This year we have decided to go with Vexpro Gearboxes, in particular the 3 CIM Ball shifter and the WCP DS Gearbox. Our reasons for choosing these are obviously based on the dual speed capabilities. We looked around and the only things we found were people who said that the Ball Shifter was less reliable than the Dog Shifters. We were also concerned with the openness of the Dog Shifter and feared that it would allow things like dirt and carpet material to interfere with our gears.
If you could please provide us your experiences with these types of gear shifting options and your recommendation our team would be very grateful!
I assume you know how both of these work?
Anyways, ball shifters require less force to shift but one of our mentors doesn’t like them, as they wear out in industrial applications. But for FRC, wear is not really a problem with them I hear. The Vexpro ballshifter is lighter than the WCP shifter.
Open shifters are probably not going to die ue to carpet grime as long as you wipe them off after a regional.
We used a ballshifter this year to winch back out catapult (several hundred pound of force) and the only thing we had to modify was to beef up the pneumatic cylinder so that it would have enough force to shift.
We ran Ball Shifters on our robot this year. We put them through a lot, 2 regionals champs and 2 off seasons full of heavy defence (We did regrease them before champs). Even after all that there was almost no wear and the shifting was only marginally less smooth. The only issue both us and 5031 had with them is they tend to sag over time but it does not seem to have a noticeable effect on robot performance.
MOE used the 3 CIM ball shifters this year and we experenced significantwear on the aluminium shifting shaft. I heard a few other teams experienced this on their winches but this was on our drive, enough that the most worn one was unable to shift. We also had some of the miniature ball bearings fail, possibly related to this. We never did get to the bottom of the problem (possibly user error related to the pneumatic coupler) but I have to stress that VexPro and JVN were extremely helpful and generous when we told them of the problems we were having. I also believe it was mentioned that this component would soon be replaced with a steel version which I know some teams already took it upon themselves to manufacture. If you are looking to purchase gearboxes in preparation for 2015 I would wait and see if VexPro has another product unveil in mid December like they have had the last 2 years. You don’t want to be stuck with “last years model” if they come out with something better.
I don’t have any experience with dog shifters but after 6 events and a bunch of practice, our ball shifter gears or plunger had no wear. The Teflon coating was not even worn. We usually only shifted about 1-3 times each match though.
WOW! That’s bad. Out of curiosity, what were you guys geared for and about how many times did you shift in a match?
This. Something to note is that anecdotal evidence is better than no evidence, but an incomplete anecdote is worse. If all of the folks commenting on the shifters could provide this sort of information (geared speeds, average shifting/match, and any other potentially relevant details), it’d go a long way towards making a very informed decision rather than a decision based on incomplete information.
We were running around 14.7 fps high and 7 fps low with 6 CIMS on a 4" Blue nitrile WCD. We shifted 5-10 times each match with hard acceleration and breaking. No damage to the teflon coating was noticed.
We were planning on using them for the drive train so I don’t think that would be a problem for us.
So those are from shifting pneumatically? Last year we waited too long and were stuck with Toughbox Minis. It is in our best interest to order these gearboxes and test them well before the build season
As the driver for MOE, I can attest to that we are running around 14 fps high and 6 fps low with 6 CIMS on a 4" wheels. On average, I did shift approximately 15 times each match with hard accelerations and sudden breakings for jukes and dodges.
Since everyone that has posted so far has posted about ball shifters, I’ll give my experience with dog shifters. Team 341 has used dog shifters in their drivetrains for the past 3 years, and we have experienced no significant wear what so ever. We found that the dogs shift and mesh so easily, that we had a servo actuated PTO in 2013 (which we never ended up using), that engaged effortlessly. Although we did use custom transmissions for the past 2 years, our 2014 gearbox was just a WCP 3 Cim DS repackaged with new plates. We purchased the gearbox and used the exact same internals of the gearbox. As driver for the past 2 years, I can attest that these drivetrains were pushed very hard. We had very aggressive gearing in 2014 and shifted very often. However, despite this amount of usage, the shifting was just as smooth and effective as it was day 1. Hope this answers your question or provides another perspective.
What do the gears that the balls were interfacing to look like? Is there similar wear on those from the balls engaging suddenly? We have been asking ourselves recently why we don’t run ball shifters, so we are very interested to see your experience. We also get noticeable wear on our dog shifters, sounds like either isn’t a slam dunk.
No wear on either (for lack of a better term) the steel ball containment shell, or the gears. This thread has some good videos of what not to do with respect to the VexPro ones. While ours was not as obviously incorrectly assembled as is shown in those videos I suspect the travel was adjusted slightly incorrectly resulting in the accelerated wear pictured.
