through a rearward displacement of the crowned pusher rod 15 without the end surface of the crown 16 being seated on the control surfaces 2 in order to facilitate this shearing movement of the crowned pusher rod 15 in the illustrated exemplary embodiment also that of the support sleeve 28 including the hinge pins 29 carried along therewith in the arrested or latched position fig2 the respective spring 26 is not compressed to contact between its windings and behind the opening in the support sleeve 28 there is provided a corresponding axial free space 31 which then serves as a limit for the shearing movement fig3 in the interest of obtaining higher necessary shearing forces two shearing locations 32 33 are provided for the arresting pin 21 in which the pin 21 is completely struck through by the support sleeve 28 or its hinge pins 29 into an oppositely located contact space 34 in order to avoid any misalignments in the embodiment pursuant to fig2 though 4 there are finally provided axial guide pins 35 which are fixed to the housing and which through engagement into hollow cylindrical inner space of the feed springs 26 prevent any buckling of the springs 26 caused by the effects of forces due to high acceleration from the.