Mechanical, Build & PneumaticsModule 2 of 12

Power Transmission and Gear Ratios

Motors spin too fast and too weak to use directly. This module covers how to convert that speed into useful torque with gears, chain, belts, and sprockets, and how to calculate ratios.

Power Transmission and Gear Ratios is module 2 of 12 in the Mechanical, Build & Pneumatics guide. It picks up where Drivetrains: Moving the Robot left off and hands over to Structure, Materials, and Fasteners. Its 4 lessons are about 140 minutes of the guide's ~21 hours.

4 lessons~140 min47 lessons in this guide

Start with lesson 1 All of Mechanical, Build & Pneumatics

In this module

4 lessons

01Why You Need Reduction: Speed vs. TorqueA motor's raw output is fast but weak; gearing trades speed for torque (or vice versa) to match the job.35 min read

02Chain and SprocketsRoller chain is the rugged, forgiving way to transmit power across a distance, common on drivetrains.35 min read

03Belts, Pulleys, and Gear-on-GearTiming belts are light, quiet, and clean; direct gear meshes are compact and efficient. Both move power without chain.35 min read

04Shafts, Bearings, and BushingsShafts carry rotation, bearings let them spin freely, and the hex standard ties the whole COTS ecosystem together.35 min read

Previous moduleDrivetrains: Moving the Robot

Next moduleStructure, Materials, and Fasteners

Jargon check

FRC terms used in Power Transmission and Gear Ratios

Gear RatioThe ratio between input and output rotation in a gearbox, trading speed for torque (or vice-versa).

Longer reads

Articles that go deeper on this

FRC Power Transmission: Chain vs Belt, Sprockets, Pulleys, and TensioningA practical FRC guide to moving power from motor to mechanism: #25 vs #35 chain, HTD/GT2 belts, sprocket ratios, center distance, tensioning, and failure modes.18 min read

FRC Gear Ratios ExplainedA beginner-friendly guide to FRC gear ratios and drivetrain gearing: how reduction trades speed for torque, the free-speed formula, and how to pick a ratio.5 min read

All 12 modules in Mechanical, Build & Pneumatics

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