Hydrostatic traction drive

The system (1) has the hydraulic machine units (4,6) whose working chambers (16a,16b,20a,20b) are mechanically coupled with the pressure medium inlets (17a,17b,21a,21b) and pressure medium outlets (18a,18b,22a,22b) respectively. The medium inlets (17a,17b) are connected with a high pressure port (28) of hydraulic pump (2). The medium outlets (18a,18b) are associated with low pressure port (29). The pressure medium outlet (22a) is connected with pressure medium input (21b) thought coupling line (34). The volume of working chambers (20a,20b) is adjustable or switchable.