One useful bit of information regarding gears is that if the efficiency is less than 50% then they are not reversible. i.e the output will never drive the input. This is most often seen with high ratio worm gears, such as used in car jacks... when you stop turning, the weight of the car does not spin the handle in the reverse direction...
Gears- Gear Efficiency For normal car gearboxes, the efficiencies are over 95% so can be turned both by the engine and by the wheels.
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Now where were we.?... Ooh yes pre-spun aircraft wheels....