The 70097 Twin Motor Gear Box uses a two motor system to provide power and speed to turn the hex shaft.
The Tamiya twin-motor gearbox is a small (3-inch long) plastic gearbox. It contains two small brushed DC motors that drive separate 3mm hexagonal output shafts. There are two ways to put the kit together: with a high-speed 58:1 gear ratio or with a slower 203:1 gear ratio. Either way, the motors provide plenty of power to drive any small robot. For a gearbox with a similar form factor and more gear ratio options, see the Tamiya double gearbox (70168).
The output shafts included in this kit are 3 mm hexagonal axles that are 10 cm (about four inches) from tip to tip. The axles work with any of the Tamiya wheels we carry, giving you many options for your robot speed. The two low-voltage motors run on 3-6 volts and draw up to a few amps, making them perfect candidates for the Pololu low-voltage dual serial motor controller and the DRV8833 motor driver carrier (2130-Pololu). 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. For motor specs, see the Mabuchi motor FA-130 (#18100) data sheet (58k pdf).
Note that you can replace the motor in this kit with a lower-current, higher-voltage motor (1117-POLOLU) if you want to use this gearbox with controllers such as the qik 2s9v1 dual serial motor controller (1110-POLOLU), TB6612FNG dual motor driver carrier, or Baby Orangutan B-328 robot controller.
Comparison to the Tamiya double gearbox
The twin-motor gearbox is very similar to the Tamiya 70168 double gearbox, as shown in the picture to the right. The gear ratio options of the two products complement each other well, but the mounting holes and overall dimensions vary slightly. The double gearbox is shorter and wider than the twin-motor gearbox, and the gears are a bit smaller and wider. This should make the double gearbox a bit more robust, though we have not heard any reports of the twin-motor gearbox gears breaking.
|Typical operating voltage:||3 V|
|Gear ratio options:||58, 204 :1|
|Free-run motor shaft speed @ 3V:||12300 rpm1|
|Free-run current @ 3V:||150 mA2|
|Stall current @ 3V:||2100 mA|
|Motor shaft stall torque @ 3V:||0.5 oz·in3|
- 1- A theoretical speed of the gearbox output shaft can be computed by dividing this speed by the gear ratio.
- 2- This is the no-load current of the motor when disconnected from the gears in the gearbox; the no-load current of the entire gearbox with the motor connected will be slightly higher and will vary depending on the gear ratio.
- 3- A theoretical torque of the gearbox output shaft can be computed by multiplying this torque by the gear ratio.