Mini Gearboxes
A mini gearbox — also called a micro gearbox or gearhead — pairs a small-diameter, precision-machined gear train with a compact housing to cut speed and add torque inside a tight envelope.
The table below compares our mini gearbox types by diameter, gear type, ratio behavior, torque character, backlash, and efficiency for quick engineering reference.
| Diameter | Gear Type | Ratio Behavior | Torque Character | Backlash | Efficiency |
|---|---|---|---|---|---|
| 10mm spur | Spur | 20:1–250:1, 3–5 stages, Φ10×8×6–9mm | 100–300 g·cm rated, 300–600 g·cm peak | Lowest per mesh, accumulates per stage | Highest of the three types |
| 13mm / 15mm spur | Spur | 6:1–360:1, 2–4 stages, 13×12×11mm | 200–300 g·cm rated, 600–900 g·cm peak | Low | High |
| 18mm worm | Worm | 42:1–2025:1 with 4 stages, 18×12×10mm | 300–400 g·cm rated, 600–1,200 g·cm peak; self-locking output | Right-angle mesh — moderate | Lowest of the three, drops further as ratio climbs |
| 16mm planetary | Planetary | 4:1–1621:1, 1–4 stages, 16.35–31mm long | 800–2,000 g·cm rated, 2,400–6,000 g·cm peak — highest torque density per volume | Compounds with each added stage | ~80% (2 stages) to ~70% (3 stages) |
Exact ratio, torque, and backlash figures are confirmed against your load and duty cycle once we review your drawing, so send your drawing for a ratio check and we'll match the mini gearbox to your application.

Module, gear tolerance class, surface finish, minimum order quantity, and sample lead time are not fixed catalog values — gear geometry changes with your envelope.
Each of these is confirmed once we've reviewed your ratio, load, and shaft/housing requirements, keeping quotes accurate instead of promising a generic number that doesn't match your actual part.
Housing and gear material is chosen for wear resistance, weight, or cost per application, and every gear train is verified before it ships.
Brass, stainless steel, powder-metallurgy alloys, or engineering plastics are selected to match the demands of each application.
Gear material is picked for wear resistance, weight, or cost depending on what the application needs most.
Every gear train passes incoming inspection before it moves further into the build.
In-process testing checks the gear train while it is being made.
Final verification confirms dimensional accuracy and consistent performance before the gearbox ships.
Each gear train is inspected on arrival, tested during production, and verified at the end for dimensional accuracy and consistent performance.
A mini gearbox works bare or pre-paired with our brushed, brushless, coreless, or stepper motors as a complete DC gear motor assembly — one part number, common in robotics and automation.
Either route keeps the gear train identical; only the drive end changes. This combination is common in robotics and automation builds where torque density and footprint both matter.


Ratio, output shaft style, and housing dimensions matched to your envelope.
Encoder integration, PCB soldering, wire harness or module assembly.
Material selection for wear, weight, or cost targets.
Send your ratio, output shaft, and mounting envelope — whether you need the gear train alone or a motor-ready assembly. Batch size and lead time are confirmed once your spec is set.
To start, Get a Quote and share your mini gearbox requirements with our team.
Need loose gears rather than a housed reducer? Custom-machined precision gears in brass, stainless steel, powder-metallurgy alloys, or engineering plastics are supplied to your drawing.


Founded in 2012 and based in a 2,400 m² Shenzhen facility, SLW Motor's 56-plus staff bring 15+ years of gear and motor R&D, including work for Japanese manufacturing customers.
Tell us your project or application requirements, and our team will get back to you with technical support, product recommendations, or a customized motor solution.

