We have used the 3CIM ball shifter from VexPro for a single season with great success but now are looking at the flipped motor variety that seem to be of the Dog type shifters.
The investigations thus far finds that the dog shifters NEED more power (Air pressure) to shift and hold into gear.
My concern and I can not find posting to confirm but I recall once a conversation that shifting under load can be more problematic with Dog shifters exploding the shifter dog. With the balls it seems like this is less of a possibility. Say we are racing across the field or get into a pushing match while in hi-gear then get stalled. Shifting while stalled to low gear seems much more violent with the square teeth of the Dog Shifter.
Everything you said makes sense. I’ll add that a dog gear on a stalled wheel will have a lot of friction, and be difficult to shift. A ball shifter on the other hand will not have any friction and still shift easily.
The VexPro ballshifter mechanism also has fewer exposed parts if you integrate them into a custom gearbox. A custom GB also has several other small things that make the ballshifter mechanism really nice that I won’t go into. Shifting more reliably both with and without load, and a lack of failure points in FRC applications drove us to use them since 2013.
I’ve actually never heard of a ballshifting gearbox failing where dogshifters seem to run into all sorts of problems over time.
Thanks for your feed back. Although I may have understood the severity of potential trouble with Dog Shifters it does sound like the potential for issues does exist.
The difference between ball shifters and dog shifters is mainly shape.
Dog shifters are shaped more like a plate with indents that looks kind of like a nuclear symbol. The indents on the plate snap into bosses in the gear in the same pattern.
Ball shifters are similar, but they use 3 balls to snap into indents.
Here’s the link to a dog shifters gearbox with drawings: