US Patent 7617890 Steering mechanism for self-propelled mower

A steering mechanism for a wheel of a self-propelled vehicle includes a wheel spindle on which the wheel is rotatably mounted, a steering motor turning a steering tube defining a generally vertical steer axis, a propulsion drive motor turning a propulsion drive shaft extending through the steering tube, and a plurality of gears providing a gear reduction ratio between the propulsion drive motor and the wheel. The wheel is offset from the steer axis and rotates on the wheel spindle if the steering motor turns the steering tube while the propulsion drive shaft is stationary.