> For the complete documentation index, see [llms.txt](https://docs.revrobotics.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.revrobotics.com/classroom-activities/mechanical-focus/gearing-challenges.md).

# Programless Drivetrain - Gearing Challenges

## Introduction

This activity pairs with the [Programless Drivetrain Build Activity](/classroom-activities/mechanical-focus/programless.md) to introduce the challenge of utilizing gears to modify the drivetrain’s speed and torque. Students will have to adjust their gearing to accomplish their goal as the servo’s output cannot be modified!

Students will take advantage of the extrusion frame to slide their hex shafts, wheels, servo, and gears into different places to adjust their gearing. Additional hex shafts can be added to expand the gear train.

This activity includes two challenge options: a short version (SV) and a longer version (LV)

<figure><img src="/files/gsqtPwy8zVBmolBpEDL9" alt="" width="563"><figcaption><p>Two examples of the Programless Drivetrain - Gearing Challenge build</p></figcaption></figure>

### Covered Concepts

* Servo usage
* Changing modes using the SRS Programmer
* Calculating the gear ratio of a gear train
* Torque vs. speed in a gear train
* \[Optional] Compound gearing

### Curriculum Connections

* Intro to Robotics V2 - Unit 2
  * This activity can replace or be completed in additional to the existing Unit 2 Challenge

### Activity Goals

Students will:

* Explore how changing gearing changes the outputted speed and torque
* Define what is a gear train and gear ratio
* Calculate gear ratios on a gear train

## Activity Files

### Teacher Files

{% file src="/files/zcz1b7sCZovzqipmqMVE" %}

### Student Files

**Build Guide** (shared with Programless Drivetrain Activity):

{% file src="/files/1HMTNcENCRt0J1tUh6hm" %}

[Programless Drivetrain Onshape](https://cad.onshape.com/documents/b2249143d02f8f9f52b4b63b/w/522ecd9864cb7ddcf9210ade/e/f40f69492fae74f24ff66180)

**Intro Worksheet:**

{% file src="/files/MIcigVek0fgVM3Ivt5XY" %}

**Gearing Challenge Activity (Short Version) Worksheet:**

{% file src="/files/T65xDF5ILYxWb0JxzOXY" %}

**Gearing Challenge Activity (Long Version) Worksheet:**

{% file src="/files/ovtKtd1bvaqGmZWGQKm3" %}

**\[Optional] Compound Gearing Worksheet:**

{% file src="/files/35YoZFx66ibIrdBMk5zd" %}