What sort of gearbox will a powered snow plough have?

This varies from model to model, but manoeuvrability and flexibility is all with a two-wheeled snow plough.

Subsequently you will find most have several forward gears and at least one reverse so you can adjust easily and get right up close to edges or obstacles when clearing snow, or adjust your path if you have ‘missed a bit’. 

The gears will, on the best models, be easily switchable so you can turn even more tightly and smoothly.