A rotary electric drive device for use in a vehicle anti-skid braking system has a rotary armature (4) supported by a thrust race (20) in relation to a housing (1). One part (22) of the thrust race has external teeth 24 for co-action with a pawl 25 which is disengaged from the teeth for one direction of rotation of the armature but engages the teeth during rotation in the other direction to lock the race part (22) to the housing. When this happens, slipping occurs between opposed contiguous faces (4A, 22A) of the armature and part (22) respectively in order to dissipate some of the rotational energy of the armature when the drive device is de-energised.