Mars 25:1 Planetary Gearbox


Out of stock


The Ranglebox Mars planetary gearbox is a miniature 2-stage 25:1 epicyclic reducer for motors with a 2mm shaft. It features M3 face-mounting holes, a ⌀6mm output D-shaft and a slotted motor mounting plate to suite countless motors. This is the ideal heavy duty transmission solution for any small robotics project!

Don’t let the Mars’ tiny 23mm diameter fool you. Inside is a chunky all-steel MOD 0.5 gearset with very little wasted space, ready to handle powerful motors like our own Mars RB1806 2000KV brushless motor or our Mars RB-180 and Mars RB-360 brushed options. Need a hub to fit the Mars’ 6mm output shaft that can handle the pressure? We also have the Mars hub!

Note that we ship the gearbox already lubricated with high quality lithium grease. If you’re fitting one of our own Mars motors, simply press the pinion flush with the end of the motor shaft; they’re already the perfect length! For long term or high stress applications (like robot combat), we suggest a touch of low-strength thread locker on the M2 screws when reassembling.

If you’re fitting your own motor to the Mars gearbox, the standard Mars pinion is a 9t MOD 0.5 gear with a 2mm friction-fit bore. The pinion should reach 7.5mm into the gearbox from the motor mount face. Alternatively, any other 9t MOD 0.5 pinion should work, as long as it’s spaced correctly!

A single package contains:

  • 1x gearbox
  • 1x 2mm interference fit pinion gear
  • 1x M3*5 high tensile caphead screw and M3*9mm washer (a shaft end bolt)
  • 4x M2*4 high tensile caphead screws (to fit our Mars motors and many others)
  • 2x plastic spacers (to align the RB180/RB370 front boss in the motor plate if you’re fitting one!)

The key technical details are:

  • Dimensions (D*L): 23*23mm + 25mm shaft
  • Shaft dimensions (D*L): ⌀6*25mm + 5.5mm D-shape and M3 end thread
  • Weight: 52g
  • Mounting holes: M3x4 (~4mm deep) for face-mounting
  • Input motor bolt mounting patterns:
    1. ⌀16mm M2x4 (for many brushless motors)
    2. ⌀12mm M2x4 (for many brushless motors)
    3. Anything between (holes are slotted!)
  • Momentary torque max: TBD (to be discovered)
  • Input RPM max (pending extended testing): ~30,000rpm

Click here to download a 3D model of the Mars 25:1 gearbox (opens Google Drive)

Essential dimensions:

We are growing the Mars line to make high quality small-scale hardware accessible for all budgets and skill levels. Everything in the range, just like the larger Saturn range, is intentionally cross-compatible and priced to be an ideal balance between performance and price. We’re really excited about expanding the suite of Mars gear and would love to hear from you! If you have any suggestions for new additions, or questions about this gearbox or anything else, please get in

Weight 0.1 kg
Dimensions 5 × 3 × 3 cm
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