The 3-speed crank-axle gearbox looks very much like half of the twin-motor gearbox; it even uses the same gears. This compact gearbox gives you options for gear ratios of 17:1, 58:1, and 204:1. This is Tamiya's cheapest, general-purpose gearbox.

The motor is rated for 3 volts but will typically work fine up to 6 volts. When using this product with the dual serial motor controller (or any motor driver based on an H-bridge), keep in mind that up to a few volts (depending on the load) are lost on the transistors of the H-bridge, so that a 4.5 volt battery delivers about 3 volts to the motors, giving them a reasonable amount of power. Motor overheating can be caused by excessive stalling, even at very low voltages. We recommend that you use stall-detection sensors, or just watch your robot, to make sure that it doesn't stall for more than a few seconds at a time.

The 3mm, hexagonal output shaft is compatible with all four types of Tamiya wheels.

(Note: This gearbox uses the 18100 motor variant)

See 'Which Wheel' tab for suitable wheels type HEX for a tight fit.