In case of marginal friction between the
fall arrester and the guide rail the person climbing accelerates at the same speed as the fall arrester.
In this eventuality, the locking mechanism triggered due to the geometry between the harness and shuttle is not provided anymore. The relatively low tensioned spring of the claw has to perform, pulling the mass of the climber against the rail, until the arrester locks into the notches.
The distance needed to perform this is usually that much more thanthe impact force, stopping the fall arrester exceeds 6 kN.