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The “fifth wheel” parallel parking tool that never hit it big (2018)

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Re: The “fifth wheel” parallel parking tool that never hit it big (2018)

#11

Post by Tagbert »

aidenn0 wrote: post #10
dhosek wrote: post #4

There was another idea I remember reading about in the 70s or 80s in (I think) Omni Magazine : Four wheel steering: All four wheels can be rotated. with the steering wheel. Turn the wheels to a full 90° and you can then move the car sideways into a parallel space. A lot more practical than this plan which pretty much destroys all the trunk space. Especially, with an EV where you can connect motors directly to each wh…

The advantages of four wheel steering at driving speeds are largely (completely?) negated by active traction control (supplying power and breaking to each wheel independently). You're not going to see a car turn its wheels 90 degrees because of both the large space needed (the cavity for the wheel to turn in) plus the complexity of linkages that can handle that amount of turning. This idea might make more sense today…

The Japanese cars (Mitsubishi and Acura) that had 4-wheel steering only used a very narrow range of deflection to the wheels. It was intended to adjust cornering but not designed for major off-axis motion.

Re: The “fifth wheel” parallel parking tool that never hit it big (2018)

#12

Post by Nick87633 »

aidenn0 wrote: post #10
dhosek wrote: post #4

There was another idea I remember reading about in the 70s or 80s in (I think) Omni Magazine : Four wheel steering: All four wheels can be rotated. with the steering wheel. Turn the wheels to a full 90° and you can then move the car sideways into a parallel space. A lot more practical than this plan which pretty much destroys all the trunk space. Especially, with an EV where you can connect motors directly to each wh…

The advantages of four wheel steering at driving speeds are largely (completely?) negated by active traction control (supplying power and breaking to each wheel independently). You're not going to see a car turn its wheels 90 degrees because of both the large space needed (the cavity for the wheel to turn in) plus the complexity of linkages that can handle that amount of turning. This idea might make more sense today…

The 4-wheel steering on modern cars is typically to help with low speed turning circle size on longer wheelbase cars, not really for high-speed performance although they do put it to use at high speeds for some marginal benefits.

Re: The “fifth wheel” parallel parking tool that never hit it big (2018)

#14

Post by TylerE »

aidenn0 wrote: post #10
dhosek wrote: post #4

There was another idea I remember reading about in the 70s or 80s in (I think) Omni Magazine : Four wheel steering: All four wheels can be rotated. with the steering wheel. Turn the wheels to a full 90° and you can then move the car sideways into a parallel space. A lot more practical than this plan which pretty much destroys all the trunk space. Especially, with an EV where you can connect motors directly to each wh…

The advantages of four wheel steering at driving speeds are largely (completely?) negated by active traction control (supplying power and breaking to each wheel independently). You're not going to see a car turn its wheels 90 degrees because of both the large space needed (the cavity for the wheel to turn in) plus the complexity of linkages that can handle that amount of turning. This idea might make more sense today…

The interesting thing with the 4 wheel steering systems is that the behavior actually changed depending on speed.

At low speeds, the rears steered (a small amount) in the opposite direction, for a tighter turning radius.

At higher speeds the steered (again a small amount) in the SAME direction as the fronts, for more stability.

Re: The “fifth wheel” parallel parking tool that never hit it big (2018)

#15

Post by mauvehaus »

dhosek wrote: post #4

There was another idea I remember reading about in the 70s or 80s in (I think) Omni Magazine : Four wheel steering: All four wheels can be rotated. with the steering wheel. Turn the wheels to a full 90° and you can then move the car sideways into a parallel space. A lot more practical than this plan which pretty much destroys all the trunk space. Especially, with an EV where you can connect motors directly to each wh…

I think you'll find that powering a wheel through a full 90 degrees about a vertical axis would be extremely challenging before the availability of electric motors.

Hell, just creating a linkage that allows it to turn that much and also maintains any kind of reasonable suspension geometry and the required clearances, etc at non-extreme angles would be tricky.

Re: The “fifth wheel” parallel parking tool that never hit it big (2018)

#16

Post by mauvehaus »

Parallel parking just isn't hard enough to justify the expense and complexity (same thing, really) of adding this device to a car. This is a lot of gizmosity to solve a problem that can be solved with a couple hours of practice on a quiet street.

Re: The “fifth wheel” parallel parking tool that never hit it big (2018)

#18

Post by blamazon »

mauvehaus wrote: post #16

Parallel parking just isn't hard enough to justify the expense and complexity (same thing, really) of adding this device to a car. This is a lot of gizmosity to solve a problem that can be solved with a couple hours of practice on a quiet street.

Nowadays automated parallel parking is a relatively commonplace thing ("it's got smaht pahk!"[1]) and we have come full circle. Hardware complexity superseded by software complexity. Kinda neat.

Interestingly, automated parallel parking systems are allowed to be used during road licensing tests in the area where I live, to demonstrate parallel parking competency. Same goes for all driver aid systems, including Tesla FSD Beta etc. Bit of a head scratcher for me.

[1]: https://youtu.be/WBvkmWDjsYc

Re: The “fifth wheel” parallel parking tool that never hit it big (2018)

#19

Post by Schroedingersat »

salgernon wrote: post #8
dhosek wrote: post #4

There was another idea I remember reading about in the 70s or 80s in (I think) Omni Magazine : Four wheel steering: All four wheels can be rotated. with the steering wheel. Turn the wheels to a full 90° and you can then move the car sideways into a parallel space. A lot more practical than this plan which pretty much destroys all the trunk space. Especially, with an EV where you can connect motors directly to each wh…

Mitsubishi (and others) in the 80s,90s had 4 wheel steering: https://en.wikipedia.org/wiki/Steering#Four-wheel_steering https://www.autoweek.com/car-life/a1871191/four-wheel-steering-demystified/ I never drove one; I had a friend that said it really didn't do much for him that he noticed.

Doesn't one of the new mercedes have four wheel steering, but it refuses to be active during parking unless you pay a subscription?

Re: The “fifth wheel” parallel parking tool that never hit it big (2018)

#20

Post by NoahKAndrews »

blamazon wrote: post #18
mauvehaus wrote: post #16

Parallel parking just isn't hard enough to justify the expense and complexity (same thing, really) of adding this device to a car. This is a lot of gizmosity to solve a problem that can be solved with a couple hours of practice on a quiet street.

Nowadays automated parallel parking is a relatively commonplace thing ("it's got smaht pahk!"[1]) and we have come full circle. Hardware complexity superseded by software complexity. Kinda neat. Interestingly, automated parallel parking systems are allowed to be used during road licensing tests in the area where I live, to demonstrate parallel parking competency. Same goes for all driver aid systems, including Tesla…

That's such an awful thing to allow in that context
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