A breakable coupling device for coupling together first and second main transmission shafts stationary in translation along a longitudinal axis of rotation of the device comprises a blocking device having a discontinuous first housing and a continuous second housing forming a closed loop; a compression device; at least one drive device connecting the blocking device and the compression device together in rotation about the longitudinal axis below a predetermined torque, wherein the discontinuous first housing is configured to receive the at least one drive device below the predetermined torque; and a shifting device configured to shift the at least one drive device non-reversibly from the discontinuous first housing towards the continuous second housing when the torque exerted on the at least one drive device is greater than the predetermined torque.