pic: Quixilver 604 Ball-Shift Transmission

Two speed: 5 ft/sec and 15 ft/sec (calculated) with 4" custom wheels.

I like the pattern that matches the Big CIM face. How effective is that for retaining it? I was considering doing that for an update for next season to our base. How else is it held in.

Also, is it just the Big CIM in there?

If it is, are you using all four small CIMs elswhere? If you’re not using all 4, what’s the reason for going with Big over small.

Why the choice to put the shifter on the last stage? Space looks a bit tight, but you could’ve taken advantage of lower forces on your ball lock.

  1. The pattern matching the large CIM is very effective for retaining, as it uses less parts and can handle the motor torque shock. The motor is also held by the metric threaded stud already present on the motor face. One recommendation for anyone interested in this method would be to also drill a hole though the tab for a 1/4-20 screw.

2.Yes, that is just the large CIM. This year our team is going for simplicity, so the transmission is designed around the big CIM 2500 rpm. We did not use the small CIM’s anywhere else.

The reason why the shifter is on the last stage is that there is not enough material on the 20 tooth gears (smallest) for the 1.00" dia. shifter. So the shifter shaft must be on the 40 and 60 tooth gears.

I’m admittedly confused about this… If no small CIMs are being used, why didn’t you build a ball lock using two small CIMs? It’d be about the same weight and over twice as powerful.

The (original) idea was to have a simple and lighter transmission by not having to include an extra gear reduction for the small CIM’s (5000 rpm) by working around the large CIM (2500 rpm). In practice we quickly found out that that this was the wrong approach, as it is lacking in acceleration and agility. There was no time or space to include two small CIM motors in the robot by ship date.

Live and learn. :frowning:

This is our first year with a two-speed transmission, and one of many lessons. Next year expect two motors per transmission, as well as a lighter, smaller, and more simpler design.