An adjusting device having an inner tubular body, an outer tubular body configured to slide concentrically over the inner tubular body such that the inner tubular body and the outer tubular body can slide telescopically from a retracted position to an extended position. An actuator is configured to move the inner tubular body and the outer tubular body along the longitudinal axis in relation to one another and a supporting tube is provided and configured to slide concentrically on the inside of the outer tubular body.