> For the complete documentation index, see [llms.txt](https://hrftank.gitbook.io/hrftank/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hrftank.gitbook.io/hrftank/ii-build-manual-hull-and-chassis/3.-drive.md).

# 3. Drive

The HRF Tank is driven by **double-pin tracks**, each consisting of approximately **58 track links**. Each track runs on five road wheels, three return rollers, and one idler wheel. Power from the motor is transferred to the track through a large **90 mm-diameter drive sprocket**.

The drive sprocket itself is 3D-printed, while the connection to the gearbox output shaft is made using a metal adapter from **Pololu**. This reduces the risk of the connection failing during sudden changes in speed.

The idler wheel is mounted on a **30 mm-travel track tensioner**, with smooth movement provided by shafts and linear bearings. A spring allows the track tensioning force to be adjusted.

In [1.5 Hull assembly](/hrftank/ii-build-manual-hull-and-chassis/1.-hull-and-gearbox/1.5-hull-assembly.md) I told you that it was the worst part of assembly process. I lied. Assembly of drive system is even worse :laughing:

Jokes aside — preparing parts for smooth-running tracks requires a lot of boring work with a rotary tool (no pun intended :laughing:). Grab a drink, pick your favorite podcast or a TV show to binge-watch, and let's go!

<figure><img src="https://673609632-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FhmKl11OGPwbKiNEUvA5L%2Fuploads%2FZwVbEYiKlMAHBjJGl7Mo%2FDSC_6999.JPG?alt=media&amp;token=f0e5ed16-4320-4807-a8ea-16eb86cbd320" alt=""><figcaption></figcaption></figure>