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Our Code: MEC-30050
Supplier: [Pololu MPN:114]
Tamiya’s double gearbox packs two independent gear trains into a compact and affordable package that is great for small mobile robots. Each side can be assembled to have one of four gear ratios: 12.7:1, 38:1, 115:1, or 344:1.
The Tamiya double gearbox is a compact unit with two independent motors and gear trains. The kit includes two motors and all gears and parts to build any of the four possible gear ratio configurations (12.7:1, 38:1, 115:1, and 344:1). Although it is not typical, it is possible to assemble each side with different gear ratios. There are two possible output axle locations (for any given gear ratio, only one output location is possible).
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. 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 if you want to use this gearbox with controllers such as the qik 2s9v1 dual serial motor controller, TB6612FNG dual motor driver carrier, or Baby Orangutan B-328 robot controller.
Tamiya 70168 Double Gearbox (left) and Tamiya 70097 Twin-Motor Gearbox (right)
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.
|Typical operating voltage:||3 V|
|Gear ratio options:||12.7:1, 38:1, 115:1, and 344:1|
|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|
Adam, who posts under the username nexisnet on the Pololu forums, has performed a detailed series of experiments to determine how operating voltage affects the lifetime of the Mabuchi FA-130 motor, which happens to be the motors used in the Tamiya 70168 Double Gearbox, 70167 Single Gearbox (4-Speed), 70097 Twin-Motor Gearbox, 70093 3-Speed Crank-Axle Gearbox, 70110 4-Speed Crank-Axle Gearbox, and 70103 Universal Gearbox.
Yes, motors are included with the Tamiya gearbox kits.
The Tamiya gearbox kits come with all of the gears and parts necessary to build the gearbox in any of the possible gear ratio configurations.
This gearbox is an eduational kit that you have to put together yourself. It is designed for use in small, indoor projects. The gearbox comes with plastic gears and small, low-voltage motors; if you are looking to build anything meant to work outdoors or in a rugged setting, you should be ready to replace the gearbox often or consider using a more robust, pre-assembled gearbox.
You can extrapolate a theoretical torque and RPM of the gearbox based on the gear ratio you build, the motor voltage, and the motor speed and torque. In general, this gearbox is a toy, so if you need very precise specifications, you might consider a more industrial gearbox.
In general, the higher your voltage, the sooner your motors will die. Because these are toy motors, the manufacturer does not provide any official cycle-life specifications, but a customer of ours has conducted his own series of experiments that shed light on the relationship between operating voltage and motor lifetime. You can view Adam’s results here.
You can mount the double gearbox to our round robot chassis without any modifications if you use the two gear ratios that position the axle closer to the motors (344.2:1 and 38.2:1). Using the the two gear ratios that position the axle farther from the motors (114.7:1 and 12.7:1) will cause the wheels to hit the chassis. Please note that the axle of the double gearbox will not go through the center of the circular chassis; it will be slightly off-center. The chassis was designed for the twin-motor gearbox, which looks a lot like the double gearbox but does not have the same dimensions (we designed the chassis before the double gearbox existed); if you use the twin-motor gearbox, the axle will go through the center of the chassis.