how does one go about making a 6 wheel config drivetrain?

[CuriousGeorge]

i am very curious to know, and would like to make one. please any details would be awesome, as well as pictures... please!

[EricVicenti]

There are many different elements required for a 6 wheel drivetrain, so to get a better idea where you are coming from, could you describe the type of drivetrain you are used to?

Essentially, the basic concept behind a 6 wheel drive is that the middle wheels are lowered, so you are only driving on 4 wheels at a time, which will reduce scrubbing immensely while turning. If your robot is balanced well, the front and back wheels will lift off the ground while turning, and only your middle wheels will be in contact with the ground.

[CuriousGeorge]

Originally Posted by EricVicenti

There are many different elements required for a 6 wheel drivetrain, so to get a better idea where you are coming from, could you describe the type of drivetrain you are used to?

Essentially, the basic concept behind a 6 wheel drive is that the middle wheels are lowered, so you are only driving on 4 wheels at a time, which will reduce scrubbing immensely while turning. If your robot is balanced well, the front and back wheels will lift off the ground while turning, and only your middle wheels will be in contact with the ground.

mainly, im thinking of getting out of anything im used to, for me it just doesnt seem to be working.

i want a fast and speedy drivetrain with the power of a tank. 25 seems to do that well.

[EricVicenti]

Well what exactly are you used to?

4 wheel, wide drive? Ackerman?

[CuriousGeorge]

4 wheel

[RyanN]

We had 4 wheel up to 2004 when we got tired of the robots tripping breakers and dancing around. Since then we've been using 6WD with the lowered center wheel. There are many pictures on our website: http://www.teamfusion364.org/Photos%20main%20page.htm)

Look at the build season photos, primarily week 1 and 2 for our drive train.

[CuriousGeorge]

Originally Posted by EricVicenti

Essentially, the basic concept behind a 6 wheel drive is that the middle wheels are lowered, so you are only driving on 4 wheels at a time, which will reduce scrubbing immensely while turning. If your robot is balanced well, the front and back wheels will lift off the ground while turning, and only your middle wheels will be in contact with the ground.

so how far would the middle wheels be lowered? 1/4 inch?

[danshaffer]

kitbot would be a good place to start, just chain your wheels together on each side (you'll probably drive the middle wheels and run chain from there to both the front and the back)
if you're feeling ambitious, you could replace the kitbot angles with 1/8th wall 2x1 or 3x1 aluminum box beam... I can post some pics of our drivetrains if you want them.

[danshaffer]

Originally Posted by CuriousGeorge

so how far would the middle wheels be lowered? 1/4 inch?

1/8" is all you really need...

[CuriousGeorge]

any pictures to help furthur my options or help me in any way would be most helpful and def accepted. i really thank you u all for helping me with this much info so far

[CuriousGeorge]

Originally Posted by danshaffer

kitbot would be a good place to start, just chain your wheels together on each side (you'll probably drive the middle wheels and run chain from there to both the front and the back)
if you're feeling ambitious, you could replace the kitbot angles with 1/8th wall 2x1 or 3x1 aluminum box beam... I can post some pics of our drivetrains if you want them.

would love some pics

[EricH]

I found some pictures of 330's 6WD drop-center drive that somewhat show the chain routing.
http://www.chiefdelphi.com/media/photos/23376
http://www.chiefdelphi.com/media/photos/27675
http://www.chiefdelphi.com/media/photos/30206

Their chain run goes like this: Trannies to center wheel and rear wheel. Center wheel has another chain, which runs to the front wheel.

Just a note, the drive's various iterations have won 3 regional wins, 2 regional finalists, 1 world championship, and 2 divisional wins, with one regional left for the team to play in 2008, just on 330.

[AndyB]

Well, the simplest way is the KOP frame. If using KOP wheels (you'll need 6 of them obviously). Put four at the ends like you normally would. There is a hole that is slightly lowered in the center of the frame that you should use for your middle wheel.

It is lowered to relieve the pressure from the corner wheels so you can turn easier.

The easiest way to run chain is with the center wheel having two sprockets and the ends having 1.

http://andyburchardt.com/robotics_re...0Drive%201.jpg

[EricVicenti]

Many teams choose to use #35 chain, but in my experience, it is way more bulky and heavy than necessary. Team 8 uses #25 chain. Keep in mind that tensioning is very important. The two ways of tensioning are to pull the wheels back, or to push the chain down, either with an idler sprocket, or some other material that wont wear out, such as HDPE.

Also, most teams don't directly drive any wheels with 6wd, which isn't a bad choice, but in terms of simplicity, we choose to drive the center wheels, and to have 2 chains run to the front and back. This year, we originally designed our drivetrain to use AM super shifters. When we found ourselves nearly overweight, we decided to make our own gearboxes from the toughboxes and the supershifters, so we ended up with non shifting gearboxes, 8:1 ratio (fairly high, higher than either the toughboxes or the supershifters), the size of toughboxes with the mounting pattern of supershifters.

[EricH]

Originally Posted by EricVicenti

Many teams choose to use #35 chain, but in my experience, it is way more bulky and heavy than necessary. Team 8 uses #25 chain.

Some teams won't touch #25 in the drive with the length of the overpass. They say it's too weak. It isn't, but if not done right, it can be. (The last time 330 used #25 on a robot was the second stage of their shooter wheel drive in 2006 going to the wheel. It was the first time since 2001, when contact was minimal and #25 was used in the drive. Later, we had a lot of problems with drive chains jumping while using 2001 as a practice bot.)