The invention relates to an auxiliary scraper arrangement, intended particularly for enhancing a scraping process performed by a scraper bar assembly in a liquid tank, such as a settling tank or the like. The auxiliary scraper arrangement (X) comprises one or more extensions (X1), driven in response to actuators (X2) to two or more working positions (I, II) different from each other relative to the scraping bar (1) during its movement in the liquid tank. In the first working position, the extension (X1) is intended for scraping the supernatant sludge present on the wall of the tank, while the scraper bar (1) is at the liquid surface. In the second position, the extension is intended for scraping the sludge present on an inclined surface (VP) at the bottom of the tank while the scraper is upside down at the bottom of the tank. The actuators (X2) are provided with a gravitationally powered mechanism, including the extension (X1) which is connected at an articulation (N) pivotally (w) to the scraper bar (1), the extension (X1) having a counterweight (z) coupled therewith on the opposite side of the articulation (N) by way of a lever arm (y).