Apparatus at a protective helmet

Locking device (2) for fixation of the position of an outer layer (4) relative to an inner layer (6), of a protective helmet (3), the outer layer is displaceable, relative to the inner layer during an oblique impact towards the protective helmet, characterized in that the locking device (2) comprises a layer-guiding member (10), that has an upper portion (12), which upper portion (12) is intended to be arranged in an opening (13) in the outer layer (4), and a resilient lower portion (16), extending from the upper portion (12), that in its free end (17) is arranged in connection to the inner layer (6), whereby the upper portion (12) is arranged in a first position (P1) relative to the inner layer (6), in such a way that the outer layer (4) is fixed in position relative to the inner layer (6) in an unloaded condition, or during insignificant load on the protective helmet, the locking device (2) is arranged such that the fixed position ends when exceeding a certain load towards the protective helmet, owing to that the lower portion (16) of the layer-guiding member (10) can be elastic in its longitudinal direction (L) and in the direction of propagation plane (P) of the inner layer and the outer layer (4, 6), whereby the upper portion (12) of the locking device (2) can be moved to a second position (P2) relative to the inner layer (6), during displacement of the outer layer (4) relative to the inner layer (6), and that the locking device comprises a display member that indicates when displacement has taken place to the second position (p2).