pic: 4WD Concept

[JohnFogarty]

Originally Posted by Kingland093

My team used 4WD set up like yours last year, and to quote our driver, "it turned like an old lady". It was poor in situations with heavy defense (glad we didn't do it this year). If you're going to go 4WD, I'd suggest to go 4 omnis or even mecanum. Other than that, I'd recommend sticking with 6WD

I honestly don't know why this would occur. The turning scrub of this drive-train would be noticeably less than that of a 6WD.

I didn't realize these were COTS bearing blocks when I made the post, which increases my confidence in them a lot.

That said, since the bearings are hex, I think there's at least an argument to be made to be paranoid about how heavily the bearings are loaded. This year, our bearings were spaced 1.75" apart (just happened to be, we didn't design around this problem) and we had no hex bearing failures. Other teams with bearings 1" apart or less had problems with some hex bearings exploding under regular drivetrain loads. Hopefully the manufacturing problems with hex bearings are cleared up for 2015 and we don't have to think about out of spec COTS parts when designing, but if you want to be paranoid it's something to consider.

An easier solution than going with a different bearing block would be to just turn that part of the shaft round and use round bearings (less prone to failure), or better yet use a dead axle bearing block (also available from 221) since your chain is on the same side as the wheels. But this might not even be a problem next year, so...

These bearing blocks though designed to work similarly to 221 systems blocks are in fact somewhat custom. 4451 and I CAD up these versions ourselves and then CNC milled them ourselves. They used this version on their 2014 6WD drive-train without issue. When you say the bearings were spaced (distance) apart, are you referring to the distance between the two bearings inside the block?