Wheel drive transmission

A speed-reducing transmission unit comprising:

• a spindle defining a longitudinal spindle axis, said spindle configured to affix to a frame at an input side of the transmission unit, and having a terminal output-side axial end;
• a hub defining a longitudinal hub axis, said hub rotatable with respect to said spindle about said longitudinal hub axis and configured to affix to a driven structure at an output side of the transmission unit;
• a planetary reduction assembly comprising:
• a primary planetary stage functionally interposed between said spindle and said hub, said primary planetary stage comprising a plurality of primary components including a primary sun gear, a primary planet gear carrier, a primary planet gear in splined engagement with the primary sun gear and rotatably attached to the primary planet gear carrier, and a primary ring gear in splined engagement with the primary planet gear;
• a secondary planetary stage functionally interposed between said spindle and said hub, said secondary planetary stage comprising a plurality of secondary components including a secondary sun gear, a secondary planet gear carrier, a secondary planet gear in splined engagement with the secondary sun gear and rotatably attached to the secondary planet gear carrier, and a secondary ring gear in splined engagement with the secondary planet gear,
• one of the plurality of primary components comprising a primary input and another of the plurality of primary components comprising a primary output, and one of the plurality of secondary components comprising a secondary input and another of the plurality of secondary components comprising a secondary output, the primary output operably coupled to the secondary input such that the primary planetary stage and the secondary planetary stage cooperate to produce a final speed reduction between the spindle and the hub;
• and
• a combination component comprising one of the plurality of primary components and one of the plurality of secondary components integrally formed as a part thereof,
• the combination component further comprising a terminal input-side axial end selectively rotatably fixable to the terminal output-side axial end of the spindle.