Tank Track Axle Arm Angle? - What degree is best?

[avadon77]

Hi everyone, I'm building a tracked robot and trying to figure out what angle the axle arms should be set at? I measured the M1 Abrams tank and the road wheels are all set to 15dgs except for the leading wheel which is set at 40dgs.

But then I looked at other robotic tracked vehicles and they look to be around 40-60dgs. Is there some special angle? Of course this dictates how the suspension will work as well so it's very important.

any clue what angle these axle supports should be placed at?

if you look at the attachments you can see what I'm wondering. I just don't know what the trade off is of having them very low like 15dgs versus very high like on the darpa robot where they are raised up very high for what seems to be massive amounts of travel. I need a rather stiff suspension because I have a high center of gravity so it can't be that spongey I don't think.

[HERMAN BIX]

Well, I'll give you that its got tracks, but how about a little about yourself in the intro section, ya know, just so we can get a bit acquainted & stuff before getting into the intimate bit !!

[avadon77]

Well, I'll give you that its got tracks, but how about a little about yourself in the intro section, ya know, just so we can get a bit acquainted & stuff before getting into the intimate bit !!

Just introduced myself in the new members. Thanks

[jackalope]

I don't see where it would matter at what angle the arms are set model vs. model I just think that's how they built the thing is all.

[avadon77]

I think it's something to do with suspension travel in relation to scale. Like the Abrams doesn't take as big of hits as something very small might. So there suspension is probably much shorter and less spongey as some of these robotic tracked platforms. I wish I would have studied more physics in college so I could know what is going on with the moment arm here.

[jackalope]

If you want more suspension travel just mod the arms or the lower hull. The M1 in real life has plenty of travel.

[avadon77]

Is there any good reference on here in regards to building RC Tank suspension?

[Raminator]

Probably not to the level you're after, since most people are basing them off kits or mimicking the mechanics of the real tank. The other builds forum has some scratch-built tanks that may help, though.

With regards to your original post, I don't think it's so much that there's any angle that's "better" than one or the other, it'll be a function of wheel size, arm length and spring type. For example, Christie suspension will give you better travel with a shorter arm and flatter angle than, say, torsion bar suspension.

You've probably got two options: you can either replicate the setup of a real tracked vehicle that has the kind of mobility you're after (or whatever you think looks the coolest!), or you can try to reverse-engineer what you want from what you need (based on the size of your robot and the terrain it will cross, work out how many wheels it should have, how big they should be and how far they should travel).