Various machines, such as mining trucks, are known to employ drive propulsion systems to propel or retard the machine, such as a mechanical drive or an electric drive. An electric drive propulsion system, for example, generally includes an alternator, or other electrical power generator, driven by an internal combustion engine. The alternator, in turn, supplies electrical power to one or more electric drive motors connected to wheels of the machine. The motors are generally connected to the wheels by way of a final drive assembly that reduces the rotational speed of the motor. The final drive of a machine may employ one or more planetary gear sets to reduce the output speed of the propulsion system. Such planetary gear sets may be partially submerged in an oil bath for cooling and/or lubrication. At high rotational speeds, turbulence and churning created in such oil baths may contribute to the loss of energy and/or the generation of heat.
Some gear train assemblies attempt to reduce turbulence and churning by providing a stationary shroud that fits closely to the gears and fully encloses the sides and outer diameters of meshing gears. For example, U.S. Pat. No. 5,048,370 (the “'370 Patent”) teaches a shroud for enclosing several gears within a gear train. The shroud taught in the '370 Patent includes an input and output port for injection and ejection, respectively, of cooling fluid. However, a close fitting, stationary shroud may not be an effective or feasible solution for reducing turbulence created by large planetary gears that are used in the powertrain of many machines, particularly planetary gear sets having rotating carriers that are partially submerged in an oil bath.