West Coast Drivetrain Shifter

Hey, now my team is using a 6WD West Coast Drivetrain with 3 CIM Ball Shifter, and we have the normal configuration with the Shifters on the middle but we are thinking to change the Shifters to the corners to get more space on the middle for our mechanisms, but have you ever made something like this? And there are problems or more things to take in mind with this configuration?

Thank you to all of you and for answer us, we will be very grateful.

The primary thing to think about is how the chain/belt runs will go, and how it affects where the wheel needs to be in the corners.

You can either run chain from the corner gearbox to each wheel independently, or to via the center sprocket/pulley.

This is fairly common in my understanding and you should be able to find several examples of similar in Spectrum’s CAD collection: FRC CAD Collection - Spectrum3847 - Google Sheets

Good luck this season!

1 Like

Note that if both chains/belts go to the center axle, this will double-load the one coming from the gearbox. This may or may not be a problem depending on how hard you load them and what chain/belt you are using. The worst case is when you’re accelerating towards the end with the gearbox, where essentially all of your force on the carpet is on the other wheels.

Another issue with running both to the center axle is that if the chain/belt from the gearbox ever failed then you would lose 2 of the 3 wheels rather then 1 (assuming you are running only a 6 wheel drive). I don’t know how much of an issue this would be though.

Someone else correct me if I am wrong but the larger a wheel you use the less speed and more torque the gearbox needs to produce for the same robot speed. This would mean the chain/belt would experience more force. So if you want to be extra carful when running the two chains/belts to the center then use a smaller wheel if possible.

Since the 2018 season we’ve been running the vexpro 3cim ball shifters from the back of the robot using a belt to the center wheel and then another from the center to the front, though I don’t see any reason why it wouldn’t still work great with chain. The most important thing to note is that although you will only have one pulley in your gearbox, that pulley also bears roughly 2x the torque that the gearbox pulleys would bear if the gearbox were in the center, so just be plenty generous with the pulley tooth count and width. We used 36t x 15mm wide HTD pulleys on 6" wheels which worked very well, though I suspect you could get away with smaller pulleys (particularly if you use 4" wheels).

See the following links for examples:
Drivetrain Generator
Build Season 2018
Build Season 2019

1 Like

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.