Abstract: A narrow backrest electric seat mechanical extension device is provided, which comprises mechanical extension units, a rear driving piece and a front drive piece, wherein each mechanical extension unit comprises a leg assembly, a back assembly and a seat panel, the back assembly is provided with an eleventh connector, a front support piece, a tenth connector, a ninth connector, an eighth connector, a seventh connector, a sixth connector, a fifth connector, a fourth connector, a third connector, a second connector, a first connector, a backrest support plate, a backrest fixing plate, a rear supporting piece and a backrest return spring, the driving device is hinged with the rear drive piece, and the rear drive piece is fixed with the sixth connector; the driving device is hinged with the front drive piece, and the front drive piece is connected to the leg assembly.

Abstract: A mechanical extension device of a swinging seat is provided, which includes a base, a first swinging rod, a second swinging rod, an actuator and two mechanical extension units, where the base is connected to the first swinging rod and the second swinging rod in a rotating way; the actuator is arranged between the two mechanical extension units; a locking device is arranged on a second connecting rod connected to the second swinging rod in the mechanical extension unit in a rotating mode, a guide groove and a locking groove formed in the guide groove are formed in the base, the guide groove is opened towards one side, the locking device can enter the guide groove from the opened position of the guide groove, and when the locking device swings and moves the mechanical extension unit, the locking device can enter the locking groove and swing relative to the base.