Re: pic: 2 Speed Transmission
 

While all of the points you guys bring up are valid, and great things to keep in mind when choosing gear ratios during the season, I just chose those two speeds because those were speeds that I thought might be useful for a game like last year.
When the new season starts, I am going to re-evaluate the gear ratios, and redesign that part of the transmission. I see no point in speculating about the next season and choosing a specific gear ratio before the challenge is released. I just started with 2 gear ratios so that I would have a basic design to build off of and adjust to the challenge when the season starts. Most likely, I will keep the 5 ft/sec, and adjust the top speed to a speed that fits the challenge better.
Thanks for all of the great input on my design.
What dimensions do teams normally use for the size of their dog, and the depth that the teeth of the dog go into the gears? I am currently using 1/2 inch hex, and the dog's teeth are 7/16 of an inch long.

Re: pic: 2 Speed Transmission
 

I use a square dog with an outside shift plate. 'Teeth' are .160" long and engagement in the gear is .140". You can see this is the white papers in our 2005 gearbox.

This design has had no problems in two years of competition. The only thing about building your own is you have to build, and break in, new gearboxes every year.

Re: pic: 2 Speed Transmission
 

I think last year I did something like .020 neutral space. I mean, if it clears, it clears; no need to clear by a big amount. Just make sure that under no circumstances are both gears angaged at once.

Our shifting dogs went something like .13" into the gears and were something like 1" OD.

Re: pic: 2 Speed Transmission
 

Yea, we found out after getting the kit tranny's that it was alot more efficient to use them. Instead of spending 2 - 3 weeks designing and machining tanny's, we can use that extra time to design and perfect another aspect of the machine. Remember it's not always about speed and strength(but even if it was, the kit tranny's provide enough speed and torque), but how efficient you are at doing a certain task as well.

But kudos to all the teams who design bot kicking tranny's! haha :D

Re: pic: 2 Speed Transmission
 

If anyone is interested, here are the Solidworks files for the transmission and drivetrain. If you end up using any part of them durring the season, I would love to know about it. Please let me know if there is a problem with the files, or something doesn't make sense.

http://www.boardsailor.com/austin/CDExport12-28.zip

Re: pic: 2 Speed Transmission
 

Remember that while engineering something it is often much easier to try to adapt existing products to fit your design instead of having to create everything from scratch. On that note look into buying your dogs and Dogged gears from a company with experience making them right(such as AndyMark) itll make your life so much easier to just buy the dog compatible pieces from them and play around with your gear reductions to make it fit your design.

-Simon