A-arm suspension questions

[ninjazoomer3]

In the future I'm planning on building an off road go kart. And I have a question about the front A-arm suspension. So hopefully you can understand what I'm trying to say. My question is, during suspension travel how does all the wheel stay in contact with the ground? Because it seems like without some type of joint the wheel would lean into the frame. Just to clarify I'm not talking about the steering pivot joint.

 

[firemanjim]

Google "sand rail" .... Looks at the front ends. They have a BIG heim end on top and bottom. That allows it to pivot up and down and still keep the wheel perpendicular to the ground. Also allows the spindle to turn left and right. Same principle used in karts. Or you can use cheap ball joints.... Make sense?

 

[itsid]

and first of all.. it's a doubla A-arm supension
that makes it a parallelogram

'sid

 

[ninjazoomer3]

So you don't use the type of joint that connects the control arms to the kart?

 

[firemanjim]

 

[OzFab]

Is that better Jim?

 

[ninjazoomer3]

I'm still a little confused. Can someone post a picture that clearly shows my question cause most the pictures I've seen are all different and I can't see the concept.

 

[OzFab]

Here's a perfect example:

This is the front end of one of the most popular buggies in the world, the Edge Barracuda. As you can see, the wheels are at different points of suspension travel but, the camber of the wheels are the same...

Here's a shot of the same machine from the rear, the double A arms work the same there

To help you understand even better, here's an experiment for you:
-Find yourself four pieces of steel, wood, plastic, whatever, as long as they have a flat surface & can be bolted together.
-You need two long pieces of the same length & two short pieces of the same length
-Drill holes in both ends of all the pieces at the same point on every end.
-bolt all the pieces together in a rectangle shape (long pieces at the top & bottom, short pieces on the ends)
-Place one of the short end pieces in a bench vice & move the other end up & down
-Observe & report your findings...

 

[mckutzy]

Im going to take a wild guess, There are multiple pivot points, in the links and in the wheel support structure.
Is this what your thinking?

 

[ninjazoomer3]

Thanks for the help guys that's been puzzling me for awhile.

 

[fowler]

Not quite what u want

If u look at the barracuda though it's whole sweep u will see it leans our at the top and in at the bottom

So as it leans into a corner the outside wheel leans in and digs into the sand
The inside wheel leans out to also dig in

It's achieved by havering the top a arm shorter than the bottom

Just look at the back end
Why would they have camber on a non steer axle


It's done on all suspension
It's just real obvious on the barra because it's off road

Even track cars have it so even though the body is leaning a few degrees over in the corner the wheels stay perpendicular to the ground not perpendicular to the body

But those heim joints are what u want
See the little spheres with holes in them
That means they can not only rotate around the hole but also side to side

So they can bend and gist with the suspension
Also u use the heim joints to mount your spindle
The king pin will go though the hole and the steering works off rotating aronud that
The the suspension swing is achieved by allowing the sphere in the middle to twist

It's real easy to see how they work once u have one in hand

EDIT
Arr
Here