a method and associated apparatus for controlling fluid levels within an axle tube , the method comprising : establishing a first predetermined level of a liquid lubricant within a transmission and an electric motor operatively coupled to the electric motor , the axle tube housing the electric motor and the transmission , where a cavity interposing a wall of the axle tube and the electric motor is occupied by the liquid lubricant reservoir at a second predetermined level ; and , lowering the first predetermined level of a liquid lubricant within the electric motor and the transmission by changing a gas pressure exerted upon the liquid lubricant , where changing the gas pressure exerted upon the liquid lubricant within the axle tube raises the second predetermined level of liquid lubricant within the cavity .