Constant liquid level automatic oil supplement / oil level gauge, can be divided into four specifications: 125ml, 250ml, 500ml, 500 m l, 1000ml,it＇s designed to achieve the automatic adjustment of the optimal lubricating oil level in the bearing box, gearbox, crankcase or similar oil bath applications, to keep the lubricating oil in the constant position of the design. Effectively solve the problem of oil level adjustment under operating conditions. Furthermore, the device can automatically compensate for the oil leakage problem, and can visually check the oil level.