The drag link converts the sweeping arc of the steering arm to linear motion in the plane of  the other steering links.

Typically, one end of the drag link is connected via the Pitman arm and steering gearbox to the steering wheel (providing the connection between the driver and the steering system); the other end is attached to the steering linkage, by the  steering arm.

Drag Links consist of a long bar that provides a means of connecting the tie rods  together, forming one big moveable linkage system.