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 range band is defined based on maintaining a power efficiency of at least E percent.
Based on this, optimal switching points relative to the motor torque are derived and the correct gear switching ratio determined. These are presented as formulas and graphs.
The peak torque and power points are shown for Lego technic PF medium motors, Lego Techinc PF Large Motors and Lego Technic PF XL Motors.
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 Applied Gearbox Theory Improved
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 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 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 oran...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 2 Speed Automatic Gearbox - Compact! With build Instructions.
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
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
Gearing Ratio Calculator Tool Help
Lego 2 speed automatic car. Part 1
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