A dishwasher , comprising: - a washing container for receiving dishes to be washed, - at least one spraying arm rotatably mounted in the washing container and forming a plurality of spraying nozzles for spraying a washing liquid on the dishes in the washing container , - a pump hydraulically connected with the spraying arm to feed the washing liquid to the spraying nozzles , wherein the spraying arm comprises: - a hub portion rotatably supported about a rotation axis , and - a bar portion extending from the hub portion in a direction transversal to the rotation axis , towards an internal surface of the washing container , wherein the bar portion forms a plurality of said spraying nozzles and is connected to the hub portion so as to rotate together with the hub portion about the rotation axis , wherein: - the bar portion comprises at least one end segment translatable with respect to the hub portion away from and towards the rotation axis , - the spraying arm comprises a synchronization device that synchronizes the translation movement of the end segment with the rotary movement of the hub portion so as to translate the end segment depending on a distance between the internal surface and the rotation axis , characterized in that the synchronization device comprises a purely mechanical synchronization transmission having: - at least one stationary reference member that is stationary with respect to the washing container , - at least one alternating member connected with the at least one translating end segment , and - a synchronization mechanism connected with the hub portion , with the stationary reference member and with the alternating member to synchronize their relative movements, and in that the synchronization device is arranged: - inside the spraying arm or - inside the spraying arm and partially inside a fixed duct portion to which the spraying arm is connected. - a washing container for receiving dishes to be washed, - at least one spraying arm rotatably mounted in the washing container and forming a plurality of spraying nozzles for spraying a washing liquid on the dishes in the washing container , - a pump hydraulically connected with the spraying arm to feed the washing liquid to the spraying nozzles , - a hub portion rotatably supported about a rotation axis , and - a bar portion extending from the hub portion in a direction transversal to the rotation axis , towards an internal surface of the washing container , wherein the bar portion forms a plurality of said spraying nozzles and is connected to the hub portion so as to rotate together with the hub portion about the rotation axis , wherein: - the bar portion comprises at least one end segment translatable with respect to the hub portion away from and towards the rotation axis , - the spraying arm comprises a synchronization device that synchronizes the translation movement of the end segment with the rotary movement of the hub portion so as to translate the end segment depending on a distance between the internal surface and the rotation axis , - at least one stationary reference member that is stationary with respect to the washing container , - at least one alternating member connected with the at least one translating end segment , and - a synchronization mechanism connected with the hub portion , with the stationary reference member and with the alternating member to synchronize their relative movements, - inside the spraying arm or - inside the spraying arm and partially inside a fixed duct portion to which the spraying arm is connected. <EOS>