View Single Post
  #22   Spotlight this post!  
Unread 04-05-2013, 21:22
EricH's Avatar
EricH EricH is offline
New year, new team
FRC #1197 (Torbots)
Team Role: Engineer
 
Join Date: Jan 2005
Rookie Year: 2003
Location: SoCal
Posts: 19,823
EricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond repute
Re: designing a three motor gearbox

Quote:
Originally Posted by 1683cadder View Post
How close do the gear ratios need to be?
This question doesn't make sense in the context of the current discussion. I believe the question you're asking is, "How close do the RPMs need to be?" unless you're looking into what the different stages of the gearbox will be.

The answer is, they WILL be the same, eventually, due to the single gear they both go to--it can't travel at two different speeds at the same time. However, having the speeds wildly different is going to really annoy one motor or the other or both. Given that you're talking about 5K RPM and 6K RPM motors, I'd shoot for within 100-200 RPM difference; that should be close enough to work with and within the rated speed tolerance.


Just in case you were asking about the different gear ratios in the gearbox, though, the answer is "it depends". Depends on design, depends on designed speed(s). Each reduction stage, as a rule of thumb, should be less than a 10:1 reduction by itself (total reduction of the gearbox can be a LOT more).
__________________
Past teams:
2003-2007: FRC0330 BeachBots
2008: FRC1135 Shmoebotics
2012: FRC4046 Schroedinger's Dragons

"Rockets are tricky..."--Elon Musk