Abstract: An arrangement in a circulation lubrication system include a lubricating oil tank, pressure pipe lines for supplying oil to parts to be lubricated, return pipe lines for returning the oil from the parts to be lubricated to the oil tank, and a mechanism configured to pump oil into the pressure pipe lines and maintaining a desired state of lubrication. The mechanism configured to pump the oil into the pressure pipe lines may include a circulation lubrication pump and a suction duct through which the lubricating oil flows out of a lubricating oil tank, an underpressure tank coupled to the suction duct leading off from the lubricating oil tank, to the suction side of the circulation lubrication pump. The underpressure tank is a tank which allows the water contained in the oil to evaporate. To prevent cavitation of the circulation lubrication pump, the underpressure tank is placed substantially higher than the lubricating oil tank.

Abstract: An arrangement in a circulation lubrication system includes a lubricating oil tank, pressure pipe lines for supplying oil to parts that are to be lubricated, return pipe lines for returning the oil from the parts that are to be lubricated to the oil tank, and a mechanism for pumping oil into the pressure pipe lines and maintaining a desired state of lubrication. The lubricating oil tank has a rotationally symmetric structure; and a return duct, positioned at the center axis of the rotationally symmetric structure, is configured to extend below the surface of the oil in the lubricating oil tank. A return flow through the return duct passes through a dividing element to a mechanism configured to separate impurities from the oil.