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> If I asked everyone on HN what steers the rear of a motor vehicle;

What does this even mean? I'm guessing you're going for 'the throttle' but it's a pretty ambiguous question.

Totally agree on advanced driver training though. If you don't know the limits of your vehicle then you shouldn't be driving it.

As for the last point, I think we need to ditch the "level X" designations and describe automated vehicles in terms of time that they can operate autonomously without human intervention. A normal car is rated maybe 0.5s. Autopilot would be 0.5s - 1s. Waymo would be much more depending on how rarely they need a nudge from the remote operators.




> What does this even mean? I'm guessing you're going for 'the throttle' but it's a pretty ambiguous question.

I am going for the throttle (you know, to stop the car from rotating too much after I threw into that corner), and yes you are correct it (the throttle) does "steer" the rear of the car. Plus 1 btw.

Ambiguous... maybe. Anyway; see you on the wet skidpad ;) .


The answer to this question really depends on whether your vehicle is FWD or RWD. It sounds like you have a RWD car and the people not answering it "correctly" don't.


Ooh I like wet skidpads! :D

Other possible interpretations that I thought of (for the record):

- The front wheels (under good traction conditions)

- The limit of traction for the rear wheels (when in a corner nearing said limit of traction... my favourite part, btw.)

- The front wheels (if you're already sliding but hoping to go mostly straight)

- The throttle (if you're sliding and planning on keeping it this way while the front wheels dictate angle of drift)

- Edit: The handbrake (if you're in a front wheel drive for some reason)

:D


> Other possible interpretations that I thought of (for the record):

I almost forgot how difficult it can be to explain the nuances of vehicle dynamics clearly and succinctly.

Let's start by using the classic Grand Prix Cornering Technique (rear wheel drive/rear engine car). We brake in a straight line, and the weight transfers forward so that now the front tires have more grip than the rear tires (as a rule of thumb; the more weight a tire has on it the more it grips, because it is being "pushed" down onto the road. You can of course "overwhelm" the tire by putting too much weight on it causing it to start to lose adhesion). As we get to the turn in area of the corner we (gently) release the brake and we (gently) apply throttle to move some of the weight of the car back towards the rear tires (if we didn't do this the back of the car would still have almost no grip and we would spin as soon as we initiated steering input to turn into the corner).

Now we are into the first 1/3 of the turn, and approaching the apex--we have all the necessary steering lock to make the corner, that is to say we will not move the steering wheel anymore until it is time to unwind it in the final third of our turn (also we are on even throttle we cannot accelerate until we are at the apex). So here we are--the front and rear slip angles are virtually equal, but we want to increase our rate of turn because we see we will not perfectly clip the apex... we breath (lift a bit) off the throttle, but keep the steering locked at the same angle and the car turns (a bit) more sharply. We have actually just steered the rear of the car with the throttle; yes we have affected the front tires slip angles as well, but if we viewed this from above we would see we have rotated the car on its own axis.

This works, to varying degrees, in every layout of vehicle--FWD, AWD, RWD. Technique and timing are critical as is the speed, gearing, road camber, and so, and so. The fact remains though that the throttle steers the rear of the car.




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