Versachassis v. Andymark-style Chassis, bumpers,protection?

A significant difference between the two main chassis types appears to be that the Versachassis-style frames have wheels on the outside, while the Andymark-style frames tend to have support for the wheel axle on both sides of the wheel.

How does the vex-style work with bumpers, which have to wrap around the corners? How do teams protect the wheels from hard hits? (Is that even an issue?) Does the lack of outside support for the wheel affect anything?

Considering a switch this year…

Links so you can see what I’m talking about:



For Vex-style (which has its roots in the WCD, or West Coast Drive), you’d add bumper supports between the wheels. In your picture, the end bumper mounts are shown already as the ends of the frame end rails, but you’d need to add more per between the wheels per the rules.

You may want to look up “WCD” and “West Coast Drive” here on CD; there’s a lot of discussions about exactly those issues. Long and the short of it is, there’s no real issues, particularly with the bumpers on. Just some minor “take a little more care” items. (This drivetrain’s roots go back to before bumpers were mandatory. And it just keeps on going…

Google ‘West Coast Robot Drive’ and your shall receive your answer.

A search here on CD will pull up a lot of good results. Hereare some examples.

I recommend that you build one in the offseason to get the practice. Then come Build Season, you will be ready. We are in the midst of building one right now and we are actually just a couple minutes drive from where you guys are. Why don’t you and some of your team come by some time and we can talk over our experience? Shoot me a PM and we’ll work it out.

To avoid jumping on the “search” dog pile, here’s a couple real quick answers.

Bumpers can be supported on a West Coast-style Versa-Chassis design a number of ways, depending on your total robot design. Some teams put supports between each wheel. Other teams have a superstructure frame above their drive chassis that can be used to mount the bumpers. Other teams run a section of backing material above the wheels.

As for wheel “protection,” your bumpers will typically have that pretty well covered. Unlike combat robotics, exposed wheels aren’t really a huge concern in FRC, and bumpers will typically make them even less so.

As for cantilevered wheels (lack of outside support), it’s typically fine for FRC applications. West coast drives don’t have a very large cantilever between the outside of the chassis and the wheel, so there’s not a ton of additional force applied to the axles. Even in rough games like 2016, bent axles were rare. As an added plus, it’s much easier to swap wheels (or even entire axles) in a cantilevered design.