As the chain is pulled in a straight line, the remainder of the chain follows an identical
path. However, as the chain is pulled around a corner, the middle portion of the chain
wants to deviate from the initial path of the front-end. On a train, there are three
things preventing this from occurring. First, the centrifugal force, as the rail car moves
about the curve, tends to push the car away from the inside of the curve. When this
fails, the wheel treads are both canted inward to encourage the vehicle to maintain the
course of the track. The last resort is the action of the wheel flange striking the rail and
guiding the wheel back on course.