Gearing Ratio Calculator

Check out the Beta version my Lego Technic Gearing Ratio Calculator Tool:

This tool allows you to upload your Lego Technic project .ldr file and analyse the gearing ratios between any two connected gears or axles. Currently supports most gears, axles, worm gears, some differentials, cv joints and universal joints. See the video tutorial on how to use it. It is a work in progress and I would love to hear your feedback on it. Click here to try it out.

Note: As of 25 Septemeber 2021 the tool supports CV joints, linear speed via the radius of the component and improves on the frame rate for higher numbers of parts in a model).

Technic Elbow Art

This is a tool to create "Lego Technic Elbow Art" - a series of intertwined elbow pieces as a single sequence. Choose your dimensions and search parameters and search for new dense solutions and set a record! 

Download your Elbow Art as an .ldr file and build it yourself. Click here to try it out!

How do you calculate the gearing ratio of a gear train?

18 Aug 2021

A gear train is simply a series of gears connected together such that each gear in the series drives the next gear either directly or via another gear on the same axle.  The diagram below shows an example of a 3 stage gear train. On the left is the input axle and on the right is the output axle.

The overall gearing ratio between the input axle and the output axle is simply the product of the gearing ratios of all the gear train stages. So in the example:

Stage 1: 12 tooth driving a 20 tooth gear = 12 / 20 = 3 / 5
Stage 2: 12 tooth driving a 20 tooth gear = 12 / 20 = 3 / 5
Stage 3: 8 tooth driving a 24 tooth gear = 8 / 24 = 1 / 3

So the overall gearing ration between the input axle and the output axle is (3 / 5) x (3 / 5) x (1 / 3) = 3 / 25

This means for every 25 rotations of the input axle the output axle will rotate 3 times.


More to explore

Lego Technic Gearing Ratio Tool Update

4 Sep 2021

This video presents updates to the Technic Brick Power Lego Technic Gearing Ratio Calculator tool specifically on underconstrained differential systems. These are systems in which the differentials are not fully constrained and therefore have 1 or more degrees of freedom within them.

The more

New Flat 12/20 Gear Friction

23 Apr 2022

The Lego Technic set 42140 App-Controlled Transformation Vehicle introduces two new gears - a flat version of the 12 tooth bevel gear and a flat version of the 20 tooth bevel gear. These gears are designed to have less friction.

In this video I measure the difference in gearing more

Measuring Gearbox Efficiency

6 Nov 2021

This video describes a method for measuring the efficiency of a gearbox using the Lego Technic Powered Up hub. Gearbox efficiency is defined as the ratio of the output power to the input power and here I show how to measure each of these values to allow you to calculate the overall more