Re: pic: Don't do this. It's a bad idea.
 

Here's a much better explanation.....but then, I do like old stuff

http://www.youtube.com/watch?v=F40ZBDAG8-o

Re: pic: Don't do this. It's a bad idea.
 

So, where's the "slippage" provided in this setup?

THANKS!

Re: pic: Don't do this. It's a bad idea.
 

Why not choose pneumatic tires over the suspension? I don think you would get much "play" before the bevel gear bottoms out.

Re: pic: Don't do this. It's a bad idea.
 

There is no "slip"* in a differential. The nature of how the gears mesh is what allows the shafts to turn at differing rates. The differential itself has no control over the situation, its just along for the ride.

*(unless we start talking limited slip differentials and lockers etc)

Re: pic: Don't do this. It's a bad idea.
 

In the differential gearing. Two of the 4 gears in the inner box are connected to the wheels; the other two are idlers. The relative speed of the wheels doesn't really matter to the idlers; they'll move as fast as they need to.

Hint: Think of this setup as 2 gearboxes. The inner box is the 4 in the middle of the "axle"; the outer is the bevel at the top and the large gear it meshes with.

Re: pic: Don't do this. It's a bad idea.
 

NOW, _that_ was helpful... ;-) THANKS, Jim!!

Re: pic: Don't do this. It's a bad idea.
 

Also, helpful... THANKS, Eric!

Re: pic: Don't do this. It's a bad idea.
 

I hadn't. I thought the big bevel was attached to the shaft not the box. After reading that article I understand, and am amazed!!!! :ahh:

Re: pic: Don't do this. It's a bad idea.
 

I Agree with your complaints about suspension geometry.

Also, The suspension on this seems to indicate a purpose of driving over varied terrain. With the completely open differential on there, the wheel with less resistance (often in the air, not making any contact) will get all of the rotation, leaving a torque on the static wheel equivalent to just the friction in the differential.

Re: pic: Don't do this. It's a bad idea.
 

true, maybe you could use a limited slip differential to prevent that.

Re: pic: Don't do this. It's a bad idea.
 

The suspension Appears to actually a three bar linkage with the link from the wheel bearing retainer to the differential frame being a spring loaded variable length link (possibly a gas shock). The u-joint is simply the joint between two links. It would benefit from more support, but the geometry should still work.

Also, by linking the axles with a slip clutch between the output gears of the differential the static wheel issue could be resolved. Like this. basically it's a primitive version of the limited slip differential.

Re: pic: Don't do this. It's a bad idea.
 

That method of using the axle shaft as a suspension locating member was used on some IRS cars for years, including the Corvette starting in 1963

Re: pic: Don't do this. It's a bad idea.
 

Also known as a "Swing axle"

First on this list: http://www.autozine.org/technical_sc...uspension2.htm

Also used on VW Beetles(busses, and most other models including porsche) 38-68

Re: pic: Don't do this. It's a bad idea.
 

There are different ways of doing it, the Corvette used Ujoints at both ends of the axle shaft, so it isn't really a swing axle like the early VW. The axle and control arm make a parallel arm setup, so the camber doesn't change dramatically like on the early bug

Re: pic: Don't do this. It's a bad idea.
 

This was just a fun project, we probably will never make anything like this.

Also I thought about making it into a limited slip diff. but I ran out of steam before getting that far.

As far as the suspension is concerned, I put it in there just so if the robot got tipped a little by another bot, it could still get some power to the floor. And I have never done anything with any sort of suspension, so I'm sure it is probably a terrible setup.

Last, the entire reasoning behind a differential module was to be able to have lots of traction, while still being able to turn the module.