A, APS front suspension

[deanroberts]

I've been trying to find more information on this quad kingpin steering arrangement but don't even know what it's called.  Can anybody help me?  If I knew what it was called it'd probably be easier to search for information, but if there's anything else you can tell me - pros & cons, build information, setup help, etc. - I'd appreciate the help.  Thanks.

[Dakin Engineering]

I think "duplex" is what you're looking for.

Sam
#6062

[deanroberts]

Thank you.  It's interesting that there's nothing about duplex steering on this forum, but a Google search gives me a toehold on the subject.  I appreciate your help.

[mtiberio]

Center hub?

[Marcroux]

Google OEC motorcycles, they had a front end like that.

[Koncretekid]

Team Sodium Distortion and SuperRat have built a couple of bikes with what's known as virtual steering.



And on a twin Yamaha:

I modelled it here using Legos:


It's really just a 4-bar linkage system with the axle mounted on one of the link.  But the trick is getting the lengths correct as well as the rake to make it work.

Never seen it on a 4 wheel machine, but maybe possible. No suspension shown.

Tom

I have just found that this type or steering is also known as "duplex steering" which brings up more examples in a Google search.

[modernbeat]

...Never seen it on a 4 wheel machine, but maybe possible. No suspension shown.
Tom

I think that if it were on a car and the two wheels were on a single axle that it would be considered "wagon wheel type steering" and be disallowed.

[manta22]

I noticed that not only does the wheel turn (pivot), it also moves laterally. What problem is this type of steering solving?

[Dakin Engineering]

Manta,
 I've modeled it and it seems to be self-centering.
But, if you're steering a motorcycle, something is wrong.

Sam

[Stainless1]

Sam, you mean something is wrong like the wind is blowing 10MPH at the gap 

[Koncretekid]

I noticed that not only does the wheel turn (pivot), it also moves laterally. What problem is this type of steering solving?

On a motorcycle, it initiates lean, i.e. steering.

...Never seen it on a 4 wheel machine, but maybe possible. No suspension shown.
Tom

I think that if it were on a car and the two wheels were on a single axle that it would be considered "wagon wheel type steering" and be disallowed.

But if the two steering mechanisms were independent from each other, it would seem to induce a camber effect.  Might be beneficial in a cross wind. Just thinking out loud.

"No suspension shown", except on Bob Horn's very interesting recumbent EX500 road racer.

Tom

[manta22]

Frankly, to me it looks like an unnecessary complication.

[deanroberts]

Thanks everybody for the information and the opinions.  Always helpful.  I'm particularly grateful for Tom's Lego model.  I'm looking for zero lateral movement of the contact patch relative to centerline for a side car streamliner so this approach isn't going to work.  On to Plans B and C...

Dean

[Koncretekid]

  I'm looking for zero lateral movement of the contact patch relative to centerline for a side car streamliner so this approach isn't going to work.  On to Plans B and C...

Dean

For zero lateral movement, it seems you would have to have zero rake.  Without rake, I think it would be difficult to ride a motorcycle at speed, as it is the lateral movement that sets the lean into a turn (i.e. counter steering). In fact, on a motorcycle streamliner, it would be extremely difficult to steer because the rider is strapped in tightly and cannot lean.  The rake of the front wheel is what initiates the lean and hence the steering.  Now on a motorcycle sidecar streamliner, you might think that it will steer like a car, but without any rake (caster), it might be hard to keep it in a straight line.  Maybe you should try the concept on a low powered, like a pit bike with a sidecar and zero rake before you go too far.

Tom

[sabat]

Here's one you could experiment with on the cheap. 


https://jalopnik.com/a-virtual-steering-monkey-is-the-weirdest-motorcycle-1847999541