The system has a sealing element including a low pressure dynamic sealing unit i.e. lip seal (4), and a reinforced dynamic sealing unit (5) formed of a static seal tightly mounted on a friction pad to isolate the lip seal from a hydraulic apparatus e.g. hydraulic motor (M). A discharge chamber is coupled to a drain (18) via a conduit placed on a surface of a shaft (1) between the hydraulic apparatus and the shaft so as to evacuate fluid in the chamber such that the chamber is not subjected to pressure in a casing (C) in which the apparatus is arranged. The conduit is a groove formed at the periphery of the shaft. The lip seal and the reinforced dynamic sealing unit define the discharge chamber.
