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!

What is an intermediate gear?

18 Aug 2021

The simplest form of an intermdiate gear is simply a single gear (the intermediate gear) connecting two other gears like shown in the example diagram below:

In this case the intermediate gear is the 8 tooth gear connecting the 28 tooth gear and 24 tooth gear. This is really a simpler case of a gear train where the intermediate gear acts as the gear being driven and driving the next gear in the sequence. To calculate the overall gearing ratio it is simply the product of the gearing ratios in the gear train. In this case we have the 28 tooth gear driving the 8 tooth and then the 8 tooth driving the 24 tooth gear:

Overal Gearing Ratio = (28 / 8)  x (8 / 24) = 28 / 24  = 7 / 6

Note that since the intermediate gear is used in the denominator in the first gearing ratio and the numerator in the 2nd gearing ratio it always cancels out and does not affect the overall gearing ratio. This means that the size of the intermediate gear is irrelevant to the overall gearing ratio.

In general you can have more than one intermediate gear as for example shown in the next diagram:

Here there are two intermediate gears (the 24 tooth and 40 tooth gears on the yellow axles) between the 12 tooth gear on the left and the 20 tooth gear on the right. Again the overall gearing ratio is not affected by the intermediate gears and is simply the ratio of the first gear to the last gear in the sequence. In this case:

12 / 20 = 3 / 5 = 0.6





More to explore

Lego Technic Gearing Ratio Tool Update

4 Sep 2021
Lego Technic Gearing Ratio Tool Update

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
New Flat 12/20 Gear Friction

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
Measuring Gearbox Efficiency

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