Gearbox suggestions

Hi, I’m looking for a gearbox that is able to support a large gear reduction (i.e. for climbing) in a stable manner when paired with a CIM or miniCIM. Does anyone have any suggestions on which one(s) to use? Thank you!

You can try pairing a VersaPlanetary CIM Adapter with a Versa Planetary. It’s relatively easy to get a large gear reduction in a tight area.


We built an all COTS climber last year out of a Mini-CIM driving a VEX Versaplanetary transmission, that then used a CIM output shaft to drive an AndyMark Toughbox gearbox. Since the Versaplanetary transmissions have the same face mounting holes as a CIM you can daisy chain it into gearboxes that normally take a CIM motor. Last year we used a 4:1 Versaplanteary into a 12.75:1 Toughbox for 51:1 overall, with the Toughbox output shaft directly winding a rope around it via velcro.

We are doing the same thing this year to drive our arm at a higher reduction, a 775pro into a 20:1 (5:1 + 4:1) Versaplanetary that feeds a 12.75:1 Toughbox for an overall 255:1, with a final chain reduction of 48:15 for 816:1 total.

Some teams used the Versaplanetary all by itself for climbing last year with more reduction stages, but we opted for the Toughbox final stage since it has an option for a long output shaft. I also saw that the load ratings for the Versaplanteary show failure of the 7075 Aluminum output shaft close to 70:1 for CIM motors, so my non-mechanical engineer fix was “Toughboxes use 4140 Steel output shafts, use that instead”.

It depends on what you would consider a large reduction. If you need between 36 and 64:1 then you could use something like a CIM Sport. If you need more than that then you might want to consider using an external chain reduction to multiply the reduction.

I’d recommend the CIMSport 64:1 with an external sprocket reduction to fine tune the overall ratio to what you need.

Several of our climbers and lifts over the years (including this year) have been TB-minis or (this year) TB-micros with an additional stage of chain reduction. We have also considered the TB3 (three stage toughbox), but we already have a bunch of TB gears and parts on hand.

For climbing, it’s hard to beat a Banebot p80.

Yes, they’re heavy, kind of expensive.

I’ve never seen one break.

Thank you everyone for the suggestions!