Rick Brooks wrote:
It looks like a Promax "400" or similar. I'd go with the "05" big brother from the start. Remember too much power is never enough.
As you correctly pointed out, adjustable timing is mandatory.
The belt drive appears to be about 1:1 ratio, so the gear box should be about 25:1 or 30:1, but not outside of that range. Plan on using more voltage than the motor rattings. Add batteries until you get the speed that you want. Also figure on a speed control that can safely handle 40 to 50 amps per side. Again, overkill is necessary.
I've never done anything with belt drive, but you may be loosing a lot of power in the idlers. Perhaps removing the idlers and eliminating the center wheel will be an improvement. Experimenting is required.
Wait. Why am I telling you all this? Forget this post.
Hi Rick, keep talking buddy... lol
OK I'm coming clean. Here is all the data so far. I've been meaning to do this anyway...
The pulleys are all 32 tooth and can accept belts up to 0.289". I'm using a standard 0.250" wide MXL belt. The idlers are 0.125" ID, 0.375" OD and 0.156" wide, I'm using two of them per position. The tires are 2.125" diameter and 1.5" wide.
I completely expected comments about the timing belts. This is uncharted territory for many. If I were building for Japan rules, vacuum and or magnets, then it would be out of the question. But with just 3kg pushing down on the drive train the bot is likely to bounce before anything breaks. Off the forum I have received comments ranging from "Those timing belts will not be a problem at all" to "The thing will fly apart!"
Here's the information on the cobalt motor.
Maxx Products PMX4812.
Weight 4.1 oz.
Typical voltage 8.4-9.6vdc
Test voltage 8.0
Static RPM 15,600
Static amps 19.2
Static Power 154W
I believe static means not flying?... These motors are for airplanes. The current demand is what made me want to try these before going to the 05 model.
The gear box is a planetary box with 27:1 reduction and dual planetary gears, just double the height of the current planet gears for more strength. Dual ball bearings on the final gear of course. 15,600 rpm with 27:1 is 577 rpm at the wheels. Which is 64.2IPS! We can slow it down from there if necessary.
I agree to some extent that 4WD has inherent advantages over 6WD, especially in my situation, but I really want 6WD...
I hope to have it moving under it's own power in a few days.
Jim Frye, the Robot Guyhttp://www.lynxmotion.com
I've always tried to do my best...