Abstract: A system for adjusting the separation distance between adjacent rails over which vehicles travel, the apparatus including a vehicle moveable along the rails and including a boom or pivoted art member mounted on the frame, the boom or arm extending in cantilevered fashion from a pivot mount to and terminating adjacent one end of the vehicle. A rail gripper is mounted on, and oriented normal to, the boom or arm and includes telescoping members extending laterally of and between the rails. Each end of the rail gripper is provided with one or more lug members adapted to engage a respective rail for the applying of a moving force to the rail in a direction substantially normal to the length of the rail and selectively toward or away from its companion rail.