The oversize steering wheels on buses seem to have no purpose, and they seem to be awkward and force other essential controls to be located less conveniently than they might otherwise. Why has no bus maker broken this trend ? Is there a purpose to the big wheel ? Is it a union thing ? A conspiracy ? If power steering was still on the drawing board I would see an obvious explanation, but we’ve more or less perfected that so I just don’t get it. Any bus designers in reading this ?
Leverage. A bigger wheel makes it easier to turn. If the power steering goes out, the driver will need the leverage.
To make it easier to make small adjustments in tight spaces with a large vechicle.
Dear OP, are you a bus driver, or are you speculating on the measure of convenience or lack thereof? I’ve had a CDL for many years and haven’t found the steering wheel size to be problematic.
Try turning the front wheels of a bus using a 14" steering wheel, with the engine off. Good luck.
Engines sometimes die, power steering pumps sometimes fails, power steering drive belts sometimes break, and sometimes front tires get blow outs. If any of those happen, the driver will need all of their strength and every bit of mechanical advantage that that large steering wheel gives them to keep from hitting things.