OIL FEEDER

PROBLEM TO BE SOLVED: To exchange oil automatically, simply and safely on the part of even an inexperienced operator by providing a feeding tank side oil feeding valve, a bearing side oil feeding valve, a bearing side waste oil valve and a waste oil tank side waste oil valve for the respective pipeline systems of a piston built-in oil feeder cylinder respectively, and letting these be so designed as to be opened/closed while being interlocked with the movement of a piston. SOLUTION: In an initial condition that a piston 2 of an oil feeder cylinder 1 is lowered down to the lowermost position, a bearing side oil feeding valve 3 and a feeding tank side oil feeding valve 4 are opened. Namely, oil from a feeding tank 7 is filled in the oil feeder cylinder 1. When the piston 2 is moved up, the bearing side oil feeding valve 3 is opened because of pressure difference, and the feeding tank side oil feeding valve 4 is closed. A bearing side waste oil valve 5 is simultaneously opened, and a waste oil tank side waste oil valve 6 is closed. By this constitution, oiling to the oil tank 11 of a rotational shaft 12 and suction of waste oil in the oil tank 11 into the oil feeder cylinder 1, are thereby performed. Discharging of waste oil to a waste oil tank 8 and suction of oil to the oil feeder cylinder 1, are performed by reversely moving the piston 2.