Just a heads up for you all. We were running our practice bot Friday with some super shifters that had about 2 seasons on them when we lost all push on one side of the bot. It was stuck in neutral. The pneumatic shift cylinder what going in and out but it did not change gears.
So, obviously the dog gear was stuck in the middle and the shift rod was no longer “attached” to it. Had to be that LITTLE screw that connects the dog gear to the shift rod.
After about a half hour of work we managed to pull the box off the bot and got it apart and sure enough the little screw was not where it was supposed to be. Found it stuck in the grease. Luckily not in a gear. Tried to screw it back in when we realized it was not long enough. Pulled the dog gear and sure enough there was a piece still stuck in the dog gear and another little piece in some grease under one of the gears. Now, off to Ace to find a new screw. NOT It is a 2.4MM screw that nobody had. So, we improvised. DIdn’t have time to wait for AM to send one(I don’t even know if they sell them). Only thing we could find close was a 4-40. A little big but only slightly. Drilled out the dog gear and the shift rod then retapped the other side of the dog gear and we were back in action.
Have any of you had this issue while pneumatically shifting these transmisions? Seems like a mighty small screw to take all that force. Do you run a lower pressure to the shifting cylinders?
Have you contacted AndyMark to let them know about the failure yet? They might be able to improve future versions of this product so this does not happen again. That being said, I think a small screw lasting 2 seasons like that is pretty impressive.
You could always try something new like the Linear Servo, although it appears that is optimized for the Sonic Shifter.
I do admit that it sucks when something like that fails this late in the build season, at least it wasn’t in the middle of a match!
This past weekend, we were informed of an issue by three different customers. The M2.5 screw within the 2010-2011 AM Shifter and Super Shifters are breaking at a rate higher than expected.
The initial fix for this is for teams to lower their shifting pressure from 60 psi down to 35 or 40 psi. Many teams already run at this lower pressure, to reduce wear on the shifting parts.
During the years of 2005-2009, we used a 3/32" coiled roll pin (heavy duty) to attach the dog gear to the shifter shaft. This past summer, we replaced this roll pin with a M2.5x20mm hardened screw. While our break tests proved that the same amount of force broke both types of pins, it seems that the screw does not handle fatigue as much as the roll pin.
The simple fix for this is to run your shifter at a lower pressure. A 3/32" hole can be added to the dog gear, in order to accommodate a 3/32" roll pin, if you wish to add this pin.
We will be doing some more testing on this, determining what exactly is going on. I just wanted to let folks know that this is going on, and they may want to lower their shifting pressure.
Keep in mind that the shifter shaft position should still be set up so that the small brass “pin saver” tube is in place so that the dog gear does not bottom out on either the full low or full high end of the cylinder stroke.
Once we know more about this, I will post the info.
We had one of ours (couple of years old) with the small metric screw break in 2012 just before ship day. Pulled out the spare shifter parts and discovered they had the new 4-40’s in them.
We re-tapped and drilled the old ones to 4-40’s, they are now our spares, I’ve heard of no problems with the 4-40’s at all.
Thanks for calling us at AndyMark earlier. To confirm what previous posts stated, we currently use a 4-40 screw in the dog gear. The current dog assembly can be found here: http://www.andymark.com/product-p/am-0020.htm
We broke one of the new 4-40 screws in a new sonic shifter on our practice bot. The bot went a few weeks of basic testing and a week 0 scrimmage on Saturday prior to breaking. We were running 60 psi on our shifting cylinders. it looks like we may want to lower the pressure to reduce wear. Have teams been successful shifting at lower pressures?