Abstract: In the case of piston-machines and in particular those having an elastically deformable sealing tube between the piston and the cylinder, which causes a relatively large structural length of the cylinder-piston arrangement and is provided if necessary with a forced feed for the lubricant, a reduction in the space requirement, in particular the structural length of the cylinder-piston arrangement is achieved by a driving member (30) associated with each piston (20) and embracing the associated cylinder (25) externally and extending over at least part of the length of the cylinder, and frictionally connected, e.g., to a rotating driving mechanism (10). The pulsating secondary space (35) formed by the driving member (30) at the outside of the cylinder (25) is connected for the avoidance of shock pressures because of filling with lubricant liquid flowing away, through a balancing channel (40) of large cross-sectional area to a pressure-balancing chamber (110).