In a machine, such as an internal combustion engine, in which a chain is used to transmit rotating power from one shaft to another, the chain is situated in an oil-tight chain compartment which is separated from other lubricant containing spaces so that lubricating oil in the other spaces cannot flow directly into the lubricating oil in the chain compartment. Contamination of the chain lubricant is avoided, and the useful life of the chain is increased. In a first embodiment, a separate quantity of oil is situated in the chain compartment. In a second embodiment, the chain lubricating oil is recirculated in the chain compartment by a dedicated pump. In a third embodiment, filtered engine oil is delivered to the chain compartment through a passage in a shaft, and through a port in a chain sprocket on the shaft.