Help with building an 8x8 vehicle
Posted 29 October 2012 - 02:12 AM
However I need some help on designing things such as the chassis, suspension, gearing, frame, and bodywork. I was wondering if any body knew of some sources or had some useful advice on their own to help me.
Posted 29 October 2012 - 02:54 AM
I would start by making four axles using the common linear actuator bracket as a steering hub that should allow you to get a decent steering angle.
Make a frame to fit on top of each axle and have the motors connected to it.I guess something like this will have live suspension so you could have the drive coming up to the pivot point of each axle.
In-between the too front and rear axles you can fit your servo motor for steering and have a drive shaft to each side,if you really want to push the boat out you could add a gearbox so you could have different steering modes ie crap,front,rear....
Edited by Alasdair Ryan, 29 October 2012 - 02:59 AM.
Posted 29 October 2012 - 03:19 AM
I have a few pics on my brickshelf page. I tried independent suspension and pendular, better with independent.
Posted 30 October 2012 - 12:09 AM
This is my first prototype of the front axle. In the final version, the shocks will be replaced with hard yellow ones, but I need to order some from Bricklink. I am obviously using independent suspension, and I have tried to model it after the real thing. I decided not to have multiple forms of steering, as from my research I see no sign that the real life BTR-80 has multiple types of steering.
Posted 30 October 2012 - 09:01 PM
BTW, I have replaced the shocks with some stiffer yellow ones, and that might affect something.
Edited by Paul202, 30 October 2012 - 09:02 PM.
Posted 30 October 2012 - 10:49 PM
On topic however;
It's a bit difficult to see from the image you posted, but when making a double wishbone setup, it's really important that the wishbones and the u-joints bend "as one", that is so that the u-joint is neither further out nor further in than the pivot point on the wishbones. Or else the geometry will misalign as the suspension travels.
An alternative could be to use CV-joints instead, as they are essentially frictionless where you put the axle, and allows for some travel (about 1,5 L I think?). However, for an 8 wheeled soviet APC you would need eight of them, or maybe even 16, as well as the "female" CV-joint-axles.. and they are not especially cheap..
Hope this helps!
I made a quick model to show you what I meant by the allignment:
This shows the concept, however it would not work, as the arms (in this case (that's not even a wishbone)) are touching the axle
Edited by D3K, 30 October 2012 - 11:12 PM.
Posted 31 October 2012 - 12:14 AM
A side note: It's possible to build a suspension with the u-joint offset from the pivot points, as long as it's offset equally on the oppposite pivot point.
Posted 31 October 2012 - 02:20 AM
Posted 31 October 2012 - 05:59 AM
If the geometry is setup correctly, you don't need the axle to slide in/out of the CV joint. If you don't have any special hub pieces or CV pieces, it is still possible to build an idependent suspension with just u-joints. It may not be as compact, but it's still doable.
Do you have any pictures of your suspension setup without the tires?
Posted 31 October 2012 - 09:03 AM
Posted 31 October 2012 - 10:33 AM
So i´ll use linear actuators now.
Edited by MarkusOSX, 31 October 2012 - 05:13 PM.
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