# Difference between revisions of "Gearbox ratios"

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Page is already in [[Fabrication | Fabrication]] | Page is already in [[Fabrication | Fabrication]] |

## Revision as of 21:51, 11 May 2017

**OBSOLETE PAGE**

Page is already in Fabrication How to calculate gear ratios for gearboxes: http://curriculum.vexrobotics.com/curriculum/drivetrain-design/geartrain-design

Note: As in the website above, the goal is to be able to go as fast as possible while being able to spin the wheels while driving into a wall.

Look on Andymark for Wheel weight, CIM and Mini-CIM output torque and friction coefficient for FRC carpet. Take into account # of wheels that are touching the ground, not just total drivetrain wheels. Note that the friction is based on the number of wheels touching the ground, but the torque is based on the total number of wheels.

Output torque: CIM: 2.42 Mini CIM: 1.4

Equation for normal force: m*g Equation for friction applied to the wheels: F=cf*FN F: Friction, cf: Coefficient of friction, FN: normal force

After above calculations, you should have a gear ratio. To find the gears that you need to order or use, search Vex for the gearbox you’re using and find the gears compatible with your gearbox.