The Tamiya 3-speed crank-axle gearbox is essentially half of the twin-motor gearbox. The kit comes with enough parts so you can built the gearbox in any of three gear ratios (17:1, 58:1, and 204:1).
- 70093 3-speed crank-axle gearbox — This gearbox is solid gray and comes packaged in a box.
- 89914 3-speed crank-axle gearbox — This gearbox is clear and comes packaged in plastic bag.
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 low-voltage motors run on 3-6 volts and draw up to a few amps, making them perfect candidates for the DRV8833 motor driver carrier. 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.
To compare all Tamiya gear box kits, see the Tamiya Gearbox Gear Ratio Comparison.
Note: The 3-speed crank-axle gearbox is a kit; assembly is required. To use the kit in robotics projects, you need to connect the motors to your own robot controller.
|Typical operating voltage:||3 V|
|Gear ratio options:||17, 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|
- A theoretical speed of the gearbox output shaft can be computed by dividing this speed by the gear ratio.
- 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.
- A theoretical torque of the gearbox output shaft can be computed by multiplying this torque by the gear ratio.
Documentation and other information
Table comparing the gear ratios available in the many different Tamiya gearboxes we carry.
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.
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