2.5 Mod Spur Gears Pinion Gear Teeth 10~30 Transmission Gear 45# Steel Flat Gear

Select your tooth count based on the gear ratio you need. Divide the driven gear's tooth count by the driving gear's tooth count to get the ratio. For example, pairing a 10T pinion with a 20T gear gives a 2:1 reduction. Also confirm that the resulting outside diameter fits within your housing or frame clearance — OD ranges from 30 mm (10T) to 80 mm (30T) for this Mod 2.5 series.

Module (Mod) is the standardised metric tooth-size system. Mod 2.5 means the pitch diameter equals 2.5 × number of teeth (in mm). These gears will mesh correctly with any other standard Mod 2.5 spur gear, rack, or pinion — regardless of brand — as long as the pressure angle is also 20°. They are not compatible with Mod 2, Mod 3, or imperial DP gears.

45# carbon steel offers a tensile strength of approximately 600–700 MPa in the normalised condition, making it suitable for moderate-load DIY and light industrial applications such as CNC routers, robotic joints, and indexing mechanisms. For heavy-duty or high-speed industrial drives, consider heat-treated or alloy-steel alternatives. Actual load capacity depends on tooth count, face width, speed, and lubrication — consult a gear-load calculation if your application is safety-critical.

The machined 45# steel surface has a light protective treatment suitable for typical indoor workshop environments. For outdoor use or high-humidity conditions, apply a suitable gear grease or anti-corrosion coating. If long-term outdoor exposure is required, consider stainless steel or plastic gear alternatives for your application.

Bore diameter varies by tooth count and outside diameter. Please refer to the variant detail page or contact us to confirm the exact bore size for your selected tooth count before ordering. This ensures a proper fit on your shaft without requiring additional machining.

Multi-piece packs (2, 3, or 5 pcs) are ideal when you need a matched gear pair for a single reduction stage, a complete gear train with multiple mesh points, or spare gears for ongoing projects. Ordering in a pack is more economical per piece than buying individually and ensures all gears come from the same production batch for consistent tolerances.

Yes — any of these Mod 2.5 spur gears can drive a standard Mod 2.5 rack to convert rotary motion into linear motion. This is a common setup for DIY CNC axis drives and linear actuators. Ensure the rack's pressure angle matches (20°) and that the pinion's outside diameter clears the rack mounting surface.