pic: 1097 Direct Drive 01

[Max Lobovsky]

It looks really pretty, but as SpaceOsc asked, why?


Sanddrag, bevel gears (I believe that is the more common name) have similar efficiency to spur gears (95%+) because they do not have any surfaces sliding across each other (like in a worm gear).

[sanddrag]

Originally Posted by Max Lobovsky

It looks really pretty, but as SpaceOsc asked, why?

My reason would be there is no possibility of throwing chains or broken chains. Also, my favorite reason for it is no chains to tension. And there's also the "it's really cool and hasn't been done before" aspect.

[Anthony Kesich]

Well, to answer the efficiency question, it's very efficient. The miter gears are aligned within .0005" and transfer the power better than chains. We have had chain problems before. Last year we threw Motorcycle (40 gauge) chain many times, so it removes the need to tension or worry about chains. We went through the entire sac regional without damaging it at all. The ony thing we had to do was check the set-screws to be safe.

As for the drive-shafts, they are .049" wall steel tubing.

As for the efficiency on the miter gears, they are just as effieient as straight-cut spur gears.

We lightened all the gears in the gearbox with 6 holes in each, similar to the wheels if you have seen them. Overall, the entire robot weighs 106.8 lbs, so we have no weight concerns.

And, as Sanddrag said, we did it mainly since no one else has done it.

My mechanic told me to tell you that there are 46 bearings and 42 set-screws in the drive-train.

And as for shaft-drive/direct-drive, we've always seen shaft-drive as a sub-set of direct-drive.

-Tony K

[sanddrag]

Originally Posted by Anthony Kesich

As for the drive-shafts, they are .049" wall steel tubing.

How is rotational load transfered to the U-joints? If the driveshaft was solid, I would put a keyway in it but since it is a tube I'm wondering how you did it. Did you put a pin through? .049 is pretty thin, thats awesome.

[Anthony Kesich]

The OD of the U-Joints were turned down to within .005" of the ID of the steel shaft. We then put set screws all the way through and have had no problems with them. Eventhough, we are still going to replace all 42 set-screws on thursday at SVR.

As for the gearbox, it is about the same ratio as the kit gearbox, but we couldn't use the kit gearbox due to the way we had to lay it out. As you can see, we needed the driveshaft to go straight through the gearbox and the kit version wouldn't allow for this. We therefore also had to put the CIMs across from eachother. This is useful in that neither side will be more powerful since in either direction, you have one motor running forward and one running backward.

-Tony K

[Projectchon]

where did you guys get the U join?

[sanddrag]

Originally Posted by Anthony Kesich

The OD of the U-Joints were machined down to within .005" of the ID of the steel shaft. We then put set screws all the way through and have had no problems with them. -Tony K

Oh okay. I was envisioning the tube going into the U joint, not the U joint going into the tube. Very clever! I hope it continues to work out well for you and maybe we'll give it a try next year!

[Anthony Kesich]

If you want to give it a shot, I'll see if I can get my mechanic to give me all of the blueprints and I'll scan them for you.

[russell]

I am drooling. I hate chains. Just today I had to replace chains four times.... That may have had something to do with the fact that I was riding on the robot, and the wheel mounts really shouldnt even hold 120 pounds, not to mention nearly 300 .

[CJO]

So, I know it has been quite some time since this discussion was last updated but I thought I would note the followiing:

1) This drivetrain has been absolutely flawless, both in competition and in post-season stuff.

2) It took tremendous time and effort to make it work, but in the long run it was well worth it.

3) I strongly encourage other teams to use this system in the future. (If you ever have any questions, just e-mail me or Kesich).

~ Christopher

[whakojacko]

i saw it in your pits, very cool and unique. Congrats on doing something unusual!. And is that the kit gearbox?