Hopefully I’m asking this question correctly:
I recently started working at a hotel and sometimes I’m driving the shuttle – a new Ford vehicle. I’ve noticed it’s steering wheel is exceptionally easy to whip left or right, making it almost fun to turn.
On the other hand, my car, a 2020 Kia Soul, has a stiffer feeling steering wheel. It’s not as snappy/”loose feeling” as in the Ford.
Is it simply a matter of engineering? A different type of steering column? Are bigger (and perhaps newer) vehicles typically designed to have a snappier steering wheel to help with turning, or is it something to do with the manufacturer?
In: Engineering
There’s a design tradeoff between being able to feel the road through the steering wheel (important in sporty cars) and reducing driver fatigue (important in commercial vehicles).
In some cars, the level of steering assist changes with vehicle speed (more assist for parking, more road feel at higher speeds), or with the vehicle mode setting (more road feel in Sport mode, more assist in Eco mode).
This is independent of whether the assist comes from hydraulic or electric actuators.
Yes, it is a matter of engineering/design.
When you turn the steering wheel left and right, there are two things actually making the wheels turn. First your muscles and physically moving mechanical parts. But more importantly, there is a hydraulic power steering system HELPING you turn the wheels. Try turning your steering wheel in the car when the engine isn’t running (and therefore the power steering is off) and see how much harder it is. Because you actually have to force the wheels to turn under the weight of the engine.
Larger vehicles like busses or your shuttle often have beefier power steering systems, because there’s WAY more weight in the wheels, meaning it is easier to turn with those hydraulics helping you.
There are a few mechanical things about steering. There’s gears between the driver and the actual wheels, and there’s power steering assist.
First, the gear ratio between the steering wheel and the actual wheels. The actual wheels might turn up to 45 degrees to the side, but often less depending on issues like what’s under the hood and how much space/clearance the wheels have to turn. It’s usually about 1.5 to 2 rotations of the steering wheel to go from straight to maxing out the turn, but that varies, and so does how far the wheels will turn, so the actual “gear ratio” varies. Smaller ratios in those gears make the steering wheel feel stiffer.
Second, implementation of power steering. Back in the day, power steering came directly from the engine as another component connected by the belt on the accessory side, including the alternator, cooling, air conditioner… add power steering to that list. As such, how well power steering worked depended on how fast the engine was spinning.
Newer cards use electric power steering. An electric motor takes the place of the main engine for running power steering. It tends to be more consistent, but also can be programmed. It can be sped up or slowed down depending on the situation. For example on the freeway the wheels are spinning fast enough that you almost don’t need power steering… but also, it’s a bad time for the driver to jerk the wheel around, so stiffening it might be a good idea. Well, with a programmable electric motor, that’s now possible.
Different manufacturers will have their own preferences and design choices.
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