An oil system is provided for use with a rotating machine, for example an aircraft generator and associated transmission. The oil system allows the generator to be run without lubrication for a short period of time. Such a situation is likely to occur when the aircraft is inverted or experiences zero G conditions.
The oil system includes an oil reservoir 100 that supplies oil to a first pump 4 for supplying oil for lubricating and/or cooling the generator and for lubricating a variable transmission associated with the generator. The oil reservoir also supplies oil to a second pump 6 that provides oil for operating hydraulic actuators 110, 112 for controlling the operation of the variable transmission. A return path is provided for the oil to the reservoir. The oil system further includes an oil fill inlet such that a single filling operation through the oil fill inlet causes oil to flow through the return path towards the reservoir causing air to be purged through the return path.