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When a mismatched or undersized gear causes slippage, noise, or premature wear in your drive train, the root cause is almost always the wrong module or face width. Engineers, robotics builders, and machine designers who need a drop-in 2 mod spur gear with a consistent 20 mm face width will find this 45# steel pinion gear engineered to handle real torque loads without deflection.
Each gear is machined from 45# medium-carbon steel — a material known for its balanced hardness and machinability — and cut to Module 2 (2 mm per tooth pitch). The face (tooth) thickness is a fixed 20 mm (approximately 0.79 in), and the available tooth counts span 10 T through 70 T, giving pitch circle diameters from 20 mm (0.79 in) up to 140 mm (5.51 in). Bore diameter and keyway dimensions vary by tooth count; see variant options for exact bore specs.
Typical use cases include DC motor pinion drives in CNC router Z-axes, rack-and-pinion linear actuators for automation fixtures, and reduction stage gears in custom gearboxes — all applications where a 2 mod spur gear with a 20 mm face width is the standard call-out on the BOM.
| Module | 2 (Mod 2) |
|---|---|
| Tooth Count Range | 10 T – 70 T (select variant) |
| Face Width (Thickness) | 20 mm (0.79 in) |
| Pitch Circle Diameter | 20 mm – 140 mm (varies by tooth count: PCD = Module × Teeth) |
| Pressure Angle | 20° |
| Tooth Profile | Involute (hobbed) |
| Material | 45# Medium-Carbon Steel |
| Surface Finish | See variant options |
| Bore Diameter | See variant options |
| Keyway | See variant options |
| Hub Diameter | See variant options |
| Overall Length | See variant options |
| Quantity per Order | 1 piece |
Determine your required gear ratio first: ratio = driven teeth ÷ driving teeth. For a motor pinion driving a larger gear, a smaller tooth count (10–20 T) on the motor shaft gives a higher reduction ratio. For near 1:1 or overdrive applications, select a tooth count closer to the mating gear. The pitch circle diameter equals Module × Teeth (e.g., 2 × 20 = 40 mm PCD for a 20 T gear), which helps you verify center distance.
Module (Mod) is the metric standard for gear tooth size: Module = Pitch Circle Diameter ÷ Number of Teeth. Two gears mesh correctly only if they share the same module and pressure angle. These gears are Module 2 with a 20° pressure angle — they will mesh with any other Mod 2, 20° involute spur gear or rack, regardless of brand, as long as the tooth count and center distance are compatible.
45# medium-carbon steel (roughly equivalent to AISI 1045) has a typical tensile strength of 600–800 MPa and yield strength around 355–490 MPa in the normalized condition. For most motor pinion and light-to-medium industrial drive applications this is adequate. If your application involves shock loads, high-cycle fatigue, or corrosive environments, consider whether a heat-treated or stainless variant would be more appropriate. Contact us to confirm suitability for your specific torque and duty cycle.
45# carbon steel is not inherently corrosion-resistant. For outdoor, humid, or washdown environments, apply a suitable lubricant or protective coating (e.g., grease, anti-rust oil) and consider periodic maintenance. If corrosion resistance is a primary requirement, a stainless steel or plastic gear may be a better fit for your application.
Bore diameter varies by tooth count — please check the variant detail or contact us to confirm the stock bore for your selected tooth count. Because these gears are machined from 45# steel, they can be re-bored, keyway-cut, or drilled for set screws by a local machine shop to match your exact shaft diameter. Ensure sufficient hub wall thickness remains after boring.
Yes — these gears are commonly used as motor pinions. You need to match the bore to your motor shaft diameter (typically 5–20 mm for common DC and stepper motors) and confirm the keyway or set-screw arrangement. If the stock bore is larger than your shaft, a machinist can add a bushing or re-bore to the correct diameter. The 20 mm face width provides good tooth engagement for most motor-driven applications.
Yes. Select a tooth count that gives you the desired linear travel per motor revolution: linear travel per rev = π × Module × Teeth (e.g., a 20 T gear gives π × 2 × 20 ≈ 125.7 mm per revolution). Pair with a Module 2 steel or nylon rack of matching pressure angle. Ensure the rack and pinion are aligned on the same pitch plane to avoid binding and premature wear.
