A working cylinder is described which features a cylinder of compact construction. The openings provided for the tension member can be very well sealed by simple means. The tension element features a cross-section having a continuous circumferential line. The size of the cylinder is also reduced through the use of a generally elliptical piston. The tension element is preferably comprised of several plastic tension strands encased in a jacket of plastic material which also has a generally elliptical cross-sectional shape.