are “single-acting” cylinders, which are arranged vertically, and are operated by hydraulic, or more rarely pneumatic power. Lowering takes place under the weight of the lifted load. The piston rod is simultaneously the piston itself. The maximum stroke is limited by means of a turned ring at the lower end of the pis- ton rod and a stop bush in the upper area of the cylinder sleeve. The sealing ele- ments are installed in the cylinder sleeve.