Re: pic: 3CIM Ball Shifter
 

Back then we had a lot less power, to get reasonable acceleration and still have a high top speed was hard.

Re: pic: 3CIM Ball Shifter
 

Their initial design goal was 3(+) speeds, but the method they chose allowed for 4 speeds just as easy as 3. Essentially, each shifting mechanism they incorporated doubled the potential ratios. One mechanism would be two speeds, two mechanisms allows for four potential speeds. If they added a third, it would be 8 speeds. Rather than try to explain it in greater detail myself, I'll simply use the wonderful resource they posted on the gearbox (with nice pictures that explain it better than any amount of paragraphs ever could).
http://www.chiefdelphi.com/media/papers/1580

Re: pic: 3CIM Ball Shifter
 

We used the COTS two-speed ball shifters from Vex this year. Nothing too fancy. :)

Re: pic: 3CIM Ball Shifter
 

We didn't want a 4 speed, we wanted a 3 speed. We wanted a fast and very fast gear, like our current design goals for high and low, but we had less power, so we needed a low low for pushing (remember this is back before bumpers) and couldn't get away with the fast-low we like now.

But, with the resources we had, it was easier to build a 4 speed than a 3 speed (since we end up with 2 2-speeds in series). The shift patterns are then low/low,low/high,high/low,high/high, with a different ratio spread of each of the 2-speeds in series. But the 2-3 shift (going from low/high to high/low) requires a double-swap shift which is just plain nasty to execute synchronously between two shifters while under power. A possible solution is to run it like a 3-speed with two options for 2nd gear, and essentially jump-shift past the 2-3 shift. This would add complexity to the shift scheduler, although more than 2 speeds already adds complexity to our shift scheduler.

A ball shifter design can do any number of speeds just by adding more gear pairs to the shafts, so it's possible to do a 3-speed instead of a 4-speed, but it's much harder to manufacture than the dual 2-speed with andymark parts or dual 2-speed mesh shifter design (or even the dual 2-speed ball shifter).

So 4 speeds was easier to build, but the 2-3 shift is bad.

Re: pic: 3CIM Ball Shifter
 

For reference, 222 has been running a 3-speed ball shifter since 2004.

http://www.chiefdelphi.com/media/papers/1539

Re: pic: 3CIM Ball Shifter
 

I thought they'd gone to just running 2 speeds as of late?

Re: pic: 3CIM Ball Shifter
 

This is correct. We only ran 3 speeds in 2004. We didn't find the added complexity and weight to be worth the added gear ratio.

2013 was the first season since 2004 that we haven't made our own transmissions. This season we went with the vexpro ball shifter and will likely use them again in the future FWIW.