DRIVING FORCE TRANSMISSION MECHANISM AND METHOD FOR OPERATING DRIVING FORCE TRANSMISSION MECHANISM

A driving force transmission mechanism is capable of preventing breakage of an oil chamber when the internal pressure in the oil chamber rises by impact when replacing work rolls and the like. The driving force transmission mechanism transmits power of a driving source to a work roll through a spindle and includes a first gear portion disposed on one end portion of the spindle, a second gear part disposed on the driving source or the work roll and fitted to the first gear part and an oil chamber for supplying a lubricating oil to the first gear part and the second gear part, where the oil chamber is provided with a first valve for discharging inner air in the oil chamber to an outside of the oil chamber and a second valve for introducing outer air into the oil chamber.