White Paper Discuss: Team 33 Four Speed Transmission

[CD47-Bot]

Thread created automatically to discuss a document in the White Papers.

Team 33 Four Speed Transmission by Jim Zondag

[Joshua May]

Thanks for posting this White Paper, it's been eagerly awaited by many of us. I'm sure this will provide a great resource to many teams.

Not to rush, but when do you expect the software paper to be available, I'd really like to check that out.

Again, thanks for posting!

[Nuttyman54]

Team 971 is building the transmission for machining practice, and we've found a part in the inventor files that isn't listed in the BOM. It is an extention comming off of gears C and G (highlighted by red arrows in the picture below), and no one on our team can figure out where it's comming from. Also, as indicated in the CAD files, the outer diameter of this "mystery part" is set to 3/5 inches...which is not a very common diameter, to say the least. Any help on this is greatly appreciated
-Nuttyman54 and Team 971

[ChuckDickerson]

It is not an extension. Cut off a 1.375" piece of the 12T spur gear stock and turn the gear teeth off 1" of it. It is one piece. The other gear is bored and fit over the turned down section and welded on.

[lynca]

This link no longer works, would it be possible for someone else to post these files,

[Eric Yahrmatter]

Originally Posted by lynca

This link no longer works, would it be possible for someone else to post these files,

To fix the file, download the file and change the extention from .htm to .doc.

[Aren_Hill]

has anyone reliably shifted this transmission non pneumatically?
out team has developed the habit of never using pneumatics just because of the added weight from putting on tanks and possibly the compressor.
just wondering

also the link to the inventor files doesn't seem to be up anymore

[Lil' Lavery]

Originally Posted by Gear

has anyone reliably shifted this transmission non pneumatically?
out team has developed the habit of never using pneumatics just because of the added weight from putting on tanks and possibly the compressor.
just wondering

also the link to the inventor files doesn't seem to be up anymore

There have been several teams who have used servos to shift, and AndyMark does sell a servo shifting version of their shifter. However, while servo shifters often accomplish the task, many do not perform as well (ie shift as quickly or as reliably) although they are certainly more than functional.
The pneumatics vs. motor debate is an old one, and best saved for another thread, but if you did happen to have pneumatics on your robot, I would suggest using them to shift, but if you didn't it probably wouldn't be worth installing pneumatics just for shifting capabilities.

[Jorge Ayala]

Originally Posted by CD47-Bot

Thread created automatically to discuss a document in the White Papers.

Team 33 Four Speed Transmission by Jim Zondag

Thank you, this is just what I needed. I find this almost 5 years after this was released and the only thing that I can say is thank you. After an exhausting and frustrating season this is just what I needed to remind what is engineering all about. Thank you for helping me renew my passion for engineering.

[fb39ca4]

Anyone tried replacing the pneumatic pistons with a more powerful motor and a lead screw?

[Nuttyman54]

Originally Posted by fb39ca4

Anyone tried replacing the pneumatic pistons with a more powerful motor and a lead screw?

I would not recommend this. Due to the "crash" style of shifting rather than the dog-gear style used in AM supershifters and most FRC shifting transmissions, there's a high chance that the gears do not immediately engage. We noticed this when we built them in 2006. The pneumatic shifting style is well suited to this application, since it will apply a constant force, so it will continue to try to shift until the gears mesh right. A lead screw or other motor driven application has a much higher chance of breaking something, since you will either stall the shifting motor or continue to increase the force until something bends or breaks.

A NOTE TO EVERYONE:

This transmission was designed in 2004 for the drill motors that were given in the kits. These motors had a MUCH lower free speed rpm than CIM motors. 971 attempted to use CIMs with this transmission in 2006 and did not have good results. The transmission really is not designed to work at those loads and speeds, and required several extra stages of gearing before and after to bring the speeds down to what is reasonable for FRC drivetrains. It's a good transmission, but the design as-is is not really suitable for drivetrains with current FRC motors.