rail cow bar for track work It is for situations such as these that the jim-crow comes into its own. The jim crow was slotted over the rail about four or five sleepers away from the offending joint.and the screw tightened until it engaged with the edge of the rail. Then tightened the screw a further half-turn - thus bending the rail slightly.This process was repeated, moving the jim crow one sleeper nearer the joint each time and each time adding one more half-turn. This introduces a gradually increasing curve to the rail as it nears the joint.If you compare these two pictures with those showing the kinks above, you can see the difference.