LEGO MINDSTORMS Robot Inventor
This model of a manual transmission in a car includes a stick shift lever that allows you to shift between three different gear ratios, a working friction clutch with a clutch pedal/lever, a gas pedal, and a low gear lockout button! The mechanism is powered by an input motor and spins a suspended output wheel.
Engage the "cruise control" on the gas pedal to practice shifting gears with the clutch and shift lever together with two hands to make nice smooth and quiet shifts. Then for the full challenge, put the model on the floor, and operate the clutch pedal and gas pedal with your feet while shifting gears with your hand!
Using the Transmission
See the Manual Transmission controls photo above for the location of the various controls on the model.
Without the low gear lockout button pressed, the shift lever will shift back and forth between medium and high gears. Right in-between medium and high gears there is a "neutral" where no gears are engaged.
To shift into low gear, press the low gear lockout button and then pull the shift lever back towards you. Low gear doesn't engage as easily as medium and high gears (because it uses the straight-cut gray spur gears instead of the beveled beige and black gears), so keep pulling back and keep some momentum in the input motor (and some inertial momentum in the output wheel) until it engages fully. The low gear lockout should reset automatically when you shift out of low gear.
The "cruise control" buttons control the minimum (idle) speed of the motor, so you can increase the motor speed without needing to use a hand (or foot) on the gas pedal.
You can easily shift gears without the clutch if you want. The gears will just "grind" a bit as they make contact and engage.
To shift gears using the clutch (for smoother shifts with less gear grinding), practice with two hands, using the cruise control to run the motor. Right before shifting gears, push the clutch in, then immediately shift gears and then let the clutch back out. The whole sequence should take about half of a second or so.
When you are ready to try it on the floor with your feet like a car, your left foot will push the clutch pedal, your right foot will press the gas pedal, and you can shift with one hand (and use the other hand for the low gear lockout, or do both with one hand with some practice).