Holding spring loaded elevators in Brake mode

We’re using the ThriftyBot single stage elevator with a Neo on a 6::1 gear reduction. Our winch consists of Thunderhex with our 1/8” winch rope. With the Neo on kBrake mode (blue blinking LED) while disabled, the elevator still rides up on its own due to the constant force springs. We were expecting that the Neo in brake mode would be able to hold it in place.

Any thoughts or suggestions?

If you’re having trouble holding the arms when the only force comes from the springs, you’re going to have a heck of a time trying to hold them in the 5 seconds after your robot has been disabled when you add gravity to that.

I don’t have enough experience with the Neos, but suspect that your gear ratio is way too low. Our gear ratio is just over 100:1 on a 775pro, and does hold in brake mode.

We have 8:1 on two falcons and our brake mode is just barely not enough. You should try to I crease the gear ratio. I hear 12:1 is the minimum you want to aim for for the thrifty bot kits

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We have 2x neo’s with a 7:1 reduction. 1 neo at that ratio isnt enough to climb, even with both brake mode isn’t enough to hold it in place. Fortunately, we designed in a ratchet mechanism from the beginning - we knew it wouldn’t be able to hold itself up after the match without it.

AndyMark recommends 16:1 on a NEO, though that is based on their climber winch with a .787" diameter drum. Thunderhex has a 13mm or about .512. That still gets you down to a recommendation closer to 10:1 than 6:1, and that’s for the climb. Unless you are climbing to a second rung where coming down the last step doesn’t matter, I’d look to an active brake or pawl or ratchet.

We use a single falcon, with a 2 inch diameter drum and 35:1. We climb in 3 or 4 seconds to the low bar, which is good enough for us for now. AndyMark’s recommendation falls right into that same wheelhouse. Keep in mind you have to watch your current - we designed our starting gear ratio to stay below 40 amp-ish.

Later in the year we’re start getting more aggressive.

We have fixed length rotating arms as part of our climb to higher bars. We plan to use an attachment from this to hold the elevator down until it’s time to climb. Thanks.

Reminder to all: Brake mode just does a form of short circuiting the motor so it’s resistant to sudden/large amounts of movement. However, anything with a constant force may still move, just slowly.


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