How does a bus move?

Answer 1

Power is supplied to the wheels, causing them to rotate. This, in turn, propels the bus forward. Specifics of the drive system depend on the specific bus, as there are a couple different types in use in various types of buses. Most uses use a traditional configuration, where an internal combustion engine turns a flywheel. The flywheel transmits power to the transmission, which transmits power through a driveshaft to a differential, which in turn provides power to the axle shafts. Some use a hybrid drive system where an internal combustion engine turns a generator, and that provides power to electric motors which turns the drive wheels (some buses are straightforward electric, and do not have an internal combustion engine, but the rest of the drive system operates the same way). These are typically reserved for local transit buses in urban areas.

Some buses have hydrostatic drive system, where the power source is connected to a hydraulic pump. That hydraulic pump moves hydraulic fluid through the system to hydraulic motors connected to the drive wheels. The hydraulic motors convert fluid energy to mechanical energy. This system is common for off-highway equipment (e.g., a bulldozer) and its use on a road vehicle would be limited to things such as mall shuttle buses and the like. Even then, it's very uncommon.