added steering to the 6 door truck
That’s not steering, it’s dogtracking. Four wheel steering is a ball of hurt.
Uhhh… no. If front and rear turn the same, you dogtrack/crab sideways, and never turn. If front and rear turn opposite, you have tighter turns, but can hit things you’re turning away from. Unless you’re planning on having two separate steering wheels, specifying which behaviour you want is non-trivial, unless it’s an autonomous system. Manufacturers have played with this. It doesn’t work. I do vehicle dynamics all day every day, I know that of which I speak.
I am not sure, but as far as I know, rear wheel steering makes a vehicle less stable / much more difficult to control. So it could work at very low speeds, but I would switch it off gradually. This feature is difficult to implement and expensive. There are many examples of this to make (parallel) parking easier, but non of them have made it to the market.
Whats the point of a raised chassis if the stearing mechanic still limits obstacles to be driven over? Water? But then no reason for abbility to stear very sharp. You can not have all purposes in one package to stay economic if not want staying to be a gas guzzling monstrousity.
If it were turning the wheels would be orthogonal to each other. This is just like it moving diagonally. That’s not turning, it’s a translation. If you want it to turn, the back wheels would turn the opposite direction to the fronts.
The wheels can move in both directions
For the picture I only showed them in the same direction
And it would only be used in a lower speed
@Patrick_Ryan There are plenty of cars with four wheel steering that work perfectly well. Generally the rear doesn’t turn as much as the front though. The only vehicles I’ve seen where the rear steer matches (or is close to matching) the front angle are truck tractor units designed for heavy haulage but need the maneuverability that is lost when you go from dual axles to quad axles.
It all hinges on your definition of “perfectly well”. Some manufacturers have implemented it as described above, where they steer in the same direction at very low speeds, but opposite directions at higher speeds, and those kind of work. Others have done it in opposite directions at all times - those are the ones where you can hit something by steering away from it. But either way, it’s a really small benefit for a much more complex mechanism that’s prone to failure and adds to maintenance costs. It’s just a mess.
@Patrick_Ryan stock trucks don’t have rear steer
At least anymore
And
It’s for an aftermarket add on and only used on low speeds
And the truck is about 27ft long so in some cases it needs it
4WS worked just fine on my Honda Prelude back in the day, slow or fast. Probably was more expensive though, and I have NO idea how you’d make it work on the monstrosity in the pics above.
@Patrick_Ryan , you have it backward. They turn opposite at low speeds and the same at high speeds. Otherwise you lose tight turn radius when slow and flip when fast. Mine had no mechanical issues at all, the results were very much worth it, and it ran great - too great. Flew it off a highway at 115 mph. But I credit the turning for managing to let me miss the steel pylon the road ended in front of.
Not that it matters, but:
Honda’s first 4WS system, launched in April 1987 on the Prelude, was all mechanical, using a shaft to connect the front-steering rack to a slider operating the rear tie rods. A planetary gearbox determined rear-steering degree based on steering-wheel angle. At small angles, the rear wheels would steer up to 1.5 degrees in phase with the fronts, but at larger angles (more than 246 degrees of steering rotation), the rear wheels would steer up to 5.3 degrees opposite the fronts, trimming the turning radius about 10 percent.
Read more: http://autoweek.com/article/car-life/four-wheel-steering-demystified#ixzz4tPuGQSN5
@Patrick_Ryan , if it doesn’t matter, why mention it? I’ll stand corrected for both of us since neither of us gave a completely accurate description before. My link did explain the planetary gears thoroughly, though.