TOOLS

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!

Lego Technic 3 Speed Automatic Gearbox

1 Jul 2020

Here a Lego Technic 3 speed automatic gearbox is presented. The gearbox automatically switches between one of 3 gear ratios, namely a ratio of 1, 1/3rd and 1/9th depending on the load on the output.  It uses two 2 speed automatic transmissions in series to create the three speed automatic gearbox.

It works on the principle of 2 degrees of freedom within a pair of differentials. This creates two gear paths for the transmission of force and the path of least resistance is taken.

The loading points at which this lego gearbox switches gears is adjustable via two linear actuators at the bottom of the gearbox, which adjust the amount of artificially introduced friction to control the switch over points.

The workings of the gearbox are explained in detail using an example 2 speed automatic transmission gearbox. Additional details are presented in the form of a graph.

More to explore

Lego Technic 3 Speed Automatic Gearbox - FAIL!

18 Sep 2020

This video presents a lego technic 3 speed automatic gearbox design that failed to work as expected. This design is based on an earlier design of a 2 speed automatic gearbox with smooth transmission that worked very well.  That technic gearbox was extended by adding another speed to the oran...read more

Lego Technic Gearbox Theory Applied - how to apply theory to help design 2 speed automatic gearboxes

10 Nov 2020

This video applies lego technic gearbox, torque, and gearing ratio theory to design a prototype lego 2 speed automatic gearbox. First I describe the main components of an automatic gearbox, namely a gearing ratio selector and a torque detector. The ideal gear switch over torque point is described...read more

Lego Technic torque in practice - how to work with torque in automatic gearbox design

29 Oct 2020

n this video I present a ten level Lego Technic torque creation gadget for testing lego power function motors and automatic gear switching mechanisms. The effect of torque on a large lego PF motor is tested against the theoretical power curve to compare the optimal gear switching point in practic...read more

Lego Technic Optimal Gear Switching Ratios

17 Oct 2020

This video presents the relationship between lego technic motor torque and speed and shows there is an peak power for each electric motor.

The peak power is calculated and a formula presented relating the power operating point as a percentage of peak power. From this an operational power ...read more

Lego Technic smoothly switching 2 speed automatic gearbox evolution with instructions

11 Sep 2020

This video presents my latest compact and smoothly switching 2 speed automatic gearbox made out of Lego Technic.  It is both smoothly switching and compact.

The MOC gearbox automatically switches down in gearing ratio when the load on the output is sufficiently high by using a new te...read more

Lego Technic Servo Driven 3 Speed Automatic Gearbox

13 Feb 2021

A lego technic 3 speed automatic gearbox is presented using a lego technic power function servo motor to drive the gear change mechanism. The servo motor is driven by a lego electric switch which in turn is driven by a torque detector using a differential at the output.

The technic automa...read more

Lego Technic Applied Gearbox Theory Improved

20 Nov 2020

This Lego Technic video demonstrates an improved design of a Lego technic 2 speed automatic gearbox based on a theoretical approach. Typically a Lego automatic gearbox consists of two stages namely a gear selector and a torque detector. In this video, both of these components are improved upon.read more

Lego 2 speed automatic car. Part 1

3 Oct 2020

This video explores the use of the lego technic "smoothly switching 2 speed automatic gearbox" inside of a test car to see how well it works to climb up a ramp.

The gearing ratio of the 2nd gear of the 2 speed automatic gearbox can be set using a manual 4 speed gearbox to choose...read more

Lego Technic 2 Speed Automatic Gearbox - Compact! With build Instructions.

15 Aug 2020

Here I present a design for a compact lego technic 2 speed automatic  gearbox. Instead of using a differential to react to torque on the output it uses the force on the gear teeth to push a liftarm to automatically change the gearing ratio to the 2nd speed once the torque threshold has been ...read more