Re: [CAD_CAM_EDM_DRO] Problems in Timing Belt drive system in 6WD robot

Hi Doug,

I just got this reply!

I have separate motor drives on each side, no place (and no need) for a
differential.

On 1/26/2013 8:05 AM, Doug M wrote:
> Alan,
>
> You need a limited slip deferential.
>
> Check the hobby shops. I think they sell miniature Torsen (sp?)
> differentials. Check online for the Dubro line of products. I've seen
> them posted on Ebay before, too.
>
> Let me know whether this suggestion helps.
>
> Doug
> On Jan 25, 2013 3:51 PM, "KM6VV" <KM6VV@...> wrote:
>
>> **
>>
>>
>> Sorry for the cross-posting,
>>
>> I'm having problems with the timing belt drive system in a 6WD robot I'm
>> building for Robomagellan competition in the upcoming Robogames.
>> (Mechanical design courtesy DPA).
>>
>> Pictures in LM forum:
>>
>> http://www.lynxmotion.net/viewtopic.php?f=9&t=7839&hilit=6WD&start=45
>>
>> There are a pair of DC servo motors, each driving a short (3") 037
>> (3/8") .2" pitch timing belt from the 2nd level down to the first, 23:15
>> ratio for a 1.33 speed increase. The motors are mounted on opposite ends
>>
>> On the first level are three short axles on each side of the 'bot,
>> connected on 8" centers by the same timing belts, and 20 tooth pulleys.
>> There are belt tensioners (4) between each pair of pulleys pressing
>> down on the top of the belt. (I do remember hearing that the tensioner
>> pulleys should be on the driven side of the pulley, so one pair is on
>> the wrong side).
>>
>> The belt system appears to run fine in straight runs, grass, concrete,
>> etc., even when moving quite fast. The problem arises when the 'bot
>> starts to make a turn (more torque required). I start hearing loud
>> "popping" sounds, which I take to be the belt(s) jumping teeth.
>>
>> I can't determine which belt(s) is jumping. Since I first observed
>> (heard) the problem, I've strengthened up the bearing supports between
>> the axles, made a better tensioning nut for the belt tensioners
>> (idlers), and increased the tension on the upper drive belts as well.
>> Specs say 3-4 oz at 3/64" deflection on the belts, although I don't have
>> a way to accurately measure it. The belts "sing" when they run, like
>> they are being "plucked", so I think they're pretty tight.
>>
>> The angle of the upper motor belt is about 50 degrees, and I haven't yet
>> figured out a way to add a tensioner to it.
>>
>> Any ideas?
>>
>> Thanks!
>>
>> Alan KM6VV
>>
>>
>
> [Non-text portions of this message have been removed]
>
>
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