if a gas generator 23 that is mounted on the inside of the support plate 16 and communicates with the expandable element 9 is triggered during an accident the element 9 starts to expand and in so doing presses from inside against the primary section 19 this causes the retaining lip 22 to glide off the narrow side 15 of the windshield 4 and the primary section 19 and lips 21 22 swivel around the hinged section 20 into a position depicted on fig2 as a dashed outline in which they clear the way for the expandable element 9 to get out into the open as a result the expandable element 9 ultimately forms an expanded pad in front of the a column 2 which can cushion and decelerate an impacting body several centimeters in front of the a column 2 once the expandable element 9 has carried out its function and the gas has once again been drained from its interior its elasticity causes it to return to the normal configuration shown in cross section on fig2 the cover 8 also flips back in the direction of its idle configuration once again but does not reach it automatically since the.