Lego Technic 3 Speed Automatic Gearbox - FAIL!
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 orange rotary catch selector (first introduced in the Bugatti Chiron set 42083-1) to create three speeds.
The extension of this lego technic gearbox to 3 speed transmission seemed fairly straight forward...or was it?
Found out the culprit of this design failure and don't repeat this mistake yourself!
Check out my other 2 speed and 3 speed automatic gearbox designs on this channel. Also look at the massive lego 1000 speed gearbox and 1023 speed car too.
More to explore
Lego Technic 3 Speed Automatic Gearbox
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 ge...read more
Lego Technic smoothly switching 2 speed automatic gearbox evolution with instructions
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
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 Gearbox Theory Applied - how to apply theory to help design 2 speed automatic gearboxes
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
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
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 New 12/20 Gear High Speed Friction Test
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 follow up video I measure the high speed difference ...read more
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 efficiency...read more
Gearing Ratio Calculator Tool Help
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 efficiency.read more