Abstract: A mechanical proportioning trim execution device in the general configuration of a four-bar linkage including input and output levers coupled by a connecting link, with the input lever having its length determined by a movable pivot automatically adjusted by a gear motor to produce the trim function. The movable pivot advances or retracts along a path which is highly skewed to the line of the input lever in a manner such that the path is perpendicular to the connecting link at zero input displacement for minimum trim effect and is parallel to the connecting link at full input displacement for maximum trim effect.