This is a highly upgraded version of this past seasons drivetrain. It utilizes a hefty amount of plastics to help keep weight down.
Specs include:
6wd direct driven center wheel chained to outer wheels
Wheels are tensioned by sliding in slots and locking down the axle
Custom 2 speed dog shifting transmission ~7fps and 16fps
Custom UHMW plastic wheels (total weight for each wheel assembly including bearings and sprockets is .54lbs)
Bumper mounts built into end supports
The total weight for everything seen in the picture is 31lbs. THe only thing not included is chain (25 so not that heavy) and bolts. I figure the total with everything will be around 35lbs
One question I have is what kind of tread material will you use? The wheels look almost like the ones in the kit. Unless you’re using 5" wheels (or some other odd size) I’d say go with the Kit wheels. They have a lot of traction for little weight and cost (heck, you get four of them for free).
Are you going to have any support for the middle of the bumpers? I see how they will be connected at the ends, but what happens if you hit something right in the middle? Won’t the wood snap?
I really like where you’re going though. Are there plans for a prototype?
Nice, another red and black beast.
You can shave more material around the gearboxes.
We had a similar shape this past year and just had the minimal material of what we needed since the top gears were pretty well hidden inside of the robot.
Here is a side view, with two of the standoffs missing. Saved 1/4 lb overall, seems small, but that coupled with 6 lbs, we were able to calculate where we needed to add more weight to make cog right on the center wheels with the ball on the robot. http://inlinethumb19.webshots.com/43538/2283050290099908742S600x600Q85.jpg
What program did you render it in?
Thanks everyone for the kind words. I’ll try to address every question.
The wheels are 4.5" diameter, much smaller than the kit wheels. Also the center wheel is hex keyed which will be much easier than adding a hub to a kit wheel. Each one of these wheels only weighs 0.28lbs which is a lot lighter than kit. Finally the tread will be .75" wide roughtop, with a higher Cof than kit wheels.
There might be support for bumpers in the middle or not. Im not sure. Especially in the front it will probably be left open for a manipulator. If we do add supports it will likely just be delrin standoffs so the added weight will be minimal.
I was trying to build a prototype of this during the summer to test a lot of the ideas and to be a good opportunity to teach new members about design and construction but I dont think we have the money to do that.
Direct drive is accomplished by an extended shaft coming out of the transmission. The center wheel is keyed to this shaft and then the outer wheels are chained off of the center wheel. With this arrangement no matter how many chains we break, we will still have movement. This allows us to run #25 chain with a lot less worry and in turn save a great deal of weight.
This was rendered in autodesk, and as for shaving more off the gearboxes and exposing the gears, I’d rather sacrifice a little bit of weight to cover up the gears than leave them exposed. Also the inner plate of the transmission is delrin so the weight savings would be very minimal.
