Rollbar protection system for vehicles with a self retaining unlocking device

An extendable roll-over bar (1) is locked against being pushed back by a locking pawl (12) operatively engaged with a toothed segment (11) when in an extended position. To return the bar to a retracted position, a reversing lever (14) is manually brought to a self-holding position above dead center while unlocking the pawl before the bar is pushed in.