Abstract: An apparatus for reducing or eliminating rearward amplification of yaw in commercial multi-trailer highway combinations by maintaining constant tension on a cable-and-pulley system connecting a towed trailer with a towing trailer, and offering constant resistance to motion of the cable through the pulleys when the towed vehicle begins to yaw with respect to the towing vehicle. The cable is wrapped around a drum having a vertical axis of rotation. Cable tension is maintained by an air spring which slides the drum in a fore-and-aft direction. Resistance to movement of the cable connecting the vehicles is achieved by controlling rotation of the drum by means of a pneumatic brake.