An adjustment assembly for a motor vehicle seat, comprising an adjustment mechanism and a flange that is part of a seat frame, the adjustment mechanism comprising: a housing, itself comprising a bottom and a cover, an output member having a base, an end opposite the base, and a pinion between the base and the end, the pinion being mounted to pivot about an axis of rotation, a backplate, comprising a base plate fixed to the flange and an upper part intended to partially receive the output member, a pumping mechanism housed in the housing and configured to drive the pinion in rotation, the output member being in contact in the flange and in the upper part, the flange and the upper part allowing rotation of the output member about the axis of rotation.

An adjustment assembly for a motor vehicle seat, comprising an adjustment mechanism and a flange that is part of a seat frame, the adjustment mechanism comprising: a housing, itself comprising a bottom and a cover, an output member having a base, an end opposite the base, and a pinion between the base and the end, the pinion being mounted to pivot about an axis of rotation, a backplate, comprising a base plate fixed to the flange and an upper part intended to partially receive the output member, a pumping mechanism housed in the housing and configured to drive the pinion in rotation, the output member being in contact in the flange and in the upper part, the flange and the upper part allowing rotation of the output member about the axis of rotation.

A clutch unit includes a lever-side clutch part to control transmission and interruption of rotational torque input through lever operation, and a brake-side clutch part to transmit the rotational torque from the lever-side clutch part to an output side, and interrupt rotational torque reversely input from the output side. The brake-side clutch part includes a cover constrained in rotation, an output shaft to output the rotation, an inner ring to receive the rotational torque input from the lever-side clutch part, and a cylindrical roller to control interruption of the rotational torque from the output shaft and transmission of the rotational torque from the inner ring through engagement and disengagement between an outer ring and the output shaft. The inner ring includes a slide gear which meshes with the cover during interruption of the rotational torque and is released from the meshing state during transmission of the rotational torque.

A stopper is provided with a rotation shaft-side protrusion provided both on an outer circumferential surface of an outer circumferential surface part of a rotation shaft and on an end surface of a ratchet, and protrudes from each of the surfaces, an engagement member slidably supported on the outer circumferential surface, and engages with the rotation shaft-side protrusion in a rotation direction of the rotation shaft, and a support member-side protrusion provided to engage with the engagement member in the rotation direction such that a sliding surface part of a support member is formed concentric with the outer circumferential surface and a portion of the sliding surface part protrudes toward the outer circumferential surface part, wherein the sliding surface part faces the outer circumferential surface part so that the engagement member is slidably interposed between the support member and the outer circumferential surface.

A clutch unit includes a lever-side clutch part to control transmission and interruption of rotational torque input through lever operation, and a brake-side clutch part to transmit the rotational torque from the lever-side clutch part to an output side, and interrupt rotational torque reversely input from the output side. The brake-side clutch part includes a cover constrained in rotation, an output shaft to output the rotation, an inner ring to receive the rotational torque input from the lever-side clutch part, and a cylindrical roller to control interruption of the rotational torque from the output shaft and transmission of the rotational torque from the inner ring through engagement and disengagement between an outer ring and the output shaft. The inner ring includes a slide gear which meshes with the cover during interruption of the rotational torque and is released from the meshing state during transmission of the rotational torque.

A clutch unit includes a lever-side clutch section provided on an input side, for controlling rotational torque to be input through lever operation, and a brake-side clutch section provided on an output side, for transmitting the rotational torque from the lever-side clutch section to the output side, and interrupting rotational torque to be reversely input from the output side. The brake-side clutch section has a two-layer structure, in which two one-way clutches are arranged side by side in an axial direction. The first one-way clutch interrupts rotational torque in a forward direction, which is reversely input from the output side, through meshing of serrated projection and depression portions, whereas the second one-way clutch interrupts rotational torque in a backward direction, which is reversely input from the output side, through meshing of serrated projection and depression portions arranged in an opposite direction.