Why are the steering wheels of buses/trucks/lorries more or less angled horizontally instead of the angle seen in cars?
In: Engineering
There’s a few answers here…
Having the steering wheel horizontal makes it easier to pull/push the wheels as needed. A bit of a fail-safe, if you have to muscle the wheel as well… but, that’d be pretty rough honestly.
The seats help cushion the rider and can travel a good bit. If the steering wheel was more vertical, the driver would constantly hit the wheel with their knees and thighs potentially.
The steering wheel has more leverage with a direct connection to the steering box. If they used universal joints to change the steering wheel position, it would make it harder to spend 8 hours driving it.
Otherwise, it might very well be partially due to preconceived notions that a big rig should also have a big wheel. As I’m sure an engineer could design a reasonable steering box and steering wheel that would give an everyday feel… and likely be safer with a working air bag.
It comes down to engineering and physics. I’m sure a mechanical engineer can describe the calculations better than I can. But basically the bus driver is positioned as close to the front of the bus as possible. This allows the drivers perception to be precise because they are closer to the front of the bus. But being closer to the front means the steering wheel needs to be closer as well. There now is less available space for a steering wheel and the mechanics involved to move the front wheels.
Imagine taking a normal car and moving the front of the car so that it’s just one foot in front of your steering wheel to the head lights. Now there’s now where for the mechanics of the steering system to go but backwards. This results in the steering column being about 45 degrees to about 80 degrees.
Answering your question of why, it comes down to efficiency. If the area of a hood or bonnet can be taken up with more useful space to accommodate carrying a product or transporting people, then making the sacrifice of comfort is well worth the pay off.
For the types you are talking about, it helps the operator see better outside the vehicle, by raising their seating position and removing the wheel from their forward vision.
They aren’t all like that, but the ones that are is typically because the driver is sitting further forward/higher in comparison to the steering gearbox than the driver in a car does. Fewer joints to adjust the angle of the steering wheel leads to better responsiveness and fewer parts to break.
Ergonomics and what sells best to the general public. Buses with or without an upper deck don’t have to ‘appeal’ as they are designed to get the maximum amount of people onto the smallest amount of real estate. Prisons bury the dead standing up due to real estate (and lack of objectors). Having ‘laid back’ driver at the controls doesn’t inspire confidence.
These drivers are sitting nearly directly above the steering box because of the tall nature of the vehicles and their forward cabs.
In passenger vehicles we sit both behind and above the steering box.
The steering column points to where the box lands at the front axle, imagine it as a line segment with one end being the steering wheel and the other being the box on the axle.
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