Compact drive unit for traction vehicles

A traction rail vehicles compact drive unit for mounting on outside of a wheel of a traction rail vehicle, the traction rail vehicles compact drive unit comprising an electrical motor supplied with voltage or current from a power electronics converter, a gearbox divided into a high-speed gearbox stage and a low-speed gearbox stage, and a mechanical coupling to a wheelset or the wheel, wherein the high-speed gearbox stage includes an input spur/helical gearset that defines a set of pinion gear and spur/helical gear, wherein the electrical motor is a high-speed electrical motor with a speed over 9000 rpm, its rotor is supported by bearings along with the pinion gear of the input spur/helical gearset of the high-speed gearbox stage and all together create a rotor assembly having an axis of rotation that is perpendicular to the axis of rotation of the wheel,

• wherein the low-speed gearbox stage includes a following bevel gearset that defines a set of bevel gears, wherein an output shaft of the spur/helical gearset of the high-speed gearbox stage is a part of the following bevel gearset of the low-speed gearbox stage, an output shaft of the bevel gearset of the low-speed gearbox stage is connectable either directly or by using the coupling to an axle of the traction vehicle, or to the wheel, wherein at least the electrical motor and the high-speed gearbox stage are embedded in a single compact housing,
• wherein the power electronics converter is arranged to feed current into a stator winding of the electrical motor which causes production of heat due to existing losses in the electrical motor,
• wherein the heat is distributed inside the drive unit using conduction via both drive components and the housing for preheating of a lubricant of the high-speed gearbox stage before motor rotation and running the gearbox under extremely low ambient temperatures.