A coupling mechanism between a control member which generates manual flight commands and a pivoting shaft of a trim actuator of a kinematic transmission chain for transmitting flight commands of an aircraft, the coupling mechanism putting into action: -) said pivoting shaft which is mounted so to be fixed in translation and driven in pivoting about its general axis of extension by a motor, -) the control member which is mounted to tilt and is mechanically connected to a lever arm coupled to the pivoting shaft, -) a torque limitation mechanism comprising interlocking members (13, 14) which cooperate with each other by interlocking under the effect of thrust exerted by elastically deformable means, so that a resisting force resisting transmission of movement between the pivoting shaft and the control member which is greater than a force threshold predefined according to the thrust force exerted by the elastically deformable means brings about spontaneous interruption of the cooperation with each other between the interlocking members (13, 14) and release of the control member from the hold exerted by the pivoting shaft on the lever arm, characterised: in that the coupling between the pivoting shaft and the lever arm is carried out by axial engagement along said axis by means of said interlocking members (13, 14) of the torque limitation mechanism which are formed respectively on one and the other of a pair of coupling members (18, 19), a first coupling member being connected in rotation to the lever arm and a second coupling member being connected in rotation to the pivoting shaft, and in that the coupling members (18, 19) each comprise axial passages (26, 29) for the other coupling member (18, 19) to pass therethrough, said interruption of the cooperation of the interlocking members (13, 14) with each other bringing about a relative axial displacement of the coupling members (18, 19) one through the other by means of the passages (26, 29) under the effect of an axial thrust exerted by said elastic deformation means against any one of the coupling members (18, 19), referred to as "mobile coupling member". -) said pivoting shaft which is mounted so to be fixed in translation and driven in pivoting about its general axis of extension by a motor, -) the control member which is mounted to tilt and is mechanically connected to a lever arm coupled to the pivoting shaft, -) a torque limitation mechanism comprising interlocking members (13, 14) which cooperate with each other by interlocking under the effect of thrust exerted by elastically deformable means, in that the coupling between the pivoting shaft and the lever arm is carried out by axial engagement along said axis by means of said interlocking members (13, 14) of the torque limitation mechanism which are formed respectively on one and the other of a pair of coupling members (18, 19), a first coupling member being connected in rotation to the lever arm and a second coupling member being connected in rotation to the pivoting shaft, and in that the coupling members (18, 19) each comprise axial passages (26, 29) for the other coupling member (18, 19) to pass therethrough, said interruption of the cooperation of the interlocking members (13, 14) with each other bringing about a relative axial displacement of the coupling members (18, 19) one through the other by means of the passages (26, 29) under the effect of an axial thrust exerted by said elastic deformation means against any one of the coupling members (18, 19), referred to as "mobile coupling member".