Quad build with front and rear steering.

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This man build a quad with front and rear steering.
Front and reer wheels are on an axle that turn in the middle the opposite way. This gives a small turning circle.





The quad is developed trough the years. He made it each time better.
It has no independent suspension, but it has suspension in the back. But more is not really needed on paved roads.
 
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Quad-steer is a nice touch. :)
He seems to have made it FWD too, which is unusual.
 
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Emiel

Not sure I understand this ?

The front end has a single pivot somewhere between the wheels and the seat whilst the rear wheels independently turn ?

So no Ackerman on the front end ?

I can remember see this on his web site sometime ago but can't find it now.

I do like how his fairing lifts with the handle bars very neat and useful looking machine.

Paul
 
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Steering is like those soapboxes. A solid axle with on the ends a wheel. The same in the back and they are connected. So you turn in the front, the rear does the opposite. I don't know it it turns ad the same angle.

There is no Ackerman.
The quad is very stable and rides good.
I didn't ride it myself, but I want to try it.
My touring and building mate tried it and he was positive about how it rides.

I had seen it before, but I think that he removed it all. He wanted to get it in production, but he didn't find a company that wanted to build it.
He developed it in all thise years.
On printest are several images from trough the years. It got more and more complicated, but it where all improvements.
I like the look of the quad and his it steers makes it more interesting and standing out.
 
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I suspect it's ridden in flat areas, because I also suspect you wouldn't want to get up to any speed downhill on it. I do have direct experience of a trike that's quite happy under 25mph but then shows a different aspect above it and I would expect this to be similar. The minute number of cars that have used 4 wheel steering all limited the rear wheels to 3 degrees or less, often auto locked the rear at even moderate speeds, were exceptionally complex and often had the rear mechanism completely locked by owners as parts wore or broke. The most complex ones even turned the rear wheels in the same difection as the fronts at speed to reduce yaw. I would not want to get up to any serious spped on this. It may,however, be great around town.
 
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Popshot

Great insight into the problems the layout brings to the table , a fleeting though of making a new front end and adaptor to change the current python pivot vertical have now receded and life can continue.

I suspect the current interest in quads is driven by wanting a large load platform ? easily achieved on my Python by extending the wheel base on the rear end so I shall not ponder further.

Paul
 
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Popshot

Great insight into the problems the layout brings to the table , a fleeting though of making a new front end and adaptor to change the current python pivot vertical have now receeded and life can continue.

I suspect the current interest in quads is driven by wanting a large load platform ? easily achieved on my Python by extending the wheel base on the rear end so I shall ponder further.

Paul
Although lots have reported "no problems" on long-ish pythons, mine was scary and unpredictable with a lot of camber climbing, until I cut it as short as possible.
Good luck though I am sure it is doable. Maybe my pivot was just "Too-Good" for its own good. :-D
 
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The quad does not exist anymore, same as his website.
I heard today the complete story.
The man worked about 20 years on it. Each time as he changed something, he builded a new one.

Here is how the construction worked.
Front and rear where connected with steel cables crossed. This way the steering went in the opposite direction.
The rear wheels did not only rotate around the center to steer, it also kept his wheels on the ground as you lifted one front wheel.
Front steering was under a small angle. This made that the wheels stayed straight as it hits a bumb on one side.
Front wheel drive.
You could steer with your feed like the python and whit steering.
It had a diff in the front.
Front part could be removed and replaced so it became a hand bike.

The quad was very heavy and the speed was about 15km/h. So low speeds.
Because front and rear steers, you did not need a not of steering to ho around the corner.
It wasn't a racer.
 
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I looked up the 4-Wheel Steering on the internet and it did say that most of the 4WS cars have control systems that only switch the 4WS from opposite of the front wheels to same as front wheels when over about 35MPH.
I don't know too many of us that speed along at 40MPH so it still seems to me that the 4WS may have some merit.
I would think a proportional system that works through an adjustable bell-crank/lever that was "tuneable" (% of rear steer compared to the front steering angle) might be a reasonable approach.
But the "shimmying" sometimes experienced in the front-wheels like in a Tadpole might be overly amplified across a 4WS system as Popshot says?
 
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The speed isn't a problem. As high speed corners, you don't steer that much, especially not as the front anfd rear steer ad the same amount.
 
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Although lots have reported "no problems" on long-ish pythons, mine was scary and unpredictable with a lot of camber climbing, until I cut it as short as possible.
Good luck though I am sure it is doable. Maybe my pivot was just "Too-Good" for its own good. :-D
Missed a not out of my original post , sort of changes the meaning somewhat , sorry.

Paul
 
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It was at 35mph that mine started it's misbehaviour. I only get up to that as there's a monster hill into Leeds from the Dewsbury road. For certain, many folk will never see such a hill. I doubt that this would shimmy but would more likely simply bite once and the first you'd know about it would be as you were looking for a place to land. It'd be great if we could made taddys turn and deltas corner but despite many efforts I've not seen them do that without compromise.

That shouldn't stop us trying though.
 
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I am wondering How one would make a simple python-type of self-centring front end but with 2 driven front wheels and then link this to some proportional rear-axle magic.
  • How would you incorporate the FWD/2WD and some Ackerman to prevent wheel scrub?
  • How would you incorporate a modicum of Rear-Wheel Steer?
Some nice challenges in that melange of bike-bits I think.
 
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I am wondering How one would make a simple python-type of self-centring front end but with 2 driven front wheels and then link this to some proportional rear-axle magic.
  • How would you incorporate the FWD/2WD and some Ackerman to prevent wheel scrub?
  • How would you incorporate a modicum of Rear-Wheel Steer?
Some nice challenges in that melange of bike-bits I think.
As a python it is way to complicated.
Easier is, to move the rotation point, to the center of the wheels.
You cm an move your seat forward to get it on the same place as with a python, but you also get your front wheels ad that point.

You also need to change the rotation point. Nkw it is pointing to the rear, but better is, to let it point to the front. The reason is, is that as you steer, you will tilt to the outside of the corner.
The amount depends on the angle of the rotation point and the amount of steering.

Adding Ackerman is waay to complicated, but you can let the wheels tilt independently and with that, improve the cornering speed even more.
You can ad that also to the rear.
The only thing that will be complicated, will be the drive system. You need some kind of diff, axless that change in length and those parts that make that you can steer while the shaft isn't in a straight line.

Ad the system from this Trike to the front and in opposite way to the back, and ad the complicated front part and you have your tilting quad with tilting wheels.

You will need to make some changes, because as you ad front and rear steering, you turn less with the wheels compared to only front wheel steering. But that is moving some bars and change some angles and you get your tilt and the tilt in the wheels better.

But it will be very complicated and heavy.
The reason why this quad never went in production, is in my opinion because it was way to complicated designed.
 
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As a python it is way to complicated.
Easier is, to move the rotation point, to the center of the wheels.
You cm an move your seat forward to get it on the same place as with a python, but you also get your front wheels ad that point.

You also need to change the rotation point. Nkw it is pointing to the rear, but better is, to let it point to the front. The reason is, is that as you steer, you will tilt to the outside of the corner.
The amount depends on the angle of the rotation point and the amount of steering.

Adding Ackerman is waay to complicated, but you can let the wheels tilt independently and with that, improve the cornering speed even more.
You can ad that also to the rear.
The only thing that will be complicated, will be the drive system. You need some kind of diff, axless that change in length and those parts that make that you can steer while the shaft isn't in a straight line.

Ad the system from this Trike to the front and in opposite way to the back, and ad the complicated front part and you have your tilting quad with tilting wheels.

You will need to make some changes, because as you ad front and rear steering, you turn less with the wheels compared to only front wheel steering. But that is moving some bars and change some angles and you get your tilt and the tilt in the wheels better.

But it will be very complicated and heavy.
The reason why this quad never went in production, is in my opinion because it was way to complicated designed.
Yeah... but he's doing a tilter as well.
What if just your seat tilted as in Paul's proven trike?
What if you did have some ackerman and 2WD on the front axle?
What if the rear wheels had some ackerman as well as a rear-steer input?

I am still NOT convinced that this is a bad/not-possible combination. :)
I shall think on this.

Great discussion thread for sure.
 
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Yeah... but he's doing a tilter as well.
What if just your seat tilted as in Paul's proven trike?
What if you did have some ackerman and 2WD on the front axle?
What if the rear wheels had some ackerman as well as a rear-steer input?

I am still NOT convinced that this is a bad/not-possible combination. :)
I shall think on this.

Great discussion thread for sure.
OK you want the python rotation point in front and back and instead of 1 wheel in the middle, 2 wheels but as it tilts, they need to adjust a bit to get Ackerman.

That you can reach by a cimilar system as the tilting one does. You need to rotate the mounts 90 degrees, so it doesn't tilt, but changes the angle.
And because you use front and rear steering, you need only a little bit of that.
The rotating point needs to be close to the center of the wheels, but you can do it by making the tilt as the steering input like you normally do with steering. The basic is the same with Ackerman, but the bars go to the tilting part at a surten point and that decides how much the wheels change to get the Ackerman.
Then you need to put the angle a bit more flat of the rotation points. This because you also ad a bit of steering with the Ackerman.
 
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The drawing is rotated, but side view and top view from the front part without any drive system.

The scale is off. The 2 arms that go to the back need to be shorter and the wheels are closer to the rotating part. the rods need to be mounted on a separate part that is connected to the mid part. I need to work that further out.
 
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