West Coast Drive Terrain video?

[koo_04]

Anyone have a good video for a west coast drive? We are talking about different types we might want to consider, but no one here has really seen one work. We know how it does, just need to see if it is worth it.

[Grim Tuesday]

I second this request, as well as a good explanation of west coast drive.

Also, OP I think you mean drive train not terrain

[StevenB]

"West Coast Drive" or WCD, is a six (or occasionally eight) wheel design with cantilevered wheels (i.e, unsupported on one end), named for the teams on the west coast who have refined it and used it particularly effectively. 254, 968, and 330 come to mind first. For pictures, look here on CD-Media.

For video, try the Blue Alliance:
http://www.thebluealliance.net/tbatv/team/254/2007

That said, I don't think you'll know whether it was "worth it" just from a match video of another team. Team 254, for example, is very good - but that has relatively little to do with the fact that they use a cantilevered 6 wheel drive system. It has a lot more to do with their entire design process, the quality of their build, and the driving practice that they do.

[Grim Tuesday]

So all that West Coast Drive is is that the wheels are outside the frame? Does this really impart all that much of an advantage?

[Matt H.]

The advantage arises from ease of fabrication and weight. A simple West Coast drive can be fabricated in <2 days with only rudimentary tools. This allows more time for driver training and design. Often West Coast drives also require less frame material and thus weigh less.

As an example:
A West Coast drive could be made by welding a rectangular steel frame and welding on 1/2 in. steel bolts for axles.

[ajlapp]

frc910 from a few seasons back

[Chris is me]

By the way, it's called a Drivetrain, not a Drive Terrain.

[dodar]

Is it necessary to drop the center wheel on a West Coast Drive to get better manueverability?

[ajlapp]

1/8" drop is considered a minimum best practice.

Some run .150" standard, others use more.

[Mr. Van]

Originally Posted by Matt H.

The advantage arises from ease of fabrication and weight. A simple West Coast drive can be fabricated in <2 days with only rudimentary tools. This allows more time for driver training and design. Often West Coast drives also require less frame material and thus weigh less.

As an example:
A West Coast drive could be made by welding a rectangular steel frame and welding on 1/2 in. steel bolts for axles.

I think I should add some clarification here. While you could use a cantilevered dead axle and drive wheels with sprockets and chain, this is not what most people consider West Coast Drive. Using this system would require the chain to be on the outside of the chassis frame, increasing the forces on the cantilevered axle.

WCD was pioneered by Team 60 back in 2001-2003 and moved to 254 when those teams began to collaborate. From there it has spread to team 22 (4), 968, 1538, 1868 and many others. Done well, it is a fantastic drive system.

One of the basic elements of WCD is a live axle with a chain or belt on the inside of the chassis. (This allows the wheel to be closer to the bearings on the frame.) In addition, most of the teams that have developed their designs from the original WCD have bearings that are mounted on a block that can slide within the chassis rail to allow adjustments for chain tensioning.

We've developed a "poor man's WCD" that puts the mounts for the bearings on a box that wraps around the chassis rail. We've found it easier to fabricate, but it is not nearly as elegant as the systems other teams use.

In any case, fabricating this sort of drive is generally more complicated than a dead axle supported on both ends by rigid framing - especially considering what comes in the KOP and the provided Kitbot.

Having said that, there is usually an advantage in maintainability, ease of making repairs and weight, not to mention the increased space available within the chassis and the wider track width that can aid in turning.

-Mr. Van
Coach, Robodox

[sgreco]

This picture is a good example of what a west coast drive looks like.

http://www.chiefdelphi.com/media/photos/31597

This is my favorite picture of a west coast drive. It's a nice simple view of it, and there is no manipulator attached, so it's easy to see what's going on. It's pretty self explanatory how it works from the picture, but it's basically a custom 2-speed gearbox, 2x1 aluminum frame rails, live axles (I believe they're hex), and the middle wheel is driven direct from the output of the gearbox and is dropped (probably 1/8 inch). overall it's a really nice representation of a west coast drive.