Kop gearbox vs 3 CIM Ball Shifter

[Orfrith]

Team is considering using Kop gearbox instead of 3cim ball shifter on tank drive system. The 3 CIM Ball shifter takes up more space and also requires pneumatics to operate. We are looking into figuring out how to shift without pneumatics. Any suggestions.
Thanks in advance.

Using Kop gearbox motor combination would be
2cims
1cim 1 mini CIM

Using 3 CIM Ball shifter motor combination would be
2 cims
1cim 1 mini CIM
1 CIM 2 mini cim
Any suggestion.

[Joseph Smith]

Typically, the majority of teams will have at least 2 CIMs per gearbox, and those who want some extra power will add another CIM or miniCIM to each side. I can't speak much for the KoP gearbox, but we've had success with the vex ball shifter in the past. There are ways to shift without pneumatics- I believe team 67 used a window motor connected to a linkage one year. You can also shift with a servo, using a kit like this from Andymark http://www.andymark.com/Shift-p/am-0093.htm or by designing your own servo shifting mechanism.

[TikiTech]

We did a lot of analysis on this.

I think you need to asses the drivetrain ability to drive reliably.
Questions to ask yourself..

Size of tires?
Gear ratio of transmissions in question?
What amperages will this drivetrain draw when driving? When stalled?

This is when the JVN calculator is your friend.

http://www.chiefdelphi.com/media/papers/3188?

The KOP toughbox mini transmission at best can be 12.75:1 ratio. Not great if you are running 8" tires. (approx. driving speed about 11ft/s)

I think the best options for ease of installation in the KOP frame is one of the ball shifters with the 3rd stage (@64:20)
the overall ratio will be close to 30:1 which will give a good spread of torque and drive speeds.

The only issue you might run into is the VP ball shifters have the motors on the bottom and you will need to accommodate for it if you make a belly pan.

Play with the calculator and verify driving speeds and power consumption.

We decided to use our 3CIM WCP dog shifter running 2 CIMs. We will be adding an additional reduction stage since the lowest gear set isn't quite low enough (about half what we want). We also wanted to use the PTO for our climber..

It will take a bit of work but well worth it for our design.

Good luck with this,
Aloha!

[Orfrith]

Thanks for everyones input any other suggestions out there