Wash arm arrangement for a dishwasher comprising: a central arm adapted to be rotatably connected with a first liquid supply shaft for providing pressurized liquid during operation of said dishwasher, which central arm has a first nozzle arranged for outputting a jet of liquid during operation thereby providing a first reaction force F c for rotating said central arm about its axis of rotation in a first direction; and a satellite arm rotatably arranged on a second liquid supply shaft arranged on an outer end of said central arm, said satellite arm having a second nozzle arranged for outputting a jet of liquid during operation thereby providing a second reaction force F s for rotating said satellite arm about its axis of rotation in a second direction being opposite to said first direction; characterized in that said first and second nozzles are arranged such that said central arm is controlled to move with a periodically alternating speed due to said first and second reaction forces acting on said central arm wherein the instantaneous value of a resulting momentum M tot for said central arm about its axis of rotation alters periodically during operation, said resulting momentum M tot comprising a first momentum M c of said central arm caused by a horizontal reaction force portion F cy of said first reaction force F c, and a second momentum M s of said central arm, caused by the movement of said satellite arm and comprising a momentum created by a horizontal reaction force portion F sy of said second reaction force F s, which wash arm is further arranged such that said first momentum M c of said central arm is larger than said second momentum M s of said central arm, such that said central arm is always kept rotating in said first direction, wherein a minimum resulting momentum M tot_min of said resulting momentum M tot is selected to be 5 - 20% of a maximum resulting momentum M tot_max. a central arm adapted to be rotatably connected with a first liquid supply shaft for providing pressurized liquid during operation of said dishwasher, which central arm has a first nozzle arranged for outputting a jet of liquid during operation thereby providing a first reaction force F c for rotating said central arm about its axis of rotation in a first direction; and a satellite arm rotatably arranged on a second liquid supply shaft arranged on an outer end of said central arm, said satellite arm having a second nozzle arranged for outputting a jet of liquid during operation thereby providing a second reaction force F s for rotating said satellite arm about its axis of rotation in a second direction being opposite to said first direction; characterized in that said first and second nozzles are arranged such that said central arm is controlled to move with a periodically alternating speed due to said first and second reaction forces acting on said central arm wherein the instantaneous value of a resulting momentum M tot for said central arm about its axis of rotation alters periodically during operation, said resulting momentum M tot comprising a first momentum M c of said central arm caused by a horizontal reaction force portion F cy of said first reaction force F c, and a second momentum M s of said central arm, caused by the movement of said satellite arm and comprising a momentum created by a horizontal reaction force portion F sy of said second reaction force F s,