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When your build demands reliable torque transfer and repeatable mesh accuracy, undersized or mismatched gears become an immediate bottleneck. Whether you are a robotics engineer, CNC hobbyist, or automation integrator, these 4 Module cylindrical spur gears deliver the dimensional consistency and load capacity your drivetrain requires.
Each gear is machined to a 4 Mod (Module 4) standard with a 12.56 mm tooth pitch. The available tooth range spans 24T through 52T, corresponding to outer diameters from 104 mm (approx. 4.09 in) to 216 mm (approx. 8.50 in). Bore diameter and keyway dimensions vary by tooth count — see variant options for exact bore specs.
Typical applications include motor pinion drive systems in industrial automation, gear reduction stages for servo and stepper motor assemblies, and custom gearbox builds for robotics platforms and CNC axis drives where a 4 Mod gear train is specified.
| Module (Mod) | 4 |
|---|---|
| Tooth Pitch | 12.56 mm |
| Tooth Count Range | 24T – 52T (28 variants) |
| Outer Diameter Range | 104 mm – 216 mm (4.09 in – 8.50 in) |
| Pressure Angle | 20° (standard) |
| Gear Type | Cylindrical Spur Gear |
| Material | See variant options |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Face Width | See variant options |
| Hub Diameter | See variant options |
| Finish / Treatment | See variant options |
Select your tooth count based on the gear ratio you need and the available center distance in your assembly. Divide the driver tooth count by the driven tooth count to get your ratio. For a Module 4 gear pair, center distance (mm) = (T1 + T2) × 2. Use the OD values listed in each variant to verify physical clearance before ordering.
Yes — any gear, rack, or pinion manufactured to the Module 4 standard with a 20° pressure angle will mesh correctly with these gears. Confirm the face width of your mating component is compatible and that center distance is set accurately to avoid backlash or binding.
Material varies by variant. Please refer to the variant options on this page or contact us to confirm the specific material (e.g., steel, aluminum alloy) for the tooth count you need. Material choice affects load capacity, weight, and corrosion resistance.
Corrosion resistance depends on the material and surface treatment of the specific variant. Steel variants may have an oxide or zinc treatment; aluminum variants offer inherent corrosion resistance. Contact us to confirm the finish for your selected tooth count if operating in a humid or outdoor environment.
Bore diameter and keyway dimensions are sized to the tooth count variant. These details are listed in the variant options. If you need a custom bore or keyway to match a specific shaft diameter, contact us before ordering to discuss machining options.
Module 4 spur gears are well-suited for moderate-to-high torque motor pinion applications. Load capacity depends on material, face width, and operating speed. For demanding applications, select a larger tooth count (higher OD) to distribute load across more tooth contact area, and verify the material rating against your torque requirements.
Check three key dimensions: (1) outer diameter against your housing clearance, (2) bore diameter against your shaft size, and (3) center distance between your shaft and the mating gear shaft. All OD values are listed per variant (104 mm to 216 mm). Contact us with your shaft diameter and we can confirm bore compatibility.
