pic: Four Speed Three CIM Gearbox

[hectorcastillo]

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[Lil' Lavery]

What advantage(s) do you expect from having a four-speed, 3CIM gearbox over a two-speed 3CIM gearbox? A four-speed 2CIM gearbox? Heck, even a single-speed 3CIM gearbox?

Basically, why? This seems like overkill.

[AlexanderTheOK]

And for the 2016 FRC game, OVERDRIVE 2: OVERKILL. This game is played on a 10 meter by quarter mile field in the streets of Miami. Any robot to get to the finish line in 10 seconds wins by default and gets a free ride to champs!

[Kevin Leonard]

Originally Posted by hectorcastillo

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It's a cool piece of machinery, and looks pretty sick to boot. I believe you said you weren't seriously considering this, as it has no real advantages over a two-speed in most games.

Ever considered taking that third and fourth position and turning it into a PTO? That wouldn't be very important in a game like 2015 whatsoever, nor a game like 2014. But, for example, in 2013, 254 used a PTO to power their awesome climber.

[asid61]

It looks quite well done for the project. It's not useful for competition, but it looks good anyway.
Nice render too.
For the top shaft of the gearbox, instead of using a hex bearing, I would round down the end of the shaft and use a round bearing.
If you only have 2 standoffs going to the mounting plate, I would change it to 3-4.

EDIT: +1 on the PTO idea.

[Gregor]

Originally Posted by Lil' Lavery

What advantage(s) do you expect from having a four-speed, 3CIM gearbox over a two-speed 3CIM gearbox? A four-speed 2CIM gearbox? Heck, even a single-speed 3CIM gearbox?

Basically, why? This seems like overkill.

Did you read the description?

[GeeTwo]

To me, the big "why" is why have four speeds over about a total 3:1 high-to-low ratio? If you're going to bother with four speeds, spread them out a bit wider!

At a minimum, I would put the shifts a factor of 2:1 apart, resulting in an 8:1 overall ratio from high to low. At a "standard" 2.56:1 ratio between shifts, the total range would be 16.77:1. At 3:1 per shift, it would be a massive 27:1, which could be a real game changer in some highly defensive games or games with steep ramps. Especially if you want to reserve some CIMs for manipulators!

[ratdude747]

Originally Posted by Kevin Leonard

It's a cool piece of machinery, and looks pretty sick to boot. I believe you said you weren't seriously considering this, as it has no real advantages over a two-speed in most games.

Ever considered taking that third and fourth position and turning it into a PTO? That wouldn't be very important in a game like 2015 whatsoever, nor a game like 2014. But, for example, in 2013, 254 used a PTO to power their awesome climber.

Another good PTO example: 1114's hanger in 2010 (which was sickly fast )

[hectorcastillo]

Thanks, yeah I know it's really overkill. So basically to answer the question of why I decided four speed, my team is working on the summer design project thing that was put out a couple weeks ago. The end game involves chasing down a mini bot on the field, so the end game team wanted to be able to travel at the mini bot's speed (~13fps) to line up with it and a faster speed to catch up to it. We also wanted to be able to move around a little slower with more control for adjusting shots and in case anyone wants to push us. I know we could've gone with a two speed and controlled the speed with code, but that's what the team decided to go with. Also, it gave me a nice challenge which is always fun.

Ever considered taking that third and fourth position and turning it into a PTO? That wouldn't be very important in a game like 2015 whatsoever, nor a game like 2014. But, for example, in 2013, 254 used a PTO to power their awesome climber.

Our 2013 drive train gearbox used a PTO to power our climbing mechanism as well. There was something wrong with the throw of the shifter that made it not work, but it was still pretty cool. I don't think there's an opportunity in the game that we're designing for to use a PTO, but I did think about it while designing this.

[Lil' Lavery]

Originally Posted by Gregor

Did you read the description?

Description wasn't posted when I posted my comment.

[hectorcastillo]

Originally Posted by GeeTwo

To me, the big "why" is why have four speeds over about a total 3:1 high-to-low ratio? If you're going to bother with four speeds, spread them out a bit wider!

When I was playing around with the JVN calculator I was trying to get them as wide as possible. The limiting factor, though, was that the two speeds that we wanted for the end game were 17fps and 12.72fps, which put limit on how much i could work the speeds while still keeping it realistic. I guess I was just focusing on the speeds needed for this game and not the wide array that there could have been.

[mrmummert]

Originally Posted by AlexanderTheOK

And for the 2016 FRC game, OVERDRIVE 2: OVERKILL. This game is played on a 10 meter by quarter mile field in the streets of Miami. Any robot to get to the finish line in 10 seconds wins by default and gets a free ride to champs!

Hehehe..been done already sort of...


https://youtu.be/efvCDYTj0Wk

[waialua359]

Originally Posted by hectorcastillo

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Impressive Design!
Team 368 made a 4-speed transmission in their 2005 robot, IIRC also.
Cool stuff!

[zinthorne]

Sorry for me asking, but what is a PTO gearbox?

[z_beeblebrox]

Originally Posted by zinthorne

Sorry for me asking, but what is a PTO gearbox?

https://en.wikipedia.org/wiki/Power_take-off