A lifting device adjusts the height of a top part relative to a base part for a patient couch. The lifting device includes an elevator mechanism and a drive unit for height adjustment. The elevator mechanism has a scissor mechanism with two scissor arms, which are pivotably connected together via a scissor pivot joint. The elevator mechanism further includes an elbow mechanism having two elbow arms, which are pivotably connected together via an elbow pivot joint. Each of the elbow arms is linked to a scissor arm via a linking pivot joint.