Why are steering wheels on buses positioned more horizontally than vertically?
A friend casually raised this issue the other day over lunch and it stuck with me. I assume it has something to with better handling but I don’t know for sure.
In: Other
Convenience and reliability. Not every bus is set up this way.
Technically a vertical wheel is better for ergonomics. That means it’s more comfortable and less likely to cause muscle stress.
But in a lot of buses, the driver is at the very front of the vehicle and there’s no “nose” putting distance between the driver and the wheels. That means the steering gears are below the driver. Installing an angled steering wheel would mean adding more parts, and the more parts you have the more likely something will break.
But some buses have a big “nose” in front, and the wheels are further away from the driver. That means the stuff connecting the steering wheel to the actual wheels has to move forwards anyway, so it’s more convenient to tilt the wheel. That’s how most passenger cars are, as well.
You can occasionally find trucks or buses that put the driver on top of the wheels and still have a tilted wheel. It just means they decided to take on some extra costs and maintenance to make the driver more comfortable.
Buses and trucks sit a lot higher, and the driver sits a lot more forward, than a car, so the steering column needs to be more vertical to connect the steering wheel to the front axle. To make a bus with a car-like steering wheel orientation, you’d need to do some pretty creative engineering with the steering assembly that just wouldn’t be practical and would introduce a lot more potential points of failure.
The steering wheel is turning a mechanism. There’s a giant shaft behind it that you turn with the wheel. That shaft needs to reach the axle where the wheels are in order to turn them. On a car, that is forward and under the hood. On a bus, that is more straight down.
It’s a lay over of legacy design. In the era of manual steering even steering a car at low speed is heavy and difficult. A truck or bus with manual steering really required some strength. In a truck or bus at low speed you pretty much pulled on the steering wheel with your entire body not just your arms.
A large horizontal steering gave you some advantages in using your whole body to pull or push on it. Today most buses have power assisted steering so you don’t need more than the strength of a few fingers but the design remains.
It’s for leverage. If power steering fails, you’ll be able to turn easily if the steering wheel is in the horizontal plane. Notice how they are bigger for this reason. The simplicity in design other comments suggest it’s just a bonus, one extra joint it’s not big deal nowadays.
Nowadays is for ergonomics. If you have to drive for hours and hours keeping hands up at 90 degree without support is not easy at all. Having the steering wheel horizontal allows you to rest your arms on it.
Part tradition, part necessity. As somebody else already pointed out, you will want to have some leverage when the power steering goes out.
I started as a bus driver 14 years ago, and the oldest buses we had were from 1989 – we were very happy to have leverage, because the power steering did die on some of them. Interestingly, we had one on which the power steering worked, but only to the left. Interesting effects.
On the new buses we got in 2010 and 2012, the steering wheels had shrunk dramatically.
I should note that I drove city lines and short distance intercity lines in Europe; honestly I have never driven a coach younger than 1995, so I’m not sure how things developed on a long distance bus. On a city bus, you’re always close to a depot, so if the power steering dies, you never have to go far.
Time ago it was to fit the biggest possible wheel, coupled with a reduction ratio, to allow a man to manually steer a very heavy vehicle.
With power steering it is not the case anymore BUT:
The vehicle still weighs a lot and has a lot of momentum, you want to apply little inputs and with precision. On a car, going from straight to full left means less than one turn of the wheel, you can do it easily with a “vertical” wheel, and it’s more comfortable (and safer in a crash). On a bus, to be able to give little inputs, the ratio is different and you have to turn 2-3 full turn to get a full left. In this case, the “horizontal wheel makes more sense, because it allows small movements but it’s also very easy to spin it multiple revolutions when you have to follow narrow turns on the road.
And last, there is a bit of “we always did that way”, in the sense that we started with the big horizontal wheel and even with new tech, it is still viable so why change it?
In fact, it is the car wheel that evolved from horizontal to vertical in the span of a century, while the truck one remained horizontal.
Also, how does the bus driver close the door behind him when he leaves?
It’s the position of the steering wheel relative to the steering axle as well, in a car you sit behind the steering axle, buses and truck you’re above it.
Latest Answers