3-speed Flat Servo Transmission
A transmission concept focused on flat form factor, with 3 speeds available from a 3-studs tall mechanism. Free building instructions available.
LEGO transmissions come in all sorts of form factors, but sometimes you’re limited in using them in your build by one particular dimension. To address that, I came up with a 3-speed transmission that’s just 3 studs thick, including the shifter motor, so it can be used when e.g. width and depth are not limited, but height is (depending on the orientation it can just as well be width or depth, of course).
This design utilizes PF Servo motor, or a Control + motor in a stepper mode, to control the central shaft which alters effective gear ratio between input and output shafts. Assuming that the red axle joiner is the input and the green axle joiner is the output, the available gear ratios are as follows:
- 1st speed: 3:1
- 2nd speed: 1.6:1
- 3rd speed: 1:1
In addition, to make the transmission capable of handling some torque, I built it between two liftarm frames, but it’s possible, of course, to install it inside another structure. However, the central shaft is pretty long and unsupported, limiting how much torque this transmission can effectively handle.
Free building instructions are available on the Downloads page.
