinal axis define a second oblique included angle , and that the first and second oblique included angles are equal such that the first end surface is parallel to the second end surface when the first longitudinal axis is parallel to the second longitudinal axis . a frame including a center segment defining a first longitudinal axis and a wing defining a second longitudinal axis ; and a motion control assembly connecting the center segment and the wing such that the wing is movable relative to the center segment between a deployed position and a non-deployed position by means of an actuator , wherein the motion control assembly includes the actuator , a first link and a second link , each link having a first end pivotally coupled to the center segment and a second end pivotally coupled to the wing such that the center segment , the wing , and the first and second links define a four-bar linkage; with the actuator pivotally coupled to the center segment and to a control tab on the first link at a position offset from a longitudinal axis of the first link ; wherein the motion control assembly is configured to maintain the second longitudinal axis in a parallel relationship with the first longitudinal axis as the wing moves between the deployed position and the non-deployed position, wherein the motion control assembly is configured such the wing is movable from the deployed position to the non-deployed position along a continuous arc, wherein the center segment includes a first end surface , wherein the wing includes a second end surface , and wherein the first end surface is adjacent the second end surface in the deployed position of the wing and the first end surface is remote from the second end surface in the non-deployed position of the wing , characterized in that the first end surface and the first longitudinal axis define a first oblique included angle , and wherein the second end surface and the second longitudinal axis define a second oblique included angle , and that the first and second oblique included angles are equal such that the first end surface is parallel to the second end surface when the first longitudinal axis is parallel to the second longitudinal axis . <EOS>