LEGO Automatic Continuously Variable Transmission

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Published 2023-08-23
In this video, I build a prototype for an automatic continuously variable transmission. I then test how its gear ratio varies with load torque. The results prompt me to expand upon the gearbox design so it can have a higher gear ratio range. I then put the improved gearbox in a car and test it climbing slopes and encountering obstacles.

All Comments (21)
  • @Salmonman0604
    One thing I'd like to see would be the same car chassis trying to navigate the same obstacles, but with a basic transmission, just to get a frame of reference for how the continuously variable transmission is actually solving a problem that the basic transmission would simply fail at.
  • @Akotski-ys9rr
    I’d say this is more similar to a torque converter and not a cvt transmission. A cvt will basically change the gearing by changing the size of the pulleys that the belt connects to. A torque converter will slip and different amounts to create more or less torque. I hear that the motor was struggling under load. A cvt is nearly 100% efficient so if it was a cvt it would not struggle like that. Instead the pitch of the motor would stay the same and would just lift the load slower
  • @timma7
    Love the idea, I would instead reverse the transmission to make your creation go faster! Torque is a good way to show how it works, but if you can make a lego car that can go from snail to rocket that would be awesome!
  • @Tomab89
    Really cool project, great video format. Hope to see more!
  • @For891
    The only thing this channel needs is more cool content.
  • @olliej8488
    This works in a similar manner to an automatic gearbox I made and has the same modular capabilities, very cool!
  • @BrickingBadly
    The problem with this, and ALL other differential based "automatic transmissions" is the huge loss of energy from the system having to overcome a resistance to shift torque. In this case its the rubber band slipping. The "resistance" is the torque required for the pulley to slip. Another design I've seen uses a friction pin with an 8 tooth gear. About half the energy of the motor is lost with this method. In my channel you can see a LEGO speedometer that works on a similar principle, but it can be attached to the drivetrain, but not be part of it, thus you can measure the speed without losing half of the motor's energy
  • @WouterB76
    Hub van Doorne would have loved to see this, my Volvo has a continuously variable transmission. Keep up the good work, this might become a (LEGO) technically very interesting channel!
  • @danielcimanes2794
    This is a great representation of how to do science correctly, that it is quantitative and the results from data is how we end up in a conclusion. Great job!
  • @g.williams2047
    I can't believe how far we've come in the world of lego CVTs. It was only a few years ago that a small scale prototype was almost impossible, now we've got this.
  • It’d be great to see this car and another car compete at a sled pull or similar heavy object pushing contest
  • @txikitofandango
    It must be a strange feeling when you push against the vehicle and you feel it respond by pushing harder against you
  • @trm4life
    A real cvt though uses a cone shaped pulley that moves and a v- belt. You change the distance between the cones to increase or decrease the size/ ratio.