Lumbar support for a seat defining a back plane (E) comprising: a support device having an upper end (O) including an upper angle of inclination (α) with the back plane (E) and a lower end (U) including a lower angle of inclination (β) with the back plane (E) and forming a crown of a curvature (S) located in an adjustable position between the upper end (O) and the lower end (U); at least one angle adjuster connected to the upper end (O) or the lower end (U) of the support device and adapted to vary the upper angle of inclination (α) or the lower angle of inclination (β) to adjust the position of the crown of the curvature (S), and an actuator for adjusting the angle adjuster ; the angle adjuster being connected to the actuator such that a movement generated by the actuator causes a translational and rotational adjustment of the angle adjuster to change the upper angle of inclination (α) or the lower angle of inclination (β); characterised by a bearing element for the angle adjuster and by a coupling which has a first end and a second end ; the angle adjuster having a clamping member which comprises a connecting portion and a coupling point ; the connecting portion being rotatably and slidably mounted on the bearing element , wherein the first end of the coupler is rotatably connected to the clamping member at the coupling point and the second end of the coupler is rotatably connected to the bearing member , and wherein the actuator engages the connecting portion to cause movement of the clamping member relative to the bearing member by means of which the upper inclination angle (α) or the lower inclination angle (β) is changed. a support device having an upper end (O) including an upper angle of inclination (α) with the back plane (E) and a lower end (U) including a lower angle of inclination (β) with the back plane (E) and forming a crown of a curvature (S) located in an adjustable position between the upper end (O) and the lower end (U); at least one angle adjuster connected to the upper end (O) or the lower end (U) of the support device and adapted to vary the upper angle of inclination (α) or the lower angle of inclination (β) to adjust the position of the crown of the curvature (S), and an actuator for adjusting the angle adjuster ; the angle adjuster being connected to the actuator such that a movement generated by the actuator causes a translational and rotational adjustment of the angle adjuster to change the upper angle of inclination (α) or the lower angle of inclination (β); characterised by a bearing element for the angle adjuster and by a coupling which has a first end and a second end ; the angle adjuster having a clamping member which comprises a connecting portion and a coupling point ; the connecting portion being rotatably and slidably mounted on the bearing element , wherein the first end of the coupler is rotatably connected to the clamping member at the coupling point and the second end of the coupler is rotatably connected to the bearing member , and wherein the actuator engages the connecting portion to cause movement of the clamping member relative to the bearing member by means of which the upper inclination angle (α) or the lower inclination angle (β) is changed. <EOS>