# Help needed ( gear boxes)

Looking for help with what gear boxes everyone uses to pull their robot up

In steamworks we used two 50:1 versaplantarys with 775 pros and climbed in 3 seconds on a 1.125 inch spoil

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We have used VexPro single speed double reduction gearboxes with 2 CIMs for several years. Just use the 1/2" hex output shaft as a spool. Its overkill but extremely fast and reliable.

Weâ€™ve used a single 775pro geared for 100:1 with a versaplanetary. We then stick a ratcheting wrench to prevent it from backdriving. Weâ€™re likely going to change it this year though to god knows what. We havenâ€™t gotten to that point yet.

As has been stated in other threads asking about gearboxes, go plug the numbers into the JVN Calculator so that you can select the proper motors and gear ratios to get the result that you desire. There are several Youtube videos that help you use it. You will want to go to the â€śrotary mechanismâ€ť tab. It also very helpful if you have a good understanding of the physics related to the mechanism.

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A versa planetary is appropriate to use for a climb, given that you operate it within the acceptable gear ratios.

In reality, you should do the math. https://content.vexrobotics.com/motors/217-4347-775pro/775pro-motor-curve-20151208.PNG

Choose the operating current you want and find the motor torque associated with that current. Work backwards using the spool diameter and robot weight and find the appropriate gear ratio.

Operating a motor at â€śpeak powerâ€ť will net you the fastest climb, assuming you donâ€™t pop a breaker. Running a falcon 500 at peak power would draw 129 amps, which would pop your 40A breaker pretty fast.

Personally Iâ€™m not a fan of JVN and prefer to do the math myself and encourage others to do the same so that students get a better understanding of gearboxes and how optimization works.

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Crazy we did almost the same: two 49:1 VPs with 775pros on a 3" diameter spool. Super quick for 2017, not sure Iâ€™d go that fast this year though.

To OP, weâ€™re looking at pneumatic climb as an option instead of gearboxes.

I would personally advise against pneumatic climb since you need a lot of air and you can bend them quite easily and itâ€™s no fun replacing a 3 foot cylinder

I typically advise both for and against pneumatic climb.

The PRO is that as long as you set up your system correctly, youâ€™ll be able to finish a hang after the buzzer.

The CON is the air use. Picking up 150lb of robot needs large cylinder(s) which take lots of air. Thatâ€™s a slow hang.

I usually figure the con outweighs the pro, unless you have another method for picking the robot up.

Pneumatic climbs were a good solution in 2013 where the maximum climb distance was small (1-2 inches) so the amount of air required is easily achievable. One still has to do the math to ensure this.