Thrust chain device, includes a thrust chain with a straight portion along an axis and a curved portion, and links hinged on shafts, a chain guide, a driving sprocket with chain interlocking teeth, the sprocket being in contact with the chain via contact surfaces in the shape of an involute of a circle, the contact surfaces belonging to the teeth, a tooth engaging with the chain while defining a line of action having an angle with the shaft of the straight portion of between −10° and 10°, the sprocket in contact with the straight portion and not the curved and is mounted such that it can rotate on a shaft on the side of the chain opposite the curved portion's center of curvature, the contact surfaces including a convex front surface directed towards the straight portion and a rear surface directed towards the curved portion when the tooth is interlocking.