to become engaged in the lots 12 under the effect of the elasticity of the tongue 20 whenever the actuator 1 is removed from the compartment 4 of the housing 5 especially during maintenance operations in other words this difference of diameter of the extremity section 10a of the locking plate 10 with respect to the main section facilitates the removal of the actuator 1 from its lodging as illustrated very clearly in fig2 and 3 a rod 24 can control several tongues 20 belonging to several adjacent actuators for example to four actuators of one column this type of design enables to limit the number of moving parts for the control of the various catches 21 the various rods 24 are parallel to each other and arranged in the proximity of the free extremities 20b of the tongues 20 so as to interact with the respective plates 22 the rods 24 are operated by translational motion that is to say by movement according to the arrows f 4 and f 5 thanks to a cam essentially perpendicular to the rods 24 the cam 30 is operated through a reduction gear 31 by a motor 32 for example electric of which the output pinion 33 can be seen in fig3 a cover 34.